Wont start unless throttle is closed - G9

[Big Russ]

Im really stuck on this. My G9 will turn over fine but will not fire unless the throttle is almost completely closed. Then once it does fire the throttle must be opened slowly and coaxed into revving up because if the throttle is opened quickly it just dies and backfires through the carb.

I had the carb and plastic spacer off and replaced the gaskets - no better

Then I replaced the carb - still no better!! :-(

I took the rocker cover off and checked the valve timing and it looks ok. The intake rocker was a little tight on lash so i loosened that - no better

I took the fuel tank out and cleaned all the old fuel out and checked the fuel pump was pumping well - no better

I rigged up another fuel tank to gravity feed the new carb to completely bypass the pump etc - no better

I checked the wiring and everything seems ok. I did see only 10.5v at the coil so i ran a bypass wire from battery + to coil - no better

I checked the pickup coil for resistance and it tested fine - 0.55 k

Ignitor box has only 10.5v at the R/W wire but I was a little scared about hot wiring it :-O

I found a wiring diagram online and I can see there are diodes on power supply and the earths so Im thinking the voltage drop is coming from them??
So maybe 10.5v is ok??

I did see that there is a 7-9 K resistance on the earth circuit between the motor and the battery ground. The main cable to the S/G read fine to the terminal but not anywhere else .....and I dont know where the earths are attached to the block other than the small black wire on the coil mount.

Either way, I ran an extra ground from battery ground to block and no better

I guess the thing I cant get past is the back firing out the carb and its spitting out the carb between backfires ....

Oh and to be clear, I have just brought this cart .... it didnt seem so bad at first but its bad now ....

Any ideas???

[CP241]

Is the airbox complete and COMPLETELY sealed?

IF the airbox lid in particular isn't completely sealed it is going to run like poopoo if it runs at all, and then will usually only run with the choke pulled all the way.

I'd check this first.

Don't second guess yourself too much... The G2/G9 are awesome little rigs. Once you get it going you'll understand :)

[CP241]

Oh, and put the factory MIKUNI carb back on it. I'm assuming you got an aftermarket "Mokini" ($20 carb) to replace it. Some people occasionally get a god one and have luck, but 95% of them are junk and create more problems than they solve.