yz250 head on blaster

[riot7012]

will an air cooled yz250 head fit on a blaster motor, piston and all? its a 70 some model yz250 air cooled, ideas are appreciated

 

[motoman9911]

Do you already have the head? If so try it for yourself. But I assume no.

 

[fioz600r]

No but if you want to liquid cool your Blaster look into a DT200 motor. They are the same motor design.

Brandoz28 has a great link to a Blaster converted to a DT200 liquid cooled top end..

 

[brandoz28]

i really don't think that the yz250 jug and stuff will work. it'd be better to get a whole motor and work it into the frame

here's the dt200 swap link, redline on here also has a lot of good info on yz250 swaps and dt200's

Yamaha YFS200/DT200 - Yummie Yami, Upgrade The YFS; To Be The Best

 

[riot7012]

Ive always called the whole top end the head, but the main top part where the spark plug goes, it will bolt up to a blaster, i was just wondering if the whole cylinder would bolt to it, if so i was going to get the head shaved because im sure a yz250 has a longer crank

 

[brandoz28]

hmmmmmmmm give it a try and let us know how it goes.....that could be a cool idea for another big bore kit maybe, what is the bore size on that thing?

 

[riot7012]

I couldnt tell ya, i bought 3 yz250 motors and a frame 2 years ago for 50 bucks, then gave it to my cousin, i got it all back the other day because im about to go trade it all for a blaster frame, but if the head will work on a blaster then im going to keep 1 head and go buy a blaster motor for 100 bucks

 

[brandoz28]

i don't think anyone has tried it......but my gears are turning now....

these are still air cooled right?

 

[riot7012]

yes they are air cooled, they are like a 78 model, i think its like the first year they started making the yz250

 

[Blasterdude27]

Short anwser... Its not worth your time, if you want more get the head milled/re-designed.

 

[brandoz28]

ok.....how many studs are there for the base of the jug? can you measure them center to center? i'll measure mine since its apart....

 

[riot7012]

How can you say its not worth my time, if it fits and has more power than a big bore kit

 

[riot7012]

4 studs, ill measure it later

 

[brandoz28]

i wonder how much better the ports and stuff are....the bore isnt THAT much bigger than the blaster

 

[phragle]

WEll, 1st, theres nothing you could do to a yz 250 head tha you can't do to a blaster head. The only benefit would be if it had more surface area on the cooling fins. I do remember somebody putting one of the old porcupine 250r air cooled aftermarket heads on a blaster in 88 or 89. this would provde somewhat better cooling, but I havent seen one of those heads in years. True the head is a major aspect of cooling, but the real culprit in an aircooled 2stroke motor is the thermal expansion of the cylinder.

 

[riot7012]

The piston is a pretty good size bigger than a 4 over blaster piston, and just think of how much of a bigger piston u can get in the yz when its bored

 

[brandoz28]

ok.............looks like its 70mm bore x 64mm stroke......so in a stock blaster motor it'll be about 220cc's. i wonder what the port timing would look like......i'm intrigued because it'd be an interesting project

 

[riot7012]

This is all I can pretty much find on the yz Yamaha YZ250 - Wikipedia, the free encyclopedia

 

[brandoz28]

yeah i looked around a little bit and the ports are HUGE. it'd be really interesting to see how one would run on a blaster bottome end...but i'd probably just swap in the whole engine if i had it available

 

[phragle]

ok.............looks like its 70mm bore x 64mm stroke......so in a stock blaster motor it'll be about 220cc's. i wonder what the port timing would look like......i'm intrigued because it'd be an interesting project

Well, your definitly not going to get a +7mm stroke blaster crank, then there is rod location on the piston, so your going to be cutting the cylinder down and maybe using a different rod plus a 4mm crank, then trying to get the porting right, then having a pipe made... you can do a lot to a blaster motor for the dollars its going to take to get that figured out.