# Propane Conversion



## OrlyP (Oct 19, 2021)

Hi all. New here.

I have a Chinese 5kVA open-frame generator with a GX390 clone engine.

I just replaced the carb with a tri-fuel replacement and it runs fine on gasoline. But when I switched to propane/LPG, it ran a little rough at first. I loosened the fuel screw (yellow arrow in the pic below) to richen up the fuel mix and now it seems to run fine. All tests so far were done without a load.

My question; Is there a proper or detailed procedure to adjust this screw? Do I need to do it with/without a load? How far back should I loosen the screw AFTER the engine starts to run smooth?

Thank you!


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## iowagold (Jan 22, 2020)

pretty simple
make sure it is out of gasoline first by removing power to the sol on the bottom of the bowl during run on gasoline.

if the carb is in question for the gen at first run set up;
adjust with no load first.
we use space heaters when field setting the demand regulator load block flow.
then start adding load noting where you have to adjust the screw to make it run right.
and final is at the rated load of the gen set.
then check it at no load.

if the carb is matched right to the gen set.
we go right in to full load and do the right to lean and set it at the middle then check it at no or low 500 watt load.

it will depend on the pressure and the quality of the gas used.
that will depend on the gas supply on the day of run.


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## OrlyP (Oct 19, 2021)

Thank you, @iowagold.

So, based on your ideas, here's what I plan to do... correct me if I misunderstood something:

1. Start it up on propane at operating RPM (3600) with no load
2. Tighten the screw until the engine starts to lean out
3. Back-off on the screw until the engine starts to run correctly then add half a turn for good measure
4. Put it at 25% to 50% load
5. If it runs lean again, loosen the screw further until the engine smoothens up
6. Remove the load and see if the engine is running lean or rich


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## iowagold (Jan 22, 2020)

yup you got this!
grin!
LP and NG is very forgiving on the mixture as it in vapor gas form before the demand regulator..
I like a bit rich as it starts better.
so if your screw turn range is one whole turn for the rich lean set at 2/3 to 3/4.
and see if it starts when it is cold ok.


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## OrlyP (Oct 19, 2021)

So far so good.

I got it to 80% load (3,600 W) and the engine sagged a bit down to 58.6 Hz, which is expected when running off of propane. I turned up the throttle screw a very tiny bit until I got it back to around 59.8 Hz. Without load, the engine runs at 61-62 Hz.

I'll just use up the gasoline still in the tank and replace the sparkplug to iridium when it runs out. Thereafter, the generator will run primarily from propane.

It's been fun working on a small engine. I also learned a lot from James Condon's YouTube channel. I can't remember the last time my fingers reeked of petrol.

Before, with the stock carb:









After:


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## iowagold (Jan 22, 2020)

yup looks good.


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## drmerdp (Apr 10, 2018)

Looks good, I’ve seen those conversions on eBay for years and always wondered if they are worth their mettle.

One of the biggest perks is the location of propane inlet…right at the venturi.


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## OrlyP (Oct 19, 2021)

As for the stock carb, is it enough to drain all of the gasoline out of it before putting it in storage or do I still need to take it apart and clean it thoroughly with carb or brake cleaner?

This is still practically brand new... used the generator less than 8 hours.


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## iowagold (Jan 22, 2020)

OrlyP said:


> As for the stock carb, is it enough to drain all of the gasoline out of it before putting it in storage or do I still need to take it apart and clean it thoroughly with carb or brake cleaner?
> 
> This is still practically brand new... used the generator less than 8 hours.


remove the bowl drain the gasoline out.
blow the carb dry with shop air.
maybe a fog with marine fogging oil before putting back together.
that will keep the corrosion down to a min during storage for long term.


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## Bulldogger (Feb 19, 2021)

OrlyP said:


> So far so good.
> 
> I got it to 80% load (3,600 W) and the engine sagged a bit down to 58.6 Hz, which is expected when running off of propane. I turned up the throttle screw a very tiny bit until I got it back to around 59.8 Hz. Without load, the engine runs at 61-62 Hz.
> 
> ...


