What fuel you guys run with these two pistons, what cam lift will they be safe running with, what cams work best with them, etc.
Pros and cons please....

 

race gas108 octain

 

Awesome question...I always forget to ask the good questions when I get around those fast guys. I'm guessing that the PAMI builds are running the higher compression pistons and for a fact alcohol is the "best bang for the buck" fuel for the application. I don't know any specifics on cam lifts but believe PAMI "stage III race" cams are the setup in the 760 (14:1 compression) I saw this weekend. The only con that I can think of with using alcohol is the cooler ignition point and risk of fire in the event of a carb leak, i.e. stuck float. I hope to visit with MrHorsepower near Thanksgiving...and will try to remember to get some specifics...hopeful in trying a new dual carb set up also.

 

I use 110 Union 76 Race gas with my 14:1 piston. Cams should be no greater .425 lift and I have the 260 degree from RWR. With that your clearance will be .006 - .008 inches. I could have gone with the A1/A2. However, with all the torque of the 14:1, I hoped for the best of both worlds (high end power and low end torque). In my opinion I have finally found that sweet spot of very good low end power and torque (especially when used in conjuction with map 8 on the vortex ignition), and very good top end power as well taking full advantage of the race cams and moving the Vortex map to position 2 (the most advanced power curve).

Also, you should know that the RWR CDI is (IMO) just too advanced to run the 14:1 piston well at low RPM. That piston runs better with more power with something not quite so advanced at the low RPM level. However, the RWR CDI does run the 14:1 piston quite well above 4,000 RPM. This is just something to consider when you are looking at a piston.

 

110 octane turbo blue is readily available around me, being close to IRP in Indy. I was hoping it would be the ticket. alky is just not practical on long rides. How's the mileage?

the clearance you speak of with the .425 lift is practically cut to nothing with the .433 of the A2 intake cam I have, are you sure it can be used?

Thanks for the ignition info, I never even considered any of that.

Who all makes 13:1, 13.5:1, and 14:1 pistons?

 

I'd say the 760 gets most of its compression from the over bore and stroke. Pistons are probably pretty flat. Haven't seen one, just a guess.

 

You are right! The clearances on the A1/A2 intake are pretty much all used up with the .433 lift. It would be close. I know that the 14:1 is certified for cams up to .425 lift. So, to be safe, you should probably consider something with a .425 lift. You may be thinking you'll want the extra torque at the low end with the A1/A2, but I can tell you that the 14:1 piston will make your motor a torque machine; especially when you retard the ignition timing. Like I said earlier, being able to switch between power types is a real plus, especially with this piston.

JE makes the one I have.

I haven't noticed any mileage differences between the 11.5:1 and the 14:1 piston.

 

Hightower,

You may not want my opinion on what mods you should get but you're gonna get it anyway!!! LOL

E---X---H---A---U---S---T!!!!!

At 300' my Yoshi without spark arrestor was .2 seconds slower than my modded endcap!!!

The specs on the a1/a2 cams are a little decieving, i got a new brochure from RWR and it is only listed at .050" lift!!! They have MORE duration than the race cams/109s which are 260. I think your bottom end pipe is smothering out your topend cams!!! JMO

 

well they have covered the gas, but i'll add you will really like the difference[img]i/expressions/face-icon-small-smile.gif[/img] i get a 120 octane and mix two gallons of pump it's about a 109

 

all opinins are welcome, as always, and very much appreciated.
are you sure your carb was in perfect tune with the yoshi? I mean one main jet size off can make a big difference.
but .2 seconds doesn't bother me much anyway, I'm a big tall guy and no matter what I do there's always somebody faster. what I've come to look for in a pipe is durability (strictly stainless & alum), sound tunability, and removable sparky. with these three key features I can ride anywhere in the continent without ever needing to worry about getting through the gate after driving hours and days, and the Yoshi provides just that. a megaphone system like RWR or Graydon would be my choice for drags, they just don't meet all the criteria!

but then again, there's that new LTE dual exhaust coming soon - no need for tunablilty there because its already quiet enough wide open! And its all stainless! If its sparkied, I'm sold I think! time will tell....

Thanks Mark.