Hmmm... Propane 4-stroke???
- Thread starter Tad Bit Tipsy
- Start date
Very cool TBT. Just found these. Lil less cash. Amazon.com: LEHR ST025DS 25cc Propane Powered 4-Stroke Detachable Straight-Shaft Eco Trimmer:
Been wanting to do propane for a while. Would be purty cool.
Been wanting to do propane for a while. Would be purty cool.
There is no reason this couldn't work because most large stores have propane powered floor buffers so they can be run inside with the minimum of CO and no tripping hazards from cords. The engines that power the buffers are or are close enough to the displacement of a bike engine so the carburation system would work...
BUT
Yea that's the big but, be prepared to run around with a BBQ size tank on your bike because propane won't give you the same mileage as gas. Say your bike gets 100 mpg, a peanut tank roughly holds a half a gallon of gas, a large propane bottle is only 32oz so even up with gas that's only about 25 miles but propane give less mpg then gas so I'm gonna say you're only going to get 15 to 20 miles per bottle of propane.
BUT
Yea that's the big but, be prepared to run around with a BBQ size tank on your bike because propane won't give you the same mileage as gas. Say your bike gets 100 mpg, a peanut tank roughly holds a half a gallon of gas, a large propane bottle is only 32oz so even up with gas that's only about 25 miles but propane give less mpg then gas so I'm gonna say you're only going to get 15 to 20 miles per bottle of propane.
Additionally - from the converted vehicles I've had the misfortune of operating, there's a significant power loss as well... so the milage would suffer from that too 
This is still an alternative I'd like to try. I have a friend who is allergic to gasoline, even the smell makes him nauseous, he has been saving to get a LPG conversion car, but they are tons of money. At least with this he could get to work, ruffly 12 miles and get back without having to worry about gas. We had talked about a 2-stroke, but then that requires mixing gas, etc. Not for him. With this he could carry an extra tank in his backpack easily. I was thinking a friction kit on the back of his folding bike, but I don't know if the little thing would have enough torque for that. So I may just help him mount it on a rack with a chain drive, and we'll go from there. Anyhow, still an interesting concept. I have seen the go-peds with these engines on them, and they are neat, but like you guys have said, limited power and range, almost like an electric set-up. We are looking into buying the little canisters in bulk, or they make composite tanks now that are way lighter than steel, though most are 20lb tanks. We need a 5lb or at most a 10lb tank. Then range won't be too much of a problem, but LPG is still a lot more expensive than gas, but when you have no alternative price doesn't matter.
What I wish, is there was a way to fill the 16oz canisters at home with a larger tank. Any one have ideas???
What I wish, is there was a way to fill the 16oz canisters at home with a larger tank. Any one have ideas???
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Coleman and others have a transfer hose, but you usually never get the little ones completely full (pressure equalization.
Mike
Mike
Thanks, Mike! I do remember those kits for filling, but like you said, they lack the significant pressure a refilling station has. I have found some 1.5 and 2.5 gallon tanks that weigh close to 10 to 15lbs when full. These may be the better bet even though they are steel. Going to take some money to work this out, but I'll be damned if I can't get something feasible going for him. Or after we piece and price it all together, we decide its not worth it, then an electric kit would be viable. But they can be upwards of 6 to 7 hundred with a decent battery, this could easily be done for around $500. $200 for engine, $150 for the BMP friction kit/ or more for stanton chain drive. And around $80 for the tank. Then fittings, accelerometer, etc.
Very cool helping a buddy out TBT. Always a satisfying build.
There are some great how to links here. http://motorbicycling.com/f3/propane-conversion-5349.html I have yet to get around to it but only need a regulator to try it with a HF. Might try this week end. Whats the worst that can happen. hehehe, famous last words, eh?
There are some great how to links here. http://motorbicycling.com/f3/propane-conversion-5349.html I have yet to get around to it but only need a regulator to try it with a HF. Might try this week end. Whats the worst that can happen. hehehe, famous last words, eh?