 Good job and thanks for sharing information. I need to load test my generator on propane. It runs exactly at 60hz with no load on propane but 62hz with no load on gasoline. Your post reminded me that I may have to adjust the throttle spring location, in my case, with propane.


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## FlyFisher (Jun 30, 2018)

Good deal on the conversion. I did not replace the carb on mine, I made a manifold to inject the gas fuels in to the intake stream.

As to the fuel mixture - I am with Paul. Run it a bit rich. 

My small open frame gen I used a small space heater on low, draws about 750 watts, as my test/tuning load. Once I got the fuel mix (natural gas here) set where it ran best I was able to start the generator on natural gas, also. Some say the iridium plugs with small gaps are superior on NG. So keep that in mind. I don't have any yet.

I have 2 gens set up for tri-fuel - small ~2600w open frame rotary and a 15kw rotary. Then I have a Honda EU2200 that is actually my primary generator - it only runs gasoline. It is the primary because it is convenient, quiet, and very fuel efficient. For home back up as long as we have natural gas the 15kw will be used, but we've never been there with it (yet) as it is new this season. So are the gas conversions. 

Anywho, options are good! You never know what kind of fuel you'll have available. I am tempted to get a couple more 100lb propane tanks at some point down the road. We'll see.


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## OrlyP (Oct 19, 2021)

My main motivation to switch to propane is to reduce or entirely eliminate the need to babysit on gasoline. We seldom have power failures but when we do, I need backup power for I am still WFH and my kids are on virtual classes. Along with that, I need to keep a few servers up and the ever important A/C (tropical climate) to cool the house. I can keep a tank of propane on standby and it should last indefinitely. I would still need to test the generator every month to make sure that it works when needed but that’s about the only task, apart from maintenance (oil, spark plug, air filter, etc.), that I have to do. Maintaining the fuel is one less thing I need to worry about.

If the outage lasts longer than the amount of propane I have on hand, that’s the only time I put in fresh gas.


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## FlyFisher (Jun 30, 2018)

OrlyP said:


> My main motivation to switch to propane is to reduce or entirely eliminate the need to babysit on gasoline. We seldom have power failures but when we do, I need backup power for I am still WFH and my kids are on virtual classes. Along with that, I need to keep a few servers up and the ever important A/C (tropical climate) to cool the house. I can keep a tank of propane on standby and it should last indefinitely. I would still need to test the generator every month to make sure that it works when needed but that’s about the only task, apart from maintenance (oil, spark plug, air filter, etc.), that I have to do. Maintaining the fuel is one less thing I need to worry about.
> 
> If the outage lasts longer than the amount of propane I have on hand, that’s the only time I put in fresh gas.


Paul and a couple others on here are a wealth of knowledge. As far as maintenance goes - there are some tricks I've learned from them to prolong the life of some of these small engines. 

Proper break-in is very important on all engines. And once broken in using a high quality synthetic oil with ZDDP additive can vastly increase the service life of small engines. 

The contrary is also true - if you don't do quality maintenance the service life will be evident of it.

I don't have any direct references to point you to on service life extension, but hopefully some here can chime in and give you some better pointers. For me, I got a good supply of Royal Purple synthetic oil and ZDDP additive. I haven't switched to Royal Purple oil just yet, but have added ZDDP. I bought a bunch of Penzoil Platinum synthetic oil prior to purchasing the Royal Purple so the last oil changes were the Penzoil. My new engine (on the 15kw, Honda GX690) has dyno oil in it for the first 20hrs. I think I'm only at about 7-8hrs on it thus far. Once I hit the 20hr mark Royal Purple is going in.


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## OrlyP (Oct 19, 2021)

Good idea on the ZDDP. Though, they're pretty much hard to come by where I am, if not expensive.


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## Matt88-8 (Dec 27, 2018)

OrlyP said:


> Good idea on the ZDDP. Though, they're pretty much hard to come by where I am, if not expensive.


