BACK FIRE ON DECEL

[dreth]

my 450r is sometimes backfiring on the decel......new sparks exhaust, sparks filter, 190 main........runs strong though?

[Ida_Mann]

I used to call that my "warning" to the other riders behind me that there was a turn coming up ;-)

of course, that was on my LT230 Quadsport.

Id@

[DierWolf]

Backfiring is usually caused by fowling plug or excessive gas, might be funning too rich with the 190 mains.

[TRX450R_Racer]

I have heard of a lot of people with that problem. It is very common. Check out this site www.trx450r.org. It is the best 450R site on the net. There is a lot of good/usefull information there.

[DierWolf]

frikken 4 strokes


 

[kawGIRL]

 Might be Lean, back the fuel screw out 1/2 turn.

[SLOW450R]

need to make a pilot jet adjustment...........I assume you are running the stock one?   The jets are cheap and you and you can go up 1 or two sizes to fix the problem.  If it is poping now, it is only going to do it more once it gets a little cooler.  You are auctually a little lean on deceleration, which people really dont think about alot.

When you come down off the main jet there is a gap before the pilot jet can supply enough fuel, the result is a backfire or a "pop" more likely.  A little bigger pilot jet will make this transition and fix the popping issue.

[dreth]

need to make a pilot jet adjustment...........I assume you are running the stock one?   The jets are cheap and you and you can go up 1 or two sizes to fix the problem.  If it is poping now, it is only going to do it more once it gets a little cooler.  You are auctually a little lean on deceleration, which people really dont think about alot.

When you come down off the main jet there is a gap before the pilot jet can supply enough fuel, the result is a backfire or a "pop" more likely.  A little bigger pilot jet will make this transition and fix the popping issue.

my jet needle is a c51b, the stock needle was a c55a. jet needle clip is in the 3rd groove

[A.T.P. RACING]

Your needle might be fine, he is talking about the pilot jet, it and the needle combined controls 90% of the fuel metering in a carb. you probably need to go up on your pilot jet a size or two.

[Chuck_Norris]

need to make a pilot jet adjustment...........I assume you are running the stock one?   The jets are cheap and you and you can go up 1 or two sizes to fix the problem.  If it is poping now, it is only going to do it more once it gets a little cooler.  You are auctually a little lean on deceleration, which people really dont think about alot.

When you come down off the main jet there is a gap before the pilot jet can supply enough fuel, the result is a backfire or a "pop" more likely.  A little bigger pilot jet will make this transition and fix the popping issue.

That is where my problem was at, in the pilot. I picked up the Jet4power kit and found that even at a 48 pilot I was still a touch lean, got the 50  and waiting to install it.I hate Moving

[dreth]

bump

[ATOMCRF450]

Your pipe is prob loose or has a air leak..I know that will cause it to pop on decel every time.
Mine had the same problem I was trying to correct it with the jetting at first, then noticed the pipe was just a little loose and that fixed it right up.

[big-daddy]

Are still have the problem?

[Hoosier Daddy]

buy a 2 stroke!  

[big-daddy]

both anotherslow400ex and A.T.P racing are correct right the problem is in size of the pilot jet. Engine performance worsens when the air filter is removed.