banshee 1 cylinder not running rite.

[joe schmo]

Ya thanks every one!! I'm lost!!

[Mosh]

Few things I can think of...

Does it backfire out the left side pipe while acting up? If so be looking for a lean condition on the stator side. Your leakdown test may show good but the stator seal may have ripped during break in and is sucking air or leaking pressure at that rpm range. Maybe pull the stator side cover and look for oil or gas leakage...

Also check your airgaps on both trigger blocks on the flywheel. If I recall they should be .017". Any rust on the trigger blocks should be sanded clean and gap rechecked at the pick up coil.

Any up and down play in the flywheel indicates loose crank bearings which on a banshee will deform the crank seal and alter pick up gap at the flywheel under a load causing the problem you have.

If your carbs are stock and all you have is pipes for mods....310 mains may be too fat. Non of the banshees i have worked with needed much over 280 mains even with port work and other mods. The fact you re ringed it and it runs poor now may be indication it was jetted fat before to run decent on very worn rings.

Lastly.. what pistons are in it? Are you sure you used the correct brand rings and size for your pistons and bore size?

[Blown 331]

Both cylinders fire at the same time so if you aleady swapped spark plugs and wires I don't really see how it could be electrical, since that would make the other side run incorrectly. You did swap plugs right? Sorry if I missed that part. I've had nothing but problems with NGK resistor plugs. I always get the non-resistor even though sometimes I have to order them.
I just picked up my 3rd Banshee a few days ago. I bought it cheap and it had a weak cylinder after a recent top end rebuild. Turns out the rod bearing was out. The piston was hitting the head flaking off peices of aluminum which got in the rings. Weird part is, there was no apparent noise. I sold it to my brother. He's doing a crank, pistons and new domes.

[joe schmo]

Few things I can think of...

Does it backfire out the left side pipe while acting up? If so be looking for a lean condition on the stator side. Your leakdown test may show good but the stator seal may have ripped during break in and is sucking air or leaking pressure at that rpm range. Maybe pull the stator side cover and look for oil or gas leakage...

Also check your airgaps on both trigger blocks on the flywheel. If I recall they should be .017". Any rust on the trigger blocks should be sanded clean and gap rechecked at the pick up coil.

Any up and down play in the flywheel indicates loose crank bearings which on a banshee will deform the crank seal and alter pick up gap at the flywheel under a load causing the problem you have.

If your carbs are stock and all you have is pipes for mods....310 mains may be too fat. Non of the banshees i have worked with needed much over 280 mains even with port work and other mods. The fact you re ringed it and it runs poor now may be indication it was jetted fat before to run decent on very worn rings.

Lastly.. what pistons are in it? Are you sure you used the correct brand rings and size for your pistons and bore size?

when I did the leak down test I had the flywheel and stator off sprayed it with soapy water no bubbles and looked good...I have the pulse coil gap set at .018 and clean.......I didn't feel and play by hand on both sides of the crank....it ran good be for with the jets but that is what I thought also..It was stock pistons still....maybe put stock jets in again and just drive it a little see how that goes....Thanks!

[joe schmo]

Both cylinders fire at the same time so if you aleady swapped spark plugs and wires I don't really see how it could be electrical, since that would make the other side run incorrectly. You did swap plugs right? Sorry if I missed that part. I've had nothing but problems with NGK resistor plugs. I always get the non-resistor even though sometimes I have to order them.
I just picked up my 3rd Banshee a few days ago. I bought it cheap and it had a weak cylinder after a recent top end rebuild. Turns out the rod bearing was out. The piston was hitting the head flaking off peices of aluminum which got in the rings. Weird part is, there was no apparent noise. I sold it to my brother. He's doing a crank, pistons and new domes.

Its all good, Yes I swapped the spark plug wires and the same..Also the cdi,wiring and coil...Yes 2 new sets of plugs,next time I get plugs I will get them.....Thanks! At least you got it cheap.the other one I got in the deal was a 4 mill that ran,when I took it apart the one bearing pin cracked the piston and went throw the top case half by the jug skirt..

[SteveCZ28]

did you maybe pinch or crack the intake seal on that cylinder when re installing carbs? i had a 03 banshee and had nothing but carb issues with it and sold it because of that. does it have a boost bottle or something similar on the intakes, id check to see if that seal isnt cracked or leaking as well

[joe schmo]

I might try to find new clamps for it. it looks good and no bubbles when I sprayed it with soapy water along with everything when I did the leak down test....It has a tube no bottle from boot to boot..

[MTS]

Did you have your rad cap installed and coolant in the system when you did the leak down test? Wonder if it isnt a small head gasket leak...small warp in the head or jug on that side.

[joe schmo]

yes coolant full and the cap was on,that is rite? all new gaskets and seals(but crap happens) maybe I have a bad head..should I have taken the rad cap off and look for bubbles rite,It would hold with the cap on rite? It ran good be for I took it apart lol...Thanks.