Mid Range Flat Spot

jpm200

Member
Aug 15, 2002
90
0
1989 KDX200F (KDX200SR)
Has a flat spot about the middle of the rev range regardless of throttle opening.
As the revs rise the motor starts to come onto the pipe then drops off into a BRAAAHH noise then kicks back onto the pipe.
It happens at the same point in the rev range no matter what gear.
I am wondering if it could have something to do with the timing of the exhaust valves.
What is the best way to check? Can you adjust the timing of the exhaust valves?
I don't think it is the jetting as the bike runs crisply without too much smoke or ooze and the plug is a nice light tan colour.
 

jimbo

Member
May 20, 2000
42
0
I've just recently done a search on this forum about pipe and jetting performance and it sounds to me like you have a lean condition at
that spot I would encourage you to check for a vacuum leak around
the rubber intake spigot. I hope you find out before doing any damage
to your engine. If you can't figure it out yourself get some help from someone who can hear it run and diagnose the problem. :thumb:

jimbo
 

Kamofly

Member
Apr 28, 2002
51
0
Could this be a problem with the KIPS valve? Or in the powerband?
--once had a similar problem on 200--
 
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