There was a dyno event at a local bike shop today. I brought my big bore KLX250 (EFI) with 292cc big bore kit and FMF Q4 pipe to have it tested.

It wasnt a very thorough dyno, no a/f results, no torque listed and such. There were 50 people waiting to get their bike on the dyno and they said they didnt have time to measure all those things on all the bikes. However, it turns out that a proper dyno run where they measure everything isnt that expensive so I will probably get that in the future.

Its also worth noticing that my jetting isnt optimal. Im still playing around with it.

Anyway, here are the results. They did two runs, my bike was measured to 28.18 hp I was expecting closer to 25 hp so I am quite happy, but maybe the dyno is optimistic? They all seem to be different anyway. The curve seems to measure top speed vs hp...so...not that useful. Would have prefered hp/torque/rpm graph...but maybe next time.

Still interesting. I beat a CBR250R on raw hp. WR250X was also waiting in line, but I didnt get to see his results. He said he got 28~ hp at a dyno event last year, but he had since added a slip-on and wanted to see if it gave him anything.

 

My 351 got 28hp as well...

 

His test will likely offer no useable knowledge - as he explains, it isn't a complete test and it is, no doubt, using DIN correction - as is common in Europe - which is totally different than our SAE CF, producing very different numbers.


FYI: DIN CF produces higher HP numbers than SAE CF's.

 

28 is pretty high :/

 

If you have EFI wouldn't the computer have changed the jetting automatically? Unless you need a different controller etc

This guy in San Diego got 26-32 dyno hp from his WR250X which seems to jive with the OP's friend's results on the Denmark dyno a year earlier?

 

EFI doesnt change jetting automatically. Its not that advanced at all and with a big bore kit you have disabled the o2 sensor anyway (Not that it did much other than lean out stuff for emissions)

The interesting thing to note is that my bike outperformed a CBR250R that was dynoned on the same dyno, within an hour of mine. That bike hit 27 on the dyno.

Marcelino also dynoed his 250 with cammod at 25hp~

 

So how do the CBR250s usually do when on the dyno elsewhere or in magazines? Same upper 20s for hp?

There are a few of those here in town, maybe I can taunt one into a race someday

 

Problem with most all dynos are there are some differences. The real value comes when there is comparison on the same dyno (expensive) running the bike OEM, then doing the modifications to be tested. Lots of runs lots of money. But that is solid proof of performance increase in a relative measure - apples to apples.

Both the US and Euro dyno methods are close enough together that a 5 hp gain on either will be close, but the real numbers are only relevant if the runs are made on the same dyno. That is why a lot of the media list where the dyno testing is done, giving the ability to compare results regardless of timetable.

That makes his comparison to a CBR250 very relevant if the CBR is known for having a significant difference in horsepower in comparison to the stock KLX, or CRF for that matter. Which I would expect since the CBR has both a down pipe and the ability to have a well tuned air box due to the significantly increased space to do so.

Just some food for thought before all the nay saying and second guessing.

By the way, I don't know what else is going on there, but you might notice his horsepower peak came arount 10,000 rpm - nearly 2000 rpm higher than that of a stock bike. I have to ask, what else is changed besides just the bore? Cam change? Pipe? Cam timing mod? Or is the total gain due to the 42cc increase in bore? Oh, forgot - is the piston a higher compression piston?