Generator solutions

[kevm14]

Already got the manual.

And I already learned something.

You don't just turn the knob to change the speed. You are supposed to set the top no load RPM (take the adjustment knob out of the equation) and THEN dial in an RPM. I bet playing with this relationship will dial it in. They claim this will hold within 2 Hz but I am not sure if that is 60 +/- 2 or 60 +/- 1.

The only thing is I don't know if I have the "front mount" air cleaner or standard one. Either way the top no load rpm should be 4150 or 4250, as this is a 19 cid.

And if I'm intuiting operation correctly, I'll find mine a bit below the spec. It should help the governor "pull harder" on the throttle as it responds to load.

[kevm14]

So governed no load RPM of 3750 translates to 62.5 Hz. Mine is 62.6 Hz with no load. That doesn't mean it's set right but maybe it's pretty close.... we'll see.

The real question is what is the top no load rpm when I pull back on the adjustment rod? Looking for 4150 or 4250 (still not sure which). That would be 69 to 71Hz, if I use the frequency.

And that looks like it would be outputting about 340V at that point. Yikes. Is that even safe for the generator? That would also be about 480V peak (340 is RMS). I guess if everything is made to 600V dielectric then it's fine....but is it?

[kevm14]

After starting with a fairly significant cloud of smoke, I decided to tackle my experiment.

First I checked that governor pre-set RPM. I used the Kill-a-Watt to check the frequency. I expected 69-71Hz. It was 71.x. So....appeared to be adjusted where it should be. So my theory that it was set wrong does not seem to be correct. However, my overall theory of operation for the governor suggested that I could still raise the RPM by bending the governor spring tab, and then lower it with the adjustment nut. The idea is that it would flatten the governor response across the load range, bringing RPMs up under heavy load, and down under no load.

I bent it quite a bit and have not measured what the new pre-set RPM is but I'm sure it's a couple hundred RPM higher than it is supposed to be. Anyway, after a few tweaks, here is what I ended up with:
Frequency comparison before and after

Voltage comparison before and after

I'd say that's an improvement. Unfortunately I did measure the voltage differently for this test. Instead of L1-L2 I just used the display on the Kill-a-Watt from a single line so I multiplied by 2 to get the equivalent L1-L2 but it's not exact. I also did not perfectly duplicate the load combinations I used before, apparently, so there are some gaps in the curves.

You can, however, clearly see the trend. It did in fact flatten the response curve somewhat. You can clearly see the frequency is higher under heavy load, and lower under no load. I think it may have added a surge at lower loads so I may or may not stick with this. Though I won't really know until the next power outage. If I don't like it I know how to adjust it back so no big deal.

[kevm14]

For what it's worth I think this engine could use a new set of rings, a valve lap and valve adjustment (if needed). I think it probably has fairly significant blow by. I don't think the cylinder is scored based on how the Restore product didn't really seem to change anything. I think the rings are just worn out. This would be fairly cheap to do. Maybe a light hone of the cylinder just to clean it up? I should try to get my hands on a borescope and see how it looks. If the cylinder is trashed, I guess I might abandon this plan and consider swapping over the engine from the parts generator my brother in law gave me.

Edit: Just ordered some NOS rings for $11.22 total and a new head gasket for $8.15. The funny part is you can usually reuse these flathead head gaskets. $20 engine rebuild? Challenge accepted.

[kevm14]

I realized I also needed some tools that I don't have since I've never torn into a small engine.

All prices are shipped with tax.

So I got the following from Amazon:
- 2 piece valve lapper set (the suction cups on a stick that you twirl when lapping valves). https://www.amazon.com/gp/product/B004G ... UTF8&psc=1
$9.41

I was going to order some other new Chinese type tools but I got smart and hunted around for a bunch of vintage tools that I think I'll be a lot happier with, and they weren't really more expensive, either. So over to eBay for the following:
- Piston ring expander. For 2-1/2" to 4-1/2" rings which is....just about anything but really small stuff like a 2 stroke. This Briggs engine uses a 3" piston.

$26.24

- Sears Craftsman Ratchet Type Piston Ring Compressor 94716 Key Wrench, in original packaging.

$26.92

- Briggs & Stratton 299577 Gasket Set. I ordered this after I ordered the head gasket individually. Should have just ordered this to begin with. I don't need much from here (at least I don't think I do) but this is a lot of stuff for a good price so it made sense to at least have on hand for reassembly.

$17.93

- Briggs and Stratton 19063 Valve Spring Compression Tool. There are other tools that work on flat heads but I went with the OEM. Should be fine. Already received it, too.

$24.95

- Vintage "Craftsman" 9-4633 Engine Cylinder Hone 2" to 7". I struggled with this and eventually found this nice used rotary hone. The new Chinese ones had plenty of complaints and I bet this will outlast them easily.

