OS 91SZ-H Q about fuel Regulator

[Helio Addict]

I recently put a pump and regulator on my os and I was having a terrible time with the engine wanting to run lean, so I got to looking and the fuel inlet at the regulator has to be perfectly lined up with the hole in the needle adjustment barrel to let fuel into the carb. The fuel inlet that i removed from the engine prior to the regulator had a chanelled groove inside it to allow fuel to flow arround the post and into the hole without the need to perfectly line everything up. Could I have possibly purchased the wrong regulator? Has anyone else experienced this? After about 1 gal of monkeying with this and trying to get it correct I blew a hole in the piston and now I'm down for a rebuild. Should I consider just using the pump and forget the regulator? The engine was running great before I hung the pump and reg on it.

[DavidH]

Which regulator did you purchase?

Also I am going to guess this motor did not have a pump before.
Why would you add a pump and a regulator at the same time?

David

[Helio Addict]

Well, the motor did not have a pump or reg originally. My other os 91 did so I was just upgrading this motor so it was the same. Is there a reason I shouldn't or is there a difference in the motors? The reg I installed was the same part number from the other OS with a pump and reg.

[DavidH]

The carb that is on the 91SZ that comes with the pump and regulator is different than the one on the non pumped engine.

Just adding a pump and regulator will not make it the same. The carb on the pumped engine is ported different to let the fuel flow.

Your best bet would be to add a Cline Regulator from OMI. Then use crankcase pressure to pressurize the fuel tank. That will give you a consistent running engine.
Contact James at OMI. Send him the carb off the SZ. He will install the Cline and send it back to you. It is about $70. He will also send a check valve to use in the pressure line coming from the back plate. Then you will have a good smooth running setup that delivers fuel constantly to the carb.

http://www.oneals.com/Omitro.html
David

[Helio Addict]

David,
That has helped alot. I had no idea that the two engines had different carbs! No wonder the engine ran terrible! I will put a Cline Regulator from OMI on like you suggest. Also, what gearing do you suggest with this motor? I'm looking for the most power available for my bad collective management. :lol: Right now i'm using 8.45.1 (11/93) on my R90SE.

[DavidH]

I would suggest 8.18 or 8.27. 8.45 is more for the YS 91 motors. Close as I can see you get with the Raptors is 7.91. This is 95 tooth main gear and 12 tooth pinion.

David