Bike bogging waaay down when in high RPM's

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Jun 17, 2007
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#1
My KX100 was working PERFECTLY last saturday. well, yesterday i started it up, and as soon as i hit high rmp's, the thing would bog down super low and almost stall, and then when i shifted down to 1st, it would kinda ok again.

the only change i made from then to now was i cleaned the air filter.

the only thing i can think of is that it was pretty hot last weekend, and now it is kinda cool outside. so maybe itsw the temp?

it honestly seems like its getting way to much fuel at high rpms because its turning the plugs black, but i dont understand!!! i didnt change a single thing from last saturday, and it does this to me all the sudden!

any suggestions?
 
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#2
i was just riding it and it works fine in the majority of the throttle range, but as soon as i hit the probably last 1/4 of the throttle, it just bogs, and almost stalls until i let ther throttle go.
 
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#4
Thats what I was thinking. I bought some Seafoam and have been running it through my bike for like 45 mins riding it. It has been getting better, but as soon as I hit that one spot in the last bit of the throttle, it just like stops cycling. I am going to ride it tomorrow again with the Seafoam to see if that can clear anything out.
 

IndyMX

Crash Test Dummy
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#5
Don't use Seafoam... Take the main jet out, blow air thru it...

It took longer for me to type this than it would have to just do it.
 
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#6
I actually think there might be too much oil in my gas. I put my hand behind the exhaust and there were little specks of oil all of my hand. Plus it is blowing out alot more smoke than normal. I was using like 38:1, but could something have happened to it to make it go bad?
 
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#7
Few things I can think of that would cause bog:

Bad gas
Too rich main jet.
Fouling plug.
Powervalve problem (if a KX100 even has one)
Very low compression.

In my experience, being too lean hasn't cause a bog like being too rich will. I've run my bike on the lean/crisp side and never had significant bogging. Can't imagine how lean you would have to be to get a hard bog like that.
 
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#8
Binary - I agree with Indy. You need to pop open that carb. A buddy had a similar problem on his 250 and the main jet had actually fallen out into the float bowl! Ran awful at anything past 1/4 throttle.. Don't mess with oil ratios until you check the main jet.
 
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#9
Well, I bought some new gas and drained all of the old stuff. The new gas I am using is 40:1, and it is almost getting worse now. Basically anything past 1/4th throttle now just bogs.

I can clearly notice that it DOES smoke more than normal. When the bike was working fine, it would smoke a good amount until the bike got warmed up, and then there wouldnt really be any visible smoke. Well now, there is CONSTANTLY a smoke trail behind me...
 
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#14
Yep,now do a leak down test and get back in the morn'in! SUCK UP 320 BUCKS AND DO A COMPLETE ENGINE REBUILD Choice is yours! Bt quit using the frigg'in outboard motor products and think about what the hell you have ! Then go from there,not some place in between,convenient for you!