Chang Jiang 750 Restoration

OT: anything goes!

Moderator: Edi

User avatar
Korto
Jedi Master
Posts: 1129
Joined: 2007-12-19 07:31am
Location: Newcastle, Aus

Re: Chang Jiang 750 Restoration

Post by Korto » 2018-08-04 10:37am

All right, I've got to remove the cylinder, and replace the gasket right at the back, where you can see it's all wet and oily.
Image
I'll see if I can do this today. I've been busy for a chunk of the day so there's only a few hours of daylight left. Well, maybe it'll only take half an hour, or maybe it'll take two days. I have no idea, I've never done this before. I don't particularly want to do it now, but as I said, no real choice. It's not going to pass inspection leaking oil like it is.

I do at least have gaskets for it, and if there turns out to be a problem, I have gasket goo. Not actually the real name of the product I've got, but just generically what we called all the brands back in Car Maintainence in high school.

Image
Now, first I've got to remove the rocker cover here, which we do by undoing this allen key bolt. Since the bike has been running, there should be oil in there, so I've grabbed myself a nice clean...clean it out, there we go...tin to go under and catch the oil. Hey, if it's clean enough, I might even be able to put it back again. Who knows.

Is there such a thing as an M7 Allen key? Because M6 is too small, and M8 does not fit well at all. Wonder if the fucking thing's Imperial? If it is, it's being replaced. Not having another bit of Imperial on this bike, sick of it. And the bolt was very loose, too.

Image
Cover's off. Compared to more modern vehicles, it's very simple inside with just the single inlet and exhaust valves. The oil, which is quite new, could afford to be emptied and replaced from its colour to be honest, which might well happen soon after a bit more running--change the oil for some fresh stuff, rinse and repeat, clean the old gunk out.
You know, what I'm dreading is having to remove the rockers. I have this tiny hope though I might be able to remove the head in one piece, which would be pleasant, but first I need to detach the exhaust pipe.
Here's a surprise, I'm able to unscrew the big nut thing by hand. (no picture, but you can just see it in the picture of the rocker cover. On the left of the cylinder, in the shadow). OK, sure, I sprayed some WD40 on it a couple of days ago in anticipation, but I didn't expect it to work this well.
To remove the head, you've got to undo the four nuts recessed down deep in the head, which you can just see down those two deep wells. They're a bit tight, too, which wasn't unexpected. Now try and pull the head off...it seems happy to come off as one unit, except it's a bit unhappy that I haven't really removed the exhaust pipe, just undid the big nut in the hope that would be enough, and the pipe is still sticking in its little hole, which is probably going the hold the head there. Might have to actually remove the exhaust pipe, which I was preferring to avoid because, you know, more work, but I don't think I have any choice. Well, there only seems to be one other bolt holding it, so I suppose I shouldn't complain about that too much. I will, but I suppose I shouldn't.
And now let's see if the head will come off...
...
...Well, there's the head off.
Image

Image
Came off reasonably easily, actually, which is good. There's probably like, useful shit things I could do while this thing's off... I have no idea what they are... you know, clean something or other or something... ummm... I suppose I could have asked my brother. He's a mechanic.
Anyway, the cylinder head doesn't seem to have a gasket, which is interesting. It really does not, just metal on metal. This isn't where it's leaking, this is where the compression shit is. Why doesn't this have a gasket? Seems a bit naughty.
I also should have considered somewhere clean to put these parts before I pulled them apart. That would have been a good idea. Maybe I'll do that now.

Now to take the actual cylinder off. It doesn't look to me like there's anything more restraining it than the bolts that passed through the head and I've already removed the nuts from, and I've just found a small nut hiding in the cooling fins of the cylinder from somewhere else that I lost a few months ago. So that's where it went. Cool. Mine now.
Anyway, with only those bolts, already undone restraining the cylinder, it should hopefully just pull off nicely, too.
...
And it did pull off quite easily.
Image

Image
Right, well, this does have a gasket, which has been leaking, and I've just found another little nut, another one I've lost at some point in the fins and I would then have replaced from my stock. Thanks to these bikes I've bought a decent selection of nuts and bolts.
I've scaped the old gasket with my knife I've found today, after being lost for months (it's been a good day for finding things), it feels pretty smooth now, and I'll just read the instructions on this gasket goo. I'm thinking I'll run a bead either side of the paper, and try to make a really good seal. I don't feel like doing this again in a hurry.
"Clean the surface with white spirit or mineral turps" I wonder what white spirit is. Metho? Might be, can't remember. Have I got any turps hanging around? Maybe. Not sure. "And scrape if necessary" Well, it was necessary. "Coat the surfaces with paste so no metal shows, and then bring surfaces together". OK, that's if you're using the goo just by itself. I reckon coat this around the paper gasket and put it all together will make a good seal.

