Pregen riding alongside a CBR250

[babyninja1968]

does anybody here on a pregen ride with a cbr250 riding buddy ? how does the pregen fair up against the CBR250 ? My buddy rides a cbr250 and seems to think he needs to complete some mods on his bike before I get mine running and we go riding, maybe he is worried I will leave him in the dust ? maybe he has been left in the dust by a Kawi pre-gen already ? I have ridden the CBR and they seem pretty quick fer a little 250

[csmith12]

Not sure if it counts or not, but I have been in races with all 3. Pregen, newgen and cbr250. Each has their pros and cons, but none of the 3 will leave the other in the dust unless the skill of the rider is in play. And if so, there is nothing that anyone can mod on the bike for that.

You will have it on top end, he will have it on corner exit.

[babyninja1968]

will changing the intake filter on the pregen make it more responsive in that area ? or was the 4 million $ spent on the intake design well spent and I should leave it alone ? .....different front sprocket maybe budget speed outta the turns ?...lottsa twisties round here.....

[csmith12]

Gearing will go further than a filter change, no doubt about that. But both/either will help too.

Edit: I have a pregen too and opening it up a little does help. Not quite as dramatic as changing the gearing, but you will notice.

[babyninja1968]

Originally Posted by csmith12

Gearing will go further than a filter change, no doubt about that. But both/either will help too.

do you suggest a front sprocket ? one tooth smaller in front ? or one taller in the rear ?

[csmith12]

Nah, imho.. on pregens and newgens, just chaning the rear is good enough. Go higher in tooth count to gain midcorner drive at the expense of top speed. Go lower tooth count to "calm" the rpms down at sustained high speeds and to lessen the need to shift as often.

Not sure what fits your needs, but that is pretty much the general consensus around these parts.

[babyninja1968]

does altering the original design hamper the known reliability of the little pregen ?

[babyninja1968]

the little cbr's single is pretty zippy

[csmith12]

Originally Posted by babyninja1968

does altering the original design hamper the known reliability of the little pregen ?

no, these bikes have 20yrs of development behind them. you aint breaking that by changing some sprokets.

[csmith12]

Originally Posted by babyninja1968

the little cbr's single is pretty zippy

indeed, when you come in 2nd behind one... you learn that real quick.

[Triple Jim]

The key is to be in a good place in the power curve when coming out of a turn, probably a little below the peak, so you pass through the peak as you exit. On a track, corners are the same every lap, and it's possible to make an improvement to the sprocket ratio that puts you in better places in the curve on average. But on the street it's harder to make a sprocket change that helps every corner exit. It would be possible to put a bigger rear sprocket on, and then find that exiting some corner you take, you'd like a gear halfway between what you actually have.

[Ceeloo Yello]

I know that my son's cbr250 feels like it has more torque off the line but my ninja 250 has better top end.