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Kohler 20resc Natural gas

Krislu

Registered
Till now,I have only owned a Honda EU2000I portable ( sold it,after 1 month needed a ring and valve job, smoked too much, dealers would not warranty) and a Yamaha 2400 ( excellent,still have) This is my first experience with a home generator. It's a 3 month old Kohler 20resc Natural gas generator that coded "over crank " for the first time. I noticed on a Saturday night when the power was out. It happened the Wednesday before on exercise day. I didn't know it wasn't working til Saturday. Paid the dealer an outrageous rate to come take a lookse. I asked him about Kohler's Oncue and he told me to avoid, said it's down most of the time and I would need him to reset it. Anyway, he came up with a little low gas pressure, said between 5 -5 1/2 wc he said he wasn't concerned because on start up it went down a little but came back up once running. He said I should add the pressure regulator heater, said all of the unit should come with it but don't. I had the gas company come out to raise the pressure. The guy said he made it 6.8 wc. I checked the spark plug gap and discovered one was .020 and the other was not even that. So I gapped at .030. My question: Will the heater make that much of a difference? I plan on installing it myself.

Thanks
Kris :)
 

Zephyr7

Registered
I don’t see a point in heating the gas regulator. You don’t have to boil off gas on a natural gas set, it’s already gaseous fuel (propane sometimes has issues with enough gas boiling off from liquid when it’s really cold outside). Kohler sells a carb heater option, and that is usually supplied by dealers if you’re in a cold enough area to need it. He carb heater is an option you should have.

I doubt the gap was your problem unless the other plug was really messed up.

Bill
 

Mark Dieckmann

Registered
You should probably check out the spark plug gap specs. If my memory serves me, it is supposed to be .020. I would agree that a carb heater is the first thing you need. The OC fault means that it failed to start. I think gas inlet pressure is supposed to be between 7-11 inches.
 

Zephyr7

Registered
Some of the air cooled resi gensets are specced for 3.5-11” WC inlet pressure. Best not to be in the low end of that range though. I always recommend 11” pressure.

The liquid cooled sets are specced for 7-11” WC inlet pressure.

Bill
 

Newoldstock

Registered
Some of the air cooled resi gensets are specced for 3.5-11” WC inlet pressure. Best not to be in the low end of that range though. I always recommend 11” pressure.

The liquid cooled sets are specced for 7-11” WC inlet pressure.

Bill
Got one that's air cooled and spec 11" only....
Canadian version of K181EP on 3RM22 head
 

Zephyr7

Registered
Got one that's air cooled and spec 11" only....
Canadian version of K181EP on 3RM22 head
Is that for propane? It will only be the natural gas sets that can go down to the lower pressures. I think the only reason they allow for pressures down to 3.5” on some units is so that the typical residential service pressure of 7”, after some drop in the piping, will still be ok when it gets to the genset. They don’t want to scare off customers by requiring upgraded gas pressures and bigger piping. There are also some areas served by low pressure gas mains where elevated pressure might not even be an option.

Bill
 

Newoldstock

Registered
Is that for propane? It will only be the natural gas sets that can go down to the lower pressures. I think the only reason they allow for pressures down to 3.5” on some units is so that the typical residential service pressure of 7”, after some drop in the piping, will still be ok when it gets to the genset. They don’t want to scare off customers by requiring upgraded gas pressures and bigger piping. There are also some areas served by low pressure gas mains where elevated pressure might not even be an option.

Bill
The tag just says natural gas 11' W.C. inches and 63000 btu/hours.
I don't know very much about the technical details of NG or propane kits.
That's 18,500 watts thermal for 3000 watts power output or about 16% efficient. ( hoping to improve that with a purpose built high compression replacement engine )

By my math the engine is about 20% over powered for the application displacing over 300cc for a load a modern OHV engine can do on gasoline with 1/3 less cubes.
I assume this has something to do with the gas conversion
 

Zephyr7

Registered
I get just shy of 6kw out from the engine just converting 8HP to kw at 746w/HP, so you should be about 32% efficient at full engine load, assuming that’s how they rated it for fuel consumption. 32% efficiency is pretty good!

Natural gas and propane both have a fair bit less energy per unit volume than gasoline, so you need more displacement to get the same HP output when running on one of those gaseous fuels.