$17.99

- The aforementioned Briggs head gasket for $7.62. I guess I have a spare now...
- The aforementioned Briggs ring set for $10.49. I saw some different oil control ring styles so I hope this works. Maybe just design changes. This technically isn't the latest I guess....but looks similar to the latest?

So it's more than a $20 engine refresh but these tools to be great to have in my toolbox and again I tried not to buy cheap junk that won't last.

Still, the total in parts is:
$36.04 including the duplicate head gasket

Total in tools is:
$105.51

Honestly after watching so many videos this is something I've always wanted to do so when everything comes in it will just be a matter of when I want to tear into it. I am hoping I do NOT need to separate the engine and generator. If I do, I will probably practice on the spare gen first. Of course, if I do that, I would also have that spare engine handy in case something goes wrong (or I get into it and decide that rings and a light hone are not all it needs).

And yes I could also just slap the other engine on it but that's no fun.

[kevm14]

How to separate rotor from tapered crank:
https://www.youtube.com/watch?v=PjrhOOxPsNw

Not too tricky once you do a couple things. I need to check the manual and see if I even need to get into the engine on the crank side. I suspect I do not. I probably go in from the oil pan so I'll have to unbolt it from the generator chassis but that's it.

[kevm14]

https://www.youtube.com/watch?v=QubLX8WJRJo

Uhh....I need to look closer. Not sure it even has an oil "pan." I think I have to split the block which means go in from the crank. This will be pretty major surgery. Once I confirm this I think the very next step is begin pulling the generator rotor off the spare engine and see if I can handle that without breaking anything.

[kevm14]

Turns out I am on vacation so I have tinker time.

Hoisted the spare gen up onto a cheap table saw and went to work. Didn't have anything to lose and had a lot of practice/learning to gain.

I ended up using the tip from the video I linked. After removing the 4 case bolts and the outer cover (brushes, etc.), I removed the rotor bolt from the crank. That came right out. Then I simply picked up a random 3/8"-16 bolt I had laying around, tapped the hole in the rotor to this size, and tested my work. Threaded in. Next step was to cut down the original bolt (sacrificially obviously) to use as a spacer. I did that in my vice with a reciprocating saw. Then I pushed the shorter bolt (with no head) into the hole, hand threaded the 3/8"-16 bolt into the rotor and went to town with my 3/8" impact gun. It took just a few seconds and the rotor popped right off the crank taper. Awesome!

It was a little tricky with some pry bars to get the rotor/stator assembly off the engine. Something about magnetism and whatever. But I did that. The 4 bolts holding the inner stator housing to the block were finally revealed. I zipped the bottom ones off with my gun. The upper ones required a thin wall socket and that reduced the torque my gun makes enough to require doing it by hand. But that was fine. Seemed like there was thread locking compound on the bolts so I guess I'll do that upon reassembly on mine.

That didn't take long but there was an issue with the technique. I believe it bent the bolt. Also, it pushed in the first 1/4" of threads on the bolt. Like completely stripped them. Fortunately the crank is very hard and I was able to chase those threads with a 5/16"-24 tap. I may be able to reuse this as a spacer but ideally I'd insert something larger that doesn't try to push into the crank threads. Problem is the next normal size up is....3/8" which threads into the rotor. I may have no choice but to repeat and hope my threads cleanup if they have an issue.

Aside from that which, again, did not take long at all, it looks like it's just 6 bolts and the crank cover comes right off the engine. Then some more bolts on top for the head. But these old flathead engines are so easy to work on. This is why I wanted to do it. It's fun.

Some pics.

Bonus: why a taper? Like, why are generators annoying? Because the rotor needs to be precisely located by the crank. It rotates with pretty small clearances in the stator and would be too loose if it just slid onto a regular shaft with a key. There is one other way to do this actually. You'd still have to cut threads into the rotor but instead of using a cut down bolt against the crank to press it off, you could just use a slide hammer. I bet that would work. Although you'd be slamming all that force axially on the crank. Not sure if that's bad for anything or if there is enough thrust capacity (and you don't crack the aluminum engine cover). I don't own a slide hammer but I guess I'll think about this a little more.

[kevm14]

That didn't take long but there was an issue with the technique. I believe it bent the bolt. Also, it pushed in the first 1/4" of threads on the bolt. Like completely stripped them. Fortunately the crank is very hard and I was able to chase those threads with a 5/16"-24 tap. I may be able to reuse this as a spacer but ideally I'd insert something larger that doesn't try to push into the crank threads. Problem is the next normal size up is....3/8" which threads into the rotor. I may have no choice but to repeat and hope my threads cleanup if they have an issue.

Maybe a metric bolt?

5/16" equates to 7.9375mm. Not sure if 8mm would be bigger enough.
3/8" equates to 9.525mm. Maybe a 9mm bolt?? Maybe TSC has a 5 or 6 inch M8 and M9 bolt.

[kevm14]

An 11/32" drill bit sort of slips in. So I think I want to find some kind of 11/32" rod. Ideally something smooth but I'll take something threaded if necessary.