CL72 high rpm issue

[jensey]

Hi,

Perform a compression test, and a leak test.

Jensen

[qwerty]

Seems like its got good compressions since it starts easily and runs great at low RPMs - I don't have a leak down tester, and agree that valve float is an outside chance. I'm going to see if I can borrow a couple of "good coils, then try running it without the air filters attached (even though they "look new"), and maybe have another look at the petcock to make sure fuel is flowing. Am I forgetting anything? This is simultaneously frustrating and fun - I'll giggle like a school girl when it runs right!

[flathead]

Have you checked the valve clearance?.

I had the same issue with my CL72 flat track bike a few years ago.
I had backed off the valves in an effort to set the timing on a crankshaft mounted magneto ignition. When the ignition failed to fire correctly, I went back to total loss points and battery.
For some unknown reason I forgot to reset the valves. The bike started easy, idled like a swiss watch, and would pull strong up through around 5k rpm. Then it would go flat. A real dog. 38 MPH tops in the 1/8th. Went through the jet changing ordeal with no success. I was running a twingled 360 crank and figured that rpm problem was due to capability of this configuration. I didn't discover that I'd left the valve clearance at about .100" until I had the engine out to change the crank. The only symptom was the lack of power at high RPM.There was absolutely no clatter in the engine, it started first kick, idled well, and pull strong up to around 5k and themn would go flat.
I put the engine back in and set the valves.
Problem fixed. Good power and torgue through the whole range.

Mark

[qwerty]

Compression test looked good (about 120 on each cylinder) - though that wouldn't tell me if it was weak spring tension causing my problem. I also pulled my fuel lines off the carbs to see if they were getting a good flow and found the side with an in-line filter wasn't flowing well. I took the filter off and thought I might have found my problem, but when I rode the bike, it still faltered at higher rpms. Tomorrow I'll swap out the coils with a set Davo loaned me (you meet the nicest people on a honda) and see if there's any change.

[qwerty]

Two different coils went in it today and no difference. I really don't want to put springs in it and find the problem is not fixed. I would have taken it to Charlie's Place, but he moved. Where's the recommended shop near S.F. Now?

[conbs]

Condensors?

Know anyone with a Color Tune to see what your fire looks like at high RPM.

[qwerty]

New condenser -
I'd never heard of Colortune, but they look pretty cool. Seems like I could just look at the plugs to see if the mixture needed adjustment, but Colortune might save me time.

Thanks!