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Discussion Starter · #1 ·
Just putting this on here. I'm sure not everyone is into restoring old relics. Neither am I... or so I thought. When I started this 6 weeks ago, I thought of giving up a few times. I mean, if the stench of decades-old gas not leaving your skin for days on end doesn't do it, just thinking about the amount of rust to clear probably will.

This has been a basket of many firsts for me. Anyway, I'll keep the commentary to a minimum.... sit back and enjoy my feeble attempts.

The generator is a Denyo GA-3600; 3.6kW Peak, 3.2kW Running. It's a brushless generator that uses the lighting coil in the the engine as the exciter for the stator. It's not a "capacitor-type brushless" as I originally thought it was.

This is the state it was in when I started on it. It was left outside in the sun and rain for years, stored 'wet', and left for dead some 25 years ago.... by me. So I owe it some sort of makeover.
Vehicle Automotive tire Motor vehicle Tractor Automotive design

Saw Motor vehicle Automotive tire Asphalt Automotive exterior

Automotive tire Motor vehicle Bumper Automotive exterior Automotive lighting

Motor vehicle Automotive tire Tread Automotive exterior Electrical wiring

Automotive tire Wood Gas Font Automotive wheel system

Font Rectangle Commemorative plaque Number Metal


Stripping it down to the bones...
Motor vehicle Wood Gas Engineering Machine

Motor vehicle Table Public space Gas Art


Wirewheel and sanding...
Wood Red Composite material Gas Tool


Rust converter
Automotive tire Asphalt Motor vehicle Red Gas


De-rusting the bolts and screws as well as applying some organizational magic


Started painting stuff.... everything has primer, base coat, and clear coat






The ship has sailed on the silk-screened panels. All I can do was clean the surfaces as best I can without further damaging the original paint and gave them a couple layers of clear coat


Finally, the engine and powerhead went through several power wash and degreasing process before finally being blow-dried and mated again with the frame



The final results... (except for the tank):






Running like a champ.... dirty electricity and all. ;)
 

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Discussion Starter · #3 ·
Most people would have just tossed that after one look as they would have thought it to be hopeless.
Almost considered it. In the end though, I realized it was worth more to me running than its value in scrap. I also get to learn a lot along the way.

Most are still the original parts and only the following were replaced:
1. Carb - The old one is hopelessly clogged with varnish as hard as epoxy
2. Engine dampers
3. Ignition switch
4. Fuel lines
5. Gasket kit
6. Governor springs
7. Muffler (bought 2nd hand)
8. Voltmeter

Moving forward, I will just have to focus on the gas tank. I still need to remove old varnish and some surface rust inside then sand and repaint the outside. Otherwise, this generator is done.
 

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I still need to remove old varnish and some surface rust inside then sand and repaint the outside.
I have heard that POR 15 makes some good products to address gas tank issues, but they may not be available to you. Acetone would be my 2nd choice to attack the varnish. Also, throw a couple of handfuls of rounded pebbles in the tank to act as scrubbers as you shake the tank around.
 

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Almost considered it. In the end though, I realized it was worth more to me running than its value in scrap. I also get to learn a lot along the way.

Most are still the original parts and only the following were replaced:
1. Carb - The old one is hopelessly clogged with varnish as hard as epoxy
2. Engine dampers
3. Ignition switch
4. Fuel lines
5. Gasket kit
6. Governor springs
7. Muffler (bought 2nd hand)
8. Voltmeter

Moving forward, I will just have to focus on the gas tank. I still need to remove old varnish and some surface rust inside then sand and repaint the outside. Otherwise, this generator is done.
A labour of love that is….!!
 

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Pour some gravel (crushed stone with sharp abrasive edges) in the tank, strap it to the wheel of a riding lawnmower, and take it for a ride around the yard for a few minutes. The inside of the tank will be shiny like new.

BTW, given that the entire fuel system was toast, that genny would have been a good candidate for an LP or natural gas conversion.
 

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Discussion Starter · #9 ·
I have heard that POR 15 makes some good products to address gas tank issues, but they may not be available to you. Acetone would be my 2nd choice to attack the varnish. Also, throw a couple of handfuls of rounded pebbles in the tank to act as scrubbers as you shake the tank around.
I can get them if I wanted to, but unfortunately it's going to overshoot the budget quite a bit. I will have to get by removing as much crud inside and leave well enough alone. I added a B&S red fuel filter to stop debris from messing with the carb.

A labour of love that is….!!
Lol... there were cussing and expletives thrown around when a bolt or nut won't come off. We were a proper couple for little over a month.

Pour some gravel (crushed stone with sharp abrasive edges) in the tank, strap it to the wheel of a riding lawnmower, and take it for a ride around the yard for a few minutes. The inside of the tank will be shiny like new.

