I seen KLX300 web cams being used on a KLX250SF with the big bore kit.
I seen Web Cams makes performance dual springs and Titanium retainers and Stainless valves for the KLX300. So. . .Can i use them on my KLX250 SF? I'm got to be taking the bike apart this winter to do a 330 big bore so i wanted to know if i need to buy more **** to make this lil guy faster. Thanks guys!!

 

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Hey Jester,

I just looked up a few kawi part numbers....I was surprised to find that the cylinder head assembly actually had a different part number between the 250 and 300. The intake valves have have the same part # so you should be good on those, the exhaust valves had different part numbers.

I don't know if the 300 exhaust valves are larger than the 250 ones...requiring machining of the head or if it is some other non-important difference....I bet web cams would know

Lots have done valving changes, hopefully someone that has done it would know.

Oh, btw I would recommend porting your head before upgrading the valves.

 

ok thanks.. i know the cams will. I seen that done already, but will the valve springs?

 

With the compression ratio of the 250s and 300 being the same, 11:1, it would indicate that the combustion chamber for the 250s is smaller.

Ride on
Brewster

 

Could be the addition of the recirculating port at the exhaust on the 250S. Se all ended up blocking that off when we removed the smog stuff. The 300 doesn't have that, I don't think.

 

Sure, I'll go along with that....but what about the exhaust valves having different part #s ....... whats the difference? Anyone know?

I'm on Brewster's side regarding the combustion chamber size opine.

 

All you have to do is dish or dome a piston to keep the ratio the same with the same head & different displacement. The piston has to be retooled anyway--the head does not. The only way you will know is to cc the head. When you buy a high compression piston what is different? The dome they put on the piston.

 

true, but I have personally installed a klx300 piston in our lil 250 and the pistons were identical...with the exception of the piston dia.


What about the exhaust valves.

 

Springs are the same. Could be anything on the valve, heat treatment, coating, supplier, etc.

There were 3 heads for the KLX250R & KLX 300R. The 250R had one part number, the first 7 or so years of the 300R had a part number, the the last few years of the 300R had another part number. They all superceed each other. Meaning what ever the difference is, it works across the board. Again, the difference can be as little replacing worn out tooling & all new parts made with the new tooling get a new part number to differenciate what came from where. They could of also changed something design wise but when the part numbers superceed you are OK.

If you had an old 1994 KLX 250R & needed a head, the Kawasaki dealer would sell you the 2007 KLX300R head as *THE* replacement even though something MIGHT be different from your original head. You would be unable to order the original 250R head.