300ex Spitting and sputtering while racing

[Quadman4941]

My 2001 300ex, while going fast in third or fourth gear, starts spitting and sputtering, slight backfiring. I'm racing hare scrambles in FL and bike is hot. It has happened two or three races now. Usually about 3/4 thru the race. Only happens once a race. I down-shift, pull in the clutch, and rev it up, and after 5 or 10 seconds, it goes away. It makes the people behind me vewwy happy cause they get past me. It makes me vewwy vewwy sad. Can anyone help?

Thanks.

[Quadman4941]

I just read an old post about a rev-limiter. What is that and does it play a part?

[300exazzkikr]

what mods do you have on the bike? I need to know where to start.

[Quadman4941]

Not very many mods. It has a WB Series E pipe, with what appears to be 10 disks? It is about 1 1/8 inch of disks. K&N air filter. The person I bought it from told me of nothing else. I'm looking for recommendations on more engine, or something, cause 400exs, etc., are smoking me in the straights. I tried to install a 36 tooth on the rear sprocket, but couldn't get the chain to fit even with 1 link gone. Weird. Now have 37 tooth in rear. Big HELP needed here! It doesn't help that it begins to spit and sputter either. Would appreciate some help and recommendations for speed. I could have a budget of $500-$600. I know, buy a 400 or 450. I will do that next year when my son will begin to race with me, but the size of the 300 is great. How long do I have, doc? Give it to me straight.

[300exazzkikr]

I have a 36 tooth on mine. Yea the chain is kinda loose, but when i got an LSR bearing carrier and that helped a lot, don't know why but it got rid of most of the slack. THat helped for top end a lot. I believe that your just hitting the rev limiter in 3rd and fourth. Try putting taller rear tires on and see if it stops sputtering.

Mine did the same thing with the 36 gearing. Then i put the stock 22" tires on and the sputtering went away.

The reason it does this (I think) is because your going faster than what the stock ecu can handle so it cuts out.

I hope this helped, not sure if it did.

[dirtmomma]

Go to Curtis Sparks racing & see about getting a rev box for it, the guy I got mine from put one on it because he was racing iron mans & it would do the same thing as yours is doing. Also is your jetting right?? As for the sprocket I went up a tooth in the front which I think is the same as 3 in rear?? Anyway the sprocket really made a difference for on the trails keeping up w/ my husband on his 400, the only bad thing about changing the front is that I can't use the case saver:ermm: but I'm getting ready to change it back to stock for my flattrack season. Maybe this helps some maybe it doesn't but good luck!! :)

[dirtmomma]

Hey 300exazzkiker how do you like your LRD exhaust on the 300??? Do you have the full system??

[300exazzkikr]

Originally posted by dirtmomma
Hey 300exazzkiker how do you like your LRD exhaust on the 300??? Do you have the full system??

I love it, I have the full system. Great power gains all around. It's a little pricey and loud, But i got the end cap with 6 discs. That helped a lot with sound, Took away some of the throttle response away, but it keeps the neighbors happy.;)

Overall great system and i highly recommend.

[dirtmomma]

Originally posted by 300exazzkikr
I love it, I have the full system. Great power gains all around. It's a little pricey and loud, But i got the end cap with 6 discs. That helped a lot with sound, Took away some of the throttle response away, but it keeps the neighbors happy.;)

Overall great system and i highly recommend.

RIGHT ON LOUD PIPES SAVE LIVES but yeah I know alot of people don't like them. We were gonna go w/ a LRD for our blaster but ended up w/ FMF alot because of cost, but the FMF's seem to be working alright I suppose I could tell the difference if I rode one w/o an FMF.