There's a little trick with refilling the bottles, we used to do this with freon back before they put one way check valves in the shut off valves.
Keep the propane bottle in the freezer overnight to get the pressure in it as low as possible then float the tank you're transferring from in warm water to maintain the pressure when the LPG starts to boil off during the transfer process.
Keep the propane bottle in the freezer overnight to get the pressure in it as low as possible then float the tank you're transferring from in warm water to maintain the pressure when the LPG starts to boil off during the transfer process.
Propane has a higher octane rating than petrol, if the engine is set up for it ie timing and compression and the gas is injected as a liquid you get significant gains in power and economy.
Ralph Sarrich has made an injector for 2 strokes that makes them clean, combine this with propane and you have a very efficient engine.
Ralph Sarrich has made an injector for 2 strokes that makes them clean, combine this with propane and you have a very efficient engine.
Thanks for all the ideas guys. The engine is already set up for propane, I'm wondering what kind of throttle situation I'll have to deal with. The manufacturer says it can run for 2 hours off the little one pound(16oz) can, but that's running just a trimmer. I'm thinking like Kevlar, 20 miles, and maybe 1 to 1.3 HP at the most, its only a 25cc. That's why I want to put it on his fold up bike, its really light. Also he's a buck and a quarter soaking wet so it should get up and go. I'm going to stick with the canister/refill idea at first, then maybe move on to a bigger tank maybe 1.5 gallons. That way he could get a large tank installed at home something big 100 gallon/lbs, whatever the natural gas company can provide. Going to install one on my aluminum beach cruiser, too!!! Maybe do that first before I build his, that way I get some run time in. Poor thing's going to run hard pushing my large Welsh butt around though, lol.
Sorry Gareth, an American born welshman here, although I've been across the pond to visit relatives in Caersws. Never got taught the great Cymru language.
Guys I was looking at the the manual for the trimmer, and I may have problems with the throttle, it looks like it goes into a rubber shield type thing on the top. I'll have to wait till I have it in hand until I can figure out what to do with the throttle. Here's a link to the manual
http://www.golehr.com/downloads/LEHR_usermanual.pdf
Guys I was looking at the the manual for the trimmer, and I may have problems with the throttle, it looks like it goes into a rubber shield type thing on the top. I'll have to wait till I have it in hand until I can figure out what to do with the throttle. Here's a link to the manual
http://www.golehr.com/downloads/LEHR_usermanual.pdf
Getting a lil more excited that this could happen. Checked the Honda gas 25cc and it only has a .48 quart tank, that's 15.38 ounces, comparable to the propane canisters. Also with the trimmer purchase, you could disconnect the trimmer attachment and throttle then resell on Ebay, money back in the pocket. Now to design an extra canister holder to fit on top of the BMP kit! That's a nice flat space, and the extra weight couldn't hurt.
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Arghh!!! So frustrating, trying to find out just what size clutch any of these engines have is like pulling teeth. Non of the manuals list the clutch size, only that its centrifugal. If the Lehr is a 54mm its a no go. The BMP kit is only for the 76mm. Even the Honda manual didn't specify, WTF? I put in a email to Lehr and we'll just have to see what happens.
Well Stanton Inc has the option for a 54mm clutch bell, even though the kit is a little more, its still worth the try. Guess BMP doesn't justify the option since only the smaller engines have this clutch.
Well Stanton Inc has the option for a 54mm clutch bell, even though the kit is a little more, its still worth the try. Guess BMP doesn't justify the option since only the smaller engines have this clutch.
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I have had a few of the under 35cc engines over the years, both 2 and 4 stroke. If they have a clutch it's always been the 54mm clutch.
not to pick on you gareth you are correct about octane rating but octane is not btu's...the problem with lpg is that there is about 2/3 the btu's properly mixed and burned as there is in gas....now propane inject a desiel...now that will move....kinda dirty though