250 to 300

[SamCSscoot]

Hi, I joined here a few weeks ago, but have not posted before. I like the personality of this forum, not too many people here that know absolutely nothing and there are fairly intelligent conversations.

I was on another forum where somebody was asking about what scooter he should but and it seems he is being pushed towards a 400 cc or higher. I pointed out that there is a 300cc and another person was wanting to know about that and if he could get one registered in California. i don't know about that, but there are some big bore kits out there for the 250 scooters. I thought I'd share here what I found for the big bore kit.

There is a big bore kit for the 250cc to make it a 300 out there, runs about $500.00 I think, it has been a while since I have seen it, and yes it is for the liquid cooled motors, I've seen one for both the 244 cc Honda clone and one for the Linhai motor.



for the cn250 and cf250 you can get the cylinder bored out and here is the piston and ring set you need to make the conversion to a 300

gokartsusa.com/300pistonkitcn250.aspx

[Rebel]

Welcome Sam,

There is a thread here with some information on hot rodding the 250, I'll find it and start a should be stickies thread here for the 250's. Thanks for adding your information.

[bige]

be careful of those pistons, they will increase the compression to over 12.5-1, they will only make it a 272cc. a ported and polished head and cam will give very good results with out jacking up the compression

[Rebel]

here is a kit offered from Carlos, autotech335 on ebay. 75mm bore cylinder, piston, wrist pin, clips, rings, and gaskets.

link

and one for the Linhai/yamaha
link

I have no idea if these have a lower compression piston or not in the kit.

[xs650]

The 75mm piston setup form Carlos will only increase a 244 cc to 265cc. The MRP piston is smaller than that.

Marketing puffery from MRP. At least Carlos didn't claim a false displacement increase.

[Rebel]

he has a pretty good reputation for his parts and honesty

[xs650]

Ask him to explain the 300cc claim.

[bige]

most all manufactors round up the displacement , mrp is known for false stuff. carlos does have a good kit and with a performance head and cam the 250 will really be woken up.

I have had good results from my head and cam kits, tune the cvt to the new power can make a world of difference

[Rebel]

bige, I've been reading about porting the head on the 250 scooters. what I've read is that the exhaust port is pretty restricted and if you open that up it will make a big difference. Is that your experience?

[bige]

yes we open it up some, and polish it . we dont open the intake up much because there is a water jacket in there. we have found that its not so much size but flow and how the mixture gets in and out.

we do two different ways, low end and a set up for top end