Propane conversion

There is a place to look to see how small engines can be run on propane. There are some yard and garden power tools like leaf blowers and string trimmers that are now on the market that use the green one pound propane tanks for fuel. They obviously have the lubrication issue figured out.

Jim
 
http://www.davesmotors.com/s.nl/c.885035/n.1/it.A/id.7468/.f
Goped engine for propane, with bottle cage mount and fuel line
media.nl


Thanks, can you post the link? I saw some videos about them on Youtube but basically it just showed someone using the product and changing the bottle. It was called Lehr (the carb and bottle system) and yes apparently it was something that came as an option on brand name weedeaters like Stihl.

Its possible that the propane, being a petroleum product, is enough to oil the small two-strokes by itself. If I try this on my happytime though, I'm still going with the carb as an oil injection system because these little engines are probably not as precisely built as the tight new motors made for the propane. Also the cylinder on the HT is much longer, and the rings are much thicker. The cylinder does not have a cast iron sleeve either. I think it would be "cheap insurance".

I'm interested in the Goped type engines that run on the green bottle though. I think that would be awesome for a BMP build and really good for apartment dwellers.
 
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Thinking more about those yard power tools using propane they are probably 4 cycle motors with a internal crankcase with a oil resevoir and oil pump. I personally don't think propane would be a very good fuel as it reduces power by 20-25%. There is not as much energy in propane as there is in gasoline.

Jim
 
Just is more easily compressed. The reviews on most of the yard, ready made engines have a lot of similarities. Easy to start, quieter etc. Leads me to believe they do not have the proper compression. Potential energy is the same.(edit, not but close) Hmmm, slant head, Simply reduce the combustion chamber? Still, the engine would have to be timed for peak efficiency... (if I am correct. Which of course, I am) lol! run away!!!!!! In a brave and manly manner

This is a promotional thing but interesting; http://snowmobiles.yamahablogs.ca/2008/11/12/bar-b-que-sled/
 
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re: promotional but interesting

"11,000 USD! Yeah I know… but consider this, the kit contains the turbo and all its components, the propane system complete, assorted body parts and professional installation. The latter is not an option at this time, you must have the work performed by Simmons Propane Systems." Are the Simmons Propane guys not professionals?
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And a turbo 300hp snow ski? Awesome!


I really like the propane idea. I think a lot of people keep these bikes in buildings like their houses. A small bike or folding bike with a propane engine that DOESN"T SMELL OR LEAK might help a large portion of people who use these as a commuter/lifestyle vehicle.

I am going to build another MB this year, so I will try this out on my current happytime bike after I have something else to ride. I plan to use the carb for an oil "injector",
and think it will probably work just fine. Perhaps eventually an aftermarket carb for the HT's or a compatible lawnmower carb will come about. There are lots of great tinkerers on this site. Someone will nail it.

I saw on Youtube that you can buy an adapter ($20) for 25lb propane tanks, that allows you to refill the small green cans yourself. Supposedly its illegal to "transport refilled 1lb cylinders" but I guess if you are not selling them but fueling a bike, no one would care.

I don't know how the timing can be changed on china kits, but the briggs and stratton engines that people like to convert (mowers, go carts) can be changed by moving the ignition coil. One would have to bond slotted tabs to the ignition coil after modification, or weld new posts for the screws, to advance it significantly. Some go cart stores may sell altered flywheel keys.

Has anyone tried running their HT on propane yet? Maybe it doesn't need advancing. Or maybe if it is less than optimal, it is close enough to work well since these engines are gas-sippers anyway.
 
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Yehaa Happy! Do It! I mean it man. Just be cool to see it done!

Had a thought and in no way a suggestion, really light grease in the low end. Light enough to liquefy when warm but solidifies when it cools. ?

Dunno. You are right can be done and looking forward to seeing it work!
 
re: grease. The problem is that it must travel from a tank in a liquid state like regular gas mix would, pulled by engine vacuum, at a low volume.

I plan to dilute 2cycle marine oil or conventional motor oil with water methanol mix aka window washer fluid, low/non ammonia).
First I'll just try cheap motor oil and see if my spare carb (the old small one) can be adjusted at the needle, to just not use a lot. It has 5 notches, and I've heard you can order different jets or solder and re-drill the jet.

So if anyone else has a better idea, maybe a type of thin inexpensive oil that is used for similar purpose (propane motors), let me know.

Here's an idea if you want to try it: I plan to use, for a trial run, one of those home plumbing torch regulators and just clamp a good quality rubber hose to it, run into a home-made filter box, probably using lawn mower filters. I won't use the plumbing gas though, just the green propane bottles.