Image
OK, entertainment time. The gaskets I have do not match. I was pretty confident they would, but I was aware there was a chance they wouldn't, since these gaskets were for the Chinese bike, and there are some differences. OK, one of those differences is apparently the gaskets. OK, then we're going to use just straight gasket goo, aren't we? And we're going to do this by the book, a complete layer so I can't see metal, and on both sides, wasn't it? "Coat the surfaces", yes, surfaces, plural.
It turns out I've got nearly a few bottle of turps--there we go--cleaned--a generous bead of goo and use my finger to smear it around...what's this say on the back? "Warning! Do not allow contact with skin! Causes skin cancer, bone degeneration, ulcers, blood poisoning, appendicitis, and your dick will fall off!"
OK, that sounds negative. (*)
Image

I'm having trouble getting the damned piston back in the cylinder--there, got the bastard. Now put the head back on--the rubbers are being a bit stubborn, I've replaced the old rubbers with fresh ones, and I've just managed to spill half the bottle of my goddamned turpentine. Maybe I should have put the lid back on. And I'm still trying to put the head back on.
Image
I'm going to try some brute force by putting the nuts back on and screwing them down. I don't actually recommend this method, I'm going to try and be careful and sensitive to how much force I'm applying so I don't damage anything or shear a damned bolt.

That's seems as far as they're wanting to go on, and it looks pretty good. A good line of goo has been squeezed out all around the joint. I'm happy with that.

Interesting detail, the exhaust pipe and muffler seems to be held on entirely by one bolt at the back, and happy thoughts, because this bit nut at the front comes straight off the pipe. So, as far as I can tell, it's doing absolutely nothing. Oh yeah, new way of putting this on. Just screw the big nut on, then stick the pipe in. That nut does absolutely nothing. I am thinking of replacing these pipes. I'm wanting to get something to quieten the bike down a bit, while keeping the power. I don't know how to do that, but there's muffler specialists. They'll hopefully work something out.


I've also now got the reset the clearances on the rockers and push-rods, because they've definitely been mucked up. I've done this before, and it went just fine, but I couldn't remember the correct clearances, so I looked it up in the manual. I forgot the English translation manual was a Soviet joke perpetrated against the Evil Imperialistic West. Honestly, I have no fucking idea what they're talking about. Fortunately, I've managed to find someone on-line who reckons it should be between 0.05 and 0.1mm, which sounds good, and I've done this before, so should be fine.
Anyway, what you've got to do is turn the engine until one spring is completely compressed and about to come back up, and then check the clearance on the rocker arm for the other spring (which is completely uncompressed). The clearances are adjusted by loosening that top lock nut, and then screwing the bolt which the spanner is currently attached to in or out, depending on what you need. The push-rod goes into the head of the bolt there, so screwing the bolt in and out adjusts the height.
Image
I tell you now, the thing's way too tight. I can't get a 0.05 in there. It's going to have to be loosened.
There we go, 0.05 will slip in there easily, but 0.1 won't go in. Perfect. Now just rinse and repeat for the other spring, double-check both, and done. That should be adjusted correctly again.

* Note - I'm kidding! Honest!
“I am the King of Rome, and above grammar”
Sigismund, Holy Roman Emperor

User avatar
Korto
Jedi Master
Posts: 1129
Joined: 2007-12-19 07:31am
Location: Newcastle, Aus

Re: Chang Jiang 750 Restoration

Post by Korto » 2018-08-09 09:27am

OK, so what we need to do here is take about 10mm off the length of this cable. First I need to take the little cap off, which isn't willing to just pop off, so I'll have to cut it off, and then you have the coating and the outer sheaf-- and I just learnt how to make close-up photos with my camera--cool.
Image
The outer sheaf is made of a single steel wire, wrapped in a coil, and the cable runs along inside. The way I found to cut this is to use a wire-stripper first to separate out the bit of sheaf I'm targeting (the wire-stripper allows you to part the outer sheaf, while the inner cable is safe in the centre),
Image
and then I use a dremel to cut a deep gash (more than half way down) along the length on one side, and then cut all the way through on the opposite side. The sheaf will come off in little rings around the inner cable, which you can then bend away off the inner cable since it's weakened by the deep gash you cut in the opposite side.
Image
You did do that, right?
New caps can then be obtained and put on the ends, which I'll get around to, but this is done well enough to hook back up for now.





