KLX250S (EFI) Big Bore Kit

Discussion in 'Technical' started by johnnysneds, Jan 12, 2011.

  1. johnnysneds

    johnnysneds Ol'Timer

    Hi All,

    Has anyone fitted the 351cc big bore kit to either their KLX or D-Tracker. Im currently following up on previous intentions to research and possibly c/o the upgrade to my KLX.
    Have been in contact with Bill Blue in the states and he tells me that he has supplied x3 kits to Thailand, see below feedback from him:

    Hey Johnny,

    I have sent 3 351 kits to Thailand last year some of the people are using the Two Brothers Juice box to modify the injection system some have used other systems. No one has let me know how the 351 kit works with the EFI.
    You will need to send me your cylinder I dont have any cylinders to build the kits with it takes me 2 days to build the 351 kit from start to shipping.

    351 kit is $527.45 + shipping & insurance.

    Im very interested to know the outcome, if its reliable or not. Have read some positive feedback on Thumpertalk, also some negative.
    If anyone has any info I would really appreciate some feedback/details.
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  3. LivinLOS

    LivinLOS Ol'Timer

    There was (if my memory is right) 100% success reported with using stock injectors, a 2 bros juicebox and the 332 big bore..

    There was a lot of debate on if the 352 would be possible with the stock injectors and one of the posters indicated they bored out the stock ones. From memory that poster also ran dirtbike tours in northern Thailand.

    This was discussed in some depth on thumper talk, but I am guessing you have found those threads. Seems it was not simple but the juicebox may have new 'fixed' mappings.
  4. johnnysneds

    johnnysneds Ol'Timer

    I believe Juice box have remapped their unit specifically for the 351 kit. Thats my next move to contact them for further advise. Would be good to hear from the guys who have actually done the conversion and hear first hand how they got on. As per the email from Bill Blue if I go for it ill have to send my cylinder off to him for the modification so trying to find out as much info as possible before hand. This conversion on the EFi model was pretty hot 6 months or so ago, but it seems to have faded away, possibly due to issues with the conversion.
    Anybody have a KLX cylinder head they want to sell??:shifty:
  5. Ian Bungy

    Ian Bungy Ol'Timer

    Neither of the 3 Kits supplied to Thailand worked successfully! I know all three Guys and 1 had His Gudgeon Pin Clip come off or some such thing so that was the end of that! The other 2 are still trying to get theirs to Run Properly after spending a Small Fortune on parts including a Custom Injector!!! I have heard that both Two Brothers and Power Commander are in the process of making products especially for the Injected KLX but haven't heard any First Hand reports Yet? At this Stage I can not see it is worth doing until Some Techno Wiz sorts it all Out? The One Guy who had the Misfortune of Engine Failure actually had His Running the Best before Disaster struck but His Total Fuel Range was only 100kms so not very Practical and I doubt the Performance Gain is that great! Might Be Better to Buy a Bigger Bike and probably cheaper? Good Luck!
  6. johnnysneds

    johnnysneds Ol'Timer

    Thanks for the update Ian. Your comments pretty much say it all. From what ive read, and im talking about the minority who have supposedly got there kit running correctly, it was through the proper mapping of a juice box and the likes. None of them, again allegedly, changed the injector, as the EFi/ECU/MAS compensated for the increased volume and stated that the stock injector will suffice.

    This is a quote from someone who got there's running sweet:-

    Just an update on my bike. Budiman received a new program from 2Brothers on their Juice Controller and it works great! I have the 331 Kustom Kraft kit with a Web Cam 101 cam, open snorkle on the air box, large header pipe and 2 brothers M7 Vale exhaust. It would never idle before but is idling fine now. I have purchased the Power Commander V and will probably install it later just to see how it works. The Jucie Controller is working perfectly at this point.

    Johanklxindo - you may have a problem with timing. I've not heard of anyone having this problem but the heat buildup would suggest that along with some of the other issues you seem to be experiencing. You need to check your camtiming closely to make sure something didn't go wrong when the new top end was installed.

    I'm very, very pleased with the way my bike is running.

