KLX to KLF conversion???

[Curtis]

Wondering if anybody has fitted a KLF300 barrel to a 81 KLX250 before?? I believe they are a very similar engine. Or if anyone has any info on what may be required?? same old story on trying to get the little green machine to pull a bit harder. Cheers!!

[cyclegod]

I think you might have to machine the cases to make room for the sleeve to fit.

[TT5 Matt]

don't bomb it out too much as they have got a glass gearbox,for more info ask gmc

[Curtis]

mmm...yep machining the cases Id assumed that much. and yes iv heard the gear boxes dont like much more power. But surely if you dont abuse the box it can take another 50cc.

[FourstrokeForever]

Stick a big bore Honda motor in it.....that will get it going 

[Slakewell]

Use an XR 200 engine , slightly more power with alot less weight

[grouty]

I looked into this a while ago. I think I posted up pictures of the KLX and KLF base gaskets. From memory it is probably on the "Shared Disease" thread.

The barrel will fit with a bit of fiddling. I cannot remember if the cases need machining or not. The stud pattern is the same, but the dowels are different. A better solution would be to fit the KLF liner into a KLX barrel, providing the machining needed to fit it does not break through between the fins.
My KLX has been running at 270cc for a number of years without any problems. I use a Megacycle cam, and an MTC drag bike piston.  This has given me a bottom end similar to a XT500 ! ! Pulls like a train. It revs well too, but I need to sort the carb out (read - Lectron). I also use a bespoke 1"1/2 exhaust.
It depends on what you want to do with the bike. For trail riding and the odd Vinduro the 270 conversion is plenty. Ideally it needs stroking along with a bigger bore. I have never bothered as I have other bikes that fit that bill if required.
If you need pictures, just shout.

[cloggy]

 Everyone goes on about the motor, I think the KLF oil feed to the head is different. The original motor is  pathetic but it doesn't need special fuel and runs fine for trail riding as long as one sorts out the head. There is the megacycle mod, the roller bearing cam and the option of phosphor bronze bushing the big cam journal. Grouty did the first, I have examples of the second and third.
  I've spent money on suspension. Cartridge emulators in the forks and Red Rocket Ohlins on the back. Lastly I might try  heavier fork springs. Even after cutting the most coils one can get away with the forks still need about 5psi. They are so soft standard they were said to need  20.
  The brakes are truly pathetic but I don't know if any of the KDX versions had bigger interchangeable drums. Kawasakis of that era are pretty horrendous for parts in the UK.

[80-85 husky]

kdx brakes disappear at the first sign of a cloud in the sky....in the UK, they would work about 3 days a year in June....

[GMC]

From memory you could bore to 270 but you had to resleeve for the 290 kit and machine cases for the bigger sleeve
I went the 290 kit and I broke my gearbox (case exploded as well as gears ) but to be fair I was flat shifting all the time trying to keep up with mates on 2 strokes

While memories become twisted over the years I don't reckon it was worth the cost, while it was more grunty it didn't seem that much quicker.

I bought a KLX project recently so may revisit all the dramas but I have other projects in the queue first