posable disaster with my 650

[RickyC83]

he guys so updates on my build been a busy weekend.
got the loom patched up and working after a bit of tinkering got the starter motor turning and sparks. didn't get the bike to fire but oil was reaching the cam and sparks was strong, so figured some work on the carbs and we may be in business!

but then the starter stopped turning, turned out the engine seems to have locked up, in top gear i can turn the wheel a few degrees theirs a bit of a click and it stops, turn back the other way same thing,

any hints where to start would be appreciated

when i bought the engine i was told it had been rebuilt then stood. so basically know nothing about it (1980 cb650z)

[fisjon]

If there is very little momement in either direction I would suspect that the cam chain has dropped and is jammed in the casings. A strip and rebuild required.

[RickyC83]

That's what I'm thinking. Thanks.

[fisjon]

Just to be sure, remove the starter, get it into neutral and try turning the engine by using a socket on the left side of the engine (generator side)
Don't force too much just in case, if the cam chain is still ok the engine should turn and the fault could be with the starter mech.

[RickyC83]

Starters out and still the same

[RickyC83]

Ok so removed the top of the head. Exposing the cam.  The engine will now turn freely by turning the bk wheel slowly. The cam chain is in tacked but mega loose. I'm thinking it has slipped on the bottom cog and the engine wouldn't turn cos a valve was hitting the piston??
Sound right to anyone?

[mickwinf]

It does sound like a valve hitting piston so chain off sprocket or cam timing a possibility. also I had a similar problem on a 550 where something was catching the alternator and stopping it from turning so worth checking that also. Oh and never believe the previous owner, they forget/ lie/ don't know what happened before.

[RickyC83]

Timing was out. I've just finished lining everything back up. Had a play with the tensioner which seems to be working now. But still dosnt seem as tight as I wuld expect.

[fisjon]

I could be a dislodged or broken cam chain slipper or even a broken cam chain adjuster. If that has happened then the chain could jump a cog on the crank and if that happens when the engine is running then you have a disaster.
I would whip the head off and have a good look.

[RickyC83]

Done mate.
Cam timing all surted valve clearance all set. Still won't start getting the odd pop but nothing else. Will work on carbs at week end. Also gona get compression checked tomorrow.

[RickyC83]

Ok thanks

[RickyC83]

The chain is fine now. I think when it was fired they never loosened the locking nut. Or set the rocker clearance. I'm starting to think the engine was rebuilt as a project with the thought it wuld never run again lol. It was supposedly sat in a bike club house. The may be no pistons on it lol.

[RickyC83]

My mate wanted to try putting some easy start down the carbs. It blow a flame out the exhaust but no bang just a woosh sound. Timing?

[fisjon]

My mate wanted to try putting some easy start down the carbs. It blow a flame out the exhaust but no bang just a woosh sound. Timing?

YIKES! I would pull it apart and rebuild yourself or you might end up with a pile of nuts and bolts on the drive.............

[RickyC83]

So I pressure tested the cylinders I have less the 10psi fro each. DEFO valves right?