Ada dome suggestions

[kkwedell]

So I just had my 701 bored out to 83mm and I have a couple questions. Right now my compression is 205 with 33cc 701 domes. Can I run 760 domes just in case I want to go bigger in the future. If so what size should I go to get around 180 psi. If not what size 701 domes should I get to be around 180 psi, I was thinking 37cc. Thanks for the input.

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[eastcoastjumper]

Use 35cc 701 domes. You can't use 760 domes on a 701

 

[Freakrider]

So I just had my 701 bored out to 83mm and I have a couple questions. Right now my compression is 205 with 33cc 701 domes. Can I run 760 domes just in case I want to go bigger in the future. If so what size should I go to get around 180 psi. If not what size 701 domes should I get to be around 180 psi, I was thinking 37cc. Thanks for the input.

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My 735 ( 83mm) had 205 compression with 35 cc domes at sea level. I switched to 36 cc domes to be safe but probably didn't need to with 93 pump gas we have in Florida. Your compression should be higher than 205 unless you are at a significantly higher altitude. You could have your domes cut to 34 or 35 if you are concerned. There are alot of builders around that could modify them for you. 205 is not that high if you are just brapping around and aren't holding throttle wide open for speed.

 

[Quinc]

I run 701 35cc domes on my 61x bored out to 84mm.

 

[BruceSki]

Use 35cc 701 domes. You can't use 760 domes on a 701

I could be wrong but I think guys at 84mm are running 760 domes? @bigkahuna might know?

I know compression goes above what it says on the ADA chart as you go up in bore size.

 

[kkwedell]

When I called ada they said 83mm was the max with 701 domes and 760 will fit in a 701 head.

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[BruceSki]

My 735 ( 83mm) had 205 compression with 35 cc domes at sea level. I switched to 36 cc domes to be safe but probably didn't need to with 93 pump gas we have in Florida. Your compression should be higher than 205 unless you are at a significantly higher altitude. You could have your domes cut to 34 or 35 if you are concerned. There are alot of builders around that could modify them for you. 205 is not that high if you are just brapping around and aren't holding throttle wide open for speed.

Hey freakie, 215-220psi at sea level on my gauge @82mm stock bore (unported) 701 with 33 cc domes. She rips wide open for minutes straight through the inlet and the marsh!!! 93 pump octane from Mobil or Shell.

 

[kkwedell]

I went with 36cc 701 domes. Safe to run with 91 octane gas? Sometimes I do rip wot around 10 seconds.

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[Freakrider]

I went with 36cc 701 domes. Safe to run with 91 octane gas? Sometimes I do rip wot around 10 seconds.

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Did you read what BruceSki runs and how high his compression is with 82mm bore ? Your 205 compression was not up to par with 33cc domes at 131 elevation where you live in Walnut Creek. You must have a worn or scored cylinder unless you have race porting ? Have you inspected your cylinder, something doesn't add up on your numbers. Is your compression gauge of good quality? Battery and connections good?

 

[JetManiac]

Comparing compression numbers is only a rough guide. Different guages, different testing methods(throttle open or closed, plug in or out), battery condition will give a fairly large range of results even on the same motor.

There are many other variables as important like squish, hull type/weight, and timing advance/retard.

 

[Freakrider]

His numbers are way off so that why I'm asking him about his gauge, battery and connections. BruceSki numbers fit for bore and dome size from my experience.

 

[kkwedell]

Did another test with throttle wide open and plug in. 215 psi each. 36cc domes still safe?

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