Sudden G1 engine failure

[1989Marathon]

Check to see if the screws are still there that hold the throttle butterfly inside the carb.

[DirtDiggler]

Thanks for all the suggestions. There are no missing screws in the carb, airbox is all perfect,reed valves perfect and I cant get anything out of exhaust. I currently am favoring the ring clipping scenario. I really like the idea of the Bravo Motor but-(guess I'm getting old) I have been really pleased with the power of the stock motor- plus durabillity is a major concern for me- cant have the wife and kids on the back 40 and some thing quit cause something needs to be tinkered with. I ordered a Jug kit from Everything Carts (about 150.00)- they held up the UPS guy to get the order out to me today- plug for them, Crystal has given me great service for all the parts I have needed. I was just curious to see if there were any other kits with higher compression/ polished ports/etc that would be easy to do while apart- I have not seen any. Thanks for all the suggestions will update if I ever figure out what happened.