Well, the bike is almost ready to get its first test-ride, and in order to delay that moment of truth, I've decided I better fix up the headlight, which is currently in pieces.
Image

To replace the old 12v bulb, which of course won't work now since I've reverted it to a 6v system, I bought an LED headlight on-line, which has come with a number of fittings. After staring at it for a while, to figure it out, I discovered that the fitting slipped down over the shaft, and then screwed down in place. So you just picked your correct fitting, and off you go! There was even a spring included, in case you needed that.
Image

So, I went to put it in place, at which point I discovered two things.
Image
1) It actually doesn't quite fit. It's so close it's obviously meant to fit, but it doesn't. A bit of adjusting with a file would be in order.

Image
2) This isn't a push-and-twist bayonet fitting. It's a spring-clip fitting, put it in place and it's held there by a clip. The problem is, there's no clip, and I have no memory of ever seeing a spring-clip. I suspect the spring-clip disappeared a long time ago.
Sigh
So, I've picked up a little strip of steel, and the idea is I bend it into shape and make my own clip. Because, Goddamnit, I can.

Image
Image
Image
OK, the clip works, but there's too much space between the clip and bulb, allowing the bulb to bounce around. I need to tighten it up somehow.
I've got some single-sided foam tape. A couple of slivers of that between the clip and bulb might just work...
Image

And there we go, it works! Held firm, and in the right place, beautiful!
I'm running out of excuses to not give this thing a test drive.

Bad news. The LED bulb is rubbish; it doesn't work at 6v, despite being sold to me as a 6v bulb. It's too late now to chase up a complaint on ebay, and the bulb was cheap enough to take the gamble on (about $8), but it does mean the work fitting it was a waste of time. And now I've got to get another bulb. This time from a real supplier at a real address. At 10x the price.
Believe me, this one had better work, or there will be complaining.

PS - The bad LED isn't a total loss. It works well at 12v, and the postie's 12v...


Time to gird my loins, and give this bike a test ride. I spent some time yesterday re-adjusting the carbs, since I realised it was only running on one cylinder, then put some more petrol in.
God, it takes a lot of petrol. It swallowed my whole fuel can, and it's maybe only a quater full. How big is it? 20 litres? 25?
Oh yeah, I should probably mention I've been riding a postie bike for more than a decade. It has a fuel tank size of a large tea pot.

Anyway, the bike starts easy enough, although I'm concerned with how the choke no longer seems to have any effect on the running of the motorcycle, hot or cold.
It slips into 1st so gently I don't even realise it did. I then ride it gently in 1st for about 20 metres, put it back into neutral, and then back into 1st...
Horrible grinding noise, like it's not in gear correctly! Stomp on gear-change hard! No effect! Change back to neutral!
Noise goes away.
Change back to 1st...Horrible grinding noise! Change back to neutral!
Noise goes away.
Change up to 2nd...Horrible grinding noise! Change back to neutral!
Switch bike off and push back. Time to think.

Extra data - from later experiment, it also makes that horrible noise when in reverse, including when the clutch is actually released.

Hmmm....
“I am the King of Rome, and above grammar”
Sigismund, Holy Roman Emperor

User avatar
InsaneTD
Jedi Knight
Posts: 618
Joined: 2010-07-13 12:10am
Location: South Australia

Re: Chang Jiang 750 Restoration

Post by InsaneTD » 2018-08-10 02:25am

Could the gears not be syncing speed correctly?

User avatar
Korto
Jedi Master
Posts: 1129
Joined: 2007-12-19 07:31am
Location: Newcastle, Aus

Re: Chang Jiang 750 Restoration

Post by Korto » 2018-08-10 06:39am

About an hour ago, when I first saw your post, my answer was "I don't know, and I'm going to have to pull the frigging gearbox apart, aren't I?", but then, during the kids' quiet time before bed, I suddenly realised that if the bike is in gear, the clutch is pulled in and the bike is stationery, then the gears are locked to the wheel and nothing in the gearbox is moving. It can't be the gearbox. Can't be the engine, either, or it would always be making the noise. It's got to be something with the clutch.

And then ten minutes ago I checked a russian motorcycle site I joined last night just to ask this question, and someone's suggested it's the thrust bearing on the clutch. I hope he's right, because I might be able to replace that without removing the gearbox, and therefore without disassembling the entire rear-end of the fucking bike.
“I am the King of Rome, and above grammar”
Sigismund, Holy Roman Emperor

User avatar
InsaneTD
Jedi Knight
Posts: 618
Joined: 2010-07-13 12:10am
Location: South Australia

Re: Chang Jiang 750 Restoration

Post by InsaneTD » 2018-08-10 11:24pm

Here's hoping.