Bill
 

Birken Vogt

Email NOT Working
Phantom problems like this, you have just got to "sneak up" on them. Set everything back to normal and observe it next week at exercise time. Hopefully you can catch it in the act. Only call the dealer out when you have observed whatever happened in person and can explain what you saw a little better. Assuming you have a good technician who listens to customer data and can interpret.
 

Newoldstock

Registered
I get just shy of 6kw out from the engine just converting 8HP to kw at 746w/HP, so you should be about 32% efficient at full engine load, assuming that’s how they rated it for fuel consumption. 32% efficiency is pretty good!

Natural gas and propane both have a fair bit less energy per unit volume than gasoline, so you need more displacement to get the same HP output when running on one of those gaseous fuels.

Bill
There might be an error in your math Bill.
You generally need a touch more than 2 hp per kW in an implication like this.
Assuming an efficiency of 60% on the alternator is a step I think you skipped.
Such a small machine will not be efficient, the head I have here is a brush type with saturated field ( no regulator ) and lose tolerances.

Engine alone I am not sure its possible to get 30% efficiency on a gas fuel flat head.
My numbers might be even worse than 15%...
I would really have to measure and not guess so much....
 

Zephyr7

Registered
Actually, I’m sure there is an error in my math, quite possibly more than just one! :)
I also only looked at the engine, not the generator end you have. The numbers are all guesses. 32% is probably overly high. I don’t think it would be as bad as you think though, but only at full load. Anything less than full load I don’t know. It seems the general rule of thumb is you use about 50% of full load fuel consumption when running only 25% load on the generator.

It is for certain that you need a bigger engine to get the same HP output on gaseous fuels due to the lower energy density though. That’s the only for-sure thing I can say.

Are you going to be able to up the compression? I’ve heard of issues with valve clearances when doing that, but I’ve never tried it so I know little there.

Bill
 

Krislu

Registered
Kohler sells a carb heater option, and that is usually supplied by dealers if you’re in a cold enough area to need it. He carb heater is an option you should have.
Bill
Today, I ordered the carb heater.


" You should probably check out the spark plug gap specs. If my memory serves me, it is supposed to be .020. - Mark "

It is .030

I appreciate everyone's wisdom and knowledge. I am enjoying reading all the threads. Thank You !

Kris :)
 

Mark Dieckmann

Registered
They say memory is the first thing to go. I am concerned that the problem is not gas pressure or plug gap. What was the weather like on the day it failed? The carb heater is intended to prevent carb iceing during cold damp weather. Also ice usually is formed after starting and running briefly. So while I feel you should have one, I’m not sure it would have helped. On cue is normally included with the generator and merely requires an Ethernet (cat5) cable run to a router and setup. Once installed it would have warned you about the problem before the outage. Very handy.
 

Krislu

Registered
What was the weather like on the day it failed? On cue is normally included with the generator and merely requires an Ethernet (cat5) cable run to a router and setup. Once installed it would have warned you about the problem before the outage.
I am not sure what the temp was like the day it failed. Here in NY we have been fluctuating between 30 and 50 degrees. I tried to start it on thanksgiving when it was 30 degrees and it would not start. Then tried on Saturday (50 degrees) after I re-set the gap and it started right up. Yes, the generator is oncue ready I would have to run a wire from it to my router. It is not a small task for me though because my router is on the other side of the house and there are a lot of obstacles both inside and out to get to the generator. I spoke to tech who went over the genny and he said oncue is not worth it. It's down more than it works and I would need him to come out and reset it. - Kris :)
 

Zephyr7

Registered
I have OnCue running on unit at a remote cottage. No problems over the past two years. I’m not sure why the tech thinks you’d need him to come reset anything, either. OnCue just monitors stuff, it doesn’t make the generator stop working.

If you need to run a wire you could use outdoor rated cat5 cabling on the exterior of your house. Commscope makes a good gel-filled cable, but it’s messy. There is also “toughcable” from ubiquity. Lots of options. You can support the cable with the sample nail-on clips you’d use for coaxial cable and you can get those at the box stores.

Bill
 

Newoldstock

Registered
Actually, I’m sure there is an error in my math, quite possibly more than just one! :)
I also only looked at the engine, not the generator end you have. The numbers are all guesses. 32% is probably overly high. I don’t think it would be as bad as you think though, but only at full load. Anything less than full load I don’t know. It seems the general rule of thumb is you use about 50% of full load fuel consumption when running only 25% load on the generator.

It is for certain that you need a bigger engine to get the same HP output on gaseous fuels due to the lower energy density though. That’s the only for-sure thing I can say.

