KLX250S (EFI) Big Bore Kit

Aug 29, 2008
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mikerust;275481 wrote: 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.
Did it have to be sent to USA or can it be reprogrammed in thailand? My juicebox looks similar to the dobeck one
 

mikerust

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Nov 5, 2003
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alrikki;278297 wrote: Did it have to be sent to USA or can it be reprogrammed in thailand? My juicebox looks similar to the dobeck one
I can but ask.

Yes it will have to go back to US.

Technically Juice Box is a "private label" and under a private label agreement tech support is the responsibility of the vendor in this case TB.

IF Dobeck are willing to do it there maybe a small charge.
 

mikerust

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Nov 5, 2003
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Reprogramming is at no cost but the unit must be returned to the US. You may either do that yourself or for a 100B or less you may EMS it to me and I will look after it and let you know the cost.
Please remember that once reprogrammed to run correctly on a 331 kit it will not function as designed anymore on a stock 250.
 

saxonator

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Jun 1, 2003
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I just spoke to Paeng yesterday, a good old friend of mine. He is able to bore out any KLX to 300 cc, first I didn't believe him, then I took a test ride on a modified KLX, that belongs to him, this thing just pulls like a hammer, Christoph another friend of mine from France has been using this bike for touring around with groups and so far it never let him down. I think Paeng can do the job just under 10 k, everything else is just stock, but the performance is still remarkable, he make his own sleeves. Paeng is located just opposite Gymkhana Club - there's a small sign with a motorcycle sign on it. Don't know how good his english is but, I think he will be more then happy to receive you.

Paeng used to be Moto Cross Champion of Northern Thailand in his young years
 
Apr 20, 2011
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hi, i rode christophs bike a few months ago and was very impressed, i have been told that it has gone bang since!!! be careful! Paeng is a nice guy and will do his best but this is a minefield
 
Apr 8, 2011
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saxonator;280120 wrote: I just spoke to Paeng yesterday, a good old friend of mine. He is able to bore out any KLX to 300 cc, first I didn't believe him, then I took a test ride on a modified KLX, that belongs to him, this thing just pulls like a hammer, Christoph another friend of mine from France has been using this bike for touring around with groups and so far it never let him down. I think Paeng can do the job just under 10 k, everything else is just stock, but the performance is still remarkable, he make his own sleeves. Paeng is located just opposite Gymkhana Club - there's a small sign with a motorcycle sign on it. Don't know how good his english is but, I think he will be more then happy to receive you.

Paeng used to be Moto Cross Champion of Northern Thailand in his young years
Kawasaki still sell the original KLX300 cylinder, may be a better option than boring the bike oversize and you can also get the gaskets, piston & rings.
 
Jul 15, 2012
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saxonator;280120 wrote: I just spoke to Paeng yesterday, a good old friend of mine. He is able to bore out any KLX to 300 cc, first I didn't believe him, then I took a test ride on a modified KLX, that belongs to him, this thing just pulls like a hammer, Christoph another friend of mine from France has been using this bike for touring around with groups and so far it never let him down. I think Paeng can do the job just under 10 k, everything else is just stock, but the performance is still remarkable, he make his own sleeves. Paeng is located just opposite Gymkhana Club - there's a small sign with a motorcycle sign on it. Don't know how good his english is but, I think he will be more then happy to receive you.

Paeng used to be Moto Cross Champion of Northern Thailand in his young years
Do you have any more info on Khun Paeng? contact info? also does anyone have first hand experience?
 
Aug 29, 2011
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I just hit the 5000km mark on my Kustom Kraft 331 big bore kit on my D-Tracker!!

Tuning:
Finding the sweet spot between running to lean & to rich have been problematic at times but for the majority of the time the bike has been running great & a whole heap of fun with enough torque & power to make it all worth while.

Engine:
The big bore engine has been very reliable so far, with a smooth, quiet & vibration free action. The bike is generally riden pretty hard & occasionally I ride it like i stole it!! The bike always gets warmed up before riding fast & gets very regular oil/filter changes. (Between 700 to a 1000kms) with quality low priced oil. To ride such a bike slow & sensibly would be a crime, of course the engine could go bang tomorrow but so could a stock 250 engine that regularly hits 10,000rpm!!

