25cc or less

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motorhedfred

motorhedfred

Member
Jul 31, 2009
421
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United States
Aside from the old Ryobi's, does anyone know a good source, for easily mountable OHV or OHC 4-stroke sub 26cc engines ? I've always wanted to run a pair of them on a motorized bicycle. Does Huasheng or other Chinese brand make a Honda clone ?

I had an old Ryobi OHV with exposed pushrod tubes, but it would have be nearly impossible to mount or tap for power.

MHF
 
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scotto-

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
24
38
Ridin' inSane Diego, CA.
motorhedfred said:
Aside from the old Ryobi's, does anyone know a good source, for easily mountable OHV or OHC 4-stroke sub 26cc engines ? I've always wanted to run a pair of them on a motorized bicycle. Does Huasheng or other Chinese brand make a Honda clone ?

I had an old Ryobi OHV with exposed pushrod tubes, but it would have be nearly impossible to mount or tap for power.

MHF
Click to expand...
Sorry, I don't have a source for you here, but I am genuinely curious as to what you have in mind here? You want two tiny 4-strokes (the equivalent of 52cc or less) to power a bicycle? I'm a bit baffled....very low power no matter how you look at it, right?
 
diceman2004

diceman2004

New Member
Aug 26, 2009
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Kitchener , Ontario
Take a picture of that motor , sounds like it looks cool .
pushrods and rockers are sweet looking on any engine ( especially if you can see them moving )

I would love nothing more than to find an antique 4 stroke engine ( 100 - 200 cc ) with tall cylinders , exposed rods AND rockers and studs .
Guess some day i,ll just have to build one myself .

Anyways , nothing wrong with using a small engine ( just depends on the application )
if you aren,t worried about top end speed , why not use something small .

Scotto ... have you browsed around at the model airplane engines ? i,ve seen some twins ( boxer style - flat opposing cylinders ) that looked super cool .
 
cannonball2

cannonball2

Well-Known Member
Oct 28, 2010
3,682
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Colonial Coast USA.
4 mix Stihls, but they are bigger, The Ryobi should work well I think the displacement is up to 30ccs or so on the later ones. I assume you are trying to make the letter of the law on displacement, hence less than 25ccs? I have converted a Ryobi to RC use. It ran well, turned a large prop for its displacement(torquey) but was too heavy for use in anything except certain aircraft, not a problem on a bike.
The cool looking multi-cylinder model engines(glow fuel) generally dont make the power of a single cylinder/per displacement, but they are cool. On glow fuel a given displacement engine will make more power than on gasoline, but they have a pretty healthly appetite for fuel. Still just for fun I could see a large Saito twin or radial if you are a high roller driving a bike pretty well in an FD situation. They sound really cool and throttle excellently.
 
motorhedfred

motorhedfred

Member
Jul 31, 2009
421
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United States
Ok, a few years back when I first got interested in building a motorized bicycle, my search for forums led me here. One of the first things I saw was the Acme "V" twin package with the 2 china girl engines mounted to a plate to form a V. I was very intrigued by this, but thought a pair of small 4-strokes would be even better.

I bought one of the first 4-stroke weed trimmers made back in 1994 and I think in the back of my mind, I had always wanted to use the motor for something else once the trimmer portion wore out. It was a Ryobi.

It wore out, but when I took it apart last year, the engine seemed impossible to mount against a flat plate. I ended up throwing it away. I wish I hadn't but in a fit of cleaning the garage for a family reunion, it went in the bin.

The reason for 25cc or less is because here in Ohio, there's a 50cc limit for "mopeds". Having two 25cc 4-strokes geared or chained together to lock thier firing intervals in at something close to a Harley V-twin is about the coolest way I can think of to have a sub 51cc, 4-stroke twin.

That Ryobi really was a tight little package.....exposed cast pushrod tubes, a SINGLE camshaft operating both valves similar to a Honda GX series engine, but way before and with pushrods. It had tiny little stamped steel rocker arms on a ball pivot with a guide plate like a Chevy small block.

