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porting a kx500 cylinder

Joined
Aug 16, 2001
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#1
I have ported a few cr500 cylinders but I now have an kx500 cylinder for a buddy of mine witch will be using it for drag racing
and hillclimbing.
So if anyone could shed some light on this and help me with some porting specs. and or any other ideas it would be appeacated
 
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Apr 1, 2002
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#2
hillclimber .... I have a KX500, but I'm not looking for more power (fine with bolt on stuff). Probably would be best to send the cylinder/head to someone who's done a "lot" of porting, like Eric Gorr. I've not seen anything on changing porting specs for the bike (just smoothing curves and polishing have helped a little for me).

Gool luck, and let us know what you did and how it helped.
 

EricGorr

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#3
The 5 exhaust ports on that model are rough cast and plated. The KX500 can benefit from carefull matching of the corresponding port heights and widths but simple decarnonning of the KIPS systems will make the biggest difference. Other popular changes for more top end include lowering the compression ratio by turning metal from the head by setting the squish angle to 18 degrees.
 
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#4
Eric. thanks for replying I am not sure what year cylinder that I have but there is only 3 exhuast ports the main is only 60% of bore width Im thinking of widening it 6mm witch would bring it to 65% of bore width do you thank that the time area of the transfers and the intake will still be ok? I havent put the degree wheel on it so I am not sure of blowdown or anything.
Thanks again for replying
 

kawdude

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#5
What does a "standard" porting job consist of on the big KX. Is it just increasing the port size and\or head mods? How scientific is the matching of the ports.
 
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#6
The age old porting method for drag bikes has been a square or rectangular shaped port. This gives the greatest time area often at the expense of ring life.

Port matching is generally done by making sure all the related ports have exactly the same port timing. Matching the exact flow rates of the ports is often considered secondary to the actual timing. Some engines even have serious flow differences between the LH transfers and the right.

My limited experience with the KX500 engine is related to bolt ons only.

Chris

Chris
 

kawdude

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#7
Good information. Thank you!