    The thread dies shortly after this...Note the guy has replaced the cam, im sure its a case of having the correct fuel mapping for whatever cam you have installed. Also interesting to note he managed to purchase a PC V for his bike, but there was no further feedback on whether he fitted it. If the PC V is available (wasn't the last time I checked) it has a self tuning mode which might assist in the mod.

    I tried out a box from Italy called a memjet module. Which made a massive difference along with a fmf custom pipe/header. The bike did a 3rd gear roll on test against a stocker and it pulled away quite significantly. Basically what it does is adjust/amplifies the Air Intake signal so that the ECU will give the engine better ignition and injection mapping. It has a dial and is manually adjustable to suite. Easily installed and removed. I was in contact with the developers of this module a while ago and the subject of using this along with a BB kit propped up, they did indicate that the Memjet should be able to assist with the fueling/timing with a BB kit. And because its easily adjustable manually via the dial it removes the need to have a specific map.
    It is all pretty much experimental at this stage with the EFi models but there are loads of success stories with the carb models. A case of getting the correct fuel/timing combinations, but as you rightly indicated this usually becomes expensive when you experiment with these sort of things.

    Ian would it be possible to PM me the details of the guys who are attempting the upgrade to see if there is any assistance I can lend? The more people who bang their heads together on this the quicker we get results and maybe we all can benefit from it eventually.


  7. mikerust

    mikerust Ol'Timer


    According to Matt at Dobeck they have used their EFI units on big bore kits with good results but he has yet to send me any suggested settings. I have asked but obviously the first time my question was not correctly worded!

    It would be like buying a carburettor and a set of jets. But adjustment is easier.
  8. johnnysneds

    johnnysneds Ol'Timer

    Hey Mike,

    That sounds promising. Just checked out their website and will investigate further. Thanks for the info.

    Please let us know if you receive any feedback from them.

  9. mikerust

    mikerust Ol'Timer


    I should be upfront ( one post too late! and now I've changed my avatar) and tell you I am the Thai distributor for Techlusion / Dobeck.

    For Thailand we are developing units for PCX and the new Honda 250 in addition to offering the units for other bikes.

    Matt said he would look in his "black book" and send me the settings he has for KLX big-bore kits. I also spoke to him on Friday but alas this morning there was no info in my email inbox.

    The standard unit for a KLX will be able to do the job but I want to be able to tell you what settings to use rather than just suggest a "blank canvas" and following say an Amal carb. tuning procedure.

  10. Maha

    Maha Ol'Timer

    One way to have tested big bore kit, is to use Beet parts from Japan. They have complete 315cc cylinder, 11.9:1 piston, camshaft, new fuel controller and new injector available. According to them all tested to make sure the package works.

    Unfortunately all the related info in their web page is in Japanese: http://www.beet.co.jp/kawasaki/klx250/index.html

    But you can use Google translator to translate it and they seems to answer in English emails as well (at least I got an answer confirming that the 315cc kit is tested with the FI model with the IconII and new injector).

    They have English page too (http://www.beet.co.jp/english/kawasaki/klx250/index.html), but it is only covering the carburator model and not updated to FI model (so please read the Japanese page for FI info).

    Attached is the product catalog (sorry, could not attach pdf file for some reason so converted to jpg. Get the original pdf from their web page) for the 315cc kit and Icon II fuel controller. Prices are:
    - 315cc cylinder & special light weight piston 92190 yen (plus shipping). Note that you need to buy KLX 300 gasket set (cylinder head gasket etc) from Kawasaki as Beet don't include them.
    - Special cam shafts 42000jpy (plus shipping)
    - IconII fuel controller with ready curves for 315 kit 59850jpy (plus shipping)
    - New injector to work with the 315cc kit 13650jpy
    - (IconII + injector combo 72450jpy if bough together...)
    - They also sell their own exhaust that is bloody expensive, but I guess anny aftermarket pipe would do
    - They also recommend engine oil cooler to be used with this which is another expensive item
    - Total would be then: 206640jpy which is about 78500thb

    As you can see from the brochyre, they have dynoed the package for 30hp (vs standard about 22-23hp).

