Playing around with dual fuel (propane carbs)

[anickode]

Well, I got the hookup from a friend of mine... A pair of Chinese tri-fuel (gas, propane, NG) carbs today. Tonco 168F carbs, which are sized for 5-6.5 hp engines.

I've got a garage full of assorted engines, including one that as of yesterday, needs a new main jet. I think it's time to make some adapters and start playing around.

These carbs are a direct swap for GX style engines and clones (up to 196cc), and the slightly larger 170f is recommended for the larger (212, etc) engines, as well as more larger sizes for engines up to the GX390/pred420

I will post updates as I try these things out.

There's not a lot of documentation about them, save for one page of poorly translated Chenglish instructions, and apart from some YouTube videos of them running on generators, not much online either. My buddy has converted several generators ranging from a 6hp clone to a genuine GX390, and has had good results.

I may even consider getting one of the larger units and adapting it for my 10 hp Subaru generator. Running off a 100# fuel tank with no shelf life is awfully tempting.

Who's up for some propane karting?

 

[mckutzy]

I heard they're fairly ecconomical for running propane on the geny... Especially when you have the big can 'o fuel...

 

[ezcome-ezgo]

Don't some indoor concession karts run on propane?

 

[anickode]

Don't some indoor concession karts run on propane?

Yep. It's typically less stinky.

 

[B.M.800]

Sounds interesting, Ive wondered how propane would do for a gokart, or lawn mower.

 

[Kartorbust]

Well I know on an ice auger propane does well, especially when drilling in an enclosed ice fish house to drill through 3' of ice. I've done indoor matting but I can't remember if they were gas powered or propane. Checked online and they don't say what fuel they use.

 

[anickode]

Sounds interesting, Ive wondered how propane would do for a gokart, or lawn mower.

I imagine a mower would do just fine on propane, but the downfall would be fuel storage. Camping gas bottles wouldn't be cost effective unless refilled, which is a legal gray area. (The law doesn't prohibit the refilling of camping tanks, but it prohibits transporting them). And a full 20# cylinder would pretty near double the weight of an average push mower. There are smaller refillable tanks out there, all the way down to 5#, but they run $60-$70 for a new one.

 

[B.M.800]

Err, lawn mower as in riding lawn mower.
Wouldnt be bad strapping a 20lber on it.

 

[anickode]

Err, lawn mower as in riding lawn mower.
Wouldnt be bad strapping a 20lber on it.

No that wouldn't be bad at all.

Exmark, Scag, and most of the bigger commercial mower manufacturers offer propane options on their zero-turns. They just use a forklift tank strapped to the back above the engine.

 

[anickode]

Step 1- make it fit.

I'm going to give this a go on the intek 190 on El cheapo.

Obviously Honda/Clone carbs are not the same as Briggs and Stratton carbs, so the first order of business is an adapter manifold. Easy to make from a bit of 3/4" steel pipe and a pair of heavy duty 1" washers. The washers are welded to the pipe on the inside so as to cause as little warpage as possible. Everything gets ground flush, and the bore cleaned up with a carbide burr, and then flat lapped. The lapping isn't quite complete on the engine side, as you can see in the picture, but I really wanted to take a picture.

I am hoping to keep the governor and throttle linkage as unmodified as possible, so the length of the manifold is such that the vertical axis of the throttle plate is in the same place as the stock carburetor. The manifold replaces the stock plastic carb spacer, and the clone carb attaches to the manifold. (Holes are threaded on the carb side).

The ID of the pipe is larger than the ID of the stock carb spacer by quite a bit, but still smaller than the intake port on the engine. I am curious if this will cause some issues with the mixing when running on gasoline, much like porting and polishing the intake does, however on propane, which enters the carb in a gaseous state, keeping the fuel suspended in the airflow is not a concern.

 

[anickode]

It fits.

 

[landuse]

That is some purdy fab work you did there. Looks professionally made!!

 

[anickode]

That is some purdy fab work you did there. Looks professionally made!!

Thank you

Though I would hope so... It's what I do for a living.

I tend to rush on go kart stuff because of my limited free time. Keeping up with hobbies is at the very bottom of the priority list these days. It's nice when I'm able to invest the time into personal projects to end up with professional results, even if it is just on a stupid little carburetor adapter.

 

[anickode]

Step 2: figure out how to mount a 20# tank to an already cramped kart frame.

Solution:. Don't.

5# tank? Done.

As a plus, this little tank will be nice to have for short camping trips, etc. Perfect for running a tabletop grill and a Coleman lantern for a couple nights.

 

[anickode]

Step 3: get the throttle linkage sorted out.

I am running the governor on this kart because the Intek engines have a molded resin cam instead of metal. This led to some difficulties in the connection because the Honda/clone propane carb is a push-open throttle with a fairly short stroke, and the Intek carb is a pull-open, with a much longer stroke.

So I had to add a push-me-pull-you (reverser) in the middle, which also allowed me to correct the travel distance.

Only big "oops" here is that the linkage from the governor arm to the reverser is right in the way of the gas line from the tank, which I failed to notice when mocking it up because I had the line removed from the tank.

After about 15 minutes of playing with the position of the holes and wiggling everything around, I felt that I had it sorted out.

So I hooked up some propane, hit the starting aid button (gives it an extra burst of fuel), and it fired right up in one pull. It took a bit of fiddling to get the idle speed right, and the spark plug could stand to be a wee bit hotter, but it revs up and idles down beautifully on jack stands. It was pretty cool running it inside and having no exhaust stink in the shop.

 

[anickode]

I would say that if you are running a predator or Honda engine (what these carbs were designed for in the first place), these TONCO tri-fuel carbs are a 100% totally legitimate option. Basically bolt it on, find a place to put the tank, and ride.

I didn't know going into this if/how well it would idle, since these are marketed as tri-fuel generator conversions, but I can say that at least when running propane, it works perfectly fine.

Once I sort out the gas tank mount and get it put back on, I will do some testing on gas as well.

This also serves as an effective guide for putting a Honda/clone carb on the 5.5-6.5 hp Intek engines, if anybody had any reason to do so. Even if I don't keep the propane kit on here, I will likely stick with a clone carb. The throat on the intek carb is atrociously small, and I feel it's the major restriction on performance with these engines.

 

[anickode]

Step 4:. Attach the propane tank.

Ok, I went quick and dirty on this. Reason being I probably won't keep the propane rig on this kart because it's just so flipping tiny.

But I can tell you this, it hauls ***. The majority of the difference is the much less restrictive spacer and larger carb throat, I'm sure, but it does just peachy on propane.

The throttle linkage works beautifully as well.

The main point of this is that you can do this. It works, it's cheap, and it's easy.

On a predator, it's literally $30 for the carb, and $15 for a BBQ regulator. Direct swap. Grab the tank off your grill and go.

The 5# tanks cost 40 bucks at Menards if you don't want a 20#.

 

[bob58o]

I like it!!!! Reminds me I want a vehicle that runs on wood gas. Gasifier Go Kart for the end of the world.

 

[anickode]

Quick update... Throttle response and acceleration definitely improved. I did regap the plug a bit hotter for the propane.

With the original carb, this kart topped at 38mph.
I hit 43 on propane yesterday. Again, probably more to do with the bigger carb throat vs stock, but there's definitely a noticeable difference in acceleration and top speed.

 

[Jfive]

Generally you lose 10% power on propane, but maybe you get a slight increase in V/E with the pressurized fuel. Would be best to up the compression to utilize the higher octane or turbocharged with a draw thru setup. Best part is not having to stabilize for winter and the reduction in carbon added to the oil and valves.