Diesel oil. 
Lots of zddp, Very shear stabil, comes in all the right viscosity for hot weather and is dirt cheap by the pail 

Sent from my SM-G973W using Tapatalk


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## Dutchy491 (Sep 18, 2019)

Motorcycle oils are made to handle heat and high revs. Also have zero viscosity improvers to burn off and have good levels of ZDDP. Look for a synthetic motorcycle oil in your area. I prefer to use Amsoil Synthetic Small Engine Oil, made specifically for these types of applications. See an earlier post…Dutchy


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## iowagold (Jan 22, 2020)

you have to watch some of the larger bike oils as they have the friction modifier for the bike clutches.
not sure on your ams oil does it have that?


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## OrlyP (Oct 19, 2021)

I am using motorcycle oil now during the break-in period. I did that partly due to the friction modifiers possibly helping with the break-in. But mainly, I did it because basically these portable generator engines have more in common with single-cylinder motorcycles (splash oil system) compared to automotive engines (pressurized oil system). Once the break-in is done, I'll switch to full-synth automotive oil.

Good plan?


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## iowagold (Jan 22, 2020)

some of the bike oils allow more friction..
that was my point.


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## Dutchy491 (Sep 18, 2019)

True Paul. My fault to not point that out, but Amsoil m/c oils do NOT have friction modifiers, and I keep thinking other oils are similar. Most M/c oils are second best to the purpose built synthetic Amsoil Small engine oils though. Car oils don’t cut it, but will do in a pinch. If you have a cheap knockoff engine you need the best oil. If you have an expensive piece of equipment, you want the best oil too. 😉 Dutchy 
Copied the following m/c oil info from the Amsoil website…
Reduces Friction, Heat and Wear
In high heat conditions, AMSOIL Synthetic Metric Motorcycle Oil exceeds the standard for high-temperature film strength to deliver excellent wear protection. It keeps engines running cool by effectively reducing friction and heat, and it contains a heavy treatment of anti-wear additives to reduce wear regardless of operating conditions. AMSOIL Synthetic Metric Motorcycle Oil is thermally (heat) stable and contains maximum levels of oxidation-inhibitor additives. It is extremely resistant to volatility and is engineered to prevent damaging sludge and carbon deposits for superior engine cleanliness.

Smooth, Confident Shifts
AMSOIL Synthetic Metric Motorcycle Oil contains no friction modifiers and promotes smooth shifting and positive clutch engagement. It is engineered to control heat and prevent slippage and glazing, promoting longer clutch life.

Controls Foam
High-rpm operation causes some motor oils to foam. When foam bubbles travel between gear teeth or engine components, they collapse, allowing metal surfaces to contact, causing wear. AMSOIL Synthetic Metric Motorcycle Oil contains advanced anti-foam additives that help prevent foam, allowing riders to confidently push their bikes to the limit.


Premium wear protection
Smooth, confident shifts
Cool, clean performance


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## Dutchy491 (Sep 18, 2019)

OrlyP said:


> I am using motorcycle oil now during the break-in period. I did that partly due to the friction modifiers possibly helping with the break-in. But mainly, I did it because basically these portable generator engines have more in common with single-cylinder motorcycles (splash oil system) compared to automotive engines (pressurized oil system). Once the break-in is done, I'll switch to full-synth automotive oil.
> 
> Good plan?


 I sent you a pm. Dutchy


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## OrlyP (Oct 19, 2021)

Fyi, this is the oil I used: PETRON SPRINT 4T SR800 FULLY SYNTHETIC Motorcycle Engine Oil (RACER) SAE 10W-40 - Petron

In the product datasheet (PDS), it didn't say anything specific about friction modifiers other than a vague statement about having "Excellent friction characteristics for optimum wet clutch performance".

The good news is, this oil has ZDDP (up to 2% by weight), as written in the safety datasheet (SDS).

So the question now... is it ok to use this oil even after break-in? Haven't done my first oil change yet.


