my friend has a modded yfz..real nice...just had it dyno'ed and it only came in at 39hp...can this be right or is the set up wrong...here is his list of mods


full yosh comp exhaust
cdi box
cam mod
rear carb air splitter
K & N filter

thanks guys..i feel he should be gettting more

 

was it jetted correctly? other than that the dyno was prolly a little on the conservative side, but i'd say it wouldnt be pushing more then 40-44 hp with those mods

 

thats what i thought......any idea what it is stock?

 

Yamaha paperwork mine came with said 38HP stock. I to think that dyno is probably conservative. With those mods he should be getting 7, maybe closer to 10 HP over stock.

 

What kind of CDI box did he get, some of the aftermarket cdi's actually produce less rwhp on the dyno. Plug in the stock one and see where thats get him....

 

I just happened to think, was he running knobbies on the dyno? Thaty could account for the low numbers also.

 

razr'2 is what he had on with dyno....

could the tire size...20-22 make a difference

 

Well, the knobbies won't read as high as slicks, and I would guess Razr2's might be one of the worst since they have large, widely spaced knobbies.

 

Also don't forget most manufacturer's hp specs are bhp and rwhp....figure about anywhere of a 10-20% hp loss goin from the crank to the wheels.

 

yeah so if yamaha say 38 hp thats at the crank, so about 33 to the wheels, + 6 hp gain with the pipe and filter sounds about right