Flat Spot

[chevy383cid]

Hello Everyone, I have a 02 KX 250, That has slowly developed a flat spot ,in only high gears,When riding hard, it wants to take it's time going in to the powerband only in high gears!! Compresion is good, plugs always look pretty good, I keep the air filter clean,silencer has fairly new packing,I run belray H1r at 32:1 with 93 octane,I have a JD jetting kit with a 45 pilot,168 main and the blue tip needle in the 3rd(middle clip position)Now in low gears it does outstanding Its just that on long pulls up hills is where this flat spot appears. Does anyone have an Idea what could be the problem,moving the clip down to make it a little richer or makining it a little leaner by going up on the needle, or relieving some of the spring pressure on the powervalve ??

 

[ellandoh]

check your float level

 

[crazy4nitro]

Sounds like the bowl is being sucked dry,make sure the fuel flow from the tank/petcock? do you hear any pinging while it's flat?

Crazy

 

[chevy383cid]

I'll check float level today, Float level being low is a perfect result of whats happening to my bike,I've built a few drag race engines in my day and if your fuel level is not correct It will give you all kinds of headackes!! Thanks for reminding me!! I'm hearing no detonation, At low rpms or high. I'll post later today after I check floats!!

 

[chevy383cid]

Well, I just got finished working on the bike and The float level was dead on(according to the manual) I drained the fuel and disassembled the fuel peacock and it all looked clean and in good shape.The plug looked a little more oily than normal but down in the electrode it was still dark tanish brown. I gapped at .32 and in stalled a new plug (b8ev) So when it stops raining I'll give it a try!!

 

[ellandoh]

did it rev when held wide open in neutral before ?? maybe look for a preview in the garage :think:

 

[bclapham]

make sure the carb vent hoses arent blocked.

 

[SirHilton17]

Make sure the powervalve is operating freely