Chainsaw Repair

Chain - Grinders - Filing - Wood Milling - Tools - Welding - Machinist - Mowers - Tillers => RC Radio Control - other small engines => Topic started by: aclarke on April 01, 2016, 03:58:00 pm

Title: RC saw motor conversion
Post by: aclarke on April 01, 2016, 03:58:00 pm
My son just ordered a large scale RC plane (80" wingspan) that calls for a 30-50cc gas motor. Been looking at the Zenoah plane motors but they're kinda pricey. Anyone have any ideas on any saw motors in this size range that would fit the bill.  Seems like the calm shell configuration might be easier to convert.  Any ideas woukd be appreciated

Adam
Title: Re: RC saw motor conversion
Post by: 660magnum on April 01, 2016, 05:04:32 pm
Yes on the clamshells.

Stihl MS250 Chinese clone ($32.50 w free ship) would fit the bill. You would need a hub, electronic ignition ($50), and a intake manifold/carb.  Could even use a MS 250 muffler especially if you get the two piece one that comes apart so you can open it up some. Saw off the PTO side of the crank and your prop hub goes on the flywheel end

(http://i.ebayimg.com/images/g/Wt0AAOSwd4tT0NSJ/s-l1600.jpg)
Title: Re: RC saw motor conversion
Post by: aclarke on April 01, 2016, 05:38:42 pm
Ok cool, so machine a prop adapter that bolts directly to the flywheel?
Title: Re: RC saw motor conversion
Post by: 660magnum on April 01, 2016, 05:46:34 pm
there are people around that can machine you an 6061 aluminum hub that threads onto the crank which includes the magnet for the ignition timing sensor. These same people could make you the aluminum carb adapter.

A Walbro WT215 carb from Stihl is $22.50.

It will turn a 20 X 8 prop around 7,000 rpm which is ideal.
Title: Re: RC saw motor conversion
Post by: aclarke on April 04, 2016, 09:05:29 am
Good deal, Thanks for the info.  What are your thoughts on mounting the carb to the cylinder?  Hose clamps and some rubber tube? 
Title: Re: RC saw motor conversion
Post by: 660magnum on April 04, 2016, 10:02:25 am
The typical scenario is to have a aluminum cylindrical adapter with set screws impinging upon the existing carburetor spigot. You with then need a white nylon or black Delrin insulator between the adapter and the carburetor or you will have hot start problems.

If you commission someone who has made the timing/prop hub and carb adapters before, they will know exactly what you are talking about. 

I have a 50cc Echo/Kioritz 621 already converted if you are interested. it turns a 22 X 8 at 6900 - 7000. It was sold as a BME 50

These pictures are stock pictures