My best advice is to avoid copy parts & local mechanics!! Trained farang mechanics with years of experience are a super rare commodity in Thailand.....:p

Questions like, was it worth the time & expense??? HHmmm

Would you do it all again with hindsight??? HHmmm

All very difficult questions to answer because if I was back in my home country I could have bought a cheap KTM 690 or a Husky 610 so easily........But I live in Thailand & what I do have is a road legal very fast & fun to ride 2011 330cc Motard with a green book in my name, for less Bart than a high mileage 7 year old DRZ400 which usually have dubious green books in my experience.

Is the bike a blast to ride & does it have the grin factor??? Yessss
 
Aug 29, 2011
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A big thank you to Dobeck (EJK controllers) for re-programming an old 250 Juice box to a 331 MAP that I had in my possession! All for free, just post it to them in the US & they do the rest.
Me & a fellow D-Tracker have also got a Power Commander 5 to play with as well. Will be good to do some back to back testing on these controllers.

I'm hoping to ditch the APi unlimited ecu box & use something easier, with more user friendly features & better after sales technical help.
 
Aug 29, 2011
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alrikki;282298 wrote: so you're running the 330 with just a juicebox?
The Juice box (made by EJK) after re-programming just plugged & played 1st time with perfect idling & low end power. A tiny power glitch/hesitation @ 5000rpm & could do with a little more richness from 8000-1000rpm. I haven't even tried tuning thing yet & it runs very well out of the box with the stock ecu with clutch bi-pass!! To easy

The power commander V is also very easy & works great! Looks like anyone can stick a big bore on a D-Tracker now.
 
Dec 4, 2012
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I've got power commander V with auto tune ready to fit. Wondering if anyone has done same install and has tips on where to fit lamda sensor to FMF power bomb header. Also any tips on initial setup. Seem to remember someone posting on here or maybe another forum. Could have been Joelthailand.
 
Aug 29, 2011
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jimmyklx;287193 wrote: I've got power commander V with auto tune ready to fit. Wondering if anyone has done same install and has tips on where to fit lamda sensor to FMF power bomb header. Also any tips on initial setup. Seem to remember someone posting on here or maybe another forum. Could have been Joelthailand.
(I posted this on another forum, so easy for me to copy & paste here for you)

PCV is very easy, especially if someone with same setup passes on their MAP to you! Easy install & easy to use!

The Autotune (AT) is a completely different animal:

1. quite complicated to install - lots of wiring etc etc (crap instructions) & stuffing the PCV & Autotune all under the seat is a mission in it's self!! Can be done though. AT has to be this close to the PCV !!

2. your stock 02 sensor bung thread is to small & the larger bung supplied with the AT will need welding in.

3. The new Bosch wide band 02 sensor is way bigger than the stock sensor & you will have trouble finding a good spot to weld the bung. Take your time working out a place not to exposed but away from airbox plastic. (will depend on your exhaust....FMF was tricky)

4. Small single cylinder bikes are hard to tune with Autotune at low revs....just not enough reliable gas from a 250 engine for the AT to sniff for accurate readings. It will eventually work but will take way longer to fine tune than a large cylinder engine!! The 331 or 351 will work better for this reason.

5. Expect to take a week to really get you head around setting AFR's & trimming MAPS with AT & maybe a month to get really good with the software.(If your only playing for a couple of hours at a time or at weekends etc). Your gonna be doing hundreds of KM's of steady revs test riding for you to eventually get to the fine tuning side of a quality homemade MAP. No detailed video tutorials on the AT unit anywhere on the net!!! that I could find.

6. The on/off isolator switch was not suggested in the instructions. The instructions recommend taking a power feed from the rear light loom (which I did), so then the AT comes on with the ignition. With my isolator switch I can now turn off the AT when I don't want it on! When the isolator is off I can use a water-proof switch on my handlebars to toggle between MAP1 & MAP2 on the PCV.

BTW my low rpm @ 0, 2, 5 & 10% throttle position was set at a target 13.8 AFR (not to rich or to lean) & my higher rpm @ 15, 20, 40, 60, 80 & 100% TP was set at a target of 12.9 AFR for maximum power with the Auto Tune. It is still pretty good on fuel even at that the 12.9 Air fuel ratio AFR. Any richer than that & the engine bogs down sometimes & crispness of throttle is lost.

