how do you balance these without the flywheel fitted? i just ran a ryobi 31cc on glow and it shook at mid to low rpm I found the flywheel heavy on one side, obviously helping the balance when fitted??

I believe that the internals are balanced separately from the flywheel. Therefore the flywheel can be balanced by itself. I have had good luck using my prop balancer and simply removing material from the heavy side of the wheel. The flywheels that I have seen usually have some lightening holes already in the backside. I simply enlarge one or more of the existing holes until the flywheel doesn't favor one side anymore. Works for me.

I balanced my Ryobi flywheel and it doesn't vibrate any different than any of my other gassers? It was way off originally too.

A new engine will often vibrate more.

If you put like a C-H ignition on a ryobi, the new hub is balanced and they run OK.

good luck,

Jim

paleface: You could try this, if you run glow and no flywheel. Place the flywheel you took off on a hi-point balancer and try to find where the heavy portion is in reation to the piston at top dead center. Make a bob-weight with a hole in it that fits shaft back of prop. You are going to have to try to match the heavy part of flywheel that you are not using and make sure it is the same position in relation to top dead center. You will have to run engine and add or remove weight untill you get it to run smooth. Hope you get my Idea..... I seen a picture of a engine that won a speed record with a prop with one blade. The rpm was over 20 k if I remember right. It did have a small weight on the oppisite side of the one blade, for balance. Just a Idea.....hope it helps C.J.

Farmboy approach to Cap'n Johns idea
Use two hose clamps around the prop hub. By spreading them apart you can vari the amount of counterweight.
Starting point would to add more weight on the same side as the counterweight in the engine.

thanks very much guys, most of this goes with my thoughts on the subject , but keep the cards and letters com'in as we may get a common idea- fix This may help on other engines as well!!

I guess I didn't understand the original post. I thought you were using the flywheel and just wanted to balance it. Sorry. Maybe make a large washer that fits behind the prop hub. Drill holes in one half of the washer, making a "light side". Trial and error method could be used, rotating the washer and varying the material removed to get the smoothest operation.

paleface: I forgot to mention......if you had a light wood prop, try a real heavy , big dia low pitch prop. It may run smoother. It will have a flywheel effect, which is too smooth out power impulses. Let me know if you get a chance to do so. Thanks CaptinJohn

captinjohn--thanks mate , i had a 16x10 apc on it , will try an 18x8 master soon , to add a bit more , i think it was george aldrich said the counterweight needs to equal the weight of the rod , gudion pin , and a "bit" of the piston . i think the killer with the ryobi is the steel rod , im going to make one out of titanium[not an easy task] ,but it will shure chop that weight down.
i obviously like smooth running engines.

palface: are you running it on glow fuel.... if so what fuel mix are you using? Does it want to kick back when starting. Also how is the fuel comsuption? It sure should be light. Do you have any photos? I think there is a guy who makes a special piston ring for the Ryobi ........ Thanks Captinjohn

PISTON RINGS ONLY:
For discontinued piston rings, try contacting Frank Bowman. He manufactures repro and current piston rings for our modeling needs. He can make standard and Dykes type rings. If he doesn't have the ring you need in stock, you send the piston and cylinder and he will make it then. prices are $7.50 up to $9.50. His work is of the finest quality.

Frank can be reached at [email protected] or 1-505-327-0696 ( 6pm to 9pm mst. weekdays) and the following address:
Frank Bowman
1211 N. Allen
Farmington, NM. 87401

w8ye ; this is great stuff! just the sort of info i/ we need. this wonderfull webb site and computers[which an oldie like me struggles to use] was a dream when i was a kid.

captinjohn--fuel - 5% oil - methanol , yes it kicks when starting- [chickenstick] i only got 10-----/9 fingers , consumption--??? ,
no pic's.