wad9061

My Feedback: (110)

Does anyone know of a source for a conversion kit or somone who is converting the line of
Honda 4-strokes? Also is anyone converting the Honda 50 cc engine? Any help would be great!

Moderator added an "a" to the "Hond" in the original title

av8tor1977

My Feedback: (6)

www.carrprecision.com

Have fun, and let us know how it goes. I have a Honda GX 31 four stroke that I'll be converting somewhere down the road. The Hondas seem to be the best so far as far as power, and for the fact that even though they have an oil sump, they can be run inverted.

AV8TOR

hollbrow

The hondas seem to be the best of the mini four strokes burning pure gasoline out there at this time- I think some of the pre-mix burning four stroke designs may have superior power- but are more expensive and harder to locate.
There are quite a few folks using them on planes. They are fairly easy to make a prop adapter for- the crank thread on the GX35 is 8mm X 1.25 pitch. The oil isn't in a true sump- it is more like a "mixing chamber" where it is constantly whipped into a mist by a two bladed dipper on the crankshaft- then the mist is forced to flow to the critical parts. There are valved drainbacks that return the oil to the chamber. The system works very good at any orientation. The engines are high quality and very user friendly and easy to work on. Just do a search in here on "honda GX" and you can see some information on them.

I have experience with the Honda 50cc also- I use them on scooters. Very strong engine- alas, though, it is a conventional oil sump design
similar to a briggs and stratton type oiling system- it will not tolerate running upside down. The 50cc engines are heavy also- in my opinion, too heavy for RC use- except maybe for some vehicle where weight isn't a factor. The crankcase is pretty large- and can't be effectively cut down to a smaller size. I have been waiting for someone to try one on a plane- but I think when folks get one in their hands- they come to the same conclusions I have about the weight.

If Honda would take the 50cc and make it with the same design as the 25 & 35- then we would have an excellent engine to play with.

davewallace

My Feedback: (29)

Hollbrow,
Have you heard of a source for the GX35 short block or good prices on the complete power head?

Dave

cheechukranch

Dave,

I've got two GX31's that are converted and strong runners. I'll sell one for $200 or both for $375.

I just took one off a 17lb. Bridi Big Bee so that I could convert it to a glider tow plane. These are great engines on the right airframe.

Lewis

av8tor1977

My Feedback: (6)

What are you running for carbs on your GX-31's??

Thanks,
AV8TOR

hollbrow

I have only bought the engines from TEW- or Staton Inc. and just payed the asking price- never seen one for a discount anywhere. Never seen one in a junk heap either. Never even seen one on a trimmer. People in South GA just don't spring for high dollar "brushcutters"- but used Ryobis' can be had by the barrel full.

Weird things happen on these Hondas when you try to use anything but the stock carb- I have tried several different butterfly carbs
and not had satisfactory results. Most folks that have good luck with the butterfly carbs are turning the carb into an external pulse and then tapping or "teeing" into the crankcase pressure transfer hose on the engine. The stock carb on the 35 is a pretty decent carb for it in stock form. You can play with the "pop-off" on the main metering system and richen it up a bit and it will help performance some- but you better know what you are doing when you do that- or you'll be ponying up about $80 for another stock carb (special order) just to get it run again. I kid you not- these things aren't like a two stroke where any old carb that looks "about the right size" will work well.

Right now I have a 12.2mm rotary valve walbro on my 35- it is the one with the adjustable low and high metering system- I have been able to make it work pretty well. You have to port the devil out of the plastic intake piece and the aluminum intake passage to be able to have it do any good when you increase the carb size though. I use them in an RC boat I have- and I have tried to get maximum horsepower at a higher RPM-
rather than torque, which is what a plane needs.

Geoffinpdx

My Feedback: (5)

The carb on the GX 31 is small for a reason. I'm sitting here with a GX 31 intake valve between the jaws of a dial caliper. 12.5mm diameter. Their valves are TINY!!! For contrast, the intake valve on a 35cc Stihl four stroke is about 16mm. That tiny GX31's rotary barrel carb can supply all the air those little valves can handle.

cheechukranch

Stock carbs are on the two I have for sale.