User avatar
Sea Skimmer
Yankee Capitalist Air Pirate
Posts: 37274
Joined: 2002-07-03 11:49pm
Location: Passchendaele City, HAB
Contact:

Re: Chang Jiang 750 Restoration

Post by Sea Skimmer » 2018-08-11 12:19pm

Thrust bearings love to rust up and die on stuff that doesn't move, so that wouldn't be surprising. But great progress I see since I last checked this thread!
"This cult of special forces is as sensible as to form a Royal Corps of Tree Climbers and say that no soldier who does not wear its green hat with a bunch of oak leaves stuck in it should be expected to climb a tree"
— Field Marshal William Slim 1956

User avatar
Korto
Jedi Master
Posts: 1129
Joined: 2007-12-19 07:31am
Location: Newcastle, Aus

Re: Chang Jiang 750 Restoration

Post by Korto » 2018-08-14 09:19am

I removed the thrust bearing, and it seemed to be OK, I think. More literally, after finally managing to extract the bloody thing, I then promptly dropped it in the dirt :roll: , so I washed it in petrol and sprayed it with WD40, and then it was a bit sticky at first (which could have been from being dropped in the frigging dirt), but soon freed up and all the balls weere rolling nicely.
I was then going to stick the one from the CJ750 in, but a couple of its balls had seized right up, so in the absence of any alternative I greased the original up and stuck it back in.
I did actually first go to a local bearing place to see if I could replace it with something high-quality Western-made, instead of by Yuri and Boris inbetween slugs of vodka, but apparently it's a special snowflake and there's nothing standard in that size. Of course.

The noise is still there. It only happens when the bike is in-gear AND the clutch is pulled. When in neutral, or the cluch is released, there's no noise. I've got to think about this.

When the bike is in gear, and the clutch is pulled, the two separate parts of the clutch, the part connected to the engine and the part connected to the gearbox, are moving at different speeds to each other. That's not true when the clutch is released, obviously, and it may not even be true when the clutch is pulled but in neutral, as there may be sufficient drag, and lack of resistance in the gearbox, to allow the clutch plates to spin together. This might have something to do with it. It's got to be the clutch.

Other funny news--I stuck the sidecar back on to work out where to put the mirror, and noticed another thing about my new gearbox. It has the kickstarter further to the left, so it now hits the sidecar when you try to use it. As it is, I won't be able to start the bike with the sidecar attached. I'm going to have to cut 30mm off the kickstart lever to make it fit.
“I am the King of Rome, and above grammar”
Sigismund, Holy Roman Emperor

User avatar
Korto
Jedi Master
Posts: 1129
Joined: 2007-12-19 07:31am
Location: Newcastle, Aus

Re: Chang Jiang 750 Restoration

Post by Korto » 2018-08-15 09:12am

Update.
Uncovered the clutch; which involved taking off the rear wheel, differential, shaft, and gearbox. Getting surprisingly good at it. Must be all the bloody practise. Also helps that by now I've learnt, through painful experience, that trying to "save time" by leaving parts on and just trying to work around them only means everything takes longer and is more frustrating. If it looks like it's in the way, remove it!

Anyway, while the gearbox shaft and pushrod look fine (it's a bit blurry. I hadn't noticed my camera had focused on the wrong part)
Image

The teeth on the second, inside, clutch plate there is oddly shiny, and feels very sharp and jagged to the touch.
Image

It's been suggested that the shaft isn't engaging the plate correctly, which is apparently something that happens. The teeth looked fucked to me, but I'll talk to my supplier about it.
Someone else on the bike site reckons the plates look like they've been put in backwards. I am going to kill whoever it was who worked on this bike before me. :kill:
“I am the King of Rome, and above grammar”
Sigismund, Holy Roman Emperor

User avatar
InsaneTD
Jedi Knight
Posts: 618
Joined: 2010-07-13 12:10am
Location: South Australia

Re: Chang Jiang 750 Restoration

Post by InsaneTD » 2018-08-15 10:18pm

Probably some backyard mechanic who figured such an old bike would be easy and, didn't have a clue and gave the previous owner a good price to do it. Then did a shoddy and rushed job when he found out how difficult it would be.

User avatar
Korto
Jedi Master
Posts: 1129
Joined: 2007-12-19 07:31am
Location: Newcastle, Aus

Re: Chang Jiang 750 Restoration

Post by Korto » 2018-08-20 08:56am

Took the clutch apart, which I'm certain I took some photos of. Fucked if I can find them now.

