What impresses me, is that by 5000 RPM, your already making as much power as the stock bike at the top end. that's a huge improvement in bottom end, without increasing the stroke.. which is espected sicne the head has not been changed. To get the most out of a bore increase, you would need to increase the valve size, but the trade off would be less torque at low RPM's.

Nice! I'm satisfied wiht the 250 with a aftermerket pipe for now, but it's good ot know that reliable power can be had without going crazy.

 

So you are saying that your needle dia/height is off just abit? Still a nice tune. Congrats again.

 

hey nobrakes you ever thaught about gitting a Wiesco High compression piston for it?. i can find th site but I read that Team Green did all your mods as well a as a wiesco highcomp ans obvioulsly a road tire and they dynoed at 33HP, seems to easy for that much increase, huh?

 

It could be and probably is a little. But the dyno run's air/fuel reading I don't think says a whole lot about the low to mid-range throttle settings by virtue that the entire test is run at wide open throttle and at WOT the main jet dominates. So I think the above a/f graphs are an indication of main jet only.

To get the readings at other throttle positions requries a more sophisticated dyno and these are typically prohibitively expensive for small shops to afford. The next best thing within my budget and abilities was to do the O2 sensor in the headpipe which gives me a repeatable measure of the air/fuel mixture, even though it is not calibrated and also is highly non-linear, it is still useful once you know what range of its output voltage provides the optimal mixture. For my sensor, it is around 0.87 to 0.92 volts. Anything lower is too lean, higher is too rich. This gives me a/f readings at any throttle setting I choose to look at, and using that, I've pretty much got the needle setting dialed in as best I can right now. I think I could benefit by adjusting the fuel screw, but its real hard to do that because I have to remove the carb for each adjustment which is tedious to put it mildly. That's where I want to try and make the Kouba fuel screw work which is adjustable while the bike is running which is really what you want for that adjustment - you can much more easily find the sweet spot. If that works out and I do make a fuel screw adjustment different from where it is now, then I'll likely need to re-examine the needle clip position adjustment as there is some overlap with it and the fuel screw and changing the fuel screw might require an adjustment to the needle.

Thanks! This carb has a lot of adjustments which make it a bit intimidating, but with the help of several smart folks and my O2 sensor, I think I've got it set up pretty well. In case anyone is interested or perhaps considering one of these carbs and maybe want to use my settings as a starting point, they are:

Keihin 35mm FCR on KLX w/331cc

Pilot Jet: 45
Needle: OCEMN
Clip Position from top: 4th
Main Jet: 145
Fuel Screw: 1.5 out
Main Air: 200
Pilot Air Jet: 1 out
Airbox lid: off
Filter: UNI

 

Wiesco only lists a stock compression ratio piston 11:1. So I'm guessing that it was custom made or either they don't offer it anymore. To bad because it would be nice to have that option.

 

I did think about that as I was researching the 331 kits, but it wasn't really a factor to me when I made my purchase. I know higher compression generally means more power, but on the flip side I was also concerned that the higher compression my make me have to do more frequent valve jobs and other maintenance. I would have bought it either way, though.

The piston that came with my kit is labeled as an L.A.SLEEVE, J5339PS and tagged as 83mm for the KLX300 1997-02. The shop I bought it from said they didn't think it changed the stock compression ratio. I have no idea if it really did or not, though.

 

Will this work for you, Nobrakes? It was a lifesaver for me.Got it off ebay for less than half price. It goes for about $85.00 new. Just an option;I hope the T-screw works.

 

Glad you got your bike finally jetted and tuned right brian... impressive numbers..... hows that a/r ratio guage working?

 

Yike []busted! Send me back to math class. Besides, we all know the MUZZY iswhere all that power is coming from...you've just enabled it with the larger bore! [sm=badbadbad.gif][sm=badbadbad.gif]

 

Nice #'s Brian. I think I'm getting piston envy.