Shaving my head!?

[Sjetfactory]

I want to know how mm should I cut off my stock sj head to get approx 170 psi to run pump gas and to be safe about the distance between piston at TDC and the head? I heard we must mesure the squish when we mill head is that right? thanks!

 

[Mouthfulloflake]

measure compression with a head gasket, and then measure it again without the head gasket.

Measure the thickness of the head gasket, extrapolate from the ratio.

Or send it to a shop, LPW, GroupK, team scream, and get it done without worries.

 

[vomitspot]

i always did .035
but that made a little bit more than 170lbs
and i still and only buy the pump gas
but its not much cheaper these days.....
$3.33 here and its not even summer yet

 

[thegoldenboy]

Isn't their an easy aftermarket head gasket to boost 10-15 lbs? I'd like to slap one of those on instead of milling.

 

[Sjetfactory]

I never heard about these. Is this true and tested? I mean Whats is that!

 

[thegoldenboy]

I havn't heard either, I just know for tons of other powersports a thinner head gasket is usually avaliable.

 

[Big Kahuna]

you could go with a copper headgasket, they are getting harder to find but that might be one option, but milling the head would be the best.

 

[Mark44]

Always check squish before you mill the head, .045 squish will put you right around 180 on compression.


Mark44

 

[Sjetfactory]

And what is the best way to check the squish?

 

[Mouthfulloflake]

straight from the tech faq section.

http://x-h2o.com/showthread.php?t=2748

 

[Sjetfactory]

Ok Iknow now what is squish and how to measure it. But not sure to understand mechanicals tips ... I'm a french too so this may be my fault.
Ok now my stock squish with my stock head must be around .040.? If I mill the head, my squish will be higher or lower? Why? What I understand is that it will be lower, than what do I need to do?

Sry all And thanks for help!
All I want is a cheap way to get higher comp for pump gas on my sj for a bit more low end, keeping my setup safe doing things the right way, at 100% good mechanicals operation.

 

[Mouthfulloflake]

removing material from the FLAT portion of your cylinder head would reduce the squish measurement.

to restore it, the dome ( combustion area) of the dome could be re-machined.

At this point though, you are spending more than an after market head.

 

[Sjetfactory]

ok I see now ... so what type of head you recommand! girdle or not , when do I need girdle head, o-ring or not ,what is the best? ... Thanks!

 

[DaUpJetSkier]

ada girdle is the best, most ppl run them, but they are expensive.

 

[Big Kahuna]

ada girdle is the best, most ppl run them, but they are expensive.

actually they are the cheapest on the market, RIVA will run you close to $450.00 +/-. JSU/BLowsion is about $500.00 +/-
Protec may be close to the price of the ADA. R&D will be in the mid to upper $400's.

 

[Mouthfulloflake]

ADA with O ring seals and full girdle kit seems to be the safe and flexible choice.

they are right around $300 new if you shop around

 

[#ZERO]

Yep... that's the best bet, machining a stock head is just a waist of money IMO.

 

[BigDog452]

ada all the way baby. never ran anything else since on my 701s

 

[SUPERTUNE]

When using stock Yamaha heads and free standing cylinders, never use anything than a OEM Yamaha headgasket, and never a copper headgasket! (worked ok on Kawasaki's/not on Yamaha's)

 

[Sjetfactory]

Ok thanks All! I will save my money to buy an ada. :Banane01: