Perhaps race rules. Displacement limits. I was thinking 351 may be overkill to the stock carb and exhaust which I intend on keeping. My thought is what is going to give me the most for my $. Exhaust? Nope..... So should I just go 300 and be safe. Longevity? Its all a compromise. Another one of my thoughts are vibration. How much more does the 351 piston weigh compared to my truly smooth stock single cylinder bike. Like I said earlier, my next bucks are going into suspension. I got the motor running excellent.

My usual decision would to go one size less than full over bore. So I would end up with the 330 or 340. This is a pressed in sleeve, so its not like it is actually bored and I do not need room to bore it out once more if things go south or I wear it out.

On my BMW 750 I can go up to 900 cc. But I would make it an 850 so there is a little meat left in the sleeve. I have not because pistons are $400 EACH.

David

 

Anyone got a picture of a 340 jug?

It's just me but I like the sleeve to be in full contact of the aluminum. It's a beefy looking sleeve so it shouldn't be a problem but I'd rather compromise 11 ccs and not break into the water jacket if possible.

 

Has anyone ever gotten a concrete answer from the man himself Bill Blue? I have seen various threads and I have never seen a straight answer regarding why anyone would get the 331 over the 340 or the 351 for the miniscule price difference. There must be a reason for the different choices and it certainly is not price. What makes it confusing is that he offers so many choices while most companies only offer one choice ie Kawiasaki just the 300cc kit & Kustom Kraft just the 331cc kit.

 

Nothing wrong with offering all the different options vs. arguing that one build is better or worse, which some shops might to close the deal. Kudos for Bill on this.

Usually the bigger you go it revs slower and lower, the torque and hp peak gets moved down to a lower rpm. This may be a positive or a negative depends on what you want? or you might choose to compromise somewhere in the middle?

I made my crf250x a 280 and experienced the same thing. It took a different cam and more open exhaust to make it run how I wanted. If I was stuck with just a big bore I would have put it back. Luckily there are a ton of cheap used and take off parts to experiment with with the honda, not so much on the KLX.

You can say I'll just gear it up and play to the torque, which may be fine on the road or in more open county. But in the tight trails it doesn't matter how much power you have you'll be using the clutch a lot if the gearing is too high.

 

This is the kind of answer that I am looking for from Mr. Blue but can never seem to find.

It would be nice to know what the upside of the 331 and the 340 is over the 351 as the price difference is virtually a non factor. I mean if he said something like the 331 is the best compromise in terms of power and reliability etc or the 340 actually puts out more HP than the 351 but the 351 produces the same peak torque but at 2000 rpm less or whatever, then one can make their own decision on what they want.

So has anyone ever talked to Mr. Blue and gotten the upside/downside of all his different choices?

 

Pick one... once you've done it, you'll never care again about the pros and cons or any perceived differences. The difference of 11cc out of 350 is negligable. Stop overthinking and get off the pot.

 

He is 100% correct.

 

Unless, of course, you want to make the best decision before you spend your money, and not just settle for "better." I like to make the right decision. Then, again, I'm very picky.

 

Hello All,
The 300 & 331 sleeve are dry sleeves they don't bore into the water jacket. The 340 & 351 are wet sleeves they bore through the water jacket so the coolant flows around the sleeve.
I offer several size big bore kits because some people dont want a big motor they just want to increase a small amount. Each increase in kit size gives more torque & horse power as all americans say bigger is better. Using the TM33/34 carb works well on all size engines the TM36 works best on the 340 & 351. Hope this helps clear up some questions if not I will try to answer them.
Bill

 

Thanks, Bill! I might be sending you a big check and a KLX jug this winter.