Just got my son a new KTX 50 and it sucks. He was used to riding a Yahama Zinger with a PX50 motor in it and it was a lot faster. My son is very agressive and very strong so he can control the bike but the new bike is terrible Speedwise

 

Any help would be appreciated. I race a car so I have no understanding of the 2 stroke motors. Tried to pull the air filter but it tries to die. HELP!!

 

There's tons of info on this subject here, try doing a search on LT50, which is a twin of the KFX.

 

Look for postings under my handle name. I and a few other guys have posted an easy to follow laundry list of things you can do to this bike. Good luck.

 

are the restictors out???if so the best mod i have done so far is having the head milled. only cost $25 so i had 2 done. the ct pipe was a big help also.

 

We figured porting, polishing and milling the head first and made some calls to have someone do it for me today. Has a FMF pipe and the restricters removed but I could not believe how slow it was compared to the Zinger with the stock PW50 motor. I will be using everyones advice. Thanks, BTW I am briland's husband sorry for the name change but I am at work now but posted from home last night. Thanks again and keep the ideas flowing.

 

Guys just want to say thanks for the help. We did a mild port and polish, thanks familyinthedirt, and put in a 70 main jet. I could not believe the intake restrictor. He was not as fast as the really modified bikes on the straights but was much faster and passed them in the whoops and jumps. We are going to shave the head with some recommendations from some local guys tomorrow and see how he does this weekend in the actual race. Questions. The only main jet I could find is a 90. Is that going to be too big? If not where is a good place to get jets, I would rather him be too rich than lean. I was told locally that you could cut the head doing figure eights on 240 sand paper, carefully, and replacing the head gasket. I don't want him to dominate the class because he won't get better, I would rather see him be passing back and forth with the other riders. If you are bored check our website we just started www.windhamracing.com, but again thanks for the assistance. Also how much difference between the CT pipe comapared to an FMF? Does the FMF have any restricters in it?

 

Great pictures at your website[img]i/expressions/face-icon-small-cool.gif[/img] Glad to hear that you've been able to improve the KFX's performance, definitely keep us posted on your future modifications. I've seen jet kits for sale on eBay for the LT/KFX, I believe they included 5 different jets and that they were sold for around $10. I'd imagine they'll reappear, plus for those tiny things I wouldn't imagine that shipping to Guam would be overly expensive...

 

Briland, I have been haveing hot start issues with my LT so, trying to fatten it up a bit, my buddy put a .90 main in and it is too big. It will drown out the bottom end and there is no gain at all on the top. Now it has an .85 and it runs well bottom and top. I still have the hot start issue but it is a little better. I might be sucking air in some place but haven't broken the whole thing down to investigate further yet. The CT pipe will give better mid and top end performance that the FMF. It is however REALLY REALLY loud. So if you are rideing in the yard the neighbors might give you some greif. I have been very pleased with its performance on the track. Espessially in the whoops and turns. With its small wheel base an aggressive rider can do very well against bikes as big as a stock 80. I havent played with the gearing but i think "maggiesboy" has. You might take a look.

Good Luck and have fun raceing!

 

Try and upgrade with some KTX performance parts. It worked for mine.