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Discussion Starter · #1 ·
Hello,
I just finished a rebuild on my new to me 1980 CM400E. It won't rev and in 3rd I'm lucky to hit 25 lugging it a bit. The battery is dead so I had to bump start it. I'm getting a little smoke from the left side somewhere around the collector/left crankcase cover which I just put a fresh gasket on. Any thoughts?? My goal is to have it sorted for a ride this Friday.
Thanks!
Tim
 

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Go through the basics- check the plugs - fouling?
Does fuel drain from both carbs if you open the drains a bit?
How old is the gas?
Timing set right?
Low battery can do some funky things, especially if the charging system is weak.

Those are some of the first things I would check.
 

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Discussion Starter · #4 ·
Just out of curiosity... would it run at all if I had unknowingly installed the cam 180° out? Like, the cam notch at 6 o'clock and the crank notch at 12 o'clock? It does seem to run now but I think the spark would be wrong for the stroke if I had done that and it wouldn't run at all, right?
 

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Makes no difference on camshaft. Both plugs fire every revolution. As suggested above, check the basics. You can use a car battery for power as long as it is not in a running car.
 

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Part of the checks would be to verify the cam timing. Then run thru the ignition diagnosis in the sticky found in the Electrical section. That'll just take a few minutes to verify all is good or needs work.
 

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Discussion Starter · #7 ·
Update: Got it running after sanding the contacts. Power still a bit low but definitely rideable. Compression low in left cylinder (120) and 140 in the right which just got re-ringed. Won't idle without a little throttle input to keep it going. Any further thoughts or diagnoses? Just trying to sort these last few things so I can RIDE!

Edit: planning to go through the various checks in the manual, just hoping maybe to streamline the process a tiny bit... Cheers!
 

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135 is about as low in compression you can go and expect it to be rideable. 185 +/- 14 psi is spec.
Why did you only re-ring one cylinder?
 

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Discussion Starter · #9 ·
Only did one because I only broke the rings on one side. Bike seems low on power. Taking it tomorrow to get the carbs looked at.
 
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