Propane Conversion

Sneakers

Just sneakin' around....
Been thinking about this for a while for my Honda generator. It sits idle, only being started once in a while for testing, then I have to drain any fuel out of the carb and tank before storing. Thought a propane conversion might be a good idea.

Found a sub-$50 conversion that seems pretty popular and available for this motor, a Honda GX240. Dual fuel, replacement carb, propane regulator, gaskets, springs, etc... Pull the old one off, put the new one on.

And then I found a few article on how a propane conversion ruined their motors. Propane doesn't have the cooling properties of liquid fuel, no lubrication from propane. A few other comments.

So, has anyone done a propane conversion? Pros/Cons, other than less power? I seem to recall that spiders like them. A few of you out there said you had a duel/tri fuel generators, have you had any engine issues running on propane?
 

spr1975wshs

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I have a Champion dual fuel. I've only run it on gasoline thus far. Propane is the back up fuel.
However, it does have an oil pan.
 

limblips

Well-Known Member
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Here is my experience with propane fueled ICEs. Way back in the late '60s we had an Oliver 77 propane tractor. We used it inside the potato bins so we didn't die of CO poisoning. I don't know total hours on it when the head gasket developed a leak but it was a lot. We pulled the head and that engine was as clean as a new one. No carbon build up, shiny clean intake and exhaust. That being said, it was water cooled and your genny is air cooled but I converted my air cooled genny and no issue with probably 200-250 hours running at the cabin. Much less hassle than gas when off the grid.
 

PrchJrkr

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I finally saw a deal on a duel fuel carburetor and jumped. I haven't installed it yet, but hopefully I'll have some free time coming up shortly. Mine's going on a Honda 110cc 4-wheeler engine. I bought it with the idea that it would fit one of my generators, but the 4-wheeler needs one first. :biggrin:
 

Sneakers

Just sneakin' around....
Here is my experience with propane fueled ICEs. Way back in the late '60s we had an Oliver 77 propane tractor. We used it inside the potato bins so we didn't die of CO poisoning. I don't know total hours on it when the head gasket developed a leak but it was a lot. We pulled the head and that engine was as clean as a new one. No carbon build up, shiny clean intake and exhaust. That being said, it was water cooled and your genny is air cooled but I converted my air cooled genny and no issue with probably 200-250 hours running at the cabin. Much less hassle than gas when off the grid.
The cleanliness and low emissions is typical of propane, but wondering about the blown head gasket. Any chance propane was the cause? That's the kind of thing that worries me.

The genny with those hours sounds good.
 

Sneakers

Just sneakin' around....
I finally saw a deal on a duel fuel carburetor and jumped. I haven't installed it yet, but hopefully I'll have some free time coming up shortly. Mine's going on a Honda 110cc 4-wheeler engine. I bought it with the idea that it would fit one of my generators, but the 4-wheeler needs one first. :biggrin:
I got impulsive and bought the propane carb kit. Now wondering if it will fit between the genny frame. We'll see.

I also pinged a very popular YouTuber who repairs gennys and asked his opinion. He was all for it, but said, contrary to liquid gas, you want to run propane motors lean.
"It is harder to start a propane generator and you lose horsepower. Also you have to set the regulator and that is most likely how people destroy their engines. If you run an engine lean on gasoline the engine will overheat and damage will occur. The opposite is true with propane. So you want to set the propane regulator as lean as possible to keep the engine cool. Also I have heard you need to decrease the spark plug gap when running on propane. From 0.030" down to 0.020-0.025".
 

limblips

Well-Known Member
PREMO Member
The cleanliness and low emissions is typical of propane, but wondering about the blown head gasket. Any chance propane was the cause? That's the kind of thing that worries me
The genny with those hours sounds good.
My father (an IH field serviceman) thought the issue was due to neglected cooling system maintenance (corrosion) and age. I wish I remember the hours on it but I know it was a lot. I distinctly remember the cleanliness because he pointed it out to me and said that is how clean propane runs.
 

PrchJrkr

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I got impulsive and bought the propane carb kit. Now wondering if it will fit between the genny frame. We'll see.