I'm sure that people using a 4 stroke pull-start motor on a BMP build or in-frame build, can probably just use the stock carb and tune it.
That is how a lot of lawnmower conversions are done and seem to work fine if the fuel is regulated at a low pressure (around 5 pounds, dialed in with a valve after starting)
 
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Here is another idea that may work even better. Use the fuel inlet on carb with the normal needle arrangement for metering, with the propane, and run a hose into the carb venturi to siphon oil from a small tank, controlled by a plumbing valve. Just don't forget to open it when starting and riding!
The carb slide and needle might not stop the flow of gas when closed but could probably come close to it if the idle screw is omitted. The bike would die when the throttle is let off. This is how I run my gas bike anyway, for an extra "kill switch".

Some people are using the fuel jet on the briggs carbs as a fuel feed, removing the bowl etc from the carb. (don't want the needle and float shutting off the carb) (on 5hp lawnmower 4stroke) You have to put engine gasket/sealant in the appropriate holes since there is no bowl and no gasoline.

Perhaps this can be done to the happytimes as well.

Remember these motors are pretty low tech! I would say just supply it with oil and as much as it wants before it starts visibly smoking like something burning in the microwave. Better to err on the side of caution.
 
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Yeah, that site on generators gave me some ideas, but with that carb (tecumseh 4 stroke mower/generators) it does something different than the HT carb.

The fuel on those is not metered by a needle, but is controlled by the amount of air that passes over the jet. With pressurized gas, that jet kit just sends it through behind the butterfly valve, which is why they need the vacuum operated regulator. Also, generators undergo very sudden high loads, and aren't controlled by a hand throttle. Plus, generators may be left unattended and could stall, so it needs a gas shutoff automatically. On a bike, you could just restart or turn off the fuel.

On these one note charlie MB bikes, you can probably just let the motor get extra fuel at idle, to keep up with its hard running throttle settings or WOT.

I'll mess around with it some probably this summer, maybe sooner. If it runs ok and seems practical, I'll post a thread about it with steps and photos.

Meanwhile I'll read on and see if someone beats me to it. Good Luck and Happy New Year. I am having lots of fun with this website.

PS I like lawn mower tinkering too, esp as it relates to lawnmower engines on go karts (or rarely, motor bicycles and trikes).

I am wondering if anybody has put a HT slide type carburetor or similar, on a 4-5hp lawnmower, to use a BMX or V brake lever. Lots of hinged cheap brake levers are on bike shop sites.
 
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Propane has a octane rating in the 90's and is extremely clean burning (no carbon), as a rule of thumb propane expands 400 times it's volume and weighs 4.11 lbs per gallon, the hard part is getting a metering device/carb that will correctly meter the gas to air ratio for engine, on a car/truck there quite complicated. One could use it as a booster, give the engine a shot when you really want to move,,,kinda like nitrous..shft.
 
That is why I planned to just run the fuel valve for 90% power (about 30mph) and let it waste or bleed out the air filter during idle/heavy throttling. A 50cc 1 cylinder engine should be able to run just fine off it.

I've seen cars with the complicated metering systems, and in country towns I've seen some gasoline trucks that ran on propane, via lines run into the filter box. Pretty much the low-tech trucks were made to start on gasoline and accelerate to highway speed, then run on propane via a switch for cruising.

re: boost. I don't know if it would do anything to a small kit bike like a happytime, but propane injection has been used reliably for heavy-haul diesel trucks and construction equipment.
 
I had an idea this morning, while reading the Boost Bottle thread on motoredbikes.

I'm going to order one of those intake tubes for the china motor that already comes with a inlet and barb-type brass connector, and run the propane w/valve or regulator, right into the inlet. I figure I can try that, and if it doesn't work as planned, I can sell the intake part or save it for a spare.

It seems a lot harder to "flood" an engine with the propane, when doing mower conversion, because the gas can just leak out the muffler or carb if its too much, and when its running, it will just waste any extra propane gas by blowing it out the exhaust.

norm002.jpg
http://i265.photobucket.com/albums/ii237/leonane/norm/norm002.jpg
 
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happycheapskate said:
I had an idea this morning, while reading the Boost Bottle thread on motoredbikes.

I'm going to order one of those intake tubes for the china motor that already comes with a inlet and barb-type brass connector, and run the propane w/valve or regulator, right into the inlet. I figure I can try that, and if it doesn't work as planned, I can sell the intake part or save it for a spare.

It seems a lot harder to "flood" an engine with the propane, when doing mower conversion, because the gas can just leak out the muffler or carb if its too much, and when its running, it will just waste any extra propane gas by blowing it out the exhaust.
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How are you going to run that as a throttle?
 
Just like the lawnmower conversions: the stock throttle body (butterfly type on the mowers, slide type on the ht) operates the air flow, and controls it like primative diesels. As long as its getting enough propane, it will run and control it.
 
If it doesn't work as well as planned, I can easily just use the valve on the propane bottle accepting fitting, to just add a little bit of gas to the standard gasoline/oil fuel on the HT, and adjusting the carb as necessary. This should extend the gasoline mileage a lot and help with regulating the temperature of the engine in the summers. You should be able to tell when the bottle runs low/out by a change in engine sound. With a vacuum applied to the propane cylinder, it should empty readily even when low.
 
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