Super Jet compression dilemma

[lanmine657]

Im running basicly a limited setup on my 95' 701(i think 95 is all 61x), single 44 blackjack, speedwerx dry pipe, stock bore, stock porting, msd enhancer with 3 deg of added timing. I have three sets of domes to choose from and garage tested each one (lakes are frozen here) and just cant decide which is going to be best, i got 190psi, 170psi and 150psi. im currently at 5000ft and the two lakes i ride most have a over 1000ft elevation change mabe more and i hate hate hate having to mix race gas and pump gas just to ride so the 190psi at the lower lake is more like 200psi so that is out of the question for me, deto is a four letter word. im thinking 170 is best but i want my motor to last and always be reliable, im not to worried about loosing a little bottom end snap going with 150psi but definatley dont want it to be a turd. i usually like just carving glass, chaseing boats, running from the rangers, lots of long wfo runs and letting friends ride knowing they will make it back. I really like the idea of running at 150 but like i said i dont want a total turd, just a little one, any opinions?

 

[augustaf]

I suggest your 170 option in this case- presumably 35cc domes- and 93 octane gas. Good performance and reliability

 

[xjetrider]

Do you know how many cc's the domes you have are? I would highly recommend turning your stator back to the factory mark and not advancing the timing. The MSD enhancer doesn't pull enough timing out at the higher RPMs to be safe with the Speedwerx pipe.

 

[lanmine657]

I suggest your 170 option in this case- presumably 35cc domes- and 93 octane gas. Good performance and reliability

at 5000ft i dont think the cc of the dome matters but more of just the overall psi, highest octane rating pump gas in my area you will find is 91 cause of our elevation.

 

[Snivilous]

at 5000ft i dont think the cc of the dome matters but more of just the overall psi, highest octane rating pump gas in my area you will find is 91 cause of our elevation.

Depending on where you ride, Berthoud has 93 octane at their gas station next to the highway, but that's 5 miles or so from Boyd and Carter. I'd do the 170.

 

[lanmine657]

Do you know how many cc's the domes you have are? I would highly recommend turning your stator back to the factory mark and not advancing the timing. The MSD enhancer doesn't pull enough timing out at the higher RPMs to be safe with the Speedwerx pipe.

its old blue west coast head, YEP7029(im assuming thats 29cc) dome gives me 150, YEP7027=170, YEP7025=190

 

[lanmine657]

Depending on where you ride, Berthoud has 93 octane at their gas station next to the highway, but that's 5 miles or so from Boyd and Carter. I'd do the 170.

im in south fortcollins, 5min or so from boyd, i usally ride boyd and glendo

 

[Big Kahuna]

Do you know how many cc's the domes you have are? I would highly recommend turning your stator back to the factory mark and not advancing the timing. The MSD enhancer doesn't pull enough timing out at the higher RPMs to be safe with the Speedwerx pipe.

What he said. I found out the hard way.......... It is a great pipe but you have to set your ski up for it and around it.

 

[lanmine657]

What he said. I found out the hard way.......... It is a great pipe but you have to set your ski up for it and around it.

just got the pipe this winter and havent run it on the water yet, time to yank the flywheel again and turn it back to stock, my old set-up +3 was perfect, pistons had perfect wash, no sighns of deto at all. thanks a bunch, i would have kicked my own ass if i blew it up first ride out.

 

[wanderer1]

Reset your static timing to stock like has been said and with 91 run at 150psi. Really not gonna be a HUGE difference even though that pipe likes compression. Alot safer at 150psi with the 91 octane. just my 2 cents for what it worth after losing a motor at 185psi running 91, ran fine with Texas 93 but 91 no bueno.

 

[RMBC Freeride]

I'd run those 29cc domes, especially with that speedworx pipe being a brand-new setup. I'm also curious what brand/type compression gauge you're using? Because even the 29cc should be giving you 180psi or more at 5000ft.

Here at 4000ft, my go-to domes for a limited setup are 31cc's (35cc's for sea-level). Those usually indicate about 180~185psi on my snap-on gauge on a stock (non-ported) 61x cylinder. 25 and 27cc domes are for the 7000ft+ and/or race gas guys IMO.

 

[lanmine657]

I'd run those 29cc domes, especially with that speedworx pipe being a brand-new setup. I'm also curious what brand/type compression gauge you're using? Because even the 29cc should be giving you 180psi or more at 5000ft.

Here at 4000ft, my go-to domes for a limited setup are 31cc's (35cc's for sea-level). Those usually indicate about 180~185psi on my snap-on gauge on a stock (non-ported) 61x cylinder. 25 and 27cc domes are for the 7000ft+ and/or race gas guys IMO.

im sure my gauge is way off, i think chase has good gauge but im thinkn stay with the 29's and turn down the timing. i need somthing to do this do this weekend anyway cause I herd blizzard in the forcast, you guys gettn it too?

 

[RMBC Freeride]

No, we usually miss most of the snow. Just look for a brown spot on the map of Colorado, that's us! Hope boyd gets filled up, looking forward to goin up there this summer.

Sent from my DROID2 GLOBAL using Tapatalk 2

 

[lanmine657]

i didnt figure my gasket thickness, so 29+5 about 34cc giving me 150psi, sound right? and just finished re-setting static timing to stock, thanks for the info guys cause i know there is a ton of trial and error for jetski motors and i dont have the cash for a buch of errors