Hey I'll be giving the English lesson around here thank you.[8D][8D][8D] Engrish Resson......now that's funny right there. OK carry on.

 

The 250S/R was originally designed as a 300cc. Run with the 300 It can take it.

 

Yes I know it was meant to be a 300. They made it a 250 so it could meet certaion country's 250cc engine/age limits. I think yours is one of them? Anyway, I'm not worried running it with the KLX300 setup. I want to go with the Kustom Kraft 331 but worry about the bottom end of the engine. I want to do a lot of commuting as well as off-road trail running so I'll be racking up some miles. I cant find anyone who has any appreciable amount of miles on their 331 to know how it is holding together.

 

I don't think you have anything to worry about with the 331/340. There is a 365cc that is achievable by not only big boring, but then stroking the crank for a longer piston travel. That's probably the area where you might want to start looking at durability. 331's and 340's are pretty common and so far I haven't hear of any reliability concerns. Just change the oil, clean the filters, it should last through the normal maintenance intervals.

 

Hey Nobrakes,

It was thanks to your hard work on your KLX that got to this point. I was a little surprised after all that effort that you have moved on o the KTM. Thanks not only for the development, research, trial and error work you did, but thanks for taking the tim to post all that stuff back then. In regards to the 331, for as many as there are supposed to be running around out there, there isnt much data about how they are holding up. You hear about guys wanting to do them or doing them then you never hear about them after that. Or, like you, they do the work then get rid of them so the data stream stops./

 

The KLX250 basically has all the same bottom end engine parts as the KLX300, and people have been overboring the KLX300 forever. The KLX section here is relatively new, but if you check over on Thumper Talk in the KLX300 section, you'll find some old timers that have done every mod in the book and will be happy to share their experiences. While I sold my KLX331, it stayed in the family. Another member here purchased it and to the best of my knowledge it is still holding up. I only had about 500 miles on the 331 when I sold it, and that was a year ago. I'm sure Dirtsurfer has put on some pretty hard miles on it since then. But Shadetree and many others here went big bore, too and put on lots of miles. A16Tony did too, and has lots of miles, but I don't know how many he has after he big bored. Same with Finger Mullet. Too many big bores around here to shake a stick at.

And thanks for comment about my old posts. I miss doing those, actually. I always found it fun to do something "new to me" , take a few pics, and post up about it. For the more involved mods, I had an alterier motive in taking the pics - to help me remember how it goes back together. I'm just a weekend wrench so I even had to refer back to those pics a few times to make sure I put back together correctly. Also, I seem to have little mental glitch where even though I can triple check something during re-install, I'll always question whether I actually did it right afterwards when it's all bolted back together. Like when I did my 2nd big bore going from 300 to 331. I made sure I put the piston in oriented in the correct direction - there's a front and back. After it was all bolted back up, I would not start the bike until I verified through photo evidence that the piston was indeed installed correctly.



That makes me like this guy, I think:



So I guess I would not make it as a professional mechanic - I would constantly be either snapping photos or tearing apart engines that I just rebuilt to make sure I torqued that bolt, or installed that part correctly, even though I double and triple check everything going in the first time. [&:] I guess Deej isn't the only OCD case around here, mine's just a different form because I could care less if my bike stays dirty. In fact, I kind of like it that way.

 

LV...Thumper Racing parts have gone up a little since I got mine but not much I think I paid $280 in parts .... now it seems to be $314

Sleeve



$89

340 Piston and Rings



$185

Their "340" Gasket set.....I'm not sure if there is a difference froma regular 300 set...I bought their's



$40

Bill will fit the sleeve in your stock 250 for $100 last I heard So that would be a total of $414 Worth every penny.

It may be possible to just buy the sleeve from them and get the piston and gaskets elsewhere cheaper....I have no idea.

 

MartinandKTM - I wouldn't say my jetting is perfect, but yes I do mean 2nd groove down from the top of the needle (the end furthest away from the thin pointy end). I also run with the airbox lid off. My bike starts very well so I assume the 40 pilot is good, with the 35 pilot I had to wind the fuel air screw out too much.

I find the off idle to 4k rpm engine range a little woody, but from 4kup the bike pulls very hard.

I'm happy to be corrected on this, but the pilot is the easiest to tell if it's wrong or not. Wind the fuel screw all the way in with the bike running and warm. if it starts to run poorly , misfire and possibly stall then the jet is OK.... conversely, screw it all the way in then screw it out 4 turns. It should start to run pooly again at the 3 to 3.5 turn mark, which indicates it's the right size. If it doesn't run poorly screwed out a ways then you need a bigger pilot. If it doesn't run poorly screwed all the way in you need a smaller jet.

However I'm still stuck on my issue - that of woody response low in the rev range and great response up top. Perhaps I should go a smaller main and more clips down on the needle? Not sure.

 

Kbekus mine pulls great everywhere. Maybe you should lower the clip one notch to raise the needle. On mine I just have a slight hesitation when I start to roll. Then pull great at any rpm. If I blip the first 1/10 of the throttle on neutral fast a few time it will want to flood or stall. Ill try to play with the mixture screw a little bit this week-end and see if I need to got back to the 35pilot jet. I also need to check float level cause it seems to overflow sometimes. Maybe that doesnt help me either...

 

Does anybody know the actual change in the horsepower and the torque curve with each of these kits? And how much do they cost? Thinking of buying either a KLX250S or the Yam WR250 which has 50% more hp but costs $1100 more.