O&R Questions

[UnicycleParrot 1]

Hello everyone.

 

I have experience in small engine repair (mainly 4 stroke) on engines no older than 15 years old. I know how 2 stroke engines work too.  I have recently obtained an old O&R engine, which seems to be in great shape.

I do not know what the engine originally came off of, it also has no markings on it with a model number (or any number for that matter).

One question I have is about the carburetor. Every carburetor picture I have seen on this forum has a red primer button, and a slotted jet on the top. Mine, however, has no primer button or a slotted adjustable jet on the top. Instead, there is a non-slotted knurled screw.

I am also confused, because my unit does not seem to have any off switch, to stop the spark.

Additionally, I am curious as to what the single point is for on an engine like this is for. On all the modern engines that I have worked on, there are no points.

I have attached some pictures too for you to look at.

By the way, I have not attempted to start it yet, as I am somewhat unsure of what fuel ratio it needs.

 

Edited July 10 by UnicycleParrot

[Wallfish 695]

What you have is one of the early engines. Wood tone handle instead of black, early coil, the blower housing screws are from the back instead of the heads on the front, no primer carb, jet screw on the side instead of the top, etc etc.

All of those are normal things for an early type engine.

There should be a hole in the bump on the top of the blower housing which holds a metal tab to ground the spark plug off to stop it.

I'm not sure what you mean by it having a "single point". The points are under the flywheel and under that little cover that will be exposed after the flywheel is off. There are 2 point contacts that touch one another and probably need to be cleaned because they oxidize over time and that will prevent continuity because they aren't actually touching together.

You can mix modern 2 stroke oil at 32:1

If the diaphragm in the carb is stiff it will need to be replaced in order for it to pump fuel.

[CNew 404]

Very nice engine, looks to be in great condition. Might want to put some liquid electrical tape or heat shrink over the spark plug wire😁

[UnicycleParrot 1]

Thank you for such a timely and and helpful response!

5 hours ago, Wallfish said:

What you have is one of the early engines. Wood tone handle instead of black, early coil, the blower housing screws are from the back instead of the heads on the front, no primer carb, jet screw on the side instead of the top, etc etc.

All of those are normal things for an early type engine.

There should be a hole in the bump on the top of the blower housing which holds a metal tab to ground the spark plug off to stop it.

I'm not sure what you mean by it having a "single point". The points are under the flywheel and under that little cover that will be exposed after the flywheel is off. There are 2 point contacts that touch one another and probably need to be cleaned because they oxidize over time and that will prevent continuity because they aren't actually touching together.

You can mix modern 2 stroke oil at 32:1

If the diaphragm in the carb is stiff it will need to be replaced in order for it to pump fuel.

I do have the kill-switch piece of metal that is supposed to screw onto the top of the blower housing. I took it off when I first got the engine, because I figured it was some random

thing that was on there from the previous owner. I have absolutely no experience with engines of this vintage (2 or 4 stroke)

 

I know a few things about its life. The previous owner I never saw in person, but I hear he never used this engine. I also heard that long ago he was planning to make a minibike out of 

this engine. (kind of like the one you made @Wallfish) The engine has also been indoors for many years of its life (obviously)

When I said "a single point" I figured it would maybe be called that because there is only one cylinder (thus only 1 set of points)

I looked at the points when I first got the engine, and they are very clean. (like the rest of the engine) I also checked if it has spark, which it does.

It is interesting to hear that it is an earlier model. I am a little curious if it is in better condition than others of the same vintage.

 

32 minutes ago, CNew said:

Very nice engine, looks to be in great condition. Might want to put some liquid electrical tape or heat shrink over the spark plug wire😁

Yes, deffinitely!

 

[Wallfish 695]

19 minutes ago, UnicycleParrot said:

It is interesting to hear that it is an earlier model. I am a little curious if it is in better condition than others of the same vintage.

Yes, it's in very nice condition.

I have 2 of those

 

[UnicycleParrot 1]

Interesting. 

Mine doesn't even have the oil hole for the pull starter.

 

Just edited the first post for better pictures

Edited July 10 by UnicycleParrot

[CNew 404]

I have 2 engines like this as well. One has the oil hole and the other doesn’t.

[UnicycleParrot 1]

It runs!

 

I mixed up roughly 32:1 of fuel and 2 stroke oil and attempted to start it.

At first the fuel mixture screw was way too rich (lots of fuel out of muffler), but I got it dialed in and I got a handful of 1/2 to roughly 1 second runs. 

Once it finally sounded like it was about to run, the spark plug wire fell off.

 

I have a few other questions about the engine though. 

While I was taking apart the carburetor to check the diaphragm a little while ago, I noticed a small pinhole in the top of the carburetor.

I assume this is not supposed to be there. I have repaired a hole in a carburetor on a 4-stroke engine with a 2-part aircraft epoxy. Would that work in this situation too?

 

And about the spark plug wire (and the other wires connected to the magneto) is there anything I need to be careful about or worry about when soldering new wires in their place?

 

Is there any type of a runaway scenario possible on an engine like this one? (imagining we had no way to kill the spark) Could the engine keep going full throttle and blow itself up?

 

 

[CNew 404]

That’s awesome, glad to hear you got it running.  I’m pretty sure that hole in the top of the carburetor is supposed to be there, I think it allows the diaphragm to pulse.  I’ll take a look at mine and see if it has the hole.

 

can you add a photo of there you plan to solder wires?

[UnicycleParrot 1]

I figured that I would cut around here, leaving a section to solder a new wire to. 

On the other end, I want to save the little C shaped piece to solder onto the new wire, so I plan to cut it off and solder it to the new wire.

 

Also, what are the NOS engines that I have heard about and seen pictures on this forum. Are they bigger in some way? Or are they newer?

 

 

Edited July 13 by UnicycleParrot

[CNew 404]

I think I’ve had to do that same fix before as well. I don’t recall any issues with adding a new wire spliced in right about where you’re pointing. If the wire core isn’t really damaged you might also be able to just break off all the old insulation and then do a couple layers of shrink tubing. You’d still have to remove and reattach the little clip.

 

i can also confirm, my carb also has the little hole.

[Wallfish 695]

Yes the carb cap hole should be there.

The abbreviation NOS = New Old Stock

I've repaired those cracked insulation wires. Removed the cracked insulation, coated with liquid electrical tape (a few coats), covered with shrink tube.

It can be covered with different sizes of shrink tube over top of each other but it makes it kind of stiff

Yes, any engine can "run away"  with high RPM.

[UnicycleParrot 1]

Thanks for the advice!

 

On 7/13/2024 at 3:07 PM, Wallfish said:

I've repaired those cracked insulation wires. Removed the cracked insulation, coated with liquid electrical tape (a few coats), covered with shrink tube.

It can be covered with different sizes of shrink tube over top of each other but it makes it kind of stiff

Is there any specific reason on why you would suggest a repair of the spark plug wire, and not just a complete replacement?

 

Also, is there a specific gauge of wire that is best for a spark plug wire?

Edited July 18 by UnicycleParrot

[Wallfish 695]

5 hours ago, UnicycleParrot said:

Thanks for the advice!

 

Is there any specific reason on why you would suggest a repair of the spark plug wire, and not just a complete replacement?

 

Also, is there a specific gauge of wire that is best for a spark plug wire?

Yes, those older type coils are not a replaceable wire like the newer type coils are. You can repair it with a new wire but you're still soldering and repairing the insulation anyway. By just repairing/replacing the insulation on the old wire, it remains looking original. Plus, I don't know of any plug wire to repair it with.