I wish I could use one of those, but I've not no room between the bottom of the FCR carb and the starter motor [&:]:



I think my only hope is to buy a Kouba fuel screw and cut it down to where it just clears the recessed hole.

 

Thanks man! The O2 sensor is working great. I just need to make it smaller so that I can leave it on the bike. Right now its good for testing, but is too big to keep it mounted on the handlebar. I might get me one of those little voltmeters which are only an inch or two wide.

 

Holy toledo! That is one long carb body. Yeah, hopefully that scew fits. I wonder how far you could 'un-recess' that with a file without running into the threads.

 

When you replace the cylinder with a 300 or 331 cylinder, do all the origional parts fit like heads cams, etc.. Is that all you have to replace is the cylinder and piston?

 

Yep, the 300cc kit is basically just the piston, rings, wrist pin clips and cylinder. That's all; the rest fits like a glove. I'd order all of the gaskets as well. A pumper carb will really breath some life into that set-up though. The KLX250 and KLX300sharepretty much the same bottom end.

 

Yes, the gaskets are a must - there's the head gasket and the base gasket that both need to be replaced. Like tremor38 said, you are just replacing the cylinder, piston, rings, piston pin, and piston pin circlips. Don't try to reuse any of the old parts such as piston pin and clips. I guess they would work but they are only a few dollars and it'd be a shame to have a failure because you reused an old clip that only costs a few cents.

Other than that, all other parts remain: head, cams, etc, etc. But you have to remove all that stuff to get to the piston and cylinder of course. The job is not hard, just takes some time and patience and a few tools like a torque wrench. I think it took me a good 6 hours or so, but a competent mechanic that does this for a living and is not stopping to photograph every step or refilling the coffee cup can knock it out in about half that time.

 

I don't think team green was running the stock cam profile.

 

Hi Nobrakes
I am new to the forum buisness, however I have had my KLX for a while.
I read this interesting post and started to enquire about the changes you made.
The first stumble was, no one in Australia ( that I have tried so far) has any clue about this 331 wiseco piston. Would you have any part numbers for it and all the pins and clips ?
I also checked with my dealer whom I bought the bike from and he is convinced that the botton of 331 piston will not fit into the opening of the crank case and it will have to be machined out as well. (meaning total engine $trip).
I have noticed that you have not mentioned this problem, how much clearance was there when you installed yours ?
Any help is appriciated.
Thanx

 

The piston is not a wiseco, it's L.A.Sleeve, the part number was posted above. It's an 83mm piston. The only change was to the cylinder and the engine hole was not touched, I know because it was in my garage the whole time. The cylinder was bored and all parts provided through http://www.kustom-kraft.com . I recommend you contact them for exact part numbers for all the parts.

People have been running 331cc kits on the KLX300 for years. Since the KLX250S can accept the KLX300 cylinder, the 331cc also works just fine on the KLX250S.

 

Thanks

Know what i'm looking for now.
Can the 250 jug be bored out to the 83mm piston, or do I need to buy a 300 one ?