I'm at the "Where do I go from here" point. I've got a 2003 330 Trailboss which always took forever to warm up and had a just off idle hesitation which is really anoying in slow tight trails. It idles great once warm and past the hesitation it carburetes nice and clean. With it in neutral, if I slowly advance the throttle the engine will break up and stumble until I advance the throttle a bit more then it gets beyond the stumble and rev's freely. It does the same when picking my way through slow sections. I removed the carb and cleaned all jets. Installed new needle valve, seat and o-rings. The diaphram is in good shape, flexible, no holes or cracks. I purchased a Dynojet kit hoping it would help. Followed there installation instructions to the letter. DJ112 main, air screw 3 1/2 turns out, DJ needle in 1st position from top DJ slide spring (Which is strangely longer than stock?) Well, warm up is a bit better but stumble actually seemed worse. I tried going back to the weaker slide spring theorizing that it would take less vacuum to raise the slide. Seemed to make it a little better but not much. I'm scratching my head at this point and you know what a pain it is to remove the carb to make adjustments. Should I raise the needle a notch? Seems like a slight lean condition off idle but not sure. I've seen that some have gone bigger on the pilot jet. Any ideas would be appreciated.

 

I had the same thing.try changing the primary cluch spring to a Polaris white or EPI red.It will get a little more engagment speed getting past the dead spot

 

I guess you never solved the dead spot then. I'm thinking its a lean condition still in the pilot circuit as the warm up, while better after the jet kit is still longer than I would like it. I wish I could find a hand adjustable fuel screw like they make for the 4 stroke moto-cross bikes. Access to the carb is just not very good on the TB.

 

As much of a pain as it is, I'd give the needle adjustment a shot.

 

Move 1 notch richer is what you are saying? I am also trying to find a hand adjustable mixture screw for the BST carb. That in itself would make tuning less painful.

 

Are you using a needle that came with the kit, or the stock needle?

 

Scooter

I'm currently using the Dynojet needle which has a more aggressive taper. Dynojet recommends 1st clip position meaning the leanest. Above the stumble this thing runs really well. Also idles perfect but the stumble is really pronounced just off idle. I couldn't figure out why DJ gives you a longer slide spring of the same wire dia as the stock which from my experience give worse throttle response. Many CV gurus usually have you clip the stocker shorter for just that reason. I've tried both springs and do not see that it makes much of a difference in the stumble problem.......

 

I was wondering about the taper on the needle. Sometimes that can have as much to do with the hesitation as the clip position.

I know on some Honda's, clipping the spring is an easy mod a lot of people have done.

 

Scooter....I just contacted Dynojet and they suggested I raise the needle to the #2 position and return to the DJ slide spring. I guess I'll be in carburetor removal hell again this weekend. Once I get through this I'll move onto the clutching to make it better in the slow going. The hesitation is killin' the love for this thing at the moment.

 

Well if it's any consolation, the clutch is easier to get to.

When I put the RCR stage one kit in my 325, I went to the second clip on the needle. Sold it to my nephews, and they thought they would rejet it. (it was running fine) Nice, but they were way off, so I got to rebuild and rejet it. I don't miss having to take a quad half way apart to get to one small part.