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Discussion Starter · #1 ·
I thought I had fixed this problem by installing a new fuel filter, but the problem is still there.
The engine is all stock except for a K&N filter.
It starts, idles and accelerates pefectly.
The engine will stumble when holding the throttle at a constant speed around 25 MPH.
If I give it more gas, it will accelerate fine.
The problem seems to be worse when the engine is hot.
The valve were adjusted in the spring, so I'm ruling that out.
I tried to do a search on this, but have not found a post like my issue, but do recall a post about setting the floats with a clear tube, and turning the screws 3 1/2 turns.
Thanks
 

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Master of the Electron
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Try Raising the needle clips one notch each - if it gets worse, go down a notch instead.
 

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Discussion Starter · #3 · (Edited)
I just went out and removed the plug. It's blacker than my boot !! Not oil, just black soot.
The plug I'm using is a DPR8EA. I don't rev this engine very high, and rarely have it at WOT, because it's used mainly in trails or long rides.
I lowered the needles 1 notch to see if that helps.
What do think about going to a hotter plug ??
Thanks

P.S. Thanks Quad !! I posted before reading your reply.
It's definitely rich, and not sure if one notch will be sufficient. I'll find out this weekend.
I just want to add that this engine is in a buggy and completely stock. I am however running a muffler from (I think ) a Honda 450. I hope it's not too restrictive !!
Having said that, I have put almost 1200 miles on it since last year, and never had any stumbling problems before.
Dan
 

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I am unique
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I thought I had fixed this problem by installing a new fuel filter, but the problem is still there.
The engine is all stock except for a K&N filter.
It starts, idles and accelerates pefectly.
The engine will stumble when holding the throttle at a constant speed around 25 MPH.
If I give it more gas, it will accelerate fine.
The problem seems to be worse when the engine is hot.
The valve were adjusted in the spring, so I'm ruling that out.
I tried to do a search on this, but have not found a post like my issue, but do recall a post about setting the floats with a clear tube, and turning the screws 3 1/2 turns.
Thanks

All your symthoms suggest to rich jetting...............
 

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Discussion Starter · #5 ·
All your symthoms suggest to rich jetting...............
I agree !! But nothing has changed in the past 1200+ miles.
The jets are stock and have never been changed.
I was actually concerned that I was running lean due to the K&N filter.
 

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I agree !! But nothing has changed in the past 1200+ miles.
The jets are stock and have never been changed.
I was actually concerned that I was running lean due to the K&N filter.
Maybe the K&N don't flow as well as the stocker was?
 
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