XR650L carb help

I will admit I just got in my first decent ride on my 02 650L I picked up a few weeks ago. A short list of mods. Bike has 2400 miles, de smogged, ISDE? supertrapp pipe, de snorkeled,Uni filter, valves just checked, ?? Dyno jet kit installed by PO. I have no idea what the kit usually supplies or whats in it but I get quite a bit of back firing on 0 throttle decell. Theres a pretty good flat spot/hesitation on inital throttle/low rpm. Ive never had much luck with jet kits, I prefer my own doings but what done is done. Once its goin it runs pretty good It seems from reading here. 2nd gear wheelies are no problem and Im 240 lbs. Are these carbs pumpers? and what is the normal idle mix screw setting? I have mine at 2 3/4 open. If im not mistaken anything more than 2.5 out says bigger pilot? Are the jet kits bad news?

Thanks much for any help.

The carb is not a pumper its a constant velosity type. The jet kits are OK they just don't use a larger pilot jet and instead use a tapered needle to do the same. I found that after trying the DJ kit and adding to it (larger pilot) That the Daves mods from 4 Strokes only web site worked the best.

Thanks, I think I need to pull the carb and have a look. Unfortunatly I dont know what the PO did regarding jet sizees, hope the jet kit has numbers on the jets for a reference or I can find the original stuff.

I not what to expect as far as how good is good.

Thanks, I think I need to pull the carb and have a look. Unfortunatly I dont know what the PO did regarding jet sizees, hope the jet kit has numbers on the jets for a reference or I can find the original stuff.

I not what to expect as far as how good is good.

Pulling the carb is the way to go. If the carb has an adjustable jet needle, i.e.; has clips, it's aftermarket. You'd want to get the stock needle again & shim it up 0.025" - 0.050" instead. Also check the vacuum piston (slide) to see if the 2 outboard holes have been drilled out to 5/32".

With the mods your bike has I'd look at running all Keihin jets & using a 158 or 160 main jet, a 58 pilot jet with the pilot screw set at 2 turns out initially from lightly seated and shimming the needle around 0.030".

There shouldn't be any flat spots after rejetting & modifying the fickle CV mixer. But it might take more than one jetting change & possibly a few ps adjustments to get it running right throughout the throttle range.

I know, it took me a few times but it's been worth doing. My bike used to pop & stall constantly. I finally got tired of it and tore into the carb, did the standard mods, fine tuned the jetting. Now it runs strong & smoothly with no issues. :thumbsup:

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