Are you going to be able to up the compression? I’ve heard of issues with valve clearances when doing that, but I’ve never tried it so I know little there.

Bill
I have some ideas on what I want to do.
I flip flop between the GX240 and the GX270.
Both share a crank and head with only a 73 and 77 mm bore difference.
I can mill a head ( with the belt sander HA HA ) about .070 and get the compression I desire on the 240.
The 270 can use an aftermarket flat top piston and both will yield compression in the 9.5 to one range ( static ).
.009 after market gaskets also help by shaving about 1cc from the chamber volume.
Dynamic compression on these engines is low too but i am not willing to add a cam or significant speed parts to improve than.

There is a real slick new ignition for these that has a timing advance feature.

I am also looking at the heavier GX390 big block flywheel and version of this new CDI ignition for more rotating mass and better ignition control.

Then maybe look at a better air filter and exhaust to both quiet and improve flow.
I am really not concerned about power losses on NG I can easily make that up with some creative building.

I could look at a head off one of the larger big blocks and mill that with big valves for the 270, this might not work on the 240.
 

Zephyr7

Registered
Milling with a belt sander eh? I’ve used my drill press (chatters a lot), but never a sander. I guess you use what you have! I still dream of a nice Bridgeport knee mill, then I could use a flycutter...

Anyway, I wouldn’t think a belt sander would do well for flatness over the “milled” face. Have you considered getting a used grinding machine? I see them for really cheap frequently on eBay and other places, frequently with a magnetic chuck included! At the very least, such a machine could even out your beltsander work and get some precision for you.

Bill
 

Newoldstock

Registered
Milling with a belt sander eh? I’ve used my drill press (chatters a lot), but never a sander. I guess you use what you have! I still dream of a nice Bridgeport knee mill, then I could use a flycutter...

Anyway, I wouldn’t think a belt sander would do well for flatness over the “milled” face. Have you considered getting a used grinding machine? I see them for really cheap frequently on eBay and other places, frequently with a magnetic chuck included! At the very least, such a machine could even out your beltsander work and get some precision for you.

Bill
You would be surprised what you can do.
Draw filled one head down after welding up the combustion chamber.
As long as you take your time and make them flat there is no issue
 

Krislu

Registered
I have OnCue running on unit at a remote cottage. No problems over the past two years. I’m not sure why the tech thinks you’d need him to come reset anything, either. OnCue just monitors stuff, it doesn’t make the generator stop working.

If you need to run a wire you could use outdoor rated cat5 cabling on the exterior of your house. Commscope makes a good gel-filled cable, but it’s messy. There is also “toughcable” from ubiquity. Lots of options. You can support the cable with the sample nail-on clips you’d use for coaxial cable and you can get those at the box stores.

Bill
Bill- You have re-energized my interest now. I will look up Commscope and toughcable. I guess I need a male connector at the router and female at the generator ?

Thanks !
Kris :)
 

Zephyr7

Registered
Bill- You have re-energized my interest now. I will look up Commscope and toughcable. I guess I need a male connector at the router and female at the generator ?

Thanks !
Kris :)
Commscope’s part number for the stuff I’ve used before is 5NF4. It’s an excellent product but the gel makes it messy to work with.

There is another “gel free” outdoor cable by premier, I think (it’s been a while since I’ve ordered it). It has a shield, a double jacket, and is a non-halogenated cable (fancy fire rating). It’s expensive though and you’ll probably have to buy a 1000 foot RIB.

Female ends are easier to install on the gel-filled cable but you can use males too. I think the generator end can use either (it comes with a little network cable, at least mine did). I’d bring both male and female connectors just to make sure you’re not missing something you need while you’re at the remote site.

Btw, AMP brand RJ45 male ends for solid wire, the kinds where the part of the pins that grabs the wire looks like a small trident, are VASTLY SUPERIOR to any others I’ve ever used, and I’ve used thousands of the things at work. Most ends just have two little spikes and they are no where near as reliable and the trident-like three pronged fork the amp connectors use to bite the wire. The AMP ends use the same crimp tool as the regular ends.

Don’t waste you’re money on cat6 cable. There aren’t any network standards that need it. Gigabit Ethernet will work just fine on regular cat5 (not even cat5e is needed, but cat5e is most common now). 10 gigabit Ethernet requires cat6A cabling. Just use cat5e and save some money, and get the easier to install connectors.

Bill
 
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