I carry a small lawn and leaf gas blower in my rig to keep the outside rug and my "area of operation- AO (for you 'ole army guys/gals)" clean. Especially after the grass is cut.
I have had three failures in the last year of these small gas motors in blowers and weed wackers. They all have been due to failed (sheared) aluminum "keys" on their flywheels. I am told by hardware store folks that even gas push mowers have these frequent failures. Typical symptoms are back firing, or cannot start unit at all. Of course this is after fresh fuel has been put in it, spark plug is firing okay, etc.
Like Oemy, I wake up at nights and say I can fix that. I then get out in the shop and create a plan- crazy, huh? That's exactly how the "Door bolt mod" came about. For those of you who don't what I'm talking about
click on this link.
Back to the task at hand---
Here are the pictures ("images" in todays hi- tech days) of my repair.
Fly wheel from a small gas blower (top side). The culprit is the tiny cast aluminum "key" in the tapered shaft hole. It will shear in "a heartbeat"- if you have flooded the engine and/or pull too hard trying to start it. This is a picture of a new flywheel I had ordered and received after I repaired the old one. I went ahead and modified this one already because it will fail someday if I put it into service with the crummy cast "key" it now has.
Back side of the flywheel
1/8" drill bit and $0.20, 1/8" steel split roll pin (1 inch long). Lowes carries them. You could also use a 3/32" (1 inch long). This 1/8" (.125 in) roll pin measures .1335, or about .008 inch larger in its relaxed state.
Drilling the hole-
Use a sharp punch (or nail) and a SHARP drill bit to drill the hole.. It can be done, in the field, with the flywheel clamped in a horizontal position to a picnic table and use a hand drill. The flywheel is a very soft aluminum and the exact center, or being perpendicual is of little concern. Drill the hole clear through the one side of the flywheel. Make sure your not drilling into the magnet part of the flywheel.
Stop here- Go through just one side. You could go all the way through but is not necessary, or required.
Now clean up the flywheel of chips and debris and place it on the motor shaft and ALIGN the old "SHEARED KEY" with the KEY slot on the shaft. Kinda tap it lightly to seat it on the shaft. Now, using the same 1/8" drill bit, using the hole in the flywheel as a pilot bushing, drill about a one quarter inch deep hole into the steel motor shaft. You can wrap a small piece of masking tape around the drill bit before you start drilling and use it as a stop gauge for your depth setting into the steel shaft (1/4").
Now blow out the chips and tap the roll pin into the hole. Use an appropiately sized "drift" pin/punch. No need to remove the flywheel- the burr from the drilled hole into the steel shaft will keep the two parts aligned.
Here the pin is installed.
If you ever need to remove the pin at a later date, use a needle nose vise grip pliers to attach to the roll pin and a second, larger vise grip pliers, attached to the needle nose pliers- at 90 degrees, and "hit it a lick" with a healthy hammer.
If you don't have the tools or knowledge to do this repair, look for someone in the campground, or a neighbor to help you out- just show up with the roll pin and a sharp drill bit.
For twenty cents you can't go wrong. Most units suffering this problem are just thrown away as labor and parts costs will far exceed the value of a replacement unit.
I can guarantee you this "pin" won't shear off.
I called Poulan after I discoved this fix and talked to a lady in the the tech section and she had "no comment"
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Good luck,
Linear Mode
