What did I buy?

[capitalx]

I'm needing some help in identifying the power plant for my 93 SN SJ and some advice on how best to use it. The cylinder head is two shades of purple and has: PSI Racing GENESIS II TYPE 2SJ Patented engraved on top. It has never been run since built. It has been ported and bored not sure the bore. I was able to track down the builder but he could not remember all. There is something special about he pistons (ceramic or teflon) and reeds are carbon fiber or something (maybe they all are) The engine is x61 top and bottom.

Two questions to start: 1. What is the head (can't find any real info) I left a message for someone in Utah at PSIpowerinc.com. I found one listing of it mentioned on this forum.

2. I have a bottom end from a 760X - 62T - dual carbs - should i combine the two engines and run dual carbs?

Background: This project started when i bought two museum quality 440 for my 11 yo son and 13 dauguther. Needing more power for me, i bought someones stalled SJ project that came with the Yama 760.

Oh, and did i mention that i've never been on a standup, 54yo and want to do a back flip?

 

[bored&stroked]

1- Some kind of aftermarket head. They are just lumps of aluminum to seal the combustion chamber, not like a 4 stroke head, so theres nothing to them really. Check compression and run it.
2- You sure can. A 760 lower end should be dual 44mm carbs though, thats a bit too large for a stock 701. You'll want dual 38's, or just run the 61x lower end until you get lots of mods.
3- You have a long way to go for backflips, and a 701 superjet isn't going to get you there without a massive, spine tingling large wave to jump. Starts with more basic stuff first, like learning how to stand up.

 

[capitalx]

Will compression tell me all I need to know regarding fuel grade and mix? What about bore? Is this info necessary to determine the exhaust I should use?

 

[mbrick]

I'd run 40:1 mix. Yes the compression will give us a ballpark idea of what octane you should be running, or at least what order of magnitude.

Bore is not necessary for exhaust, but may help with tuning the carb. I think the only two common exhaust choices are probably stock or a B-pipe.

 

[orangefinger]

PSI made stuff for snowmobiles ...they made a pipe and a head for SJ somewhere along the lines...very rare

 

[sjetrider]

"44mm carbs though, thats a bit too large for a stock 701."

Above statement is not true at all. I have run 44mm carbs on ported 701 no issues.'
Use the 760 cases and carbs with this top end for best results as the 760 cases are way better, the crank is interchangeable so use the tightest one of the 2 and make sure wrist pin area is smooth as a baby's azz on the crank you choose.
good luck.
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[bored&stroked]

"44mm carbs though, thats a bit too large for a stock 701."

Above statement is not true at all. I have run 44mm carbs on ported 701 no issues.'
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How is a ported motor a stock 701???? And I'm farily sure you have a pipe and head to go with that porting, don't know many who don't but still ported is not stock.