There were countersunk internal hex screws holding it together, which is interesting because I can tell you that those screws don't exist. I spent a couple of days looking on the net and phoning around because I loathe slotted heads. They don't make them. Looking closely at the screws, they look to be a home-made job. Bloody glad they did, because one of the screws was on so tight I needed an extended breaker bar to budge it. If they were slotted, I would never have gotten them off.
After removing all but two of the screws, I drilled some holes in a piece of plank and tightened it down using the protruding engine bolts over the clutch plates to hold the plates down while I removed the last two. That was a bit of a funny story in itself, actually, because I get the idea to do that, then I remember I lent my drill to some friends. No worries, I also have one of those old manual egg-beater drills. I'll use that. Drilled a couple of holes through some pine 3x2, put it in place, and then discovered the amount of protruding bolt was a little less than 2 inches. OK, I'll use some hardwood plank.
I broke the fucking drill. Not the drill bit, the drill.
OK, it's just some little bolt holding the handle to the gear that's snapped. I'll replace it. An m5 countersunk bolt wuld be just perfect here. You know, if I had one. Got some m5 cap heads, so I spend the next half an hour with a dremel modifying a cap head to fit into a countersunk hole. Took a ridiculous amount of time just to drill two bloody holes through a piece of wood.

Of the clutch plates, one might be fine, but the other has all its teeth half cambered off, which didn't inspire much confidence. I've ordered two new plates, and also a new inner disk (a disk that presses against the plates). It's not damaged, but it doesn't seem to be the right type for a bike with reverse. I won't blame the previous owner for that, considering I changed the gearbox.
I was also wondering if I needed to replace the springs, and I sent Magnus (my supplier) their full relaxed length to see if he could tell me anything. All he could tell me was that they're supposed to be 21mm at a load of 17kg (+/- 2kg), and I thought "I can totally test that!"

So here's my rig.
Image
And they all checked out OK. Too long at 15kg, and too short at 19kg. And yes, I did include the bucket and chain in that weight as well.
“I am the King of Rome, and above grammar”
Sigismund, Holy Roman Emperor

User avatar
LaCroix
Sith Marauder
Posts: 4539
Joined: 2004-12-21 12:14pm
Location: Sopron District, Hungary, Europe, Terra

Re: Chang Jiang 750 Restoration

Post by LaCroix » 2018-08-21 04:39am

Need a tool, make a tool...

I like that setup. So simple, yet doing what it needs to do, just fine.
A minute's thought suggests that the very idea of this is stupid. A more detailed examination raises the possibility that it might be an answer to the question "how could the Germans win the war after the US gets involved?" - Captain Seafort, in a thread proposing a 1942 'D-Day' in Quiberon Bay

I do archery skeet. With a Trebuchet.

User avatar
Korto
Jedi Master
Posts: 1129
Joined: 2007-12-19 07:31am
Location: Newcastle, Aus

Re: Chang Jiang 750 Restoration

Post by Korto » 2018-09-10 09:01am

Since the LED headlight I bought previously is absolutely shithouse and won't work at the voltage it's supposed to--at 6 volts you can get it to flicker if you rev the bike hard enough, although it works fine at 12 volts!--I've had to write off the $8 I spent on it, and buy another one for $80, which I've been assured will work; in fact it's supposed to work all the way down to 3 volts. Well, we'll see. At least they have a real address, instead of something I've just bought through ebay.

Image
Naturally, it comes with a H4 plug, which my bike doesn't have, so I've bought this little H4 extension cord, off ebay, which I plan to cut in half, and then use one half to make an adaptor for the Russian bike, and the other half to make an adaptor to put the crappy LED on my postie, which happens to be 12 volt.
This is a simple job, so don't expect a lot of photos. Just cut some wires and crimp on some new connections.
Actually, what I could also do would be to solder the wires together, which will make a better connection that won't come loose, but it's more annoying to do and I won't be able to easily remove it, or just crimp on some spade connectors and be done with it.
I'll stick with the spades. I'll be rewiring this headlight later, and little point trying to get my little soldering iron to do this gauge of wire just to pull it apart later.

All finished, plugged in, and she lights up fine. And that's without the bike revving, since I can't start her up since I don't have my clutch plates yet! Where are my clutch plates? :cry:



Yay!!!! My clutch plates have turned up. Finally. After spending weeks watching them through the tracking screen and making pathetic noises at them, which didn't really work. What I've got here are two new clutch plates, because one of my old ones is rat-shit, so I figured I better replace both, and this new disk thing, because my old one seemed to look different than this over the computer screen, so I figured I better buy it to, to be on the safe side. Better to buy it and not need it, than not buy it and have to wait another frigging three weeks for it to arrive.
Image


And, a little detail I'd forgotten about, but it arrived today as well, with the same postman, is a high quality German thrust bearing. I'd forgotten I'd ordered that, too.
Image


So, now I've got my stuff, and I can see about putting it all back together, and I'll be able to see if I'm right that it's mechanically all ready to go.
Yeah, it still needs blinkers, which someone's making me some mounts for, but mechanically, it's ready! And theoretically, I could give hand-signals! OK, yeah, theoretically it's not actually registered and so isn't allowed on the road anyway, so I absolutely totally won't be test-driving it on the road! No sireee! Because that would be wrong! :mrgreen:


After re-watching the video, and paying Oh my God careful attention to the way everything goes in together, which way around, let's see about doing this.
While waiting for the clutch plates, I picked up some m8 fine bolts, and in combination with the m8 fine nuts that hold on the gearbox, I'm hoping to come up with an easy way to put the plates in.
Image


Image
One trick someone before me used was to stick down the springs with some silicon. This seems like a good idea, and I'm going to do it myself.


