kdx220r bog and light top end knock

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openthrottle55
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kdx220r bog and light top end knock

Post by openthrottle55 »

I have a top end knock after riding for a few hours. Only does it when in really ripping on it n riding it real hard. Also it has a low end bog and hard start issue now.. fresh plug n oil.
openthrottle55
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kdx220r bog and light top end knock

Post by openthrottle55 »

Im Afriad im running too lean. Bike plug is chocolate brown amd im mixing 32:1 and running a fmf gnarly pipe h n fmf silencer
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Re: kdx220r bog and light top end knock

Post by s10gto »

That was my first thought. Whats your jetting and elevation?
openthrottle55
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kdx220r bog and light top end knock

Post by openthrottle55 »

Ok I pulled it all apart all looks good. I cleaned everything back to perfection. Reeds were pretty bad. Im in ohio. Cincinnati. . Running a 165 and 48 with a fmf gnarly header and fmf silencer
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Re: kdx220r bog and light top end knock

Post by s10gto »

I believe 145 Main 42 pilot is stock. You should be rich. At 800 feet + above sea level should be very rich. I would change the reeds and go from there.
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adam728
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Re: kdx220r bog and light top end knock

Post by adam728 »

Before jumping down a mountain of jet sizes, what mods does the bike have? A bored carb will require larger jets than stock.

Is your knock possibly detonation?
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Re: kdx220r bog and light top end knock

Post by s10gto »

It sounds like 200 jetting. Is it the stock 220 carb or the larger 200 carb? I believe 33mm VS 35mm.
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Julien D
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kdx220r bog and light top end knock

Post by Julien D »

openthrottle55 wrote:Ok I pulled it all apart all looks good
What does that mean, exactly? You pulled the top end apart? Cylinder wear is within spec? Piston likewise? Piston is stock or forged? Details!

165 is wicked rich even for a 200. If you are running lean using those jets you have air coming in from somewhere it shouldn't.
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adam728
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Re: kdx220r bog and light top end knock

Post by adam728 »

Julien D wrote:
openthrottle55 wrote:Ok I pulled it all apart all looks good
What does that mean, exactly? You pulled the top end apart? Cylinder wear is within spec? Piston likewise? Piston is stock or forged? Details!

165 is wicked rich even for a 200. If you are running lean using those jets you have air coming in from somewhere it shouldn't.
If it's a 33mm 220 carb then even an airleak couldn't take it from 140's to a 165 main and still be lean when hard on the gas. I betni could drill a 3/4" hole in the cases and not get it there! Anyone have a bike they want to test my theory on? :)

Really though, op needs to know what's stock and what's not on his bike.
A plug chop needs to be performed to determine how its actually running.
Engine, reeds, compression, etc need to be assessed.
After that a direction can be taken. No sense throwing parts and jets at an unknown issue, yet. The parts cannon should always be a last resort.
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Re: kdx220r bog and light top end knock

Post by Jaguar »

could be crank seals letting air in. were the reeds frayed so that they weren't sealing when closed? was the head gasket sealing completely? was the main jet partially obstructed by trash?
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