worm top ?

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l2f
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worm top ?

Post by l2f »

Hello,

I am wondering how to detect a worm top, I'm reading (http://justkdx.dirtrider.net/printcarbtuning.html) about jetting the carb of my 2002 kdx220

Thank you in advance for your help

l2f
chkdx
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Post by chkdx »

What is a worm top?
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Julien D
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Post by Julien D »

I"m guessin you mean worn top end?

Compression test would be a good place to start. Even better, if it's a used 2 stroke you picked up, go ahead and throw a new top end in it. since you ride a 220 you need to be sure there's a forged piston in there. The stock pistons are not reliable int he 220's, and if they drop a skirt, could cost you a bundle.
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Post by factoryX »

What would be average compression? Mine is currently at 140lbs
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Julien D
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Post by Julien D »

They did change the usuable compression spec a couple times. I'm not 100% sure off-hand what it is for an H bike, but my 89 manual says something rediculously like 90 - 180 usable range. AFter break in on the last top end my gauge showed 160.

(btw, i'm moving this to general Q/A as it does not relate to RB mods at all)
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OLHILLBILLY
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Post by OLHILLBILLY »

H model (200 anyway) usable compression range is given as 95-151psi.
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l2f
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Post by l2f »

>|<>QBB<
juliend wrote:I"m guessin you mean worn top end?

Compression test would be a good place to start. Even better, if it's a used 2 stroke you picked up, go ahead and throw a new top end in it. since you ride a 220 you need to be sure there's a forged piston in there. The stock pistons are not reliable int he 220's, and if they drop a skirt, could cost you a bundle.
The previous owner did it, he put a wisco.

Thanks
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Post by l2f »

>|<>QBB<
juliend wrote:I"m guessin you mean worn top end?

Compression test would be a good place to start. Even better, if it's a used 2 stroke you picked up, go ahead and throw a new top end in it.
I will double check the compression and see with the manual. My 220 is a used one but it runs good. In the "how to jetting", before doing the jetting session you have to check the worm top end and the gas carburation level that why I ask this question.

Thanks
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Post by fuzzy »

The previous owner did it, he put a wisco.
That's great. I'd just start jetting it. Unless damage is done due to running lean/etc the top ends on these last A LONG time.
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Post by l2f »

>|<>QBB<
fuzzy wrote:
The previous owner did it, he put a wisco.
That's great. I'd just start jetting it. Unless damage is done due to running lean/etc the top ends on these last A LONG time.
Happy to hear that :grin:

thank you
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