- Location
- Winnipeg Manitoba
What is the smallest dome I can run with a 61X cylinder bored to 84mm? The exhaust port was raised about 0.5mm, just enough to clean it up. It is a Superjet with a B pipe.
Smallest Pump Gas Dome 84mm 61X Cylinder?
- Thread starter robertg
- Start date
SUPERTUNE
Race Gas Rules
- Location
- Clearwater Fl.
It all depends on the set-up...What gas your using, what timing curve can you run, (stock CDI, MSD inhancer, Advent CDI, MSD total loss) Who's head are you using and what's the spec's for piston to head clearance and squish ratio? Are you riding freestyle only or race ski with lots of WFO throttle? If running dual cooling... what pistons are you using (forged or cast) and what is your piston to wall set at?
I have built lots of motors running 200 lb cranking compression on pump gas (93 super unleaded) with no problems, but YOU need to address the entire set-up to do so.
I have built lots of motors running 200 lb cranking compression on pump gas (93 super unleaded) with no problems, but YOU need to address the entire set-up to do so.
waxhead
wannabe backflipper
- Location
- gold coast
what supertune said
but with your basic setup you have
i wouldnt go anysmaller than 33
however if you put bigger carbs on etc then you may find hassles
but with your basic setup you have
i wouldnt go anysmaller than 33
however if you put bigger carbs on etc then you may find hassles
Mile9c1
X-H2O.com
- Location
- Grand Rapids, MI
I'd guess more like 38cc, that number rings a bell for me.
waxhead
wannabe backflipper
- Location
- gold coast
my bad i was thinking 81mm bore
doh
doh
- Location
- Winnipeg Manitoba
We can get 91 octane or 93 octane blended with ethanol. I am using a MSD enhancer, ADA girlded head, OEM pistons. 0.003" clearance, and dual cooling. I rarely go wide open for more than five seconds, most of the time is spent going slow. The cylinder had the transfer ports cleaned up to match the openings and the exhaust is about 3mm wider than stock. The cylinder was not decked either.SUPERTUNE said:
I was thinking 38cc myself but I just wanted some other opinions. I am running 35cc domes now with a GP760 cylinder but the exhaust port is approx 2.5mm higher on the 62T cylinder.
nobody mentioned elevation?
- Location
- Winnipeg Manitoba
I'm about 750' above sea level. Matt I never use the ethanol blended fuel in my watercraft. I use it in my car because it calls for 89 octane and it is the same price as 87 octane.
D-Roc
I forgot!
- Location
- Dirty River Rider
robert, do you use the standard ada domes for the 84mm or do you have to get special ones for the 760 to get the o-rings to seal, Basically i want to know how big you can go on the 61x bore before you need to get the bigger domes.
D-Roc
I forgot!
- Location
- Dirty River Rider
squish changes the bigger you bore? or are you saying to check to make sure it is within spec when you bore to 83mm
The ADA 701 domes are already bored to 83 or 83.5mm (don't remember which). But obviously, the closer you get to the outer edge, the less squish there will be, as it's angled slightly.
So, you need to check it at max bore.
I ran ADA 701 domes on an 83mm bore, and the squish was perfect, right at the limit.
So, you need to check it at max bore.
I ran ADA 701 domes on an 83mm bore, and the squish was perfect, right at the limit.
D-Roc
I forgot!
- Location
- Dirty River Rider
ah yes that would make sense. so after the 83mm bore you will have to step up to the 760 domes. i take it that there is still enough sleeve lip on the 61x stock sleeve for the 760 rings to seal?