Miss at top of RPM curve

[fastlanesimmons]

I have an 05 Kicker w/ full LRD exhaust, Jetted (not sure what needles, I am guessing just big enough for normal elevation) CDI box, K&N filter and Lid removed. Just recently I have been noticing my 450r cutting out at the top of the RPM range(Seems to do it more when its good and hot, not so much when its cold or very cool weather)...just about 500+ or so shy of the rev limiter. Through every gear when I am full throttle it pulls hard and then begins to miss almost at the top. I am thinking its a fuel problem but wanted to see if anyone more mechanically inclined would give me a direction of what the problem may be. Also, when I am in 5th I can only give it about 1/2 throttle before it starts giving me trouble. Is it running Lean? If so, what jets do you recomend me to change? Sorry ahead of time of not knowing what jets I have in the bike, they were installed prior to me owning.

Thanks!

[rt20ps]

If it runs better in cold air your rich. Try to lean out your main jet one size at a time until it pulls strong all the way to the limiter.

You need to see what jet is in there. How do you know you are 500 RPMs from the limit?

[fastlanesimmons]

Thanks for the reply. I was guessing on the RPM range of when it starts to cut out. It very well could be more/less. By no means I have a tach to verify what RPM the problem happens...all I know is that it isn't the REV limiter.

What I don't understand is how/why it has started to just happen. It always ran very well, then lately it has been getting this problem has started. Maybe weather related? That don't sound right...

I ran it real hard about a month or so ago, where I was running down a county road all out for 4-5 miles (Banshee next to me was just cruising along in sixth with alot more to go). That's when I started to notice the cutting out...but then again..it may have been there, but never had the chance to find the issue.

[warr72]

I would check the jetting, then check your valves.

[fastlanesimmons]

I was going to ask about the Valves maybe being the problem...I was doing some thinking and have realized the Valves have never been adjusted and there is about 40-50 hours on it. Could this possibly damaged anything? Or is it just not going to run right until they are adjusted?

Thanks for the responses!

[warr72]

If your valves are out of adjustment no it will not run right and yes it could do serious damage.

[04TRX400EX]

As others have said, your problem which has occured 'out of the blue' is likely attributed to either your valve clearances being out of spec or possibly a spark plug going bad. You definitely need to check your main jet as it is responsible for all fuel flow from about 1/4 to full throttle. Try to back it down a size or two and see what happens. You're basically flooding the engine with too much fuel.

[Johnson]

I also have the same problem only its on a 07 450 I have changed carb, wireharness, coil, cdi box, stator, sparkplug and value clearness was good it runs great until you get to the top of the rpm range. I've got a 05 carb with a 180 main with the lid off. Could the bad values cause this?