JCaste

Hi guys,

Well, here's the engine. Sorry for some dumb comments, but this engine was quite I mess when I got it.
I'm posting it more for the curiosity of finding a 4 stroke, than for the rather doubtful RC usage of it, but here it is anyway.
Some things about it:
- 29cc 4 stroke engine, has 2 side valves (the admission one is slightly larger than the other). It's a Flathead, like some HDs.
- It's a japanese engine, and uses a Mikuni carburettor. It was in fairly good conditions althought it had quite some time of use.





- I guess it is a slow turning engine, as the valve timings are identical to the theoric cycle.



- I'm afraid it has no RC plane usage, but maybe could be used for an airboat or other applications where weight is not so critical, and you can enjoy the popping sound of a 4stroke...
- The oil pan (I don't know if this is the right word) is quite big, in my opinion. Anyway, this engine was probably made to be running all day long and carelessly.
- There's a electric pump or a similar device in that area (see the black thing in this pic). This engine had lots of tubes around (I guess for lubricating purposes). I supose this electrical pump did the job, also oiling the springs and valve guides.



- There's also an automatic throttle control. As the plastic gear spins quickly, that cilindrical object protrudes out of it and pushes an arm, which does close the accelerator (see the link between the arm and the carb). In the previous pic, that cilinder is hidden.



- The flywheel is made out of iron and looks massive, but in fact is about 1cm or so thick (ok, it's massive anyway).
- A view of the oil pan, gears, cam... Notice a small fin in the piston, this should be to squirt oil all over the place. That small arm on the right is what the cilinder pushes forward when it reaches a certain speed.



- Here you have the springs. There's a metal piece covering this, an it has a tube connected, so I just can figure it is some kind of lubricating device.



Do you think this can be useful for an RC application (as I mentioned before, I was thinking of an airboat, or maybe a fast-build ship)?
Any ideas on how to start?

Thanks!!!

Juan

KenLambert

My Feedback: (107)

it will most likely work on a 1/2 scale go cart or something like that mabey a boat

blackbaron

My Feedback: (92)

Boat Anchor maybe. I have been told that any of the small 4-cycle engines are slugs in aircraft.

tkg

My Feedback: (1)

Only 29cc??? What is bore and stroke???

Eagle Flyer

My Feedback: (84)

Almost looks like some ones attempt to copy a Briggs & Stratton??????????

Flypaper 2

Smells like a Honda. They had a motor somewhat like this on a small 110 volt generator.

Prop Nut

My Feedback: (3)

Hey BlackBaron1,

You where told wrong. Sorry, dont mean to start a flamefest. A buddy of mine (two now as a matter of fact) have converted the Ryobi 4 stroke weedwacker engines to RC airplanes. They are tall but very powerfull. One is on a FlyBaby the other is gracing a Fokker DVII 1/4 scale. You have got to hear the sound to believe it. One of these days I will capture some footage of the flybaby in...er....flight.

JCaste

I jusat can't remember exactly what bore & stroke did this engine have, but I remember its diameter was slightly bigger than its stroke, each around 3cm.
Blackbaron, I have to disagree with you. Four stroke engines are nearly half as powerful as 2-strokes for the same size (as an example, a 500cm^3 2-stroke GP bike used to have nearly the same output as the newer, 4-stroke, 990cc machines), and I guess for model engines this ratio could even be a bit worse than that.
However, they have enough power for a lot of applications. Unless weight is critical (such as in a 3D plane, or a heli), I believe that you can use a 4 stroke. If you don't need pure power, but enjoy swinging a larger prop, or hearing a realistic sound, or a smoother and quieter running, then you can use those "slugs".
Propnut, I'd really like to see some pics or video footage of them... My jap engine was not made to fly, but in case I make it run again, I have planned some wicked ideas.

Antique

My Feedback: (4)

Small 25cc four stroks have no more torque than the same size 2 strokes...a 25 cc Honda or Shindaiwa turns the 18-6 Mejzlik the same rpm as a G23, same with an 18-8..A 20 inch prop really drags one down..Been there....
have not seen a Ryobi or Stihl, can't see how it could be much different....

darrenervine

Funny you mention that Ken, that is what I am using the Craftsman 25cc for, a 1/2 go-cart I built for my son.
See post http://www.rcuniverse.com/forum/RPM's_of_Craftsman_25cc?/m_2385933/tm.htm
It was electric, but I am converting to gas.....I need the RPM's in order to determine my sprocket ratios.

Thanks
Darren

JCaste

Hehehehe nice buggy!

I found a 250cc bike engine, but when I came to pick it up it was too late... If not, I'd be welding a tube frame instead of tinkering with converted engines.
Darren, why don't you visit wackerengines.com or any gas engine shop (us engines, for example), you should have some figures there that would be helpful with the sprocket thing.

darrenervine

My son is only 2 1/2 years old so I need something that will keep him in control.
The electric motor (12v wiper motor from a truck) is great speed wise, but as soon as there is any load, it drops.
I built the cart with the intention of a 2-3HP going on it eventually.
The other oprion is to put that on now and use a governor.

Cheers,

Darren

JCaste

Chainsaw engines come with their own clutch, and they tend to are bigger. Maybe the stock clutch could be useful!
You will already know that, but cover all moving parts! An watch out for hot spots!
Good luck with your buggy!

darrenervine

Fair 'nuff.
Every chain saw I have ever used has been louder than $#@&, we live in a major city (Toronto, Ont) and they are already talking about banning trimmers. A chainsaw engine would never fly (no pun intended in this forum), way too loud, the Craftsman engine is just the right loudness.
I agree that the saw's will probably have more torque which would be useful, ie I would rather have a "tugboat" engine than a "motorcycle" engine.
Short stroke and big bore is perfect, but you gotta work with what is available.

Thanks Darren

Flypaper 2

Darren:
There is a place, I think they're in London Ont. Called Carts& parts. when i used to have a small motor business. They have sprockets, clutches etc,. They are very helpful and could recommend a gear ratio. I'll see if they have a website.