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Discussion Starter #1
Hows it going all new to the forum and to the KLX250
I've ridden motocross for 7ish years. And Have always done my own work.
Hence why I purchased a Moto, and even more the KLX.

However it i slacking in power and when I bought it it was pretty well opened up.
Currently Im at
Two bros pipe, dynojet stage 2, 13t sprocket, rerouted crankcase breather, removed and capped emission exhaust setup.

So now for the questions, I've tried a bunch of searching of probably and hour a day for the past two weeks, to try and get up to speed on the 351 kit.
What I've gotten myself into is a bunch of open-ended questions on the net i cant seem to find and answer for.
So any help with these questions will be greatly appreciated.


I've seen somethings about the big bore kits causing bad vibrations in the bars. Anyone with the 351 have any input on this?

Id like to have a top speed of 95ish (so cruising 70 on the highway doesn't have me so tapped out), My hopes are to put a 14 or 15t front in combo with the 351 currently with the 13t I'm hitting 85 downhill.

Has anyone heard of blowing up a 351? Im asking because in motocross bikes its common and then you just bore out a little bit. I understand the 351 is as large
as the cases will accept so what happens if you skunk a motor?

Has anyone tried a keihin Flat CR (FCR) motocross carb in conjunction with the 351? if you have how does it fit in relation to the frame? This topic I'm really interested in because I know these carb's like the back of my hand.

Has anyone done the Cycle-pro kit? I hear they nikasil plate there kit where as BB perhaps does perhaps not?

Lastly does anyone have a pic of Bill Blues 351 cylinder? I understand its sleeved which gives me concerns about the water jackets. I know guys have been running his 351 unit like dogs but I'm always a bit timid when playing around with re-sizing cylinders.


Thanks alot guys!
DWilson
 

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I have the BB 351 kit going on 2 years now.

To answer as many of your questions as possible:

I have no increased vibration in the bars. I'm running Pro Taper SE's.

I have seen an indicated via GPS top speed of 98. I'm a chick though, 105 lbs., so that might affect your top speed. I tossed the stock 14tooth sprocket when I did the 351. It does MUCH better with the 15 and the bike has no trouble pulling wheelies and getting off the line with the 15. It helps cruising quite a bit. My bike cruises effortlessly at 70mph.

I've heard a few reports of the 351 failing. One was clearly operator error on the install and the subsequent operation of the bike. Another was a failure that was reported that Bill got a bad run of parts from one of his vendor's. I can't recall what exactly it was though.

If you will go to this website, you 'll be able to see all the 351 info you need. Search 351 and you'll see lots of install reports with pics and just about anything you'd want to know. http://www.kawasakiforums.com/forum/klx-250s-71/

Lots of folks run different carbs. I've seen guys running the FCR, and a couple of different Mikuni pumpers, TM 33 and TM 36-38 I think, IIRC.

I too was concerned about the Bill Blue 351 kit in regards to the water jacket. My buddy who used to build drag bike engines looked it over and said that yep, it was getting pretty close, and he was a bit concerned over that, but I was determined to get the kit. I haven't had any problems with it at all, and I do not baby it. Lots of running up to the redline and lots of engine braking. I think this bike runs pretty cool though. I've only had the fan come on once, and that was during the summer on a really hot day, and it only ran for a minute. I'm running Engine Ice coolant, that's supposed to help, but not sure if it makes any difference really.

If you will go to the website I posted above, you can read about the 351 til your eyes cross. Lots of good info over there. I used one of the guys threads on installing his kit when I did mine. My drag bike buddy helped me with the install, but if you know bikes, it's really pretty straight forward.

I think it is truly the best bang for the buck for this little bike.




 

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Discussion Starter #3
Mel,
Thank you very much, you are the woman :clap:

Like I said Ive been scouring for info but the way these things go on forums you can get quite a bit of info with no clear direction to take it.

Thanks again,
Dave
 

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Discussion Starter #4
Part II

So I pulled the Trigger today and ordered the 351 kit.
Bill blue said as far as jetting goes for the stock to step up 2 Steps on the Main and 1 On the pilot, for anybody wondering.

I have some cam chain slap, and the tensioner seems to be at full throw.
I have a manual tensioner coming in a few days.

Has anyone thrown a chain in these?
While I have the bike apart I'm debating swapping out for a new one.
Cheapest one I can find is 100$...My 07 YZ250f runs a bigger beefier chain and that 35$ from Pro-x...:headscrat
 
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