BTW, given that the entire fuel system was toast, that genny would have been a good candidate for an LP or natural gas conversion.
I have a bottle of acetone to get most of the varnish out and likely give it a 2nd acid bath to clear the rust. It will be properly neutralized this time, that which I failed to do before so flash rust came back in a matter of minutes. I am a fast learner, though. lol

I did consider doing a fuel conversion but I soon found out that this engine does not have an aftermarket bi/tri-fuel kit. Although, permanently converting the old carb for LP-only is a possibility that seems worth considering.

That looked like a really fun project. I'm jealous!
It was! I could've likely finished it in a week or two, but I also need to take care of less important stuff... You know, work, family, kids. lol

Nice job! I'm sure you'll get many years of use out of it!
I think so too. Setting this up as a backup to my main gen. The engine is very reliable and are commonly used here in construction. Parts are also widely available. Though, the power head is a different story. If it dies, that'll likely be the end.
 

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Discussion Starter · #10 · (Edited)
Let's rewind a bit to the time prior to starting the engine.

The oil inside was particularly black, thick and a little low. I drained it all out as much as I can. But instead of using new oil, I poured in the old oil from my other generator just to help agitate the crankcase and dilute the really old 90's oil. I heard that Diesel fuel is a good engine flush... good solvent properties and still slippery enough to offer short-term protection. Do you guys recommend using Diesel fuel as engine flush?

Here's the plan...

1. Drain the oil and pour in Diesel fuel up to the full mark
2. Run the engine at idle (1800 RPM) for 3-5 minutes
3. Drain the Diesel fuel
4. Add fresh oil to the full mark, run for 5-10 minutes
5. Replace the oil one final time to flush out the Diesel
 

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I’d flush diesel through the engine but without running it. Maybe even let the diesel sit overnight soaking the internals? Just pull the recoil several times, but carefully with the spark plug removed. I don’t think there’s enough lubrication to run the engine with just diesel fuel in the crankcase. Then drain that and run the used oil for a few minutes and drain that before a fresh and quick new oil change… Awesome progress, nonetheless 👍
 

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Discussion Starter · #13 ·
I don't get why many small engine mechanics still prefer L-heads/flat-heads over OHV. They say that the former is simpler. I feel it should be the opposite.

Anyway, I noticed that this Robin engine was a little hard to pull-start and I had to feather the recoil to get it past a certain point in the compression cycle so I don't break the recoil or my arm. Compression is 120 psi... which should've been just around 85 PSI or lower (@ <400 RPM). Well, I discovered that the tappet clearances on both valves were a little loose at 0.13 (Standard is: 0.10 ±0.02).... probably why the compression release wasn't working.

Apparently, you can only correct the clearances by grinding off the valve stems if the gap is too tight, but once it becomes too loose (valve stem has become shorter), the only recourse is to replace them? Seems like a waste.

On the other hand, OHV valves can be adjusted almost infinitely because of the adjustment screw. You can practically use the valves down to their stumps. lol
 

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Apparently, you can only correct the clearances by grinding off the valve stems if the gap is too tight, but once it becomes too loose (valve stem has become shorter), the only recourse is to replace them? Seems like a waste.
If you have access to a valve seat cutter, you can recut the seats to reduce the tappet clearance.

Also, you’re only .01 out of spec. That should not greatly effect the operation of the compression release.
 

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Discussion Starter · #17 · (Edited)
Is the measurement and specs you gave in mm?
Yepp. Everything is in Metric.

TAPPET ADJUSTMENT
Lower the tappet all the way down, push the valve, and insert a feeler gauge between the valve and tappet stem to measure the clearance.

NOTE: The correct tappet clearance for both intake and exhaust valves is 0.1 mm ± 0.02 mm as measured when the engine is cold.

NOTE: If the clearance is smaller than specified, slightly grind the top of the valve stem, and measure it again. On the contrary, if the ciearance is too large, replace the valve with new one, and polish its contact surface with a compound to obtain a good fit. Then adjust the clearance.
Also, you’re only .01 out of spec. That should not greatly effect the operation of the compression release.
Come to think of it, 0.13mm was still a little loose. My feeler gauge oddly didn't have anything above 0.13mm and just jumps over to 0.25mm.

It still runs like new but can be hard to pull-start, especially if the engine is already hot. I think that's about as much tolerance that is needed to affect the compression release.
 

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The lift created by the release should be much greater than the .01mm out of spec you’re at. While not knowing the compression release lift spec of your engine, and assuming it’s a mechanical compression release, I’m guessing it’s at least 1mm lift.
 
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