MHF
 
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cannonball2

cannonball2

Well-Known Member
Oct 28, 2010
3,682
221
63
Colonial Coast USA.
Heres some pics of the Ryobi. It has beam mounts for RC use, could be mounted this way for single engine use(like FD). If you look the the frontal pic you will see 3 holes, the engines could be ganged by mounting through a plate with a drive shaft between them maybe? I had forgotten this engine. It was set up to run glow fuel, notice the glow plug. It really rock n rolled! Threw in a pic of my jet turbine I am awaiting bearings for($90 ea, ouch!). Wonder how the Locals would figure displacement on that-lol.
 

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scotto-

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
24
38
Ridin' inSane Diego, CA.
Cool, now that makes perfect sense. I just wasn't grasping what you had in mind.

On a similar note, there was a twin 48cc china girls bike built by Big Boy Bikes at the Grange race track. That thing sounded incredible, it sounded almost indentical to the old Yamaha 100cc twin (2-stroke) with dual expansion chambers. The BB Bike used a 2 into 1 exhaust and it wasn't even an expansion chamber....it sounded crazy mean!

Good luck on your project here, those little 4-strokes are reliably awesome!

dnut

motorhedfred said:
Ok, a few years back when I first got interested in building a motorized bicycle, my search for furums led me here. One of the first things I saw was the Acme "V" twin package with the 2 china girl engines mounted to a plate to form a V. I was very intrigued by this, but thought a pair of small 4-strokes would be even better.

I bought one of the first 4-stroke weed trimmers made back in 1994 and I think in the back of my mind, I had always wanted to use the motor for something else once the trimmer portion wore out. It was a Ryobi.

It wore out, but when I took it apart last year, the engine seemed impossible to mount against a flat plate. I ended up throwing it away. I wish I hadn't but in a fit of cleaning the garage for a family reunion, it went in the bin.

The reason for 25cc or less is because here in Ohio, there's a 50cc limit for "mopeds". Having two 25cc 4-strokes geared or chained together to lock thier firing intervals in at something close to a Harley V-twin is about the coolest way I can think of to have a sub 51cc, 4-stroke twin.

That Ryobi really was a tight little package.....exposed cast pushrod tubes, a SINGLE camshaft operating both valves similar to a Honda GX series engine, but way before and with pushrods. It had tiny little stamped steel rocker arms on a ball pivot with a guide plate like a Chevy small block.

MHF
Click to expand...
 
cannonball2

cannonball2

Well-Known Member
Oct 28, 2010
3,682
221
63
Colonial Coast USA.
I could see taking two of these, making a nicely shaped mounting plate from .250 aluminum, mounting the engines at a nice 90 degree v-twin angle. Then adding a bearing "tube" maybe even the right lawn mower deck spindle housing between them. Adding a 5/8 shaft to that. Then linking the engines to the central shaft with timing belts. 90degree timing is smoothest but set it how ever you want. The shaft could drive out of either side of the engines or both.
 
S

silvaire

New Member
Jan 25, 2009
36
1
0
North of the Golden Gate
There are several under 25cc four stroke engines.

Here are a few that I know about:
Honda GX25
Honda GX22 (superseded by the OHC Honda GX25)
Subaru EH025 (these are also sold by Makita and are used on some Makita leaf blowers)
Lehr (a 25cc Subaru Clone that runs on propane - used in Lehr trimmers and blowers, and also labeled Craftsman)

I have seen Chinese clones of all of these engines that have popped up from time to time.
 
motorhedfred

motorhedfred

Member
Jul 31, 2009
421
17
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United States
That looks very close to the one I had. The biggest difference I see is the integral cylinder and head. Mine had a seperate head. The the mower deck mounting piece is an awesome idea, as is the way that mount attaches to the cylinder bolts....never thought of that either.

Imagine 2 of those with the fins rounded and detailed, chromed valve covers, polished pushrod tubes, mounted 45 degrees apart....exhausting though bigger chrome tubes covering the pencil thin ones the engines need for torque...sitting in a lightweight fixie style frame with fatty 700c tires and a Brooks B33 saddle, suspension stem in a braced fork...drinking from a torpedo tank....

At least that's what I see.

MHF

BTW, don't be shy about using this idea anyone....I had no plans to make money or become famous because of it...: P
 
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