Hammer Down
Member
I'm looking for jetting specs for PSI TWIN PIPES. The sled is a stock 93 that is getting switched over to 800 clutching and chaincase. Other than that the motor is stock. Are these pipes worth any gains? Am I better off using 800 pipes? I'm looking to make more noise and the PSI pipes are restored nicely already.
Throttle Junkie35
New member
Psi claimed 153 hp @8250rpm for the twins on a 750. Vs stock 133.5hp
yamahamark
Member
Your better off with 800 pipes and jetting. If you want lots of noise add a bender can or Hauck performance can. I have a Hauck performance can on my 800.
YAMMIEGOD3:16
Active member
stay with them if their psi twins for the 750. the psi twins for the 800 were very close to the stk 800 pipes. psi made their pipes for each engine, not one pipe fits all. not to say they won,t work. the 93 was 140 stk, figure 9 horse if jetted correctly. i should have jett spec. 3:16x (yammie tony)
Hammer Down
Member
Well, PSI used 142.5 mains in one of those dyno tech pipe shootouts. Seems pretty rich for a stock 750? I run 137.5 in my quad piped psi 750 with no issues.
toydoc
Member
You would go by BSFC not jet size for rich vs lean on the dyno.
A better pipe can sometimes take less jet (pull more fuel) and make more power with it
A better pipe can sometimes take less jet (pull more fuel) and make more power with it
YAMMIEGOD3:16
Active member
toydoc post was right on. and thats what most of the pipes built by psi required. especially his quads. 3:16x(yammie tony)
Hammer Down
Member
Finished a fun little project. Updated to 800 secondary, chaincase,jackshaft; with Hauck Orange and billet helix 
45-41@70*. Installed PSI twins(sound fantastic)!cleaned the carbs and went 143.8 mains. New bogie bearings, slides and ice ripper track. Too bad the 14" of snow from last week melted to nothing.
45-41@70*. Installed PSI twins(sound fantastic)!cleaned the carbs and went 143.8 mains. New bogie bearings, slides and ice ripper track. Too bad the 14" of snow from last week melted to nothing.