Topic: Starter clutch problems

[Moose1906]

Hi Everyone,
After a bit of help with my 1973 cafe racer cb 750.
I finally got to the point where I'm about to try and start it after a complete high modification rebuild.
The problem I have is when I tried to start it.
It turns over ok but when it tries to fire and the engine fires past the starter clutch , allowing it to free wheel and there is a horrible rattling sound.
I took the alternator cover off and I noticed some filings in the bottom.
They seem to be coming from the starter clutch rubbing on the internal casing.
I also noticed that there was a washer missing which is the starter clutch setting plate.
Not sure if this is the cause.
Any suggestions or thoughts greatly appreciated.
Enclosed are a couple of photos to show where the rubbing is occurring .
Cheers

[Jerry Rxman Griffin aka MuthaF'er]

Seriously??!! WTF is that a picture of? That is NOT a picture of a stock CB750 crank taper. How about a few more pictures of all the affected components?

[Moose1906]

Sorry about that.
I purchased this bike as an unfinished project from the U.S.
It has a lightened crank, but I thought it was standard crank end.
When I posted the photo it would only allow me to attach 1 photo.
Here's one of the starter gear.
The first photo showed where the rubbing is happening.
The crank has a recess of about 3 mm I initialy thought there was a race or seal missing.
I can take some more photos today if it helps.
Again thanks for any help,
First time poster.
Not sure Iv posted this in the right forum.

[HondaMan]

You'll probably have to disassemble the starter clutch and look at the rollers inside. If they have flat spots on them, you'll have to replace them. Maybe also polish up the crankshaft a little to remove the roughness? If you don't then the new rollers will wear quickly and you will be right back in there, replacing them again.

If the engine has lots of spark advance (like a fixed-advance unit), maybe consider changing [something] to a less-advanced startup setting, like 0 to 5 degrees advance. If the engine is very high compression or has forged pistons, this will be needed. Forged pistons will tend to bind in the engine if it is run briefly (like 5 minutes) and then shut off for about 5-10 minutes, until the thermal equilibriums balance out again. This is why those pistons usually require more clearance than cast pistons. When it binds, the starter clutch can take a real beating!

[Moose1906]

Hi Hondaman
Thanks for responding
I replaced the springs and checked the roller.
They were all good.
The engine is a 1000 cc ape kit with Corelli rods ,bigger valves ,  port jog and cam.
I'll look into the advance .
The motor turns over quietly , but when the starter rolls on after sort of firing the horrible noise starts.
I'm hoping it has something to do with the starter setting plate not being there.
I'm away at work for a couple of weeks, so cant try anything just yet.
Starter setting plate ordered.
Thanks again