Runaway choke

[DEEBS11]

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[DEEBS11]

And yes, buy the tool for changing shims.

[Appie]

Ok Deebs, will do thanks 🙏. I guess trying to remove the cams at this stage would be just asking for trouble…

[Ccitis]

Probably controversial but I have the shim tool and found it much easier to just capture the valve with a piece of heavy wire (I used two wire) to keep the valve down and allow me to get the shim out. The tool made me very nervous as it screws into the case, and if it catches there goes your case.

[Appie]

Shim tool has arrived! But it seems the old boy still has lots of lessons to teach me…

So I’ve measured and checked these clearances ( cylinders 1-4 left to right)

EX. (cm) 0.15 0.15 0.33 0.05
(In). 0.006 0.006 0.013 0.002

IN. (cm) 0.13 0.05 0 0.05
(In) 0.005 0.002 0 0.002

All are tight except Exhaust 3 which is very wide. Putting compressed air down Exhaust 3 spark plug with both valves closed (camshaft lobe 3 facing up) I can hear air coming from the exhaust.

So it looks like a leaky exhaust valve 3 not sitting correctly? Where to go from here? When turning the engine by hand, I don’t get resistance when the cam depresses the shim on 3 and the valve lifter seems to depress and return normally. I did wonder if intake 3 is leaking as well since there is zero clearance there but I can’t hear any air escaping from the carbs. It’s only at the exhaust.

Engine was running beforehand (but carbs not synced), I’ve been waiting for that shim removal tool before checking valve clearances. I have only removed the camshaft cover and measured clearances, I haven’t touched the camshafts or camchain tensioner nor changed the timing (yet 😂) Timing marks on the cams and holders line up perfectly when timing plate indicates top dead centre. It’s possible I bought the bike with a bent valve and never picked it up. Until now it’s been all carbs and electrics. Besides starting it when it arrived and a short test ride a couple of weeks ago the bike hasnt been ridden.

[Radioguylogs]

There might be a piece of dirt under the #3 exhaust valve.

If it were bent, I'd expect to see no compression at all.

If it were me, I'd re-shim #3 to be in spec and run it a few hundred miles and check it again.

[DEEBS11]

I agree. Shim it correctly and continue with getting it running. The valve can sit on some carbon which can make it act like that. But a bent valve is not out of the realms of possibility with a used bike. You said the timing was lined up at the cams and I assume you also meant at the timing marks at the crank as well? If so, shim it and run it and see what you got at that point.

[Appie]

Whew I was hoping you guys would suggest that. Ok will reshim and get the bike running again. Deebs, yes the T mark at the crank lines up with the pointer as the cam dots align with the arrows on the caps.


Thank you so much for the help 👍