    Here is the google translation of the 315cc kit brochyre:
    "Includes: pistons, piston pins, piston rings, cylinder sets, pink lip
    - Plated cylinder is not included in the sleeve (Seramikkukonpojittomekki employed) and durability, 計Rimashita, may increase reliability.
    - Forged pistons melt 81φ things, our original design and development to optimize the new profile.
    Lighter than conventional forgings (78φ casting molten metal forging Akira Makoto = 202.3g BEET 81φ = 203.9g), the expansion rate of the genuine
    Finished products that are stronger than castings, and in parallel with the compression ratio is about 11.9.
    - 1.2mm thick, the top piston ring and second ring parts only 1.0mm thick, plated cylinder Both durability and reduced friction.
    Already released - camshaft (part number 0602-K38-tax 00 ¥ 42,000) and the muffler and BT-Motard The combination of power, can be more.

    D-Tracker / KLX250 / 300R / 250SB for
    Super SHERPA KIT for sale 292cc bore up well! [Price ¥ 88,200 (tax included) ※]
    315cc BORE UP KIT 0600-K38-Price No. 00 ¥ 92,190 (tax included) ※"

    And this is the IconII translation:
    "D-TRACKER X NASSERT 315cc bore-up Injekushonkontorora for KIT
    Kawasaki '08 ~ D-TRACKER X NASSERT Injekushonkontorora KIT 315cc bore up for KIT The new line will be UP.
    • Contents: · BLUE LIGHTNING RACING (http://www.blr-jp.com/) made by i-CON Ⅱ, a set of special Injectors
    - optional NASSERT-R muffler, we 315ccKIT, that incorporate a cam shaft, D-Tracker X Potential It is possible to demonstrate.
    · BLUE LIGHTNING RACING (http://www.blr-jp.com/) i-CON datasheets available for delivery Ⅱ
    D-TRACKER X NASSERT 315cc bore-up Injekushonkontorora for KIT Products

    No. 0678-K97-00 including tax 72,450 - (tax 69,000 -) JAN 4582346457862 Code
    No. 0679-K97-alone incidents Ekuta s 00 including tax 13,650 - (tax 13,000 -) JAN 4582346457879 Code
    I-CON 0676 alone Part Ⅱ-K97-00 including tax 59,850 - (tax 57,000 -) JAN 4582346457855 Code
    With a special harness ※
    ※ KIT This is a racing parts. Be sure to use the public highways race car parts can not be built."

    Attached files [​IMG] [​IMG]
  11. BignTall

    BignTall Ol'Timer


    When I moved to Thailand about 5 years ago my first bike was a carbed KLX 250. I bolted on a 331 big bore, pumper carb, and WebCams high lift cam. That motor was thrashed across three countries for a few years and was as reliable as a top. The big bore really gave the KLX some mid range poke which as most KLX owners are familiar, stock there is a severe shortage. Just a data point to say that I never had issues with any of Bill Blues work.

    That ole KLX is still running around with the new owner and he's thrashed through various countries as well.

    One downside that Ian touched on was gas mileage. Duking it out with Luke and his DRZ on the 1148 had me wringing its neck and gas efficiency suffers a bit.
    Luckily I had a larger 2.8 U.S. gallon plastic tank mounted that gave still gave me a 200km range.


    I know the stock tank on the fuel injected KLX sold here in Thailand is tiny and might not give you the same range if you're hammering it with the larger bore.
  12. mikerust

    mikerust Ol'Timer

    Here is the skinny straight from the horses mouth

  13. LivinLOS

    LivinLOS Ol'Timer

    Dont think its as cut and dried as that.. ALSO direct from Bill..

    I hardly call that a ringing endorsement.
  14. mikerust

    mikerust Ol'Timer

    Oh well not good news for anyone with an FI bike that wants a big bore kit. Until we learn more the only option seems to be the Japanese kit which appears to come with a bigger volume injector.
  15. KLX331 Crazy

    KLX331 Crazy Active Member

    Gents, have installed a 331 Kustom Kraft big bore kit to my 2010 KLX and it hammers but I must add that I also included a few other options, ie Barnett clutch plates, 2 Bros full carbon system, BEET race cams and oversize injector, 2 Bros Juice Box and then I had the head ported and polished. Almost forgot the silicon rad hoses.:wink:

    I also changed the gearing from standard and am now running a 48 rear with a 14 front, the thing will lift the front end easily in 1st and 2nd and with a bit of help 3rd. No difference to top end speed but it gets there a whole lot quicker. Bike is used around 90% off road, I dont like that black stuff.
  16. bill

    bill Ol'Timer

    Roughly, what did the engine mods and pipe cost ?

