Ported 701s, what's your favorite dome size?

[Roseand]

I previously ran 35 cc domes with my stocker and a b pipe and it hit pretty hard, but now my cylinders are ported too. My builder told me that more compression doesn't always mean more bottom end power. I was planning on running 33 cc domes this season but he said it'd be a good idea to compare them to 35 ccs as well.

Is there a decent gain with the 15 psi from 33 cc domes? What about to 31 cc domes? Keep in mind this is in a lightweight freestyle hull that won't see much WOT time.

 

[yamanube]

Still running a B pipe? What ignition?

 

[Roseand]

Yeah limited b pipe that I had adjusted very well on my last hull.
61x with a lightened flywheel, and a modded protec cdi raised to 8000 rpm.

 

[yamanube]

With a stock ignition curve I would think that 31cc domes are going to be very risky on pump gas.

 

[Roseand]

Wouldn't be pump gas.

 

[eastcoastjumper]

Not worth running a 701 on race gas. You keep saying you're a college kid on a budget here. Use what works!

Yeah you might be able to get away with smaller domes if you're not WOT but what fun is that?

I'm unsure of your elevation but me at sea level used 35cc domes and my sh it ran WOT as much as i wanted. Reliability is worth more to me than a minimal power gain if any...

 

[Roseand]

Not worth running a 701 on race gas. You keep saying you're a college kid on a budget here. Use what works!

Yeah you might be able to get away with smaller domes if you're not WOT but what fun is that?

I'm unsure of your elevation but me at sea level used 35cc domes and my sh it ran WOT as much as i wanted. Reliability is worth more to me than a minimal power gain if any...

In summer I finally bring in some money Haha. I'm on a short freestyle hull, I don't care about doing that much WOT. Last summer on my square I was going 4 gals of premium pump to 1 gallon race gas cuz it's right at the station I use. So I don't care if I need to go half and half.

 

[Quinc]

I prefer 35s over 37s. Domes are cheap, get a set of each and keep the setup you like more.

 

[CRJ]

Id keep the domes higher in the cc's to lower the compression. 180psi is tons. Stock high hp machines run 150ish. Ill most likely be running 40cc's this year on my 760 so i can bomb around with pump fuel. I run through a ton of fuel in a season, so i cant afford 110 VP. thats my tip

 

[tatronation]

Race gas on a 701 isn't worth it to me... Save that money for a bigger motor.

Favorite dome size : 35cc but more importantly, what your engine builder recommends.


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[Roseand]

If anything I'll only go to 33s. My builder told me it's best I try both, so I'll probably do that. Probably going to see how I like my motor with 35s and go from there..

 

[Quinc]

How about 34's?

 

[Jhucke]

If anything I'll only go to 33s. My builder told me it's best I try both, so I'll probably do that. Probably going to see how I like my motor with 35s and go from there..

Yeah shouldn't it depend on how it's ported, too? Seems like your guy should know whether or not it needs more compression for it to run right.

 

[Roseand]

Yeah shouldn't it depend on how it's ported, too? Seems like your guy should know whether or not it needs more compression for it to run right.

Yeah 35s are what's usually used, but he said it wouldn't hurt to try another size. Depending on how my pump and pipe are setup, it could help.

 

[Roseand]

How about 34's?

Aren't those custom cut?

 

[Jhucke]

Yeah 35s are what's usually used

Then use 35's and no need for race gas.

 

[Quinc]

Aren't those custom cut?

You can order them from Ada and other vendors. 192psi