This is my mess under the seat!

287214=14696-pcv%20install%20(Small).jpg


This is where Bob from Indonesia fitted his 02 sensor.

287214=14697-bob%2002%20sensor%20(Small).jpg


This is where I fitted my 02 sensor.

287214=14698-02%20sensor%201%20(Medium).jpg


A helpful little video:

Good luck ;)
 
Dec 4, 2012
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Cheers for reply. Not home for another 3 weeks but plan to get stuck in as soon as I can.
On a different note why on earth does Dynojet supply a mild steel bung for O2 sensor when all aftermarket systems (and most OEM) are stainless or titanium?????
 
Dec 4, 2012
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PCV & Autotune fitted and running well, bit of a drama welding O2 boss because Girlfriend sent me to someone who could 'weld anything'. Could've done a better job myself with a soldering iron and some chewing gum.
Anyway, just got to get to grips with maps and should be fine.
 
Oct 20, 2012
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I have just put a deposit on a 2nd hand 2011 klx250. I havnt got a clue what you fellas are on about for the power mods.i am in mexico now and can get my mate in America to bring me the kit to me in mex so i can just take it home to thailand.
Do i need to take the cylender off my bike.and is there anyone in thailand i can give the bike to so it comes back all sorted.
How much dyou recon it will cost.ide like the 331 kit
Thanks guys ime not mechanical at all
 
Aug 29, 2011
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jimbobs;288969 wrote: I have just put a deposit on a 2nd hand 2011 klx250. I havnt got a clue what you fellas are on about for the power mods.i am in mexico now and can get my mate in America to bring me the kit to me in mex so i can just take it home to thailand.
Do i need to take the cylender off my bike.and is there anyone in thailand i can give the bike to so it comes back all sorted.
How much dyou recon it will cost.ide like the 331 kit
Thanks guys ime not mechanical at all
http://bandbcyclerestoration.com/ 331 kit is cheaper. A sleeved klx250 jug. About $550

http://kustom-kraft.com/klx250bb.html 331 kit is more but it's a nikasil plated bored out klx300 jug. About $800

If your not mechanical minded or into tuning...DON'T get a big bore kit.

Be prepared to do a lot of tinkering to get a BB kit running well. It's shouldn't be to difficult with a PCV + Autotune but still won't be easy! My 331 PCV MAP will be close to what you can use but not perfect & then let the Autotune fine tune it for you.
 
Dec 27, 2007
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To add to the list, the time tested and much loved Bill Blue 351cc big bore kit for the KLX costs about $530.

http://bandbcyclerestoration.com/

Bill also makes 300, 331 and 340cc big bore kits for the KLX 250.

The FI bikes we get here in Thailand apparently can not be tuned to fuel such a large increase in displacement as the 351, so if you go that route you'll need to get rid of your FI and upgrade to an old school carb.

The KLX 351 will run fine with standard carb but Bill recommends the Mikuni TM33 which adds even more punch.

I'm super-happy with my KLX 351, it's got ~14,000km on the clock now and goes like stink.

MyKLX351a.jpg

Let the Good Times ROLL!

Tony
 
Oct 20, 2012
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Bloody hell Joel youve just depressed me there, the standard KLX is awfully underpowered, thats the reason why i have gone for the klx to get the big bore, i was looking at the 351 like Tonys but i thought that would require a modicam of knowlege ,i was not expecting any troubles with the smaller kit.
Have you any ideas how i could get around this problem , i am in the sticks so a good mechanic will be hard to find who will know about mapping tuning etc, i would not mind paying to get the bike sent to bangkok or where ever to be fitted and tuned is this a viable option, or will it need looking at regularly.
Once again thanks for your knowledge guys
 
Aug 29, 2011
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jimbobs;288976 wrote: Bloody hell Joel youve just depressed me there, the standard KLX is awfully underpowered, thats the reason why i have gone for the klx to get the big bore, i was looking at the 351 like Tonys but i thought that would require a modicam of knowlege ,i was not expecting any troubles with the smaller kit.
Have you any ideas how i could get around this problem , i am in the sticks so a good mechanic will be hard to find who will know about mapping tuning etc, i would not mind paying to get the bike sent to bangkok or where ever to be fitted and tuned is this a viable option, or will it need looking at regularly.
Once again thanks for your knowledge guys
Sorry Jim didn't mean to depress you,

To do what Tony has done with a 351 kit with ripping out the EFi & fitting a carb is a job for a very good & creative mechanic!! be warned....