    I guess with all those mods it would be up to 30 horsepower now ?
  17. KLX331 Crazy

    KLX331 Crazy Active Member

    Bill, all up not cheap, all pricing in US$, the pipe around 720, big bore kit 1000, cams around 500, oversize injector 150, Juice box 270. Dont know what hp it is producing but the torque is much better.

    All up with everything probably just over 3000.
  18. Aki Anis

    Aki Anis Member

    So how much this set up cost you? Thanks.
  19. KLX331 Crazy

    KLX331 Crazy Active Member

    Gents, Just an update, I have now updated the bike and am running a Power Commander 5 & AutoTune setup. The setup works ok but the bike hesitates down low, mainly when I go from no throttle to open throttle. Does anyone else run this setup and can you share your AFR maps?

    I will try manually modifying the AFR maps but if someone has one tuned on a dyno, I would appreciate a copy of there AFR maps.

    Reminder: 331 kit, Beet cams, Beet oversize injector, 2 brothers big bore carbon fibre exhaust and ported and polished head (standard valves).
  20. Tom Forde

    Tom Forde Ol'Timer

    Hi all, with all this high tech performance, what are you using your KLX's for?
    By the sound of it, it is fast hard core low and mid range dirt riding or motard racing?

    If so, fuel range isn't an issue. (you probably take it to your designation on the back of a pickup.)
    If you intend to do some travelling you have a real problem, no one is manufacturing a larger fuel tank for the fuel injected KLX at the moment.
    This is because of the metal pressured tank and built in pump, which incidently weighs in at 5kg empty, and costs 7000bht and 8000bht respectively.
    So you may need to carry additional fuel on your rear rack.
  21. mikerust

    mikerust Ol'Timer

    Dobeck now have a TFI unit for the 331 conversion. it was developed using a Kustom Kraft kit.
  22. KLX331 Crazy

    KLX331 Crazy Active Member

    I believe that the Dobeck and Juice box are the same item, tried the Juice Box and it wasn't a real sucess.
  23. KLX331 Crazy

    KLX331 Crazy Active Member

    Tom, fuel not an issue, pleanty of road side shops selling fuel, even in the middle of the jungle :). Depending on the riding can achive over 120 km's per tank.
  24. mikerust

    mikerust Ol'Timer

    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.
  25. Tom Forde

    Tom Forde Ol'Timer

    Sorry KLXcrazy, fuel is an issue, I have done alot of km's in LOS if you use the KLX for what is designed for the quality of the 'fuel' out of 44 gallon drums will be a lottery.
    With your fuel injection bad fuel will really play up with your filters and minimum gas rating.

    A few years ago I rode from OZ and the Chinese boarder and return.
    My fuel injected BMW only had problems in small towns with 44gal. drums with pumps or beer bottles full of 'petrol'.

    Best of luck on you 100-150km fuel stops. Especially with a hotted up motor, even less km's/km.
  26. KLX331 Crazy

    KLX331 Crazy Active Member

    Gents, just a bit more information with the installation of the PCV and AutoTune units. Initially had a major problem with the bike hesitating and running ruf just off idle, thought that it was the PCV unit that was causing the issue. Found out after much thought and experimenting that it was actually the throttle position sensor that was causing the issue. The standard setting allows the butterfly to open without injecting fuel thus the bike leans off and in some cases will actually stall. Just adjusted up the sensor, so when the throttle is openen of the stop then fuel is injected, everything works perfect.

    This is a common problem that I see with many KLX riders, bike stalls when coming off idle, check the throttle sensor adjustment and this will fix the problem. I used the PCV and software for adjusting the sensor but others may have to get a proffesional to check the adjustment on there bike.

    Cheers and good riding.

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