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John Deere 200C/Echo HT200 boat conversion


Old 06-07-2017, 10:14 AM
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Default John Deere 200C/Echo HT200 boat conversion

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.
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Old 06-15-2017, 05:36 PM
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I suggest using a Walbro carb over a Zama, and it must be a two needle carb. Many of the newer carbs don't have dual needles for adjustment of both high and low mixtures, and having this is a necessity. The carb bolt hole spacing on all the carbs are the same, so no worries there. The pulse hole orientation can be changed by grinding an annular groove in the carb adapter to line things up, so this is no problem either. Many carb adapters already have a groove in them, so mounting the carb either upside down or right side up is possible with no mods. In any case, an external pulse is also very easy to set up.

What you want for that engine is a carb with an 11.1 mm venturi. The Walbro carbs have a number cast into the carb throat, such as a "24", or "32", etc. This is the size of that carb's venturi in 64ths of an inch. (24/64" for example) What you want for that engine is a "28" carb, which is a 11.1 mm venturi. If you have the carb number, such as WT-317 for example, you can go to the Walbro website and look up the venturi size.

With a larger 11.1 mm carb, and if you gut the muffler of all baffles, screens, etc. and provide a much larger outlet, you will see a nice large power increase. You are correct, the Echo engines are very good. MUCH higher quality than the current Chinese engines. The Echo engines, like Stihl, are among the best.

Good luck and have fun,
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