Now, six bolts hold the clutch together. I'm going to put three long bolts through the holes, and tighten the plates down, and then I'll be able to put the proper small bolts in and screw the clutch together nice and easily. Everything will work out fine.
A little patch of surface rust, I think, on the steel plates. I'll just give it a little rub with some steel wool and clean it up.
Image


There we have the plates being held in place by the three bolts. Now, the idea is I'll screw in the nuts to push the plates down further, while making sure it's properly over the little stalk things, and when it all succeeds I'll congratulate myself as a genius!
Or if it fails, I'll scratch my head and say "Huh? It doesn't work? Why doesn't it work? What's the matter?" :cry:
Image

Image


One problem is, these stalks the bolts screw into, and the holes in the steel disks fit around those stalks. The problem is, it's a very tight fit around the stalks, and it's all under tension, because the springs kick in before that, so under tension I'm trying to get these holes and stalks all lined up. Which is probably going to be a little bit of a pain in the arse.
Well, I'm sure we can manage it.
With enough brute force and swearing.


Image
This is working beautifully. Just screw the nuts down, compressing the disks. Had to loosen the disks a couple of times, and tap the steel plates a little bit, just to get the holes to fall over those stalks, but I've done that, the holes have all gone over, and now I've just got to tighten the plates enough to put the screw in.
I'll be reusing those screws someone made with internal hex, because basically slotted heads suck.
Ooopsie. One of the plates is lying over a stalk. Lets see if I can get you a decent picture, so you can see what I'm talking about (I can't. The camera doesn't know what to focus on). Now what can I tap the plate with that won't damage the gear teeth... hold on, I can tap it on the outside of that centre ring... and there we go. All good.


Image
And then I just screw in three of the proper screws that hold the plates in place, remove the long bolts, and then screw in the other three screws.
I can't help thinking that the guy on the Youtube video was talking about loctite; you know, a proper job, done with loctite. Well, I'm not putting any loctite on, mainly because I don't have any. I could wander over to SuperCheap, and pick up some loctite, but I don't wanna. I just wanna do this.
:(
I'll probably be wandering over to SuperCheap to pick up some frigging loctite, and I'll continue this tomorrow.
“I am the King of Rome, and above grammar”
Sigismund, Holy Roman Emperor

User avatar
InsaneTD
Jedi Knight
Posts: 618
Joined: 2010-07-13 12:10am
Location: South Australia

Re: Chang Jiang 750 Restoration

Post by InsaneTD » 2018-09-10 10:56pm

Sounds like it's gone easier then just about anything else on the bike so far. :P

User avatar
Korto
Jedi Master
Posts: 1129
Joined: 2007-12-19 07:31am
Location: Newcastle, Aus

Re: Chang Jiang 750 Restoration

Post by Korto » 2018-09-11 10:03am

TD, are you counting chickens?


Now, one thing that has me worried is the teeth in the middle of the clutch plates, that the shaft slides into. What has me worried is, there's two plates, and if they don't line up, pretty much exactly, the shaft isn't going to be able to slide in, and with the bolts tightened, then the whole clutch is held tight by those fairly strong springs, so I can't really move the plates around. Even if I could move them, lining them up by hand and by eye is going to be a pain in the arse.
I suppose what I could do, is loosen the bolts back up and try to line the plates up. Maybe if I made something to slip between the teeth...a bit of flat-bar that can fit between the teeth, that will then force then to line up, and then I could tighten the whose thing back up. Maybe I could do something like that...
Don't have much flat-bar lying around though, anymore. Had a bunch leftover years ago from the fence, and I've been using it bit by bit. It might now be all gone. Fortunately, I do have those two old plates, so I can use them as a guide for whatever I make.
Measuring between the teeth, it's 25mm, by 4.5 mm across. So a bit of 25 by 3mm will do fine. I wonder if I have any?


Image
After a bit of a search, I've found a small scrap of 25 x 6mm, and a good-sized piece of 32 x 3mm. One I'll have to make thinner, the other narrower (you can pick which is which). I'll use the 25 x 6mm. I can leave the thickness in the middle, and it'll give more strength if I have to use force. A grinding we shall go! (You know, I only make these to make LaCroix happy).


