'95 750SXI Coffman exhaust Carb Settings question...

[Erik Jolliffe]

All,

I am at my wits end. I have a built 750sxi with a coffman exhaust, Jetski Unlimited head, and stock 38 Keihn dual carbs. I have tried running stock carb setting, Factory B pipe settings, combo's of both, and I can not for the life of me get this thing running/tuned correctly. Any help or carb settings (hi/low/pop off/jets) would be awesome!

PS - I am not sure of the type of coffman exhaust I have, but can post a picture of it if needed. Looks similar to a Factory pipe.

Erik

 

[JC-SuperJet]

Both Cylinder Compression Readings? Engine air-leak tested? Good Spark? Crankcase Drain removed and blocked?

650 or 750 Coffman Exhaust? Coffman Sizzler, Signature or Lightning?

Stock OEM Airbox or Aftermarket Flame Arrestors?

Original Waterbox, A/M Waterbox or No Waterbox?

Keihin Carb Fuel Pump rebuilt? The Keihin FUEL PUMP Rebuild Kit is a separate kit from the regular Keihin Carb rebuild kits. Thus, most never rebuild the tired old Keihin Fuel Pump. As opposed to the Mikuni Rebuild Kits that do come with the Pump parts...

Post a Photo of the Engine Bay.

 

[Erik Jolliffe]

Both Cylinder Compression Readings? Engine air-leak tested? Good Spark? Crankcase Drain removed and blocked?

650 or 750 Coffman Exhaust? Coffman Sizzler, Signature or Lightning?

Stock OEM Airbox or Aftermarket Flame Arrestors?

Original Waterbox, A/M Waterbox or No Waterbox?

Keihin Carb Fuel Pump rebuilt? The Keihin FUEL PUMP Rebuild Kit is a separate kit from the regular Keihin Carb rebuild kits. Thus, most never rebuild the tired old Keihin Fuel Pump. As opposed to the Mikuni Rebuild Kits that do come with the Pump parts...

Post a Photo of the Engine Bay.

Stock air box, rebuilt Keihins last year, and I think it's a rocket pipe straight to the exhaust tube, no water box. I just put in a new relay this why the ebox is split...

 

[Erik Jolliffe]

Compression is 150/150
I am at 1800' above sea level
I'm pretty sure I have 125 main and 75 pilot jets. Popoff was set about 18 or 19psi

 

[JC-SuperJet]

Seen where Pam Coffman wrote that the Rocket Pipe was NOT made for the 750 SXi.

If there is no Waterbox, you will have a hard time trying to dial in the Carbs. 2 Strokes need some Exhaust Back Pressure.

You didn't say if the Keihin Fuel Pump itself was rebuilt...

The Jetting and Pop-Off you posted is what another guy with the same Rocket Pipe had. Said it ran but not optimally...