Ok, so my father in law picked up a 1979 340 Drifter and a 1978 440 Intriguer. He put the motor from the 78 Intriguer in the 79 Drifter. He was missing the airbox on the intriguer and a local snowmobile mechanic he knew said the carb off the 79 Drifter would work fine with the 78 Intriguer motor so he did that because the Intriguer carb wouldn't fit into the 79 Drifter airbox. We got it running the other day and at first it backfired out of the airbox a few times but then ran great in the garage with the track lifted up but then when I went to run it down the road it bogged down and didn't run good. He took it to his mechanic friend and he replaced the jets on it but it's still not running as good as it should. Looking through the service manuals I have found that the 1978 Intriguer carb is a Mikuni VM 34 Zinc and the 1979 340 Drifter is a VM 32 Econo Jet, the Intriguer 440 has a 270 main jet and the 1979 340 has a 230 main jet. I'm not sure what main jet that guy put in it, but my question to you all is whether or not you think that carb from the 79 drifter will work well with the 78 intriguer if the main jet is changed to match the engine or if other parts of the carb need to be replaced? For reference the 79 drifters had the same carbs for both the 340 and 440, they just had different main jets, air jet, jet needle, and needle jet.