broke_n_bummin

I have an ASP 1.08 with an OS 7D carb. I know about the compression and using a cooler plug, but the stoopit thing just won't run reliably inverted. I can get it to idle fine, but at mid to full throttle, it just seems like it's too rich. I tried an OS P8 and #8 plug and just for S&G I tried an OS #F and got the same results. The needle valve is only open about 1 1/4 turns, and once it winds up to about 10k RPMs it starts leaning out and running right. I've tried a few different props, APC 16X4W, Zinger 15X5, MAS 14X8, APC 16X6. I was looking at the recommended prop sizes and the manual says 14X6-8 up to 18X6. I also read the manual on the carb, and it says the venturi is removable. Has anyone ever removed it? If so, what were the results? Oh, by the way, I'm running Byron 5%.

w8ye

My Feedback: (16)

You need to check your tank height position.

Typically with inverted engines, the tank is too high.

broke_n_bummin

It's a U Can Do ... the center of the tank is actually lower than the carb throat.

w8ye

My Feedback: (16)

A big prop will make your midrange rich

Flyer95

My Feedback: (1)

The OS7D is a great carb, one of my favourites actually The venturi size is big enough for any engine as big as 2.1cu.in. or 35cc, so I would suggest to leave the restrictor in there.
There is a small screw thats for idle and midrange adjustments, on the same side where you have the pushrod connected to the carb. Turn this screw clockwise just a hair and try again.