Turning a KLX250, into a KLX300

Moto-Rex

Moderator
Jan 5, 2008
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This article maybe of interest to those that want a little more power out of there KLX250.

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Moto-Rex
 

Kaelixke

Member
Oct 9, 2009
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::J:: wrote: would love to have more infos on turning a KLX250 EFI into a KLX300 EFI
That has no sense! It costs TOO much, so you better buy a 300 - 400cc or more for the same total price. Believe me! 8)
 

::J::

Member
Mar 10, 2008
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Ok, can you just give an exemple of a 400cc supermoto officialy available in Thailand and it's price ? :lol-sign:

And i'm not even talking about those imported and rebuild DRZ400 with greybook.
 

Kaelixke

Member
Oct 9, 2009
15
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::J:: wrote: Ok, can you just give an exemple of a 400cc supermoto officialy available in Thailand and it's price ? :lol-sign:

And i'm not even talking about those imported and rebuild DRZ400 with greybook.
I know, I know ...
Here in Belgium, it 's the same problem with restricted bikes.
But the "old" DR 350 and DR 400cc can be "prepared" in a easy way. The total cost is affordable and you have a powerfull bike for a very honest price.
If you are satisfied with the KLX250 S FI like the bike is and you can find a good performance ecu set, you are a happy driver ...

I own a KLX250 S FI 2009, but finding a GOOD and RELIABLE performance ecu set here ... ??? :cry:
 

dirthonk

Ol'Timer
Jun 21, 2006
408
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Rexy, I reckon you've got one of those kits in your luggage, after all after 40,000 odd kms you're probably due a fresh top-end!

I
 

Moto-Rex

Moderator
Jan 5, 2008
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dirthonk wrote: Rexy, I reckon you've got one of those kits in your luggage, after all after 40,000 odd kms you're probably due a fresh top-end!

I
The more KMs you do on them, the better they seem to go.

So Ill wait till its "run in" before I consider any modifications.

Cheers Rex
 

alrikki

Ol'Timer
Aug 29, 2008
255
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is there a good reason why the klx 250 barrel cannot be bored out to take the klx300 piston?
btw my 330 barrel has a sleeve
 

NN

Member
Oct 29, 2009
20
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^ As far as I know the barrel can be bored out to take a klx300 piston. The problem is the EFI. I was wondering about buying an older carb version, this would make the upgrade much easier. From what year did they start making the KLX250 in Thailand? Has the carb version every been made here?

From what I've read the earlier versions were lighter and more off road orientated.
 

bill

Ol'Timer
Mar 29, 2004
295
3
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Interesting link
Reading that thread and a few others, it seems 26+hp might be achievable with 2brothers juicebox, 330 big bore, open pipe, and cams.

Cost is the next issue
B&B 331 Big Bore kit $487 http://bandbcyclerestorations.com/page_4.html
2 brothers Juice box $300 http://www.twobros.com/cgi-bin/shopper? ... ey=008-171
Webcam Hotcam pair $320 http://www.webcamshafts.com/index_blank ... earch.html
Open exhaust. Local made ? $300 ?

SubtotalTotal $1137

New bike cost $4500
Say another $200 for decent bars, wide pegs and skid plate.

Total $5837 for a reasonably powerful, brand new, fully legal dirtbike

Alternatively, save a few hundred by starting with a low km used bike.