yamaha gp 1200 - PWC Forum: The best hang-out for Personal WaterCraft enthusiasts

madcrisis · 11-10-2008, 06:09 AM

i just purhcased a 97 gp1200with ride plte solas impeller and riva racing head. i was wondering if with this head were the valves replaced and do i need to run a higher octane fuel?

**JUST-IN-TIME** · 11-10-2008, 10:56 PM

check compression psi

Wetracer · 01-12-2009, 01:03 PM

That motor is a 2 stroke. It does not have valves. Depending on what your cylinder compression is you might or might not have to run race gas. Let us know what you find and we can steer you in the right direction. Mike

shlbyntro · 01-13-2009, 09:39 PM

Quote:

Originally Posted by madcrisis

i just purhcased a 97 gp1200with ride plte solas impeller and riva racing head. i was wondering if with this head were the valves replaced and do i need to run a higher octane fuel?

a gp1200 is a 2stroke motor. the only valves that are in them are reed valves and they make no difference. you either have them or you dont. a 2stroke will run either way. they just run better with the reed valves in. the 1200cc 2stroke used in the carbureted 1200s had a fairly low compression ratio (somewhere between 7-8:1). for this matter you could probably get away with running midgrade fuel seeing as how i doubt the head stepped up the compression that much. but i do reccomend that you run premium fuel in any 2stroke engine. otherwise you may start to see the fuel precombust in the air-pump (crankcase) while it is building up pressure to scavenge the exhaust gasses. this precombustion in the crank case will fight the engines natural power. (there are those who may disagree with me but i have seen first hand a 2stroke with a cracked block spit out white smoke from the block so it can and a lot of times does happen depending on which engine ur dealing with)

Breck McVay. Wyotech Daytona Graduate (NTHS)

gkecorp · 03-24-2009, 09:43 PM

I have a 99gp1200 with solas imp, r&d plate, and r&d head. The head does change the compression, but you can use 93 octane usually. You should check compression to know what is "inside", from that you can give a better estimate of octane needed. PS. my compression is at150 for each cyl.