I'm new to the conversion thing, but was under the impression that if a flywheel was faced off on a lathe, it would stay in balance. I purchased a new converted homey 33. Flywheel had been faced, not sawed and sanded. Engine had a bad vibration at all speeds (prop is well balanced), so I removed the flywheel and checked it on a dubro prop balancer. It was severly out of balance. After correcting this, the engine runs much smoother.
Just thought I'd throw that out there. Some others may want to check their's as well.

cfaw,
All that facing does is retain the state of balance before facing. How easy is it to start your 33cc?

Dave

Have not been able to start it by hand. No problem with a 24 volt drill.

That's good to know. I'm going to go back and check mine.

Jim

It's probably a good idea to check the flywheel balance on any mag equipped engine....

AV8TOR

I'm kinda new at this conversion game myself. Correct me if I am wrong, but if the engine ran smooth in it's original configuration ( i.e. in the weedeater or chainsaw ), shouldn't the original balance be kept after machining the fins off whether it was heavy on one side or neutral ? I thought some were heavy on one side of the flywheel to help counteract the weight of the rotating mass of the crankshaft of the single cylinder engine.

The Phelon flywheels seem to be out of balance more so than the Walbro ones

Try aligning the prop with either the magnet in the magneto or TDC (both are within a few degress of each other). I suspect you'll find smoother running and higher top end RPMs (about 600 extra RPM in my case).

The Raven: Was the engine smoother with this re-indexing the prop. What engine was it and what prop? Thanks Capt,n

I've tested this on both Homelite and Ryobi engines running Master Airscrew props (16x8 and 18x8 respectively).

On my Homelite (25cc and/or 30cc) I got about 600rpm more. On my Ryobi I have yet to measure the difference but, a friends Ryobi went from a vibrating mess to something far more tolerable. Note the vibration was most noticable at low revs and, the top end had about 500+ more rpm.

I'm no expert but for a single cylinder engine they are inherently unbalanced (you can only get so much balance in the design). So, by indexing the prop the essentially line up with the crank throw you are probably making only a negligible alteration to the overall balance. By not indexing you are potentially adding another plane of imbalance to the engine, which may either cause or magnify any existing imbalance... Well, that's my theory.

In other words, best to have the imbalance matching the rest of the engine. If you're using electric start, there is no harm in indexing the prop so why not do it.

The Raven: Thanks for your explanation of props and balance. I am for one going to try your Ideas you came uo with. Very Good! Best Regards Capt,n

I have a Phelon flywheel on my Poulan 32 that has an unacceptable amount of vibration. Putting the flywheel on a balancer, I can see it is quite out of balance, heavy at the magnets. Removing material from the heavy side has always been the preferred method for balacing. I would have to remove a great deal of the aluminum (TOO MUCH) from the flywheel to achieve balance.

Are there methods for adding weight to the flywheel such as inserting lead into the hole left by the starter paw and encasing it in epoxy?

The lead works well if you have it in a front-to-rear hole where centrifugal force cannot make it come out

It is difficult and not advisable to remove weight from the magnet side of the flywheel.