Spitfire carb swap

[Mikesbikes]

Swapped out my mikuni butterfly for a round slide from a 81 trailfire. The round slide doesn't seem to perform as well as the butterfly carb. Jetting is good the plugs have good color to them the idle and throttle all work well but it lacks the snappiness of the butterfly carb. I would swap back but the float is bad on the butterfly carb and I had not been able to find one. So my question is has anyone ran a kehin flat slide 36/38mm from a 125-250 mx bike? And if so where are you at for jetting? So someone's going to say there to big but if it works on a 125 2 stroke it should work in a 340 with correct jetting.

[75522]

So, I just swapped out the Mikuni butterfly carb on my 79 Spitfire. I bought a new VM 30, and it works great. I would suggest looking at that option, as it only cost me $79 for a brand new carb. Also, I have the original butterfly carb still if you'd like it for parts?

[Mikesbikes]

I have a vm34 on it now, works well but I was happier with the throttle response of the butterfly carb.

[AirborneX4Special]

When Deere updated to the Snowfire, they put a VM30 in place of the 34mm butterfly carb from the Spitfire. I'm not sure going bigger is going to help your situation.