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help with sm570r jetting and new carb. 2001

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can any one help get me ballpark jetting for a new carb in my :ride: 2001 sm 570r

I built a straight through exhaust using the stock muffler shell and it now has a two inch out let no baffles, I also drilled the intake, to be the same as the nox is. the bike is hard to start still (d. o. carb stock jets) and the bike has pretty large flat spot in mid range, but theres more power after the mods.

I got a carb from a 2004 honda 450 quad its a keihin 42 thats 42mm inside . I don't actually know what the needle is but its got a small main like a 165 or 168 and a 48 pilot

what size main do you recommend

which pilot

what is a leak jet, and where is it , what size should I run.

which needle should I use

I have a c550 needle in there right now. any sugestions?

I have all mains and pilots between 155- 185 and 40- 50

the carb is not a fcr but should work

what is the purpose of the electrical inputs in the keihin carbs and are they critical for operation

wow thats a lot of info.

any help would be great. thanks again

Derek :thumbsup:

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I have a Keihin on my Yamaha WR 450, and I took a DO off my 01 TE 570 and replaced it with a Mikuni from the 04 TE 450.

THe electrical connectors you refer to may be the TPS (throttle position sensor). I do not have it connected on my TE 570 because there was no wire for it--I assume it was added for the 02 TE 570.

I believe that the leak jet lets gas leak back to the bowl from the big hit of gas the AP pump gives it. So, the smaller the number, the less gas leaks to the bowl, and the richer the mixture remains. You get to the jet by taking off the bowl, if I recall right. Yamaha WR guys run from zero (soldering it closed) to 60 on leak jets--I think 40 is the stock.

As for jetting, I don't think my 03 WR 450 jetting info will help because of the differences in the bikes. But, if you are curious, go to the Yamage WR section and a stickied post there has a chart of different jetting recommendations for altitude, temperature, etc.

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You say its a Kehein but not an FCR????? I would hold out for an FCR. First because they are the best carb made, second because there is so many similar engines that have it that we can establish a starting point.

IF it where an FCR I would have to know what needle it has as its taper has a huge effect on the jet sizes. Not knowing the needle makes everyones opinion tainted.

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