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joe schmo
05-04-2014, 11:32 AM
My first banshee and i'm new to banshees.. I tried other forms (it's a 4wheeler:/),with no help at all..I have a 99 that was running good but the sprocket and shifter seals leaked, then I rebuilt it. now after build the one cylinder some times runs then brakes up, in neutral it will rev out ok on both. if i hold the gas at the rite spot the left stator side brakes up,same if i drive it but in powerband its ;ok if i can get it in when i'm riding it. I have new rings and lite hone job 150psi on each,new gaskets with All seals,leak down test it held 6psi for 10min then I let the air out.....new plug's,I switched the spark plug wires,checked the reeds,cleaned the carbs 3 times, the brass ball in the bowl is on choke lever side,slide cut outs on air filter side,coke tube is clear,carbs synced,tors kit with the tors unplugged also is the parking brake, the whole exhaust is clear..I even used a other set of stock carbs with stock and same jett size..I have fmf fattys headers with paul turner tips,prodesign kit with k&n filter no lid,i think stock carbs with 310 main jets and 30 pilots.. I'm sure I forgot some things,Thanks.

bansheekx
05-04-2014, 11:43 AM
Have you tested the stator? Pickup gap set correctly?

joe schmo
05-04-2014, 11:49 AM
Thank you,yes I did..The side with the line i set at .018 but when I turn it to the other side the gap is a little bigger..stator tested ok with a good ground..I have a pair from the deal but the 87 has no motor but every thing else. She ran good before I built it.

bansheekx
05-04-2014, 12:00 PM
When it's running on one cylinder try pulling the choke out a little to see if it will start firing the dead cylinder. If that works you have a carb problem. You may also want to check the spark plug caps.

joe schmo
05-04-2014, 12:03 PM
Thanks,I tried the choke and it got worse.

bansheekx
05-04-2014, 12:13 PM
The best advise I can give you is to check the whole electrical system out. If you don't have a manual here is a link below that will show you how to check the whole system.

http://www.dfn.com/agservices/elecfaq.html

joe schmo
05-04-2014, 12:16 PM
Thank you..sorry I meant to say I swapped every thing over from the 87(even the stator plug) and its the same..

MTS
05-04-2014, 04:08 PM
Sounds as if you may have bent the lower compression ring upon install...had a twin cyl sled do something very similar..it was to the point it would not run at idle on one cyl.

brd812
05-04-2014, 04:28 PM
I'd say it's the carbs, check the carb on the dead cylinder . Are they stock carbs? If they have separate chokes try them by themselves first. If that doesn't help clear up the identification, switch the carbs and that will tell you if it's carbs or electrical. Good luck it not fun chasing gremlins w/ cylinders.

joe schmo
05-04-2014, 05:01 PM
Thanks,I will check it..Will I still have 150psi on it with a bent ring? I'm totally lost!! lol.......I cleaned the stock carbs 3 times also used a other set of stock carbs with stock and same jets,also swapped the hole electrical system from the spare one.....Damn Gremlins!!!!

MTS
05-04-2014, 06:22 PM
Yes, just taking into account you seem sure everything else is ok, would leave me to belive so, you could use a timing light to see if your losing ignition on that cylinder, one other thing yamahas sometimes have the ground wire in the kill switch un insolated and will arc to the bars, im not real familiar with banshees but it may be worth a look, might have to tape the bar before tighting down the switch, this is a consistant problem with just one cyl correct?

RIDE-RED 250r
05-04-2014, 06:24 PM
I don't know if a Banshee has 2 separate CDI's or 1 single..but have you tried any swapping around with CDI's???

I had a Ski-Doo triple that would do that.. Cleaned all the contacts and connections for the small wires connected to the coils and the problem went away.

Your issue sounds electrical to me... Just going off some experience I have had with twin and triple cylinder sleds.

joe schmo
05-04-2014, 07:03 PM
Yes, just taking into account you seem sure everything else is ok, would leave me to belive so, you could use a timing light to see if your losing ignition on that cylinder, one other thing yamahas sometimes have the ground wire in the kill switch un insolated and will arc to the bars, im not real familiar with banshees but it may be worth a look, might have to tape the bar before tighting down the switch, this is a consistant problem with just one cyl correct?
I will have to take it apart and check the rings and end gap again.I don't have a timing light I should get one again,I swapped the spark plug wires and same problem on the same side..I also will try e-tape on the bars and yes this problem ever since the re-build but not before.. Thanks.

joe schmo
05-04-2014, 07:06 PM
I don't know if a Banshee has 2 separate CDI's or 1 single..but have you tried any swapping around with CDI's???

I had a Ski-Doo triple that would do that.. Cleaned all the contacts and connections for the small wires connected to the coils and the problem went away.

Your issue sounds electrical to me... Just going off some experience I have had with twin and triple cylinder sleds. Only one CDI,I swapped the wiring harness,CDI,spark plug coil and kill switch..thanks.

RIDE-RED 250r
05-04-2014, 07:11 PM
Only one CDI,I swapped the wiring harness,CDI,spark plug coil and kill switch..thanks.

OK, that's all I have... Good luck bud! Hope you get er straightened out....

joe schmo
05-04-2014, 07:27 PM
Ya thanks every one!! I'm lost!!

Mosh
05-05-2014, 07:06 AM
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
05-05-2014, 08:15 AM
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
05-05-2014, 08:13 PM
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
05-05-2014, 08:16 PM
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
05-05-2014, 10:49 PM
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
05-06-2014, 05:24 PM
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
05-10-2014, 01:23 PM
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
05-10-2014, 05:25 PM
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.