20cc domes on pump gas?

[jacowils]

Im at 700 feet and have a set of 20cc domes for my cool head and am not sure if im in the safe zone or not. Mods are k&n pods, boyesen power reeds, .020 over with wiseco's, dmc 916's and cool head obviously. I would do a compressions test but my engines in pieces and the cylinders are off being bored right now.

[sheerider11]

Well when you get everything back, check. People have gotten lucky, some haven't.

Only one way to find out.

[RobertR]

My old motor was 30 over pt mids, noss coolhead with 20cc domes, 28mm pwks open air box elevation is around 760 and I had to run mix 110 and 91.

[Jereme6655]

sorry to tell you jacowils......your gonna be over.  Im about 95% sure you're going to be too high to continue on jut straight premium fuel.  My setup I run 20cc domes, k&n pods, fmf fatties, vf2 reeds, and a dune/play port by Jeff at FAST and my bike runs absolutely great on premium fuel.  However.....your setup being that it is still on the stock port jobs (I think it is because you never mentioned a port job) will have more compression when you put in 20cc domes vs if you had a port job done and then tried the same 20cc domes.  It has to do with the port timing.....when the piston moves past and either opens or closes the ports.

[Tedder]

You're definetly asking for trouble with 20cc domes at 700ft on pump gas. It's not worth destroying your fresh rebuild over is it?

[jacowils]

Obviously not. I ordered 21cc domes and received 20's so i wanted to see if i could use them or not before i sent them back.

[Bennett131]

I ran 20cc domes on pump gas at 1200ft with zero problems and I didn't have any port work I was at 152psi I believe

[ATV Galaxy]

20cc domes can go either way. every machine is a little different. I always suggest mix with 20cc just to be safe and pump gas with 21cc+.. with 20cc it depends on other motor work and strongly suggest a compression test before selecting your fuel

[RagunCajun]

Mine cranked 167psi at sea level with 20cc domes. Lost a bore and 2 pistons due to that on 93 Pump gas.

 

Run race fuel or get different domes. Don't gamble.

Edited October 8, 2013 by RagunCajun

[mike0chek]

Mine cranked 167psi at sea level with 20cc domes. Lost a bore and 2 pistons due to that on 93 Pump gas.

 

Run race fuel or get different domes. Don't gamble.

 

agreed, not worth the $$

[jacowils]

Yep thats what i thought. Just gonna go with 22's to be safe since they dont make 21's anymore. This is why i love this site honest answers and learning from other peoples mistakes. Thanks guys

[ATV Galaxy]

pro design makes 21cc domes

22cc is stock

[jacowils]

Thought 23.2 was stock.. And that would be great if i had a pro design head which i dont.

[Tedder]

What head do you have?  Pro Design domes fit most aftermarket heads. I thought 24 was stock.  Personally I wouldn't go below 22cc at 700ft with pump high test.

[Starwriter]

Let me see if I got this straight. Earlier you started a thread asking what kind of head you have. It was determined that it is a White Knuckle head and White Knuckle gave you their phone number. So, you ordered 21cc domes that are specific to their head, and they sent you 20cc domes, because they don't make 21 cc domes for their head anymore? That's BULLSHIT! That would be like going to McDonalds, ordering a Big Mac and have them hand you a bag with a McChicken sandwich  in it because "They don't make Big Macs anymore"