What makes a 295 kit?

[Derrick Adams]

...and is it better than a 310?
I'm still doing the research on engine combos. I was originally thinking of just buying the ESR 310 kit and installing it, but Deathman had said that those bigbore kits are harder on the counter balancer and bottom end.
So I know that i'll be MX racing this bike and reaming on it all the time. Not sure if I want to sacrifice durability for extra power. But I would definately like some more power to be able to keep up with the pack in those straight aways.
No matter what I'm adding a V-force reed cage and PT high rev pipe this winter along with a 39mm Keihin carb that I already have. I'm sure those parts will help greatly.
Does anyone know the characteristics of each kit? power vs. durability, rpm range vs torque, etc.

options are:
250cc with port polish & bolt-ons
295cc with polish & bolt-ons
295cc with port polish & bolt-ons
310cc with any port & no bolt-ons
310cc with any port & bolt-ons

[Mr. Sandman]

In my opinion, you won't notice much of a difference in revs between a 295 and 310. Yes the 295 will rev quicker, but with a 310, if needed you could lighted the flywheel to compensate for the weight of the larger piston. You will gain some HP with the 310 over the 295, but how much, I couldn't tell you. I also think the extra power will have a negligible effect on the lower end as long as it and the bearings are in good condition.

Something else to consider since you'll be racing, would running the 310 force you to race in the open class? If you can answer or deal with all the different variables, I'd say go for the 310 as there's no replacement for displacement.

[deathman53]

the bigger pistons are harder on the rod and counterbalancer. a 310 is really a 295 sleave bored all the way out, most 310 kits are 295's, most 330's are 320's, they figure in a few rebuilds. You won't notice any difference(maybe the pro will), but the normal guy won't, he'll think the same thing that I do about my 310pv(295pv), its really fast and at times very scary. My advice: put your money into suspension, extended axle, more slidable tires, maybe a extended swinger to get more power to the ground with less wheelie, short track kit if you are doing short course racing. Suspension and handling will make your bike much faster than beat suspension and a hot motor.

[Derrick Adams]

Suspension is done. Swinger is done. Axle is on the list. Tires are done. Time for the Power Plant!
I know from experience that more power isn't always needed. I mean you can throw all sorts of money at a bike, but on an MX track, if you can't ride you ain't going to win. But I also know, I can handle more power and use it effectively. Just not sure how to go about getting it.

[deathman53]

if you have the money get a 310pv, best money you will spend. I have a paul turner hi-rev pipe, also the cr ingnition is on the list of the best things I ever got, but you lose the lights, no lights on my bike, no big deal. I'd go for the cr ignition next, it will do things to a stock motor you will never believe.