I've been thinking of going all out. KUSTOM KRAFT 331, WEB CAMS (RACE ONLY) with oversized valves and springs TM40 carb not a TM36-68 cams are mid top power and a bigger carb would work better I'm thinking. Any input would be good before I spend my money.

 

You're caught in the same problem as me. Big bore the KLX or get a bigger dual sport. The big bore does look promising, but a new 650 dual sport also sounds nice.

For what you are going for. Sounds like you are going all out and get the engine setup first.

 

I think the tm40 will be to big. If you want bigger than the 36mm, I would get a fcr37 from a 250mx bike. You can find some good deals on Ebay for one.

 

Get a KTM450EXC. You're taking the KLX way out of its envelope. It will become unreliable in that config...especially when you start messing with different valves and springs.

Just my take.

 

Dunno about that one Lear.....I got a ktm 640......and yeah it's got tons of power a torque...big time....but I still ride my lil bored out klx with buds on tight sugar sand trails thru trees and such....my 640 is a beast....but I do luv her...I think ya need both bikes

 

I had a 580 Predator worked awesome. If I was to buy a bigger bike thatsbigger insurance and I'd just go back to a ninja. Had an 05' 636. I perfer the looks of the klx 250s over the klx 650(and I'm a die hard kawasaki man.) I'm looking for a fun fast accelerate ride that speeding tickets will not follow. I can rip throught the roads and cops just laugh at ya. On my ninja they looked for any reason to pull you over. I'm an engine builder so I like to play with stuff. I've own nothing that remain stock. As soonas I get it home piped, strip all extra's just to the basics. Shave the weight andteak the motor. Besides It's always fun to do thing people think will not work. Once I put GM TBIfuel injection right down to the distributor on my Jeep yj with twin I beam 3/4 axles and 38 inch boggers running a bull lo with 4.10 gears. That any one wheel could come off the ground over 3 feet with the others on the ground.

I think I get just get bored easy.

 

+1

 

Bigger isn't always better in some respects. Luke Heaney with Luke's Racing did my head work and said that the valves were plenty large for the displacement I was running...331 by Marvin at KK. He did remove the eyebrows in the combustion chamber, knife edged the ports and polished the exhaust ports. Very nice work. If you haven't ridden a big bore 331 with cams yet, give that a try before you go with the larger valves. Jerry Leighton has stroked this engine too, if you really want to get radical. He seems to have good reliability with that configuration and boy will it go! I saw his stroker crank setup...very clean. Carb wise, Jerry has used up to a 39mm, but he says it's all on top with any larger than a 37. 35's ideal for most setups if you want anything in the low to mid range. It takes a lot of rpm to pull enough air through the bigger carbs to get the velocity up to snuff. These little bikes are a blast with the extra punch of a 331.

Bill Dragoo
Norman, Oklahoma

 

hey slimenylman, How's that sprocket ratio working out for you? I was thinking of running a 13/49 combo which would be pretty close to what you're running.any feedback is appreciated

 

I like it. I find a 54 t I'd like to try. Good ratio if cruising around 50 to 55 mph. It will still do a good speed full top end but I don't think it would be a good idea. I drove alot of hilly back roads. No more down shifting to get up a big hill. Very torquey. You roll in and out of corners with good power too. Makes it rev right up and move throught the gear great as well. 13 t front is small, and rubs alot more on slider and wears it out faster, that why I just change the rear only.