I'm looking to gain some horse power in the good oldKLX. My research has been turning up infromation that tells me to buy a dynojet kit, remove the airbox cover, replace the factory crank case breather hose with a bigger one and then vent it into the air box and attach a re-usable airfilter to the end of the hose in the air box, andtake off the restrictor plate from the stock scilencer. Some additional advice I read about told me to replace the CV carb and put on a bigger header. Has anyone had any experience with performing these mods, ordoes anyoneknow how well they work once completed? From my best estimates it sounds like a 7-9 hp gain is to be espected, but how does the throttle response increase without changing carbs? Any other advise is appreciated pertaining to moding this bike out.

 

Take a look at the klx250S forum
or http://www.dirtbikeworld.net/forum/s...ad.php?t=19279
or http://www.thumpertalk.com/forum/forumdisplay.php?f=27
or http://www.planetklx.com/
These will give you plenty of good info
cheers hatto

 

Hey man just bought my '99 300r. it came w/ DynoJet stage 2 (needle & main jet), complete big gun exhaust w/ silencer, K & N air filter w/out box top. I found the bike to be running doggish, excessive backfiring, blowing bad fumes, and hesitant. I studied the dynojet kit instructions and decided to raise the needle to the 4th groove from their recomm of 3rd groove and i replaced the main w/ a 132 from their recomm 128 (the 132 came w/ the dynojet kit). I alsodecided to cut 2 coils from the slide compression spring to increase throttle response.According to some i could have removed3 to 4 coils from the spring but i figured i'd start w/ 2 for now. I noticed a huge difference in how the bike runs: idle, low, mid and high speeds. No more backfiring, bad fumes or hesitation in the motor at all. Also cutting the coils seems to have improved throttle response a little bit. Either way, i don't know how it is compared to a stock 300r (i've never ridden one) but i can say that i'm very happy with my 300r now. goood luck! let me know how you make out with it.

 

That seems strange that the factory reccomended settings were so far off. Could it have beenthat theelevation setting was off for where you lived? I plan on putting a big gun scilencer on and most likely the dynojet kit or a pumper carb, along with a few other mods reccomended by planetklx. When I get it setI'll let you know how it works out.

 

I don't know why the factory settings were off. I bought the bike used, and it already had the big gun & the DJ stage 2 kit installed and removed the air box cover. the owner told me that he never had a problem with the way the bike ran. He also said that he hadn't ridden it for over a year but started it up 1 or 2 times since that last ride. When i test rode it, it was backfiring profusely on the decel, and it was very choppy at idle and low speed. I'm at 0 elevation/altitude (charleston, sc) and he owned it in charlotte, nc which is about 580 ft above sea level, so i don't think the elevations had anything to do with how it was running. The other thing i should mention is that although i want to believe he was straight with me, after i raised the needle and upped the main to a 132, i found that after i started it up i had to significantly lower the idle **** more than 5 complete turns. that tells me that he had to dramatically increase the idle in order to get it to run for me. Also, the fuel mixture screw was turned out at least 3.5 times, again that tells me that he had to richen the mix to make it run. I now have it turned out 1.5 times(where it belongs). The DJ kit installed was installed in accordance with their instructions, however out of desparation, modifying it was all that i could think of doing as a possible means to fix. It worked. By the way, this is a '99 model w/ very little wear on it. I bought it for $1150.00. He was asking $1250.00. I think he sold it cheap because he thought the engine had major problems or something like that. There is always a reason why someone would sell so cheap. I also recognized that he didn't do any of his own maint/work on the bike, so he was probably stumped about why it ran so poorly and therefore decided to sell it cheap just to get rid of a lemon. Well, "one mans garbage is another mans fill", because this bike is not a lemon at all. It now purrs like a kitten and has decent pull in the woods. I'm thinking of going pumper, but i think i'll ride like it is for now and decide later.
Good luck! Let me know.