I am working on a 48" mono hull and have a John Deere 200C trimmer motor that is 21.2 cc. These were made by echo (model HT or GT200) and I have read good things about reliability for rc use. This is a low-budget build so I will not be replacing the two coils with an rc ignition at this time, but wondering what carb people have used for performance upgrade. It has a Walbro WA 81 on it and it seems like a small carb. I will be retaining the factory cooling fan/shroud as I don't have the desire to try to make it a liquid. I am not expecting nor intending this to be the fastest boat on the water it is for putting around. I eventually will upgrade to a bigger trimmer motor or a zenoah when I get bored with the current set up or funds allow. I would imagine stud spacing being the biggest concern for using a different carb, but is the impulse hole different on some too. I expect to have to do some fabrication but only have access to simple tools.

Any suggestions on carbs would be great.