Bike won't idle, poor compression.

[mattcfish]

The plugs are carbon-fouled, not oily at all. As for the type, I've tried the stock Champion G63's and nearly any other Japanese substitution. I think there are CR7E's in it now as they are a warmer plug on the cross-reference chart. The wires are new, the coils are green Dyna's and there is a fat spark when I crank it over.

I'm not actually sure what size plug your heads require, I've searched but haven't come up with anything. A NGK CR7E is a hotter plug than a Champion G63. The actual cross reference is NGK C8E. For manufacturers (NGK and Denso), the higher the number, the colder the plug. With Champion, Autolite, Splitfire and Bosch, the higher the number, the hotter the plug.

Are you running points? A Dyna Green 3.0 ohm (1.5ohms x 2) resistance dual output coil should be used with points.
If you're running electronic you need less resistance.

Black carbon on the plugs generally means an over rich mixture. This could be caused by weak spark, the wrong fuel mixture, low compression, wrong timing (cam or ignition). The good news is... low compression caused by bad rings is usually accompanied by oily residue on the plugs. Then again, your oil control rings may be good and your compression rings faulty.

[mattcfish]

How are your Mikunis mounted to the heads? A bad conection could cause a vacuum leak.

[Krauser4valve]

Are you running points? A Dyna Green 3.0 ohm (1.5ohms x 2) resistance dual output coil should be used with points.
If you're running electronic you need less resistance.

There's a Dyna 3 igntion on it, manual calls for at least a 3 ohm resistance, hence the green single output coils.

[Krauser4valve]

How are your Mikunis mounted to the heads? A bad conection could cause a vacuum leak.

With something that looks like marine fuel hose, doesn't seem to have any leaks, but would be worth it to replace them. I saw some intake hose on ebay that looked like it would be an improvement.

[Major Softie]

Rocky point has a lot of Mikuni conversion kits. Good place to check for manifolds and connector tubing.



http://www.rockypointcycle.com/Merchant ... y_Code=B12

[mattcfish]

Are you running points? A Dyna Green 3.0 ohm (1.5ohms x 2) resistance dual output coihttp://boxerworks.com/forum2/posting.php?mode=quote&f=1&p=24913#l should be used with points.
If you're running electronic you need less resistance.

There's a Dyna 3 igntion on it, manual calls for at least a 3 ohm resistance, hence the green single output coils.

I believe two 3 ohm single output coils actually adds up to 6 ohms resistance....too much. Double what you want. This would give you a weak spark. That's the way it works with coils, multiply the ohms resistance by the number of coils (when they fire at the same time like our bikes do). I ran a Dyna 3 ohm (total resistance) dual output coil (1.5 ohms x2) with my Dyna III. That worked fine. But less resistance would be better with an electronic ignition.
http://www.motoelekt.com/ignition.htm
http://dynatekuk.com/sport_bikes_ignition_coils.html

[Krauser4valve]

And to think I went to school for EE. Forgot the coils are wired in series on this ting, not parallel. I have a set of green Dual-output coils that have never been used, I'll throw one of those on instead. Maybe this was the problem all along, THANKS!

[mattcfish]

And to think I went to school for EE. Forgot the coils are wired in series on this ting, not parallel. I have a set of green Dual-output coils that have never been used, I'll throw one of those on instead. Maybe this was the problem all along, THANKS!

Can't hurt. Good luck

[Krauser4valve]

Well, it is at least ridable now, took it around the neighborhood today. Right cylinder still doesn't want to idle, but fires fine above 2k rpm, pops randomly on trailing throttle. The clutch is ridiculously heavy and only engages with about a mm out, making shifting and standing starts interesting. Thanks to everyone for the help.

[SteveD]

. Right cylinder still doesn't want to idle, but fires fine above 2k rpm, pops randomly on trailing throttle.

When one of my past bikes had this symptom, it was a dodgey HT lead or cap. Try swapping sides and see if the left cylinder then plays up.