quick jetting question

[ridered03]

on my 450r when under hard acceleration then let off it pops and backfires but other than that it runs really good is it running too lean or too rich and is this on the main or pilot jet.

thanks

[mstrav1]

You are lean on the pilot. next time list your mods and what jetting you have so we can help. what air box lid, main size, pipe etc....


thanks, matt

[ridered03]

I have an LRD full exhaust, hrc cam, k&n filter, no air box lid I am running a 190 main with the clip on the third notch down on the needle. the pilot is the same size that came with the hrc kit, not sure what it is. So I need to go up on the pilot size?

[nowukno]

If you have a full system exhaust , be sure that you replaced the copper crush gasket in the exhaust port on the motor , even though it may have only been rode very little with the original gasket it only crushes once and can let out air causing backfiring. I know this because my old 400ex did the same thing with my pro circuit t4 full system and i tried messing with the pilot jet first since that is what it is most of the time but after talking to a few people and getting some info it turned out it was the copper crush gaskets that i did not replace. Anyways i hope this helps.

[ridered03]

how much for a new gasket?

[2001400exrider]

like $2.50 each for me (canadian)

[ridered03]

ok so replace the gasket should I up the pilot jet size still? it is what ever size comes with the hrc kit if so what size ?

[mstrav1]

no do not up the size of your pilot. the "hrc" does not come with a pilot jet. you need to adjust your idli mix screw. it should be 2 1/2 - 2 3/4 turns out. it is on the bottom of the carb. if you have to go past 3 turns to get it right, you may want to go up to a 50 pilot.

[ridered03]

I tried the idle mixture screw and if I go past like 1/2 a turn it starts to leak gas out of the hose coming out of the float bowl on the bottom of the carb. what gives????

[mstrav1]

that is the carb drain!!!!!!!!!!!!!!!!!!!!!

under the carb (you can't see it unless you use a mirror!)

you can loosen the hose clamps holding the carb and turn it. before you adjust you should count how many turns it takes to go in so you know where you were to begin with.

again the one you are turning is the carb drain and yes gas will leak after 1/2 turn or so out of the tube!!


sorry but this did make me laugh:D

[ridered03]

LOL ok man laugh away my mistake and yes it was funny. so I bought a new copper crush gasket and will try the scew UNDER the carb(LOL) I will let you know how it goes. Thanks for all your help so far!!!