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## Dutchy491 (Sep 18, 2019)

Yep the Petron oil looks pretty good, albeit with limited info. Better than run-of-the-mill stuff. However, racing oils aren’t meant for normal oil change intervals, they typically get changed out after each race, so see what the manufacturer suggests or look for a non-racing synthetic Oil instead. Good on you to be pro-active in your maintenance!!! Dutchy


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## OrlyP (Oct 19, 2021)

I wouldn't take the "Racing" moniker too seriously. It's just marketing people making their products sound cooler. It's a top-tier full-synth motorcycle oil, no more. 

I very much appreciate your insights!


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## Dutchy491 (Sep 18, 2019)

What I meant was that if it’s labelled as a race lube, hype or not, it might not have the long life of a regular service interval as it’s intended to be changed after every race. It wouldn’t have a high TBN rating…needed to neutralize acid buildup over time. 😉


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## OrlyP (Oct 19, 2021)

Ah, makes sense. Thanks.


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## iowagold (Jan 22, 2020)

cool! dutchy!
yea i knew the amsoil was its own thing.
but formulas change in other brands.


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## tabora (Sep 6, 2018)

An interesting propane issue I ran across this past weekend... I was running my mini gas grill with a 20lb tank to make a couple of burgers for lunch, but it was taking forever to cook them. I thought the tank might be getting near the end, so I swapped tanks, but the tank was still very heavy. I put it on my 25,000 BTU tank-top heater in the cottage, set it to a steady medium burn, and as I watched it the flame dwindled down to almost nothing. If I opened the tank valve fully again the burner would come back to life, but at anything less than that the gas supply would slowly choke itself off. 

This is the second 20lb Blue Rhino tank with this issue I've had in the last two years. Sadly, the propane filling station near me closed, so I've been doing the $14.92 swaps at Walmart. Looks like I'll be driving farther to Tractor Supply for refills from now on after I swap out this lemon tank. That's where I've been going to fill my 40lb tanks.


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## iowagold (Jan 22, 2020)

tabora said:


> An interesting propane issue I ran across this past weekend... I was running my mini gas grill with a 20lb tank to make a couple of burgers for lunch, but it was taking forever to cook them. I thought the tank might be getting near the end, so I swapped tanks, but the tank was still very heavy. I put it on my 25,000 BTU tank-top heater in the cottage, set it to a steady medium burn, and as I watched it the flame dwindled down to almost nothing. If I opened the tank valve fully again the burner would come back to life, but at anything less than that the gas supply would slowly choke itself off.
> 
> This is the second 20lb Blue Rhino tank with this issue I've had in the last two years. Sadly, the propane filling station near me closed, so I've been doing the $14.92 swaps at Walmart. Looks like I'll be driving farther to Tractor Supply for refills from now on after I swap out this lemon tank. That's where I've been going to fill my 40lb tanks.


hummm air in the tank?? not purged right?
or bad load of fuel?


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## OrlyP (Oct 19, 2021)

I have ran the generator until it stalled from the last drop of gasoline in the tank. From here on, it’ll be running off propane primarily... but still maybe switch to gasoline for longer outages. The tank is literally dry with only the gas fumes in there. Do I need to do anything to keep the metal tank from rusting/corroding? The cap is the vented kind (pinhole), if that makes any difference.


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## iowagold (Jan 22, 2020)

use the staibil marine fogger.
that works great for tanks!
and fuel pumps in tanks!


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## OrlyP (Oct 19, 2021)

Is it necessary to run a dual-fuel generator on gasoline every so often?

The premise here is that the generator has been converted to be able to run on LP. After that, the metal tank, sediment bowl, fuel lines, and the carb has been totally emptied of gasoline... not one visible residue remains.... just the fumes.

On one hand, the whole point of installing the conversion kit is so that gasoline doesn't have to stay inside, go stale, and cause all sorts of nasty things to happen. But, is there a downside leaving it in the opposite extreme; totally dry?


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## GenKnot (Dec 20, 2021)

OrlyP said:


> Is it necessary to run a dual-fuel generator on gasoline every so often?