I also pinged a very popular YouTuber who repairs gennys and asked his opinion. He was all for it, but said, contrary to liquid gas, you want to run propane motors lean.
Good advice that I didn't know. I figured it wasn't a slap it on and go type of modification and plan to research quite a bit before jumping. My 4-wheeler is a mutt. I mated the Honda 110cc motor to a Yamaha Blaster frame, because it was what was available at the time. I lost the fuel tank to the overhead cam motor requiring more head space. It's either mount a gas tank or a small propane bottle somewhere that I don't have room for either. With a camp stove bottle, I'll have less of an issue with space and height. I thought of installing a vacuum activated fuel pump, but the Honda has a crankcase vent and I don't know if it would have enough pulse left to run the pump.
 

Sneakers

Just sneakin' around....
Good advice that I didn't know. I figured it wasn't a slap it on and go type of modification and plan to research quite a bit before jumping. My 4-wheeler is a mutt. I mated the Honda 110cc motor to a Yamaha Blaster frame, because it was what was available at the time. I lost the fuel tank to the overhead cam motor requiring more head space. It's either mount a gas tank or a small propane bottle somewhere that I don't have room for either. With a camp stove bottle, I'll have less of an issue with space and height. I thought of installing a vacuum activated fuel pump, but the Honda has a crankcase vent and I don't know if it would have enough pulse left to run the pump.
FrankenWheeler.... :lol:

Why not an electric fuel pump? I assume it has an alternator and battery?
 

PrchJrkr

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FrankenWheeler.... :lol:

Why not an electric fuel pump? I assume it has an alternator and battery?
I had toyed with that idea as well, but the tank would have to go behind the seat. Propane, if it even runs, would still be easier in the long run. If you like this combination, you would've really been impressed with the Harley-Yama-Honda-Ski I built when I was a teen. It was the talk of Cabbage Alley back in the day.
 

Sneakers

Just sneakin' around....
I got impulsive and bought the propane carb kit.
Well, the kit I bought was supposed to be for a GX200, and I thought they meant a GX200 series. I have a GX240. Didn't fit, throat way too small, studs don't line up. Made for a much smaller engine. To much like work to return.

Did a little more research and decided to go with a US company that has a good reputation for propane conversions, and their parts are used in other vendor's kits. It's not as clean a product, in that the first carb was an integral unit with a pretty small diaphragm valve. The one I just got is better designed, made specifically for a motor, but is a bunch of separate parts, so looks a lot more kludgy. But it uses the original fuel carb so if I want to run gas it's still all original.

Just finished putting it together. Took about 3 pulls to get it going, and after adjusting the flow it runs terrific. Let it run for 30 minutes or so. I still have to fine tune it under load. Has a problem with the auto-idle-down. Won't idle, surges. Can't seem to tune it out, so I'll call the vendor next week. Not a big issue, hardly use that feature anyway.


20230722_161014.jpg
 

LightRoasted

If I may ...
For your consideration ...

Well, the kit I bought was supposed to be for a GX200, and I thought they meant a GX200 series. I have a GX240. Didn't fit, throat way too small, studs don't line up. Made for a much smaller engine. To much like work to return.

Did a little more research and decided to go with a US company that has a good reputation for propane conversions, and their parts are used in other vendor's kits. It's not as clean a product, in that the first carb was an integral unit with a pretty small diaphragm valve. The one I just got is better designed, made specifically for a motor, but is a bunch of separate parts, so looks a lot more kludgy. But it uses the original fuel carb so if I want to run gas it's still all original.

Just finished putting it together. Took about 3 pulls to get it going, and after adjusting the flow it runs terrific. Let it run for 30 minutes or so. I still have to fine tune it under load. Has a problem with the auto-idle-down. Won't idle, surges. Can't seem to tune it out, so I'll call the vendor next week. Not a big issue, hardly use that feature anyway.


What is the conversion metrics from using gas to propane? Say if a gallon of gas will run a gen for 3 hours, how much propane does to take to run the same 3 hours? More or less than gas?
 

Sneakers

Just sneakin' around....
For your consideration ...



What is the conversion metrics from using gas to propane? Say if a gallon of gas will run a gen for 3 hours, how much propane does to take to run the same 3 hours? More or less than gas?
You need about 1.35 gallons of propane to equal a gallon of gas. Also means less watts because the engine doesn't have the same horsepower rating with propane.
 
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