Partially Restored 74 CB550

[taysidedragon]

Well done. Such a relief when it works. 👍

[davidcumbria]

So another good day yesterday. After filling the sump with Castrol power 1 10-40 semi synthetic I wanted to check that the oil system was working properly since one of the original reasons for stripping was a dry and noisy top end. Even though everything coated in assembly oil  to minimise initial wear on my new bearing shells I tried to syringe oil into the main feed through the centre filter hole but not too much luck there. Then I did manage to get over 0.2l down the pump oil pressure  switch hole which looking at relative heights should have partially  filled the oil filter, it’s feed drilling and primed the pump.

With no looms in place I wired a test bulb in series with oil pressure switch to positive battery and used a starter lead between earth battery and the engine casing illuminating the bulb. Finally connected the other starter lead between the starter motor cable ready to touch other end on battery positive. No spark plugs or valve cover in place so minimum resistance, maximum pump speed and easy to see any oil delivery into the bath at the ends of the  cam shaft.

First spin was for about  3 or 4 seconds light on, no pressure and no oil at the top. As expected but hopefully not too much more of this. 😐 Second spin light went out and oil flooded the baths to their limit so I had to stop after a couple of seconds  - a really strong flow so much better than before stripping. As Alan Millyard would say in one of his brilliant YouTube videos ‘ I was really pleased about that’  😀👍

[McCabe-Thiele (Ted)]

Nice one Dave I haven't turned my engine over using the starter motor yet - its not far away though.

[Oddjob]

I tend to test mine with the cam not in place, I just hold the camchain up on a socket bar or screwdriver. No plugs of course. This way all the oil holes are exposed and IF anything did come up with the oil, like a speck of rust or maybe some blasting media you can see it and it doesn't get trapped under the cam.

[davidcumbria]

Edging towards getting carbs back together got all the floats and jets back in and reset.

 Wanted to try the clear tube level check while carbs still separate and was glad I did because first carb was dripping from the overflow.

using lungs to blow down the fuel inlet suggested float valve working ok.sure enough as well as dripping the overflow pipe revealed a nice jet of air into the removed and fuel filled chamber when gently back flushed with air. Classic split overflow tube which I soldered up per the you tube videos. All ok now and satisfying to solve the problem without resorting to the cheque book or pleading for spares. Other carbs ok and levels look consistent - close but not too close to top of bowl.

 Should have the carbs back on the bike this weekend. I do wonder if blasting air through the overflow while cleaning up the carbs should maybe have an health warning to take it easy on these vulnerable components.will never know if that’s what did it.  Any how -  Onwards….

[davidcumbria]

One of the bushes at the end of the throttle spindle has been damaged. Suspect attempt to drive out shaft before removing axial location pin since that has been sheared. A long shot, can’t find anything about these bushes, has anyone sourced or replaced them ? For clarity  I mean the spindle in the long throttle mechanism across all 4 carbs not the small shaft going into the carb for the piston. Going to replace sheared  pin with a retapped grub screw as seen in another thread.

[Oddjob]

Ted had the same problem, bush was broken in half. Might be repairable but it was cheaper to just find another bracket tbh

[McCabe-Thiele (Ted)]

Yes one of my bearings was similarly damaged, when I drilled out the small pin I found the inner right half of the bearing was missing. I suspect it had been broken for some time looking at the crud that was there.
Surprisingly the shaft seemed pretty well supported with one and a half bearings. Sourced a good one from Ken, as a one off repair it would have been too expensive to have a new part specially made.

I think Florence might still have a spare worth a PM.

[Oddjob]

Just remembered I have a nos bracket, mint condition but it’s not cheap. Think CMS want around £350 for one last time I checked.

The bracket is now 877 euros 😧😧

[davidcumbria]

Have had all the parts vapour blasted so they look good. Shaft has no significant free play, the  bearing is 80% intact on one side and 100% on the other so it’s not worth replacing the bracket and I’ll just monitor it for now. Not going to be doing massive mileage anyway.

Replacing the axial securing pin with grub screw that can’t nip the shaft leaves it loose in the threads. Do you use loctite or I was thinking of maybe some epoxy to hold it in place ? I wonder if threadlock works when the thread is not pushed tight by coming against a hard stop.

[McCabe-Thiele (Ted)]

I think Ken did not approve but I used a blob of Hondabond on top of the grub screw with a small stainless washer as a cap.

[Oddjob]

Not my place to approve or anything Ted, just wasn't needed though IMO.

Get something like these Dave to secure the rod, I put them in a drill and rest a file on the point as it spins to reduce the tip down until it fits inside the groove in the rod, I'd go with 10mm, maybe M5. Depends on the size of the hole you end up with after drilling out the locking pin

https://www.ebay.co.uk/itm/313583380550?var=612402648480&hash=item490306a846:g:XvIAAOSwVORg1sj0&amdata=enc%3AAQAIAAAA8DGZkN3dMdU6oZ1%2FXUF2wYy4uDn8uTx5w%2FccUdFWpkkwYU3zk97NDpXUpjcjUhFYieAaa%2BoQ6Fa%2FWGYDQg0o253pEmtkSqE3%2FNc3mKmmjYKomemf%2FbRfJPdB%2B74BOMv9bzbXkEbA2sQygCsbvJcC04VGpAGamK0UW%2BpdI8nsU8HjL0Dxa%2BxYda9oLaCJYh61bru%2B3vkqR4zVDeq72nociFNF0kK%2B%2FNFu6zzoINGD4qf2gU2UQG1s25RFd%2FyNUbYNlJILctm%2FeZzvNF8zkbtfb9eXGMZn75aBbHYZQrp%2B1oPLFdh1pWNNgNPiej8rGa%2Bmlg%3D%3D%7Ctkp%3ABk9SR-SLqueAYw

[McCabe-Thiele (Ted)]

Not my place to approve or anything Ted, just wasn't needed though IMO.

OTT v OCD. 😁😁😁

[davidcumbria]

Not my place to approve or anything Ted, just wasn't needed though IMO.

Get something like these Dave to secure the rod, I put them in a drill and rest a file on the point as it spins to reduce the tip down until it fits inside the groove in the rod, I'd go with 10mm, maybe M5. Depends on the size of the hole you end up with after drilling out the locking pin

https://www.ebay.co.uk/itm/313583380550?var=612402648480&hash=item490306a846:g:XvIAAOSwVORg1sj0&amdata=enc%3AAQAIAAAA8DGZkN3dMdU6oZ1%2FXUF2wYy4uDn8uTx5w%2FccUdFWpkkwYU3zk97NDpXUpjcjUhFYieAaa%2BoQ6Fa%2FWGYDQg0o253pEmtkSqE3%2FNc3mKmmjYKomemf%2FbRfJPdB%2B74BOMv9bzbXkEbA2sQygCsbvJcC04VGpAGamK0UW%2BpdI8nsU8HjL0Dxa%2BxYda9oLaCJYh61bru%2B3vkqR4zVDeq72nociFNF0kK%2B%2FNFu6zzoINGD4qf2gU2UQG1s25RFd%2FyNUbYNlJILctm%2FeZzvNF8zkbtfb9eXGMZn75aBbHYZQrp%2B1oPLFdh1pWNNgNPiej8rGa%2Bmlg%3D%3D%7Ctkp%3ABk9SR-SLqueAYw

Sure Ken that’s what’s I’m buying but my question is how to make sure it doesn’t unscrew itself with the motion of the shaft ?

[Oddjob]

Use some thread lock if it worries you. So long as the tang is smaller than the slot, so not a tight fit it should be ok.