For what's is worth, I have been storing my gasoline engines for years by running a VERY rich mixture of Walmart Super Tech TC-W3 Outboard 2-Cycle Oil (only about $13/gal.). I empty gas tank and then run carb dry first. Next, on the gen, I run about a 1/2 cup or so of the 2-cycle mix (slosh around in gas tank first to get it coated with oil) until carb runs dry again. The drain plug on your conversion regulator would make it easy to verify that the carb is completely free of any gasoline. I have similar conversion regulator on mine for NG use.
Contrary to a lot of recommendations, I have never used any fuel stabilizers, nor do I store my equipment with gasoline in the tank(s). I do rotate the gasoline in my cans by running in my car to keep them fresh.
The marine oil is blue in color, and it makes it very easy to see what is coated with oil. I have been doing this on my lawn mower (15+ years old now), generator (a 2008 model), gas edger (20+ years old), and a few other small engines. I have never had an issue with starting them up again in the spring. As for the generator, it has set for several years at a time without a run. I pull the rope until compression TDC after carb has run dry. I also lightly spray used motor oil on the outside of the muffler to minimize the rusting (it burns off when engine is started). The 2-cycle oil in the exhaust coats the inside of the muffler.
I have taken some of the carb bowls off to examine them, and I find the blue oil still coating everything in the spring.


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## drmerdp (Apr 10, 2018)

OrlyP said:


> Is it necessary to run a dual-fuel generator on gasoline every so often?
> 
> The premise here is that the generator has been converted to be able to run on LP. After that, the metal tank, sediment bowl, fuel lines, and the carb has been totally emptied of gasoline... not one visible residue remains.... just the fumes.
> 
> On one hand, the whole point of installing the conversion kit is so that gasoline doesn't have to stay inside, go stale, and cause all sorts of nasty things to happen. But, is there a downside leaving it in the opposite extreme; totally dry?


I don’t think so. My old champion went 8 years from it’s first break-in on gasoline with a bone dry tank. No signs of rust anywhere. Tank and carb was emptied thoroughly and sat without issue. For good measure, now a days I spray tanks with wd-40 with the flexible straw that articulates to get really good coverage all over the inside. 

Like genknot mentioned a bit of 2stroke oil mixed with the gas before draining helps keep a nice coating as well. If the tank is easily removable then you can always add some gas oil mix and slosh it around before draining.

Fogging spray is handy for coating the intake track of an engine for storage but Im not sure if it will truly “Fogs“ the inside of a tank if spayed inside and left to it’s own devices.


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## OrlyP (Oct 19, 2021)

Thanks. I've done turning the crank over and leaving it at compression... not at TDC, afaik. I just pulled on the rope, felt a small bump followed by an even bigger bump (presumably the compression stroke) and stopped at the onset.

I might try misting the inside of the tank with WD40, but let me think it over. This, having a vented cap, I wouldn't want the oil film to become a dust magnet. Or am I overthinking this? lol


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## GenKnot (Dec 20, 2021)

OrlyP said:


> I wouldn't want the oil film to become a dust magnet


I try to keep my gen covered to minimize the dust issue. Seems to be working so far. 

It doesn't have to be exactly at compression TDC...just near it. In that condition the valves are closed thus sealing the cylinder. It also relaxes the valve spring tension. But you already know that. I am including it here so that others coming upon this will know why that is done.

One thing I failed to mention is that now that I have converted to NG, I will still use the same shutdown/storage procedure except with one modification. I will do the storage run with the gasoline & 2-cycle oil mix using an IV setup. That way, I don't have to deal with putting gasoline into my tank again.

I haven't put my gen back into storage mode yet as I am still doing some testing after the NG conversion. I have avgas in the tank, and it can stay there awhile.

I am trying to decide on replacing this 3KW genset with an inverter type in the 5KW range. Decisions, decisions...


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## OrlyP (Oct 19, 2021)

Yeah, the dust cover does help a lot. 

Overthinking it is then. haha


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## drmerdp (Apr 10, 2018)

OrlyP said:


> I might try misting the inside of the tank with WD40, but let me think it over. This, having a vented cap, I wouldn't want the oil film to become a dust magnet. Or am I overthinking this? lol


lol, a little. No need to worry about dust.


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