I have a 2003 SJ 701 and just checked the compression and both cylinders were at 140. I am looking for the best head I can buy that will still let me run pump gas. As far as motor mods I have a limited B pipe, Zero lighted fly wheel, vforce 3 reeds, and msd enhancer. I would like to know if a girdled head is necessary? Also the best brands and what doam size? Possibly could get higher octane race fuel if the gains were noticeable for the extra hassle. Thanks!
High comp head
- Thread starter danimal!
- Start date
Wakerider26
Peter Waldron -doing jetski tricks
- Location
- Alabama
Ada girdled head is the way to go. If you are starting with 140psi in a stock head, I'm going to guess 30cc domes will get you close to 190. I believe there is a chart in ADA's website.
Mike W
Infidel
- Location
- North Florida
ADA is the way to go. Easy to instal and a simple yet very well engineered. In a nutshell, what the girdle kit will do is keep stress off the cylinder and keep it from cracking at the base. If you still want to be able to run pump gas then 35cc domes will put you at ~180 psi. Any higher than that than you will have to run higher octane fuel. With your setup and a good low end prop, you will be happy with it.
Quinc
Buy a Superjet
- Location
- California
If you are wanting to run pump gas and not break the bank you can go with a non-girdled head. Riva, Pro-Tec, ADA, etc ,etc. If you are planning on porting your cylinders you should go with a girdled.
- Location
- s.w. Fl
Or just have Ur stocker milled?!
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Blue
Judging your cheapness
- Location
- St Cloud Florida
If you currently have 140 pounds of compression in each cyl you should be at 155 on a stock head. It's possibly time to re ring it or possibly rebore it. Once you address that issue then you should look into an ADA head with 35 cc domes that will give you 185 to 190 compression. 33cc will get u around 200
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- Location
- Victoria BC
Your gauge might be off, has it been checked against a known good gauge?
Blue
Judging your cheapness
- Location
- St Cloud Florida
No their director bolt ons. you need to have the cylinder bore check while you're at it
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Quinc
Buy a Superjet
- Location
- California
Make sure and check the ring gap even when they are new.
what should the ring gap be?
do the ada girdled heads have o-ring gaskets instead of your regular stock head gasket?
i have been thinking about getting a new head too but im all stock except for a coffman sizzler, maybe i should be upgrading something else first or is the ada girdled head a worthwhile upgrade even on a mostly stock motor?
sorry danimal! not trying to steal ur thread!!
Blue
Judging your cheapness
- Location
- St Cloud Florida
If u go with 35cc domes in the head u will raise compression from 150 stock to 185 with the ada head plus it uses orings which are reusable and cheap to replace. As for ring gap if ur cyl has some wear on it u will be fine or if u have it bored with 4 and a half thousands ur good. I have never had to adjust the ring gap on pro x piston sets as there pretty consistant.
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