breaking up on top

[smokin 421]

I have a 96 shee with vitos 421 10 port cylinders hemi head 185 psi running vp 110, pj 34mm carbs 200w ricky stator and new coil...

 

First of all am I chasing my tail with 34mm or should i just go directly to 38s..

 

Its breaking up on the top end and burning out plugs it gets better when I gap the plugs at .014 could this be a weak cdi. I had the same issue after going high compression on my old 404 motor. Just built the 421 and having the same problem.

[FATBANSHEE]

I would check the jetting if I were you B4 I thought it was an electrical problem. How did the plugs look? you said it was burning out plugs. were they wet oily/fouled. Clean the carbs filter, check for leaks torn boots etc. check all the obvious and then do a WOT (wide open throttle) plug chop. if the plugs are wet and oily/ fouled try dropping down a jet size on your main jets.

..FB

[smokin 421]

I would check the jetting if I were you B4 I thought it was an electrical problem. How did the plugs look? you said it was burning out plugs. were they wet oily/fouled. Clean the carbs filter, check for leaks torn boots etc. check all the obvious and then do a WOT (wide open throttle) plug chop. if the plugs are wet and oily/ fouled try dropping down a jet size on your main jets.

..FB

not a jetting issue i have had to lean it out like crazy from where i had it with my 404 cylinders i was at 185 main and im down to 160s with my 421 the plugs are golden/tan not even brown at all but if i run the stock plug gap it breaks up mid to top every time and when i cut the gap down half way it runs alot better sounds like weak spark to me but im not sure....also boots are in great condition and the filters are clean and everything is sealed tight.

[smokin 421]

so after searching around I found that "original87" was having the same problem..

 

 

So its either a bad flywheel, problem with the ricky stator, or the cdi...

 

Im going to start chasing it starting with the cdi as one of the guys I did a build for has the same year banshee as me...

 

are the 34mm carbs going to be big enough and does anyone think of any other ideas or feel I should start elsewhere and its not jetting.

[sleeper06]

sounds electrical to me,coil or stator,cut in harness

[FATBANSHEE]

If your jetting is good and you can rule that out. you may also want to check you don't have a broken reed. You also said it's burning out plugs. what do you mean bye that? is it melting the electrode down? what do you have your timing set at?

if that all checks out, then move onto the electrical. you will need an Ohmmeter and a manual. here are the specs.

Stator resistance:

Ignition coil 13.7-20.5 Ohms connect the red to green wire

Pickup coil should be 94-140 Ohms connect the white/red to white/green wire

Lighting coil should be 0.26-0.38 Ohms connect the black to yellow wire

 

Coil resistance:

Primary coil 0.28-0.38 Ohms

Secondary coil 4,700-7,100 Ohms

 

Pickup coil gap: 0.015"-0.020"

Sounds to me like you may have an ignition coil that is going bad.

good luck and let us know how you make out.

...FB

[smokin 421]

found out the flywheel was slightly out of round.. we put a new unit on and it ran great all day today, in fact ran so strong it twisted the sprocket off the hub... should have used red locktite instead of blue!!

[bonerific250]

use red loctite, it is for high vibration applications,but don't forget next time you take off the sprocket off you need to heat up bolt a little to get the to break free, also clean the threads before reinstalling.