Is this flywheel key bad enough to cause rough running?

[PeteAU]

Yes the key is too far damaged. I think i would put a standard key in there and properly torque it and see what happens. The key doesn't keep the flywheel in place it is just for timing alignment, and the proper torque on the flywheel holds it in that location until you hit something that causes the flywheel to not stop when the engine does.

I will get a new key. I was referring to the damage to the key-way (slot) in the flywheel. Maybe it won't matter if I can tighten the nut without it moving, but then you can't see if it did.

 

[keakar]

I've tried prying while hitting the nut/shaft with a hammer. Tried gentle hitting from underneath. Tried heating it with a heat-gun (paint stripper). Reluctant to really hit it hard, I realize it's aluminium.

what works best is to hit the flywheel itself, not the shaft, never hit the shaft because all you are doing is beating against the bottom bearing.

give the flywheel a good hard whack while pulling up hard with your hand and it will pop right off, but sometimes it takes 5-6 whacks to let go

with aluminum flywheel be a bit gentle with the hard whacks and only go as hard as needed to release it

in your case yes, replace that flywheel, the key way is deformed and will no longer hold in place correct timing, it will slip on you again unless you can only keep the key way down on the still undamaged area (unlikely)

 

[Mower King]

what works best is to hit the flywheel itself, not the shaft, never hit the shaft because all you are doing is beating against the bottom bearing.

give the flywheel a good hard whack while pulling up hard with your hand and it will pop right off, but sometimes it takes 5-6 whacks to let go

with aluminum flywheel be a bit gentle with the hard whacks and only go as hard as needed to release it

in your case yes, replace that flywheel, the key way is deformed and will no longer hold in place correct timing, it will slip on you again unless you can only keep the key way down on the still undamaged area (unlikely)

I'm curious as to where you learned this method of removing a flywheel ? " what works best is to hit the flywheel itself, not the shaft, never hit the shaft because all you are doing is beating against the bottom bearing"

Experience, school, youtube ?

 

[PeteAU]

in your case yes, replace that flywheel, the key way is deformed and will no longer hold in place correct timing, it will slip on you again unless you can only keep the key way down on the still undamaged area (unlikely)

That's a pity, it was a free throw-out mower, but it looks nice, nothing else broken, no rust, year 2010. I'm just tinkering with it while there's nothing to do during lockdown 2.
I'll try a new key and see if it holds. Maybe move the coils 2-3 mm to the left to compensate?

It's a 450 series 148cc 9T502-0152 B1.

 

[Scrubcadet10]

What's the engine model and type numbers?
Sometimes you can get lucky and find a flywheel used on ebay for cheap,.

 

[Mower King]

That's a pity, it was a free throw-out mower, but it looks nice, nothing else broken, no rust, year 2010. I'm just tinkering with it while there's nothing to do during lockdown 2.
I'll try a new key and see if it holds. Maybe move the coils 2-3 mm to the left to compensate?

It's a 450 series 148cc 9T502-0152 B1.

"Maybe move the coils 2-3 mm to the left to compensate?" 2mm = .080 - 3mm = .120 I don't think the coils will move that far.....and they won't need too!

 

[PeteAU]

Just for a laugh I put the bent key back in but rotated 180 degrees (left-to-right), it felt tight in there. Put everything back together and tried running it.
It's smoother, but not 100%. Then I undid the nut again to see if it has shifted, surprizingly it's straight as an arrow (photo is after the engine ran).

So, I suppose this motor has more issues. It runs well enough to mow my little grassy area, I'll take it for $0.

I also tried two used spark plugs (cleaned, de-carboned, gaped, multimeter tested) and that didn't help. What else could it be:
- Get a brand new spark plug
- Intermittent coil
- Intermittent cable to spark plug
- Deeper motor issues like the valves
(I already ruled out the carby, because I have two of them and one has a new gasket/diaphragm).

What's the most likely/common with these Briggs 148cc classics?

 

[Mower King]

Just for a laugh I put the bent key back in but rotated 180 degrees (left-to-right), it felt tight in there. Put everything back together and tried running it.
It's smoother, but not 100%. Then I undid the nut again to see if it has shifted, surprizingly it's straight as an arrow (photo is after the engine ran).

So, I suppose this motor has more issues. It runs well enough to mow my little grassy area, I'll take it for $0.

I also tried two used spark plugs (cleaned, de-carboned, gaped, multimeter tested) and that didn't help. What else could it be:
- Get a brand new spark plug
- Intermittent coil
- Intermittent cable to spark plug
- Deeper motor issues like the valves
(I already ruled out the carby, because I have two of them and one has a new gasket/diaphragm).

What's the most likely/common with these Briggs 148cc classics?

The key itself is only for timing, it's the taper that holds it on !

 

[PeteAU]

The key itself is only for timing, it's the taper that holds it on !

Right, so I don't need a new flywheel, as long as it holds the correct timing after being tightened (which it is, for now).

What the hell is this little hole near the exhaust? It looks like the head-bolt threads go right through. Normal?

 

[Mower King]

Right, so I don't need a new flywheel, as long as it holds the correct timing after being tightened (which it is, for now).

What the hell is this little hole near the exhaust? It looks like the head-bolt threads go right through. Normal?

Yep, looks like head bolt threads, I wouldn't worry about that!