To go down the 331 road with EFi is a much easier option imo.

1. You need a Kawasaki or a competent mechanic to fit the big bore kit! Fit an aftermarket exhaust & open the airbox up with a bigger snorkel etc.

2. Fit the PCV & Autotune. A good 2 or 3 hours work to do properly.

3. Block the clean air system from the PAIR valve into the cylinder head. Or your Autotune will NOT get correct gas readings.

4. Load my 331 Map into your PCV & set Autotune to make/tune your own MAP that suits your engine & mods. DONE!

Not to difficult but pretty time consuming. You can do it Jim with some patients & it will be worth it. :thumbup:

Five months after using the PCV i'm still farting about with different target AFR's in Autotune & fine tuning my MAP!! It is very addictive getting my bike running faster, faster & smoother, smoother etc etc. Just when i think it can't get it any better I try a different AFR or a new riding technique that gets better results from the Autotune & bingo it's pulling the front wheel up off the throttle even easier!! :smile1:
 
Oct 20, 2012
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you dont fancy a working holiday in Issan do you Joel ha ha , thanks mate youve give me something to think about, the versys ive got is ok on journeys but for pottering around the village and the dirt roads in the wet its abit heavy, also i wanted to see cambodia, loas etc and the klx/ crm seem to be the vehicle of choice.

I dont pick the bike up untill the 1st of may when i get back to Thailand so i will look around to see what can be done, thanks again for your help, ime just a thick construction guy who likes to thrash motorbikes, ive never changed a spark plug.Time to man up and start looking at this character flaw haha,,,
Nice one
 
Dec 27, 2007
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Joelthailand;288977 wrote: Sorry Jim didn't mean to depress you,

To do what Tony has done with a 351 kit with ripping out the EFi & fitting a carb is a job for a very good & creative mechanic!! be warned....

To go down the 331 road with EFi is a much easier option imo.

I would respectfully disagree on this point Joel. Setting up a carb can actually be a lot easier than tuning fuel injection on a modified engine.

There are tons of detailed write ups and guides on various forums that take you step-by-step through the installation and set up of the Bill Blue big bore kits. I've never searched but assume that there are plenty of guides for the Kawasaki OEM 300cc big bore kit as well.

Armed with the KLX service manual, proper tools and a good installation guide I reckon just about anyone could install a big bore on their KLX 250.

Here are some of the best instructions / installation guides I've found:

http://www.kawasakiforums.com/forum/klx-250s-71/351-mod-31703/

http://www.kawasakiforums.com/forum/klx-250s-71/bill-blue-351-install-pic%92s-links-32538/

http://www.advrider.com/forums/showthread.php?t=405545

FYI, API claims to have an aftermarket ECU can fuel KLX Big Bores all the way up to 351cc, but as Joel mentioned, tuning these units by yourself is quite tricky-


The API ecu allows you to adjust fuel ratios and ignition timing-
271468_242166972469814_100000295404285_1008420_669  6921_o.jpg


267137_242166929136485_100000295404285_1008418_127  652_o.jpg


Considering that the API software interface is still only available in Thai (I think?) and requires quite a bit more "fiddling" I personally think that setting up a carb is WAY easier!

Another option would be to take your bike to API and have them install and tune the performance ECU for you. You can find contact info for API on their website (ask a Thai for help if you can't read Thai) http://apitechonline.com/

:happy1:

ps. I see that Joel already did a write up on the API performance ECU for the KLX here: https://www.gt-rider.com/thailand-motorcycle-forum/showthread.php/35250-The-API-unlimited-fully-programmable-ECU-has-been-delivered-!!

T
 
Aug 29, 2011
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I would respectfully disagree on this point Joel. Setting up a carb can actually be a lot easier than tuning fuel injection on a modified engine.
Agreed Tony, the setting up of a carb is way easier than playing with EFi software. I don't think I made myself clear on this point, maybe this will help but I was meaning to say.....pulling the EFi system out of a stock D-Tracker (KLX) & converting it into a carb bike seams to be a pretty full on job & not easy for your average Thai mechanic with pigeon English & might effect the re-sale value of the bike after such a unique big modification.

