Jetting input/ not running right

[Mattchev]

Recently picked up a banshee

mods - fmfs, vforce 3 reeds with new petals, brand new pod filters, TORS delete

Compression  just about 150psi on each side

leak down Tested and perfect

got the bike and it had been sitting for long time- ran like shit. Cleaned out carbs really good. There were gold needles , but I replaced them back to stock needles. Pilot jet had no markings on it, so after some research, I started at 30. Bogged off throttle and wanted to die as I unscrewed air mix screw. At .5 turns it idles and revved a little better, so I went up to 32.5 pilot and at about 1.5 turns right now. Main jets were 340. Needle on 2nd clip from top. At sea level. 

when coming off throttle, it struggles a little/ wants to stall, but runs great when past that point. If I give it a good rip down the street, when I get to a higher gear/rpm and pull in clutch, the bike will stall. 

 

carbs are synced with sync tool, and carbs are rebuilt with float height about 21mm both sides.  

[Yaxy]

With the assumption you are using stock carbs  a 30 pilot jet should be plenty.  From what your stating I would start by

1) Verifying your carbs are in sync by turning your idle screws all the way out and make sure your cables are in sync first, then sync with the idle screws

2) Verify your spark plug gag is not too large, I have experienced idle problems when the spark gap is opened up too much

3) Verify you have Mikuni jets.  There is a difference.

 

Rule of thumb I live by with low end jetting: Run the quad at low rpm in a higher gear, apply throttle wide open quickly. If  falls on its face you need more fuel down low and less air.

 

Chris

[Mattchev]

15 hours ago, Yaxy said:

With the assumption you are using stock carbs  a 30 pilot jet should be plenty.  From what your stating I would start by

1) Verifying your carbs are in sync by turning your idle screws all the way out and make sure your cables are in sync first, then sync with the idle screws

2) Verify your spark plug gag is not too large, I have experienced idle problems when the spark gap is opened up too much

3) Verify you have Mikuni jets.  There is a difference.

 

Rule of thumb I live by with low end jetting: Run the quad at low rpm in a higher gear, apply throttle wide open quickly. If  falls on its face you need more fuel down low and less air.

 

Chris

Appreciate the info Chris. On your 3rd point about the mikuni jets... how would you tell the difference between a mikuni pilot jet and a pilot that is not mikuni but looks the same?

[Mattchev]

right now, I have 32.5 pilots. Idle sounds little weak still. When I pull choke out halfway, the idle gets a lot stronger and sounds a lot better. 

[Yaxy]

The Mikuni jets have a symbol on the side of the jet.  I haven't used stock carbs in a while and I am not sure if you can even get a Mikuni pilot jet larger than 25 for the 26 mm carbs.  This 26 mm carbs pilot jet is unique in comparison to the Mikuni pilot jets I am experienced with.

If you pull the choke out and it idles better you need more fuel down low.

When you put the slides back into the carb did you put the proper slide into the proper carb?  The right carb has a right slide and the left carb has a left slide.  When you look through the window on the side of the carb you need to see the window in the slide.  If they are backwards the quad won't run right.

 

[hoppedupandcutdown]

I've read Banshee Mikunis use  a unique (to Banshee and Blaster only) pilot, specs are here.

https://www.jetsrus.com/a_jet_kit_atv/yamaha_350_YFZ350_banshee_1987-2006.htm