Well you can add me to the list of happy 331 customers.

I have been riding my KLX 250 w/300 and cams, pumper, exhaust around Southeast Asia for about 29,000 KM's off road primarily. Even with those mods I was never impressed with the bottom end of the motor.

I sent the cylinder to Kustom Kraft for their Big bore kit and JE piston. Marvin was marvelous at KK and can recommend his work. After a few heat cycles and an afternoon dialing in the jetting I ended up with a 147 main and Bill Blues needle. My jetting in Thailand is usually a bit leaner than in the states due to the heat and humidity. Can you say 98% humidity and 105 degree heat[:-].

Right then off for a ride. My old 300 would beat a friends bored and stroked XR 322. Said friend has since bought an XR650, uh oh!! i pulled up for the ride and another friend was there with a DRZ400. he asked what I had done to the bike since it sounded a lot different but it may of just been the Big Gun needed repacking.

The added torque down low is noticeable right away. It actually pulls quite strongly and is now what I would call a great small bore bike. Coming with the six speed tranny gives it far more speed ranges over my two friends DRZ400's.

Bottom line the bike for me now ranks above the DRZ with these mods. before the big bore i liked the 400's torque but hated the added girth. The 331 tips the scales soundly into the KLX domain.

I did some roll on tests with the the XR650 that has a Big Gun exhaust. Rolling on in the bottom of second and topping out in fourth the KLX was only behind by four bike lengths. Not too shabby for being 200+cc's in the hole. No doubt the XR would of pulled some more distance if the straightaways were longer but after three tests the results were consistent.

We then threw motard rims on the bikes and went for a thrash. The XR had more grunt out of the corners and this guy is generally a fraction quicker than I. Most regard him as a loon with his cornering speeds. Anyway chasing him up and down the twisties I could keep him within about 35 feet without him getting beyond 50 feet. In other words he could not get away and this was my first ride on a bike in fourth months. The KLX lighter wieght made it easier on corner entrance where I could make up time and i would see his heavy XR bucking, weaving and sliding the rear on entrances trying to fight the girth.

To summarize I have finally got the KLX to where I could truly be happy with this bike. Its not a cheap bike now but you could eliminate the cams and not lose much out in the dirt. In motard trim the camshafts pay for themselves.




A tip of the hat to the board for all its help and friendly posters. Enjoy.

 

Good stuff I am waiting for my Bill Blue 331 kit to turn up hopfully in a couple of weeks time [8D]

 

Awesome man, now if I can do that on my 250 with the jetting and muzzy then I can't imagine what it must be like with the 331. Very nice.

 

that write up just put me over the edge... i'm splurging for the 331 as soon as i have enought money.

did you get the pumper carb from kk too? whos got the best deal on the 331?

 

Great write-up! Thanks!

What exhaust are you using? Full system, or slip-on!

Jeff

 

Nice report, Justin. It's cool you had those other bikes to compare too, and to the 292cc kit as well. When I did mine, I moved up from the 292cc and was night and day between those. And then to the pumper carb and that was night and from what it was before that. It really is a totally different bike after 331+pumper vs the baseline pipe/airbox/jetting mods.

 

Maverick - Enjoy that 331, Bill Blue does great work.

pie4fou - Got my carb from Bill Blue, the modded 33mm to 34mm Mikuni. On a dyno it posted a bit better results than the 35mmFCR according to one poster and was easier to jet according to him. Plus it was cheaper than the FCR.

Sherpadude - Its a Big Gun full system. I bought it used for $135 off a KLX 300. Not the greatest build quality. Quality of metal is one step above tin.

Nobrakes - Well my friend I do beleive the KLX is finally sorted. I have the perfect smallbore street legal fun bike with both sets of rims. I bought the KLX used for under $2000 and have put another $1800 into her which resulted in quite a decent bike for the money. Overall very impressed for its capabilkities. The 331 really makes it shine.

However there is something i'm putting together now that is not as fiscally prudent as the KLX, hahaha.

 

Maverick, what happened I though you had a complete 300 kit waiting to be installed. What made you go to 331?