There are tons of detailed write ups and guides on various forums that take you step-by-step through the installation and set up of the Bill Blue big bore kits. I've never searched but assume that there are plenty of guides for the Kawasaki OEM 300cc big bore kit as well.

Armed with the KLX service manual, proper tools and a good installation guide I reckon just about anyone could install a big bore on their KLX 250.
Agreed Tony, pretty easy to fit a big bore kit but Kawasaki wouldn't fit my kit or my friends Bill Blue kit & we know the mechanics really well....we offerded some tea money & also told them it's at our own risk.....No No No cannot, big modify cannot sorry!

Your average Thai mechanic will not follow or simply cannot read a English language printout of a forum big bore kit install guide. A good mechanic on the other hand can fit a BB kit in 4 hours flat & tell you it's easy! If you know a good mechanic with a TORQUE WRENCH! This is Thailand.

Considering that the API software interface is still only available in Thai (I think?) and requires quite a bit more "fiddling" I personally think that setting up a carb is WAY easier!
In the early days I wish I just pulled out the EFi system & fitted a carb, like you say it would have been way easier to jet/tune for a BB kit but now my EFi is working well i'm glad i stuck with the EFi tuning.

Jim mentioned earlier in this thread he was thinking of getting a Power Commander (PCV) & Autotune (AT). Personally I think the PCV is a much better product. The APi software is glitchy & the instructions are badly translated and worse still the unit is incredibly complicated to use. In the 9 months I used the APi programmable ecu i never worked out how to really use it well. I had 5 tuning sessions with APi tech man, that got the bike to about 85% perfect.

My bike within 2 weeks of running the PCV was running better than with the APi. Now my bike is running 100% better with the PCV...nice idle....super smoothness....great power curve etc etc & i'm doing it completly on my own because the software is easy to use.

Do not buy a APi programmable ecu unless you live in spitting distance of APi HQ in Bangkok, there is only one tech guys left at APi that can get a big bore klx running properly!!! btw Tony there is an English interface version of the software but a user still needs a degree is quantum physics to tune effectively with it, especially without a dyno machine.

If you do get a 331 BB kit & get a PCV, you are welcome to my latest fuel MAP & then let your Autotune fine tune for your bike.
Good luck with you decision Jim
 
Dec 27, 2007
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Cheers Joel,

All good points! I agree with you that it would be quite a challenge to find a Thai mechanic who could be trusted to install a big bore kit properly, which is why I'd recommend anyone considering such a modification to take the time to read up on the procedure and do it yourself.

FWIW I love wrenching and while I'm no mechanic, if anyone wants to bring their bike over to my place I've got all the tools necessary to get the job done. I've installed and tuned plenty of PCV's on Kwacka 650's, never on a 250, but should be same same.

I can't speak for other Big Bore kits, but the Bill Blue kit comes with detailed instructions which, along with all of the online installation guides previously referenced, make it a very straight forward job.

Of course if you're going to increase the displacement of your bike you are going to use more fuel. The stock tank on the KLX is already very small. About 7.7 liters I believe? There are no aftermarket tanks on the market for the Fuel Injected KLX 250. For folks who like to tour a bigger tank is a very worth while investment. But if your bike is Fuel Injected you are out of luck.

I went with an 11.3 liter IMS tank that is a lot lighter than the stock tank and after several tours I find that I get about the same range on my 351 as a stock 250 with 7.7 liters.
IMSTankKLX351dsm.jpg
 
Oct 20, 2012
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Hey Tony name your price. I just want peace of mind though Thai mechanics can be good i have had a motorcycle brought back to me in bits and left in my drive, with the diagnosis of the motorcye have problem,

I would be looking at getting it done around July as i will need my American friend to bring the Bill Blue kit to me, i would like to leave my bike with you as i go back to work so you are not rushed, i would ba able to leave the bike in yours untill my next leave or get my family to pick it up if its in the way.

Please PM me if interested in doing the job.

Regards
Jim

[email protected]