20cc Domes = 185psi compression

[CadillacBanshee]

My friend rebuilt his engine and put 20cc domes in his coolheads. The compression went up to 185psi. The bore is 3 sizes over and the bike runs good on 91 octane. Is that too high for that bike? Will anything happen when runs 110 octane like he should be? One person in know blew his engine when he milled his head and raised his compression to 165psi and ran high octane. What should i advise him to do? (smaller domes maybe?) He wants to know if his engine will get messed up if he keeps that high compression.

 

mod list:

320 Mains

4th clip needle

t6's

v-force 3

reed spacers

no air box

coolheads

13F/41R

Engine Ice

skat tracs

[wesw]

you need 100 octane or better

 

you could try some 100LL from your local airport.

[hittintrees srh]

i'd use VP C12-just my .02

[sand rocket]

if his crank isnt welded, tell him to plan on another rebuilt!!

[Dead Op]

Whats youe elevation at! 185 with 20cc domes!

[Big Blue]

Whats youe elevation at! 185 with 20cc domes!

471246[/snapback]

 

 

That is what I was thinking, sounds like your gauge might be off.

[CadillacBanshee]

My elevation is 300' above sea level. I just put 21's in my bike and got only 155psi.

[sandgrencivic2k1]

That sounds about normal to be 155 psi.

 

I had 19cc domes and was at 185 psi at 50 feet above sea level.

 

He better run 110 fuel if he doesn't want to rebuild it again. Also you would not want to go to smaller domes. The smaller the dome the higher the compression. But I would check the gauge, cause 185 seems high even at sea level.