Sure it will Graham, there is a 3cm gap between the top of the chain & under the guard. Plenty of room for a bigger sprocket....Mine is 39t btw

 

haha, it's one of the few bikes that a person of a certain age can get away with a bit of bling!!! My girlfriend thinks it's a mid life crisis....lol She rides a bleedin Honda 400 steed chopper, how dare she comment on my bling!!

Sure it will Graham, there is a 3cm gap between the top of the chain & under the guard. Plenty of room for a bigger sprocket....Mine is 39t btw

 

Well guys, used the bike all summer and it has been awesome, the new springs and mods make all the difference. I have even been smashing it off table top jumps in the motocross park with no bottom out at all

Soooooooooo, we are hitting winter over in the UK and I think I have decided to go Big Bore before next spring.

Wanted some advice really, got a few questions and it seems you three are probably the best to answer.

1. What is in your opinion the cheapest way to go big bore?
2. Should i go 300cc or 331cc?
3. Where can I get the parts needed in Europe. (was planning to maybe even bolt a klx 300 cylinder on, but struggle to get parts in the UK.)
4. Any draw backs, nightmares to watch out for?

I know that once I do this final mod, I have a keeper in this bike.

Any input will be greatly appreciated.

Thanks

Ledgini

 

Here are the part numbers for the 300. This is the route I took as I got all the parts in a kit for 300 Oz Dollars from my brother. This, along with the pipe and header and filter makes an awsome little machine. You will have to get a controller to add extra fuel, as the standard mapping will not feed the bigger displacement. There are 2 routes taken with success by various members. Most well known seems the programable Powercommander, for which you will need maps from someone with similar conditions to you, or do the programming yourself on a laptop.
I use a product called EJK (electronic Jet Kit ) from Dobek performance. ( They make all the units for Wispeco and Two Brothers racing etc. just rebranded) DO NOT ORDER THE 250 KLX unit as this is programed for 250, not 300 or more. e Mail Matt Stoxen [mstoxen@dobeckperformance.com]or Dallas Fisher at Dobeck and they will send you a unit programed specifically for 300cc or 331cc.
The reason I went 300 is that no one had tried bigger on EFI bikes and speculation the the injectors would not feed more than 315cc put me off. Subsequently guys like JoelThailand have done the 331 efi with success. Joel however is using BEET injectors and you will have to verify independantly if the stock injectors will in fact feed 331cc.

I hindsite I would have gone 331, at the time I got a good deal on 300 and was not wanting to be a pioneer.
Here is a link to a discount parts shop that will ship.
PartShark.com - Motorcycle Parts, ATV Parts, UTV Parts, PWC Parts, Powersports Apparel, Motorcycle Accessories for OEM and Aftermarket.

300 Kawasaki KLX kit
1 x barrel p/n 11005-1983
1 x gudgon pin p/n 13002-1109
1 x set piston rings p/n 13008-1071
2 x gudgon pin clips p/n 92033-1054
1 x Head gaskit p/n 11004-1314
1 x cylinder gaskit p/n 11060-1740
1 x Piston p/n 13001-1463

 

Many thanks for this info Graham, as ever, very helpful.

Looking at this I think it is going to cost me around £500 to complete, including all parts, shipping, PCV etc etc which I have to admit is a huge amount of cash to throw into this bike. So true to previous from, I have a few questions

Is the power gain substantial enough to justify the cash outlay in your opinion?

You bike seems very similar to mine in the other modifications so did you see any top end speed increase or is it all low down torque & acceleration?

Will the front wheel lift under full acceleration in first and second gear without dropping the clutch?

Again, any advice is appreciated.

 

Hi Ledgini, if you going to spend a substantial amount of cash be 100% sure that you won't regret buying a 300 kit. There is a huge difference between 292cc & 331cc.

I use the KK331 with the PCV & would happily pass on my MAP to you. The bike will lift the front wheel in 1st gear just accelerating & will lift easily in 1st & 2nd with a little snap of the throttle.....no clutch required!! btw my bike is running 14/39 & can easily do 150km/h, with a 13T sprocket it does pull up the front wheel like crazy & becomes a stunt bike!!
I weight a ton, about 230lbs (100kg+) & the bike is still exciting to ride....my mechanic is about 130lbs (60kg) dripping wet & it puts a mega smile on his face...lol.....I can't imagine how fast my bike would feel if i dropped a 100lbs.....must eat less burgers!! I don't think spending $20,000 on a carbon fibre frame & titanium forks would equal his 100lbs weight loss......lol

I have a good friend here with a BB331 kit with a re-programmed EJK controller & a STOCK injector.....the bike goes great......100% the injector will work.

I'm happy with my snappy, grunty, rip roaring klx331sf......the klx250 compared to a strong running 331 is absolutely night & day in comparison!!

Think carefully & good luck with whatever you choose.

 

I am not sure how you would justify the spend. A WR 250 goes better than a KLX 250 but costs about 2 K more. You can get the KLX to go better than a WR for less than 2 K.
What I enjoy most about the big bore EFI is how smooth and sedate it is in low revs, off idle. Creeps along quite and smooth. Open it up and it roars like a beast. I would do it all again, given the choice, but would go the 331 route. It is a big spend, if you on a budget like most of the planet, but hell, you gotta get your priorities right.

The 300 needed clutch in second for an effortless wheelie. Alternativly just back off a touch and wind it back on, and up she goes. I have now put on a 48/ 14 combo which I love and produces spectacular wheelies at will. Top speed on my 250 was 130 km/h. Top speed on 300 is 130 km/h. Speed stopped climbing at max revs. Difference is that the 300 gets there quickly on a flat road. 250 battled and needed lots of road to get top speed. ( 13/42 combo)

 

Thanks guys, you've both been very helpful with this.

The funny thing is, everytime I ride the bike in its current state I am reminded that it is bloody brilliant and really doesnt need this big bore. The big bore will be a real nice to have but its not vital. I just know if I have it I will stop looking at other bikes as the KLX will do everything I want it to.

My problem is, I love other bikes!!!

I don't know if you guys have ridden a CRF250X or KTM 250 EXC, but I can tell you, the power diffrence on those compared to my KLX is huge, both of those bikes accelerate much much much quicker and will lift the front wheel in every gear on the moto track. Now I know that the compromise with both of those are hardcore servicing schedules and a pain in the *** of a general upkeep which is why I dont own one, but I really want that sort of power, with the ease of ownership of the KLX and the little servicing needed.

I think if do go this route it will be a Bill Blue 331 and an EJK. The only thing playing on my mind is the fact I could sell my KLX, add the money on top that I would spend on the big bore and for that I could get a mint, low mileage WR250R, that I would then spend millions of pounds on upgrading

Where does it stop.....................

Decisions decisions :S

 

You will spend more money on the WR250R in the long run imho!!

I have pretty done everything i wanted to do on the bike & my wallet is starting to slowly recover from all the surgery....

haha, yes indeed where does it stop!!! Make a decision, pull the trigger & open your wallet.....

 

I would suggest you consider the KK opposed to Bill Blue. When you factor in return shipping of you jug it narrows the price gap. KK also does not seem to be related to engine failures similar to Bill Blue.