Image
There we are, a fit with a minimum of wobble.


Image
Now, on the end of the clutch push-rod you can see there, there's a square end, and it fits into a square hole in the bottom steel clutch plate. It's a 5mm square, and if I can replicate that square end, it might be good for getting everything lined up. I'm not sure if I back myself to make a 5mm square right in the centre, but I'm going to give it a go.
Image


Image
OK, there we go, there it is sticking in the first plate, with a...handle...attached to it, but I'm going to have to loosen the clutch right up to move those plates around, which might mean I lose the exact placement over the holes, and I'll have to fix them up again, but there's nothing else for it as otherwise I can't move the plates to line them up.

That may actually have worked. I've definitely got the plates lined up with each other, I may have lined them up with the centre hole too, it's hard to tell.

Shifting the plates around did mean I lost the alignment of the centre steel plate, and so now I've got to get the holes in the middle steel plate back over the stalks. This is an aggravating nuisance until you can get one in. Once you have one hole in, you can just tap the plate a little to the left or right and the whole thing will just fall into place. It's that first one that's the problem.

Anyway, that's done, and now to put the clutch screws back in. I'll first give them a test-run in, put them all in, and then take them out one at a time, put loctite on, and back in again.

Hmmm. Some aren't seeming to fit in properly. I'll give them a clean with a wire brush on the dremel.

OK, they're all clean now, and some fit nicely, and others just go in a short way before seizing up. It's not the hole, because some screws are going in just fine, and others are locking up, and the thread on all the screws is nice and clean and...and...hang on...I need to check something, something looks wrong here...

WHAT THE FUCK!?

The screws that go in the clutch are metric fine. The screws I have here, the ones that fit are home-made metric fine. The ones that don't are shop-bought metric coarse! It's definite. I went and grabbed my thread-checker because I didn't believe what I was seeing, but it's 1.25mm thread! But all of these screws came out of the fucking clutch! What the fuck?

Some investigation later.

Well, the three screw-holes I left open are metric-fine. But here's the interesting thing--the three holes I put the (metric fine) bolts in will take both metric fine and metric coarse. Straight up, this bitch is bi. OK, whoever you are before me, what did you do?!

Unbelievable.

Fuck it. They were in before, they seem to hold, and I've got loctite. They're going back in.


Image
Having decided that sufficient loctite will cover many a sin, I've put the clutch back together, and I'm about to put the gearbox back on.

Image
Now for the easy part. Ha ha. You see that thin rod protruding there, that's the clutch-rod, and deep in the recesses of the clutch there's a little hole it fits in very snugly. I've got to try and get it in that hole, and then fit the gearbox on. Before, I had the gearbox very close in, and I was using a pair of needle-nosed pliers through the narrow gap. I found it very difficult, bit I managed it. Now I can't find where the hell I left my pliers last, so I'm going to have a bigger gap I can get my hand in, and see if this'll work. I'm sure it will. It'll probably be better, no worries.

Does this rod even fit in the new plate? Lemme check...
Image
Guess so. Now I've just got to do that with the gearbox there.

I seem to have gotten the rod in, and I'm putting the gearbox on, and doing up the bolts...it goes on most of the way, but when the bolts feel tight, there's still a slight gap between the engine and gearbox. What I think it is, is that although the clutch gears were lined up so the shaft has gone on, the plates may not have been directly on top of each other, creating an angled passage, so the shaft can't quite slip in all the way, and with the clutch tight, the plates won't move.
What I'm thinking here is that I hook the clutch up, and use it, that'll release the clutch plates from their durance vile, and then the shaft will be able to shift them to a more comfortable position. Sounds good.
The clutch button at the back is sticking out too far. I don't think the rod is in the hole properly, which is a pain, but the clutch should still be usable for this.

And yes, that worked. The gearbox now goes on all the way on. The clutch plates should now be all fine. Job done.


Tomorrow, I've just got to come back, pull the gearbox back off, and try to get that stupid clutch rod in its stupid bloody hole. At least the clutch plates shouldn't move out of position. The springs have it all locked up again.
“I am the King of Rome, and above grammar”
Sigismund, Holy Roman Emperor

User avatar
InsaneTD
Jedi Knight
Posts: 618
Joined: 2010-07-13 12:10am
Location: South Australia

Re: Chang Jiang 750 Restoration

Post by InsaneTD » 2018-09-11 10:40am

I did say sounds like. :P

I'm trying to remember the stuff about thread from my training but for the life of me I can't. I have a vague recollection that fine and coarse shouldn't work together at all but I haven't had to worry about it at all and training was about six years ago now. I think I should go get me training books back off the mate I lent them too.

