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Dr350 96' Backfire after jetting:

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Hello guys, i need your help with some backfire problems.

My bike is dr350 96 with an aftermarket exhoust (SuperPower), and i just installed K&N air filter and the DynoJet stage 1 kit.

The backfire happen's in 2 diffrent situations:

1) In neutral when i hold the throttle stadly on 3000-5000 rpm.

2) In riding when i shift down and relase the cluthc lever, or just relase the throttle.

What can be the solution to this problems? (Maybe diffrent main jet? or something else?)

Thanks alot.

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The K&N filter is the problem. The Jetting kit you bought assumes you are using the stock filter. The K&N passes too much air (and LOTS of dirt, by the way). Use a foam filter, or you will have to increase the size of your pilot jet by two steps.

also, you hav to adjust your fuel screw to compensate for the jetting changes

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thanx for the help. right now im using the 140 main but the needle clip is on the 3# from the top. moving to the 4# would make that big change?

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Hey while we are on this I have a 1995 dr 350 (dirt model) with a 440 big bore kit. What jetting should I have in it? It runs great but dies off at wide open throttle so I'm thinking the main jet is to small.

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thanx for the help. right now im using the 140 main but the needle clip is on the 3# from the top. moving to the 4# would make that big change?

Yes...You have open pipe and free flow filter...You should be on clip 4

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ok guys, just finished to do what you all said (140 main with clip on the 4#).

actually it sounds much better, the backfires almost gone.

There are still few pooping when i leave the throtle in 3# gear.

is it normal?

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yep, folowed those steps and still some pooping.

I have a stock air box without any mod, does this can be the reson? is it recomended to modify it if i planing to do dirt rides?

thx alot.

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