For a moment I almost started to laugh when I seen the title of this thread it should have specified what WR it was refering to Because any KLX250-351 Will NEVER compete with a DeRestricted WR250F, I just had a set of hotcams put in my bike and am running in the 35hp (approx26-27 stock) range and athena makes a 290kit..... Do not get me wrong I still love my KLX250 it has just turned into the bike I ride around town on a nice day bike, and my wifes ride when the family goes trail riding!! cause' it just does not have much offroad finess for hardcore trail riding!! However I cannot make judgment on the R/X versions I hear they are underpowered in stock form as well.

 

You made a 35% increase in power from cams (and I assume a pipe)?

 

Yes the WR F gains 5-7hp just from jetting, exhaust, YZF throttle stop(Stock wr throttle stop only allows half throttle) and grey wire mod ( changes ignition mapping to the YZF ignition allowing the motor to rev like its MX counter part. Doing these mods will bring you up to the 32.5 - 33.5hp these figures I found on thumpertalk and other sites. I am just guessing But for 500.00 I should get at least 2hp more from the cams, as soon As I can get it dyno'd I will, cause I'm curious!!! the AIS kit Does not increace performance, just cleans up the motor and stops the poping on decel, Ais adds air into the exhaust to make the exhaust EPA legal.

 

Are the WRX and WRR equipped with a different motor than the WRF? They look like shim and bucket designs so maybe a de-tuned wrf motor? Anyway, the wrf is a formidable bike with the right mods...build it to yzf specs or as said, an athena big bore kit. The later models have good ergos with a big tank. I don't have any experience with the bill blue motors but if they are like the Thumper big bore kits, you get more torque and revving it doesn't give you more power...not big on HP. I find in the woods more hp on a smaller motor gives you a fast bike. My klx331 was dyno'd at 38hp and it runs with 450's in the woods..quicker thru the trees and stays with them in the short straights. I hardly ever use lowend torque and it's very close to a 2 stroke in regards to the powerband and isn't a hard transition from the 331 to my yz250.

 

I have a KLX 300 and a WRF 250 so I can't speak for the 351 engine but the frame and suspension and ride I can. Without knowing the WR bike you speak of it is kind of an apple oranges answer. I just returned from 1,500 miles of trails on the '09 WRF (jetted, wired, new header, exhaust to be fair) so i am in real good recent feel with that bike. Yes the klx 300 out pulls the WRF after 2nd gear - on the street. However the WR rips the plastic off of the Klx in the woods with no comparison. Way lighter handling, suspension tuned for off road not on road. A higher revving engine that responds more like a two stroke, I can pull wheelies in 3rd and 4th gear no problem on the WR- on the klx only 1st and 2nd as it is just not snappy enough. The Klx is like a tank in comparison (to any race bike) but every other dual purpose is too.
If i were to go back in time to 2009........ I may have bought the dual purpose Yamaha instead had i test rode it.
Just my unpaid riding observations. Btw: I ride the Klx from sea level to 6,000' and the Wr lives at 7,000 and i ride it to 12,000'. The klx seems to lose more power at altitude but starts right up and the the WR becomes harder to start but still has a good pull.

 

I was under the impression that the 351 bill blue kit only produced around 28hp or less. I swear the thread was on this forum, there was even dyno charts.( I could be wrong bud i do not think I am) Do you have Dyno charts for your 38hp thats more than double the stock hp not sure how 80cc (331kit) can add 20-21 hp, cause a stock klx is about 17hp. And YES the WRF Has a completely different motor than the WRR/X. the engine is close to the YZF. The cases are different to accomadate a larger crank on the WRF Tranny is different, top ends on the WRF and YZF are interchangable.

Link to KLX351 Dyno charts: http://bandbcyclerestorations.com/page_2.html

351 kit is only 26hp how in hell do you get 38hp from a 331 kit???????????????????????

I REALLY DO LOVE MY LITTLE KLX, I JUST DISCOVERED HOW WONDERFULL A RACE BRED MACHINE IS!!!!!!

 

Mine was built with the Stroker 331 kit, 36mm mik pumper,team green hot cams, porting and headwork, BG race muffler and headpipe, team green porting and shaved flywheel. I actually had the paperwork on the dyno runs but that was 10 years and 2 moves ago. After looking over the blue build sheet, it looks like the kit's put together for torque and is probably mildly built for longevity\reliabilty but I have no real-world knowledge of that.

 

I'd believe 38 hp from a 331 before I'd believe a 35% increase in power from.... oh, never mind.

 

Me too!

 

Check the WR/YZF section there is a guy that has literly done at least a dozen different things on his wrf and dyno'd every step from exhaust to cams and big bore. and all the dyno charts are in the thread( so believe what you fu#@$k'in want!!) So from what I gather You had a complete 331 Race engine built and probably spent a small fortune, which seems friggin retarded but each to there own?!? Even a piped and jette'd KLX450 Dyno'd barely makes 40hp the least of all the offroad 450s. And to the other person who said 35% increase from....WTF are you talking about?? It is Well documented that what I stated about the Mods I have done to increase the power as I stated Do some reserch befor you get on your high horse!! as far as cams go I have stage 1 cams which I hope to increase power by about 2hp they are low/mid cams so I should see a great low end increase!! I by no means deserved the ****ty comments that were left, I was just stating facts, not BS. Attack me for no reason and I will fight back!! all I want is to have a civil factual tread. how hard is that guys!!!!!!!!!!! with no BS and opinion based on ****!!!!!!!!