My other 300cc thread was getting way too long withing having to load all those photos. So this will be short and sweet.

If you are wondering what the 300cc feels like, the closest thing I can think of would be the gearing change mod that many have done. But it's feels a little better than that, but analogy should give you and idea of what to expect if you've already done a gearing change. I changed my gearing a while back from the stock 14/42 to 14/49. While I loved what it did to the bike, I did not like losing the high gear - basically this change took away sixth gear and was like riding the bike stock but never shifting into sixth gear. Of course, you gained a gear down low which was great.

The 300cc kit feels like the bike did after that gearing change, except I'm still running stock gearing so I don't lose anything on the top gear. There are a few hills around hear and I can accelerate up them in sixth gear now where before I'd generally need to gear down to fifth. There is more power across the whole RPM range which is expected. Most noticable is the increase in torque across the range - definitely it is making more horsepower, how much is anyone's guess. I've love to dyno it - perhaps I'll see if I can find somewhere to do that.

The front end comes up much more easily now, even with stock gearing. If I sit back a little and pull up a bit on the handlebars and blip the throttle when the bike is around 2500 to 3000 RPM, the front will pop right up. I don't have a lot of practice at wheelies, so I'm not brave enough to keep it up and ride it out so I let it drop back down. Those that have gearing mods would most likely find it _very_ easy to lift the front end.

Regarding the torque all around - it did something today that it has never done. Mind you it was raining and the roads were a bit slick, also I have the harder compound Kenda 270's on which don't have the best road traction. However, I was in sixth gear going about 45 MPH up a hill and I figured I'd see how well it accelerated up the incline. I was about halfway up when I laid on the throttle. The rear wheel broke traction with the road! I know the road conditions had a good bit to do with it, but it has still never happened until this upgrade.

So to summarize - more power across the board, from first through sixth. Front end lofts much easier. It feels similar to what you might have felt when moving to higher gearing ratio - somewhere along the lines of 13/45 or 14/49'ish, but with stock gearing - this is not a direct analogy because it also feels snappier similar to the jetting / pipe mods. Basically it's sort've like all the mods I've done to date (airbox, jetting, pipe) times 2. So think about how your bike felt the first time after doing all those mods and call that 1 notch. The 300cc kit will notch it up again.

To me this was definitely worth the money and effort, especially since I didn't care for the higher gearing mod since it tended to reduce the roadability for me by losing sixth gear.

Hope this helps anyone trying to decide whether to do this or not.

 

Sounds really good nobrakes, thanks for being the guinee pig. I think that this might be an upgrade for the future. Now how bout warranty

 

Warranties are for pansies

 

Ahahah, good one, I didn't get extended warranty on mine, so I'm free to upgrade to the 300cc kit with no worries lol. Oh by the way nobrake, just wanted to let you know that this Rotella 5W-40 motor oil is friggin amazing with the KLX 250s. No more hesitations when I start the bike and blip the throttle. Warms up quick and its synthetic, what more could you ask for.

 

I've been watching the thread rather aggresively from start to finish so far with great interest, as I have no doubt I'll end up doing the same conversion myself. I grew up primarily with MX bikes, and though I'm not trying to make it an MX bike, I feel the desire to get alot more power out of it now.

Its seemed hard to find all that much information on these mods however..., some of the things I'm curious as if there is any stroker kits out there, or big bore kits for this 300cc head. Alongside that.., I've been trying to find out if there are any other aftermarket pistons available for this head, something that would give me a 12.0:1 or 12.5:1 compression ratio.

So many options to explore.., so many.

In any case, great job!, and thanks for sharing with everyone. Sounds like the bikes running great and it was well worth it.

 

I was told by my Dealer that I can get a 382 Kit for my KLX. Could be project for the winter



[IMG]local://upfiles/2315/553766ED7F0F4410890CC77EEF3FEFD1.jpg[/IMG]

 

hay how much power can the bottom end of a 250 handle? stroker crank stronger ?

 

You want extreme KLX power ?????? read this my friends

 

6th gear burnouts .... [sm=yikesomg.gif] [sm=gears.gif] [sm=jawdrop.gif] [sm=nxsmile.gif] now I have to upgrade mine [sm=wootwoot.gif]

 

Please tell more about the 382cc kit! Where get it? Who makes it? Price? ANY information about this would be greatly appreciated -- I would like to do one this fall/winter.
Any links to info about it?