KLX250S (EFI) Big Bore Kit

Jan 7, 2015
17
0
1
Hi there,

Yes all these mods are the bench mark for the KLX 250S transferring a lemon of a engine into a beast. Big Bore kits range the most popular is the KAWA factory 300 kit. This is great although it will not give you the wheel popping front end. The 331 shall accommadate. In regards to pipes there are many from Thai made which work very well. Up to FMF etc.. Of course the key is the EFI controller. Keep in mind the EJK is the best in the world and all the other names like JUICE BOX are merely made by EJK and branded. I can offer you the full BACK UP service along with our head programmer in Thailand. The rest are not worth talking about sorry.
 
Jan 7, 2015
17
0
1
Yes Juice Box is manufactured by Dobeck.

The "big bore" KLX version is "new" having been developed using a Kustom Kraft kit. My understanding is that it is a KLX unit reprogrammed to be adjustable to suit the 331 kit. It will not work on a stock 250 KLX.
If you have a stock KLX unit you can send it back to Dobeck to be programmed for a 331 or vice versa. As they made the Juice Box it maybe true for a Juice Box as well.
Because you did not have it setup properly LOL.. Racing all over the world with great success.
 
Mar 30, 2010
2,136
300
83
API ECU
KLX has done 20,000 km in Thailand and Lao
80 plus percent off-road.
Went for the 300 upgrade as uses Kawasaki OEM parts.

Done by Keng in Chiang Mai.

Cheers
Brian
 
Jan 7, 2015
17
0
1
I would not use API if you threatened me to with a gun LOL. Thai crap it is. Reports all across BKK thru 45K that blown engines are right across the board. Besides that its made here LOL. Sorry call me as you may. I will stick with the best
 
Mar 30, 2010
2,136
300
83
I would not use API if you threatened me to with a gun LOL. Thai crap it is. Reports all across BKK thru 45K that blown engines are right across the board. Besides that its made here LOL. Sorry call me as you may. I will stick with the best

Very willing and happy owner of API.
I know loads of people with API and never missed a beat.
Second generation API on my current KLX - 20,000 KM mostly off-road speaks for itself.
The other KLX I have at least 15,000 km with the first generation API.
Only engines blowing up I know of are from Big Bore jobs done incorrectly.
None of them were using API.. But the 'Best' from the USofA...
Not your best.. but some other Best in their self indulgent opinion.

I wont call you, as I may get banned.. LOL.

Cheers
Brian
 
Last edited:

primo308

New Member
Apr 26, 2017
1
0
1
44
Japan
Hi Guys i have been struggling to find a definitive answer to the EFI KLX250 big bore.
after reading so many threads here and on other places from the pieces of information i have what i think is the only big bore combination for the KLX250 EFI , But im after input as to who has this combination and does it work without issues
EFI KLX250 to 331
Kraft 331 kit or Bill blues 331 kit
Dobeck Fuel controller (Juicebox) to suit the 331 kit
is this all that is required to do this conversion to 331 ? is it all that is required ?

thanks to all who comment and previous comment that helped me to come to this conclusion
I know a lot of people have said the PCV works but i don't want to go that route as from what i read the dobeck controller should work best.
anyway please let us know your results and outcome with using the above combination.
 
Mar 30, 2010
2,136
300
83
Hi Guys i have been struggling to find a definitive answer to the EFI KLX250 big bore.
after reading so many threads here and on other places from the pieces of information i have what i think is the only big bore combination for the KLX250 EFI , But im after input as to who has this combination and does it work without issues
EFI KLX250 to 331
Kraft 331 kit or Bill blues 331 kit
Dobeck Fuel controller (Juicebox) to suit the 331 kit
is this all that is required to do this conversion to 331 ? is it all that is required ?

thanks to all who comment and previous comment that helped me to come to this conclusion
I know a lot of people have said the PCV works but i don't want to go that route as from what i read the dobeck controller should work best.
anyway please let us know your results and outcome with using the above combination.
Not really much help. I know a couple of people went down the path you list above and only had problems.

So I stuck to basic. 300 oem parts with api ecu..

If you are open to alternatives with big bore and more cc.. speak with keng yuttana.. his name on Facebook. May be has a local solution that will meet your needs. He is in chiang mai. But can sell and send you what ever you need.

My 300 kit from him has been working great.. you might want to look at a larger fuel tank too if planning any big trips.
 
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