Anybody do just the 292cc upgrade plus re-jet on their bike?
I like my KLX 250 and plan to keep it, but it would be nice if I could pick up 2-3 ft-lbs of low to mid range torque.
I always seem to find myself running back on about 15- 20 miles of Highway and the little 250 frequently has to be shifted into 5th and run at 7500 rpm to keep up.
Thoughts and opinions welcome.
Also I am cheep so I would like to keep the mods under $750.00 and do the work myself.

Regards,
Jim

 

That 300 cylinder, piston and rings sold to "mustang". I was bidding on two at the same time and won both. Then CWGOFF turned me onto the 340cc Thumper Racing kit which I will be installing soon.
I'm glad that a couple of you guys on the forum got em. Plus it saved me from having to relist them. Thanks guys.

 

Does your 340 cylinder have sleeve? The only 340 jugs I knowfor this bike have a sleeve..usually from LA Sleeve.

 

It is sleeved. Bored right into the opening of the water jackets then steel sleeved. It looks very high quality. Iused calipers to measureO.D. of both the OEM 300 cylinder and the Thumper Racing and they are exact. Came w/ Wiseco 84mm Piston, rings, pin, clips and gaskets. I noticed on their web site that theyoffer jets to go with each kit. I'll give them a call Mon. or Tue. to inquire. This kit is from www.thumper-racing.com. Whats your take?

 

My take is I'm waitingforthe install and ride report.[sm=bounceybounce.gif].

The opinion of most people that work in machine shops is that the Nikasil/electro fusion coating has better heat transfer and wear characteristics than a sleeve, but most riders of the KLX250s don't dog-out their bikes as bad as riders of bored-out ATVs, so this has really got my interest peaked.

We won't know for sure until you and other 'sleevers' have loggedsome serious miles, but my feeling is that it will hold-up just fine for most riders. Marty ishaving Bill Bluemake a sleeved 331 from the stock 249cc cylinder which will be another good test bed for those who want big bore, but want tostretch their dollars.

You guys are true 250s pioneers...my hat goes off in salute.

OBTW, I cannot open www.thumper-racing.com. It seems that the domain doesn't exist. Either that or it's another DNS issue with my Japanese ISP. I can, however, find www.thumperracingusa.com which supposedly offers a 340cc, kit, but I only see the 292 listed in their 'kit' catalogue. Their is astorein the U.K. called the dirt bike store who will let you order the 340cc kit and cites thumperacingusa as their source though...weird. I suppose a phone call would clear it up, but I'm not at the buying phase yet.

 

Yeah, as Tremor said, Marty is experimenting with having a 249cc cylinder bored and sleeved. It's my old 249cc cylinder in fact - glad to see it put to good use. If you can use your stock cylinder, that will save some folks some money in having to either buy a 292cc cylinder new or even used.

But even barring that, Iowaguy had some good suggestions to stretch that $750. But just to mix that up a little, if you wanted to try and get 331cc out of that using a 292cc cylinder, you could wait for one to come up on e-bay. A KLX300R seems to always be being parted out there every few weeks or so. Good deals can be had depending on demand, but I've seen them go for around $150. The condition of the cylinder doesn't matter too much since you are getting it bored anyway. If you can get one for that, then do the Kustom-Kraft 331cc kit, that would put your cost at $600. That leaves $150 to work on the exhaust and I think I would suggest getting a Four Stroke Works headpipe and picking up a stock KLX300R silencer and remove the butt-plug. You should be able to find a stock KLX300 silencer cheap as, like us, many replace them with aftermarket pipes. But the KLX300 guys all say the headpipe needs to go and since you are looking at improving the top end more than the bottom end, I think the headpipe may have more effect up in the higher RPM range you are looking at improving. So I think you can replace the headpipe with a FSW headpipe for that amount and pick up a cheap KLX300 silencer cheap. That would give you 331cc bore + headpipe and silencer upgrade. Then just pull the airbox lid for $0 and rejet for just the cost of the jets which is probably less than $20. The stock carb will perform just fine as long as it is jetted correctly and you drill the slide vent to 7/64ths.

If you do that, you WILL see a dramatic difference in your bike's power and performance.

 

Thanks Iowaguy and Nobrakes.
I think I am going with the 292cc stuff from Ron Ayres, at around $480.00 with shipping plus some exhaust upgarde. I do appreciate the suggestions.

Regards,
Jim

 

Try, www.thumper-racing.net. Sorry!