yz250 motor

[blaster429]

I was looking around to see what kind of other 2-stroke engines yamaha has that are single cylinder and I can across the yz250 motor from a dirtbike....i know its bigger displacement but does it offer more power...and has anyone ever put a dirtbike motor in the blaster? and is there anything bigger that is a single cylinder 2-stroke? Im pretty new to the quad modification scene and I want to make the best of the blaster I just bought, because it looks like the perfect quad size wise but it has no engine...so i figured Id see if there were any better options than stock.

 

[jlsparky7]

They make big bore kits for the blaster that are over 250 cc's. My womans dad has a 1982 yz 250 and its pretty quick. Thats with the weight of a dirtbike though, not a blaster. Im sure its doable.

 

[blaster429]

yea i was looking into big bore kits but i was getting mixed signals on that, and hear there are overheating problems and its hard to control that with just an air cooled engine. And the kits i was looking at were 240cc's but to get a good amount of power from the big bore you need to get a good port and polish job but the ones that are ported and polished well, you have to use race gas which is something i dont want. I want to stay with pump gas. which is why when i found the yz250 2-stroke it made me think....it starts out with more cc's and i dont have to run race gas and it is also water cooled i believe so thats a few plus. also you can build onto that with a slight bore, milled head, and a good trail port and polish....i kno its hard to compare a dirtbike engine to a quad engine with the weight difference but is there somewhere with specs on these engines?

 

[jlsparky7]

Just because you have a port and polish doesnt mean you have to run race gas. If you get a .060 over stock cylinder a .020 milled head you can run 93 oct and have just as much if not more power than a yz 250 motor.

 

[blaster429]

see thats why i was confused partly, i know a port and polish wont make you have to run race gas but the one fire breather 240 big bore runs race gas but it didnt give a description as to why and the only thing i saw that was different was the p&p....i was just throwing the yz250 idea out there to see what the opinions were...im still learning about making power with these types of engines. I think i just need to get my blaster up and running to see how the power feels in the trails and the pit and base what I do off of that.

 

[jlsparky7]

Go with a stock cylinder bored next size bigger with a P&P. Then get the head milled .020 over and run 93 oct gas. Higher oct gases burn cooler so it will take care of the overheating.