OS 91SZ-H going lean after first tank :(

[jambo]

I installed an OS 91SZ-Hyper in my second Stratus last weekend, it has a Hatori SB18 coupled with it. I have added the 2nd no.2 shim as I'm using 30% coolpower. I am not using muffler pressure, with the tank vented to the atmosphere via a check valve. The check valve is orientated so that you can blow into the tank but not from it.

It started first time without any problems and sounded lovely and smooth. The first tank was fairly uneventful, some light hovering and a bit on the rich side.

The second tank was a different story, after a couple of mins into the tank the engine revs started to go up slowly and then started to go nuts. I landed it immediately. Checked the fuel lines etc and tried again, same thing as soon as it gets into the hover it went lean.

I then took it home and replaced all the new fuel lines and checked the needles for dirt, etc, couldn't find anything wrong!

Went to the field again and the problem is still there, I opened up the middle needle to 3 and the high end needle to 4 turns but this didn't really make any difference :(

I have read that the carb can come lose causing lean runs but mine isn't.

How do I check the correct operation of the regulator and pump?

Any other ideas?

Thanks

Steve

[SteveL]

remove the check valve

[Gary O]

If you're not running the Kline or the new OS reg system you don't need the valve.

[jambo]

Yes you guys nailed it on the head. It was the check valve. Won't fuel run out of the tank when the heli is on its side without the valve?

[R-4-L]

http://www.helifreak.com/about12360.html