carb question xt600e
 

Hi all!
Fitted a venom silencer to my bike. No rejetting was supposed to be needed. However i struggled to get rid of the hesitation that occured when accelerating but only up to 3,000 rpm. Once past there it was fine. I turned the mixture screw out little by little and testing it inbetween. The mixture screw start point was 4.5 turns out. By the time the bike had started to improve it was 7 turns out. So i went and fitted a bigger pilot jet (48) and started again. Im up to three turns out with this bigger jet and still getting the hesitation upon accelerating. Am i going in the right direction with this? Do i need the next size up in the pilot jet? Or keep the current jet and lift the primary carb needle a little?

Didnt really want any of this messing about btw. Got the exhaust cos it was supposed to be a straight swap and married up to the motad headers.

Cheers for any help

Bill

The screw is fine about 2,5-3 turns out, its only doing a little difference in the low rpm idle-1400?. I change jets to 115 and 140 fitted with KN filter and no snorkel, then its drilled a bigger hole in the diaphragm. Thats the dynojet kit and it works fine.

The only thing ive changed is the exhaust. The air filter is all standard. Everything else is bog standard. But you think i should leave the mixture screw and concentrate on the main jets? As i said once ive got past 3,000 rpm it pulls fine with no hesitation at all. I think my main and primary jets are bigger than those as standard. 120 and 130.
Cheers for the help

Bill

Yes i would do the main jet, why not set the original exhaust back and check if everything is ok. When you pass the 3k second carb is opening. I recomend changing filter and bore the diaphragm, i can measure the drill i used.

When you say bore the diaphragm, do you mean the slide that holds the needle?

As for the OP, my bike only needed a size 48 idle jet. The co-screw should not be adjustet out over 4 turns, and in a perfect world not over 3. Perhaps it would be wiser to lift the needles half a notch with small shims/spaccers.

Hi xtrock.Original exhaust is full of holes which is why i went for a replacement. Hoping to find an easier solution really. Jens, i had read about the more than 3 turns out rule. This is why i went up a size with the pilot jet from 46 to 48. Do you suggest raising the needles in both sides of the carb? I was only thinking of raising the needle on the side with.the throttle cables attatched. ( primary carb?)

Bill

http://www.horizonsunlimited.com/hub...it-worth-72218

Drilling the secondary slide only does much good above the 3000rpm that he's having issues with so not sure if it'll do anything for him. By the sounds of it your hitting the throttle and the primary carb slide is opening up so a bunch of air but not enough gas for it so the hesitation till enough gets in there, (prime spot for a pumper setup). I have a motor built up,ported,hicomp, exhaust, open airbox. I only need a 48 pilot with the mixture screw about 2 turns out, and it is rich 11.2 to 11.8 on my wideband O2 sensor. I even see 10.5 at times. It might be the float is low or something is slowing the fuel down. I'd raise the needle .03"(.9mm approx.)

Yes i know, the suggestion about drilling was the suggestion for doing the upgrade all the way when he first have changed exhaust. This is my advice because i know it works and no more problems..

Okay to keep things simple (for me) the number 48 jet is plenty big enough for the bike with the only modification being the exhaust? The float height i checked when i had the carb out as per manual guidelines. I will try to raise the needle on the primary carb when im off work in a day or two. The mixture screw is at 4.5 turns out now and i still have hesitation up to 3k
Thanks for all the advice so far! I will update you all when i have made the latest changes.

Bill

Check the syncing of the secondary carb also. Make sure it isn't opening too soon , it would add a bunch of air.

Hi jjrider. Im assuming that the carb syncing is okay because all this really started with the exhaust change. According to the manufacturer it should have been a straight swap. Cheers

Bill

Update!

Finally had a chance to get the carbs off and raise the primary carb needle one notch up from its original position. Put the mixture back down to 2 turns out as well. The bike is a lot crisper now and the hesitation has mostly gone. A little fine tuning and i think its sorted. Thanks for the advice guys much appreciated!

Bill