Runaway choke

[DEEBS11]

..........

[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 👍

[Appie]

Good day gentlemen

Heres wishing all you gurus a healthy, happy and succesful 2026! My resolution this year is to ride this beautiful bike more than I work on it so here goes…

I’ve had some time to work on the bike so have all the valve clearances correct now. Except one 😵💫

We went with the shim replacement tool (Ccitis, I thought I’d leave the valve holding method until I’ve more experience) and it worked well.

But here’s the thing, Intake Valve 1 was tight (0.005in). On removing the shim we found it to be the smallest thickness (2.0mm). So I have taken a 2.0mm shim and am getting it ground down so that my clearance is correct. Im wondering if anybody has had to do this? I don’t like having a shim that is thinner than spec but can’t see another option short of removing the valve and grinding the end down.

It doesn’t end there… I was inspecting my leaky CCT and it seems the adjusting screw threads have been stripped so I have to repair this. I’m worried about the camchain slack when I remove the CCT housing, how do I keep tension on the camchain? My son is back at varsity so I’m a one man band, so hesitant to put the bike in wheelie position by myself as LarryM suggests….

Any suggestions or advice will be very much appreciated, thanks all for the best website

[Radioguylogs]

To remove the CCT safely, put the bike on the centerstand on level ground.

Rotate the crankshaft clockwise (from the left end) until the timing plate pointer is pointing to the "C"

Now you can safely remove and re-install the CCT without any worries, as long as you don't rotate the crankshaft until the CCT is re-installed.

[DEEBS11]

That might be a bad (shim) idea. I think shims are surface hardened. Machining off the hard surface might ruin the shim and it will wear very quickly (as well as the cam lobe). Perhaps you could face the relieved surface down towards the cup. Those valves must be very low in the seat. How many miles on the motor?

[Appie]

Noted about the CCT, Radioguylogs, thank you!

Deebs, I bought lt with 96000km on the clock and I’ve ridden it once since then around the block for a test.I thought that was high mileage but reading on the forum I see these bikes are capable of a lot more than that. I can’t say that this bike was properly maintained though and this engine has been opened at least once before.

I’ll turn that shim over, great idea. It does seem unusual that the valve is so low. I have been looking on the forum and haven’t seen this problem before. The other shims I replaced varied from 2.10 to 2.5

Thanks again for the help.

[Larrym]

"so hesitant to put the bike in wheelie position by myself as LarryM suggests…."

Tow straps at the Triple Tree/Handlebars.



Sturdy overhead beam in the garage.

It's a one-man job if you gots/get wut is needed. (O_o)

Walmart Clearance 2024!1 Pack - Universal Wheel,Rope Hoist Block And Tackle 2200 Lbs Breaking Strength Pulley Block 1100lb Loading Capacity For Animal Husbandry Constructions by Niaviben" is only $25.69 when ordered online.

I paid way MoAR for what I gots.... ( ⚆ _ ⚆ )

[Radioguylogs]

this engine has been opened at least once before.... The other shims I replaced varied from 2.10 to 2.5

Maybe the valve seats were re-cut.

[DiverRay]

Maybe the valve seats were re-cut.

And if they were, they did NOT trim the end of the valve stem, hence the close fit!