Spits,dies sumtimes runs good.

[flyingbyfast400]

Can anyone help me out befor I rip my 400 apart.? Last weeked I put my spare k and n filter on my bike and took the dirty one off, changed the oil, and put a new plug in it.... I rode for a nice long day after that and it ran like a top.... Then I got it out to go for a lil joy ride last night and no probs. Then today I got it out to do sum riding befor I go to slive lake to see what needs to be done... and it started to run like crap. It runs sumwhat good in low and mid but on top it spits, and act ike it wants to die when you pull the clutch in. But i did also noitice it dont have the pwoer in the low and mid like it did befor.. It runs fine when its just sitting there. Im going to go look it over a bit and post in a lil while to see what more i can fine..... Any help would be great. Thanks
Vic

Motors stock for the most of it but for a lrd full pipe and k,n filter and its beem jetted.

[TC426EX]

Well, if it runs fine on the bottom and sputters and dies on mid to top it COULD be your main jet. If it is you are in luck it will be a simple fix. I had a similar problem last weekend. I was practicing at my buddy's big backyard track and toward the end of the ride mine was showing the same symptoms yours is. Turns out that when I put my bike back together a week ago after splitting my cases (since I broke a shift shaft), I must not have noticed that I had a stipped bolt on the airbox boot clamp, (the one that connects to the carb...). As a result, from jumping, the boot came disconnected from the carb and I was sucking in mad dirt for a lap or 2. I took my bike through a big field behind the track, as well. When I took the carb apart I found a big grass seed jammed in my main jet! I removed it, sprayed the carb out with cleaner, put it back together, and now it runs like new. Basically Im saying check your main jet or carb for debris, and hopefully that is your problem. If not, I dont know what else could be causing your problem without more info.... Good luck man...

[flyingbyfast400]

Hey Paul...... thanks for the tip, Ill give it a try sunday and see what it does.... Lets hope ot does the trick....
Vic :)

[Mofo Racing]

I changed my oil, cleaned my filter and changed my sparkplug before I went to the dunes and rode it hard . The next two weeks it rained and I never even cranked it up. So I finally got around to riding it at a family BBQ and the sob wouldn't crank. Fouled the plug. That is the 5th plug I have put in since I put my sparks pipe on. And the pipe is only 3months old. So I guess I better go ahead and jet that carb. It would be wise.