Missing on top-end....

[tacundra]

Was having this problem bad when the spark arrestor was removed(for about 1hour)....The spark arrestor is back in the R currently.

Basically, when I get to the upper RPM range, the R starts sputtering. It is totally stock. It is acting like it is a lean condition.
I don't understand why mine would run lean stock when the rest of my friend's are running fine stock.

Any ideas why this might be happening?

Thanks, Jimmy:confused:

[exrider44]

My bike does the same top end it sputters but still goes pops alot and stalls alot when I come to a stop. I took the spark arrestor out changed the main jet to a 180 and removed the airbox lid.Im so frustrated I may just put it all back to the way it was. Any ideas on whats wrong.

[steveatv3]

When i got some water/snow in my air box it did the exact same thing as what u guys are explaining. Make sure ur air filters are clean and that they are NOT over oiled cuz that can cut down on restriction.

normaly when it goes pop and back fires it is running lean and will stall out. Perhaps adjust the throttle mixture screw.:confused:

[911]

you can try adjusting the needl clip down 1 pos. and def turn out the air screw in the front of the carb at least 1/4 turn . good luck;)

[Martin Blair]

Make sure the filter is clean, clean it if it is dirty It can cause this, also you might want to clean your carb out, mine had little plastic shaving in it from the factory, other have had the same problem. Mine ran fine when It was stock with no s/a.

[sulnz450r]

On top end they will also sputter if they are too rich. When I first got mine I kept on trying to put larger main jets in it. But quickly realized that the main jet did not do me any good unless You can get enough air to it. So I got me an ehs racing lid ( gets plenty of air now ) and now I can run a decent size main jet without any sputter on top end. hope this helps.

[fearthis_450r]

If yours still pops when you let off the throttle change your pilot jet it will stop the popping.

Originally posted by HN400exracer
Make sure the filter is clean, clean it if it is dirty It can cause this, also you might want to clean your carb out, mine had little plastic shaving in it from the factory, other have had the same problem. Mine ran fine when It was stock with no s/a.

Hey, HN400exracer. Sweet avatar, dude!!

[tacundra]

I appreciate all the input guys....I think I have resolved the issue.

I am glad my friend has a new R I was able to compare against.

I took off my seat and his and compared for any differences around the airbox as I knew this was a fuel/air problem...

Well, it turns out, whoever assembled my R installed the little robber debris guard(in front of airbox) incorrect. The rubber guard
was basically hanging over the air inlet on the white plastic tube.
When revved hard, the airbox would draw alot of air and pull the rubber guard over the air intake, therefore, restricting airflow altogether.

I reinstalled the rubber guard and think this is problem resolved.

Jimmy