User avatar
Korto
Jedi Master
Posts: 1129
Joined: 2007-12-19 07:31am
Location: Newcastle, Aus

Re: Chang Jiang 750 Restoration

Post by Korto » 2018-09-14 08:15am

Noooo, they shouldn't work together at all. What they should do is lock up pretty quickly. It would probably be easy enough to cut two different threads into something, as long as they were two very different threads so there was sufficient meat left to keep the strength, but no real reason to do it.
What's happened here, is either someone's forced a coarse screw in, or used a tap, and has cut a second thread. The thread inside the hole is probably absolutely shit.

Good news is, when I mentioned the problem to my Estonian guy, he told me he also supplied the flywneel "fingers" (apparently that's what they're called) separately. I'll be picking up a set.

For now though, I'm going to put my trust in the loctite, and ONWARDS!

Image
Now the gearbox is back on, it's time to put the bits back on. Clutch lever, kick start, and so on.

The clutch goes on, lever attached, seems to be working fine. I've got to say, the first time I put it on, I didn't like how far in the clutch button didn't go. It seemed to be sitting too proud. So I took the gearbox back off, pulled out the clutch rod, and then put it back in again, making sure it went in its hole, and then put the gearbox back on...and it made absolutely no difference, the button was still sitting quite proud. So I've decided to assume that everything's fine and that's where it's supposed to be. I wish I could think of some way to test that, but I can't. As far as I can see, the thing will act just dandy and normal, until suddenly it abruptly decides everything sucks.
But I think it's fine.

Now to get this rubber disk thing back in--just curious, does anyone remember how I got this rubber disk in before? And please don't tell me it was by putting it on before I bolted in the gearbox, because that will not be appreciated.
Image
All good. Gear-box in, then put the disk in by itself, on the gearbox-side two-prong forky thing, tap in on all the way, and then the shaft-side two-prong forky thing can slip in and on.

Now, these things are a pain. This bolt slips in a hole to hold the kickstart in place, and the inclined side tightens it up and then you put the nut on. In theory. I've seen four of these so far, and they never fit. I already filed this one before; I still had to bang it in, and I damaged the thread a bit, and now that I'm trying to put it in again it doesn't want to go in.
Image
I'll get the angle-grinder. That'll fix it. What could go wrong?

The bolt slips in nice, and tightened up so the kickstart's back in place, the pipes from the air filter are reattached, the carburettor bolted back on. All I've got to do is reattach the back end. Tomorrow.

This is basic, by-the-numbers stuff. Slip the shaft back in place, re-attach the final drive and wheel. Bolt back on the back of the rear mudguard. Done it all before, simple, fast, done.
(OK, not really. The shaft was a stubborn cow, not wanting to go in one end, and then not wanting to go in the other, either, but it eventually did, and then it was just tighten this, reattach that, search for a goddamn M8 Fine nut for a quater of an hour, because for some reason I didn't screw it back onto the bolt when I took it off last time).

Done! Let's see if she'll start!
She bloody starts! (OK, it started before, but it's nice to know I didn't destroy something in the meantime). Test-ride time! Where's me bloody helmet?

Image

Image

Image

Image

Image

Image

YEAH!


After-ride autopsy - She starts really easy, with one kick, although I'm a little concerned that the choke and ignition advance has absolutely no effect. It changes gears so smoothly, you can't even tell you've done it, although I didn't have enough space to test third or fourth gear.

I keep on feeling "YAY! It's done! Finished!", but there's still the indicators and sidecar to go. But still, I'm going to enjoy this moment.
“I am the King of Rome, and above grammar”
Sigismund, Holy Roman Emperor

User avatar
LaCroix
Sith Marauder
Posts: 4539
Joined: 2004-12-21 12:14pm
Location: Sopron District, Hungary, Europe, Terra

Re: Chang Jiang 750 Restoration

Post by LaCroix » 2018-09-14 08:51am

*slow clap* *waits for others to join in*
A minute's thought suggests that the very idea of this is stupid. A more detailed examination raises the possibility that it might be an answer to the question "how could the Germans win the war after the US gets involved?" - Captain Seafort, in a thread proposing a 1942 'D-Day' in Quiberon Bay

I do archery skeet. With a Trebuchet.

User avatar
InsaneTD
Jedi Knight
Posts: 618
Joined: 2010-07-13 12:10am
Location: South Australia

Re: Chang Jiang 750 Restoration

Post by InsaneTD » 2018-09-14 07:37pm

"Starts clapping."

Good to see it working. Here's hoping the advance is just a minor issue and quick to solve. How clean is the inside of the carby?

Post Reply