Okay I changed a couple minor things on the ole Banshee and the jetting now seems odd.

Set-up before changes All stock except: Pump gas, Pipes, Reeds, Reed Spacers, Pro-Design Adapter, K&N Air filter W/pre-filter, No air box lid. Had 310 Main Jets, & size 30 Pilot Jets, needles @ stock or third position, running right near sea level.

Recent Changes: Removed TORS Caps, disconnected TORS wiring, added Vito's power needles, carb caps & throttle cable. changed Pilot jets to 27.5's, mains changed as noted below.

Problem: Plugs looked grey or lean. Started increasing Main jet sizes to get it to blubber (run rich). Once there I was going to back down a step or two untill it cleared up/out. Problem is I've gone from 310 up to 420 main jets and it's still hasn't blubbered. On the last change (mains from 380 to 420's) it now seems to have a stumble from off idle to 1/4 throttle. In looking @ the plugs they now look more like a slight ghostly/transparent black color than grey as was previous. Anyway it's still running good and clear on the top end (no blubber) and it idles fine. My initial though was that I must have an air leak somewhere. Well I've sprayed carb cleaner on and around the carbs, carb tops and rubber boots front & rear and haven't found one. Carb Slides are in correctly and syncronized. I can't believe I should be up to 420 main jets, something seems odd or wrong.... Any help would be much appreciated...

Rude Dog

 

I've done a lot of bikes in Michigan (700 ft elevation) which have been using Vito's needles on middle clip, 25 pilots and 280 mains with a the mods you have done. Never went over 370 mains with a stock air box and a ported cylinders.

 

Only size 25 pilots? That's the stock size that banshee's come with. Was the jetting you mentioned run on a Banshee with a stock/non-altered air box system. My air box is modified with "no air box lid, pro flow adapter & a K & N air filter"? Based on my set-up, I know my Banshee would run lean with 280 mains. "No dis-respect meant", it just sounds more like a setup for a stock (air lid on) airbox system. I'm not saying it didn't work for you, just sounds weird...

Thanks a bunch! Rude Dog

Guys..... C'mon, can anyone else offer some advise here ????

 

Bump..... Little help here guys... pleaseeeeeee

 

Ok, you definately should not be running anywhere near 420 mains - 310 sounded like a good number. The only thing I an not familiar with is the Vitos needles but I assume they are similar to dynojet needles and shouldn't really have an impact on your jetting. The TORS changes or carb caps make no difference in jetting so I would say that you probably should be at 310s still.

Remember, that the mains control fuel flow from 3/4 to full throttle. Also, remember that you need to run a while to get a real plug reading at the desired throttle range. It seems odd that you are not losing top end as you go up on the mains or that your plug color isn't really changing much. It sounds like you are not running long enough to get eral results.

You need to have a straight open area to open it up and leave it that way for as long as possible to get a half decent plug reading. Running through the gears donw the block won't tell you anything. Personally, I think many people try to get a plug reading from too short of a run and have a tough time jetting because of it.

 

I dont know dude, but 400+ is BIG!! I mean on my 370 im not NEAR THAT! Here is my 2cents, take it for what its worth, but perform a leak down test, you might just be surprised and find a leak. Even if you tried it with carb cleaner, try the leak dow, it is FAIL proof.
Let us know what you find

 

Latest Changes:


Put back in the 30 pilot jets and moved the needle clip down one notch (Raised needle). Changed main jets to 360's and ran it. Plugs seemed much more blackish in color. Power is good throughout. ATV spins tires and fish tails around corners. Bottom does feel slightly slugish when cold. Otherwise all feels good. I'm going to run it a bit more and watch it. I might end try changing the main jets to 350's to see how it feels.

Rude Dog

 

How is it now?


800

 

Sounds like Wyoduner was on target. Odd that the machine did'nt load up with the oversize mains (still oversize..lol). How many hours are on this engine? I am thinking a possible bottom end seal problem.

 

Updates:

Changed the mains (only) to 350's and went to Pismo over Thanksgiving. Did some some wide open throttle jetting runs. Bike seemed to run well for the most part, clean on top, plugs looked fairly nice and brownish in color. Starts first-second kick. Slight blubber on idle when cold. Once warm there's no blubbering on the bottom or top end. One (new) thing though, it didn't seem to have as much "snap" on the low end when doing the usual 2nd gear starts at Comp Hill. Almost seemed as though the clutch is starting to slip. Made adjustments to cable @ clutch perch and it feels week. No matter how it was adjusted it only grabs on the last 1/4"-3/8". As the clutch is the original I went ahead and ordered a new Hinsen clutch basket and clutch kit for it.

Garyc660r:

The engine is a little old (1989). There's probably a decent amount of hours on the motor. I only ride it on about 5 dune trips a year. Each typically 3-4 days long, but not long on hours. One of the longer trips is Dec @ Glamis (Xmas/New Years) it's 5-7 days. The top end was rebuilt once by me about 2-3 years ago. The lower end is all original and hasn't been apart/rebuilt yet. Possibly a leak down test would be a good idea in the near future. Thanks for all of the emails...........

Rude Dog