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Honda EU1000i

How to modify a Honda EU1000i to run propane or natural gas.  With a few other add-ons and tweaks of my own.

 This page is a project in progress.  Not everything on this page will be completely correct.  Except the pictures which are proof of work done.


1.        Install hour meter  (Finished)

1.    I install the hour meter facing the on/off switch side as thats the side I'm most likely going to see it from.  I also used a pair of quick disconnects to allow removal.  Research #


2.        Modify case for regulator mount  (Finished)

2.    This was tricky as I didn't want bolts to stick out when this regulator wasn't attached.  So I used the honda as inspiration, all the bolts have sunken nuts.  I plan to do the same with SS hardware and JB weld.

3.        Create removable mount for demand regulator  (Finished)

3.    This is the rough cut of the demand regulator bottom bracket.  I made this almost the width of the maintenance door.  To allow room to turn the wing nut bolts that will hold this on.  I wanted the regulator to be able to mounted without the need for tools.  If vibration shows this won't work, I have a second idea to counter it.

6" SS 1/4"x20 rod cut in half.

Silicone rubber attached to 1/4" fender washers.
Cut end of threaded rod in toward wingnut.
Wingnut, nut, 5/16" SS tubing, nut, split washer, washer
faucet washer used as retainer - I think this was a 1/4" or maybe a 32" smaller than a 1/4", I can't find the package.
finished assembly

4.        Create an all weather enclosure.  (Researching parts)

4.    This was the cheapest plastic enclosure I could find $8. 

            Doesnt fit with regulator installed.  Will need to find something else.
            this is big enough for the generator and an extension cord for storage.

5.        Exhaust extension

        For use with outdoor enclosure to make sure the evacuation of exhaust gasses.  I had to trim a bit of the plastic to make it fit.  This is a 1/2" half coupler 316L Stainless steel from McMaster-Carr.  Tig welded onto the end of the muffler with stainless rod.  Plastic housing trimmed away to fit with rasp on a dremel tool.

xx.    Everything about this step is in research link #1

6.        New Run/Stop Switch

This was the best place I could find to mount it out of the way of everything inside and be in a place thats useful to operation.  With the marks to see how I lined it up.
Engine run is UP, STOP is down.  Because this shunts the coil, the switch being on means the engine is off.  I wish I used an unmarked switch, but owell.
Quick disconnects are siliconed in the back for vibration/extra seal.
I made it this way JUST IN CASE I ever needed to revert back to the other switch.  No, no I never will go back.

7.    New gas jack mount.

This is for quick removal of regulator when in storage or not needed when running gasoline.

8.    Carburetor modification.

Toothpick to hold tube while JB weld sets.
Very tight fit
From the carb there is a loopback on the top then to left with the shutoff then down and to the right and up to the jack.

Finished testing view after adjusting load regulator.

    I needed to leave the valve in place for Gasoline shutoff.  I just could not find an easy way to mount a shutoff inside this housing.

Parts Used:

    Impco KN Garretson Regulator #039-122
    1/4" x 2" brass tube for carburetor - input
    1/4" gaseous fuel hose - input
    2x fuel shutoffs for 1/4" hose (this includes the above needed hose)
    Hex bushing 3/4" x 1/4" - for input
    90 street elbow 1/4" - input
    Hex nipple 3/8" x 1/4" - output
    Female pipe tee 1/4" - DIY load block
    1/2" x 13TPI SS Cap screw - for load block control
    1/2" x 13TPI SS Nut - for locking above bolt
    1/2" I.D. faucet washer/O-ring
    1/4" NPT to 1/4" barb - to feed engine
    Camco 59853 QD - for input feed
    Bostich 1/4" air coupler female - input
    Bostich 1/4" air fitting male - input

Other Parts:
    Sendec hour meter, But I wished I used THIS one.


Natural gas has an octane rating of 130.

Propane Notes:

    Propane is 74.04% the energy density of Gasoline and has an octane rating of 103.  Has a 1.52 specific gravity.  91,502BTU per gallon.  Can also be stored near indefinite amounts of time.
    Calories per gallon 6.1030^6
    about 4.24# per gallon
    20# tank has about 4.7Gal of propane,  so the equivalent energy to ~3.48Gal of gasoline.
    That means @$3.50 a gallon for gasoline it would cost $10.50 to be equal to a 20# tank for the same energy
    about $20 is what it cost to get a tank exchanged and a hair less to refill
    This means propane is definitely not a cost saving endeavour.  Besides the fact the engine will last longer.  But propane will never go stale and the carburetor will never get clogged.
Run TImes:

    Usage of propane per hour:

        2/4 load .33496#     ~8.3904#  /24hrs
        3/4 load .424#        ~10.176#   /24hrs
        4/4 load .5936#      ~14.2464# /24hrs


        1# of propane lasts


So for a "weekend camping trip assuming its on ALL the time (~48hrs) would use ~16.7808# - 28.4928# of propane.  Granted I'm not going to do that.  But shows it's easily possible to do with 2 20# tanks and an auto changeover.

Using a 1# cylinder would last         1.684 ~ 2.985 hrs.
Using a double 1# holder                 3.369 ~ 5.97 Hrs
Otherwise a 20# tank would last      33.68 ~ 59.7 Hrs

Other notes:

Overhead cam, aluminum block with cast iron sleeve.

Dimensions rounded up:

    Height: 15"
    Width: 10"
    Depth/Length: 18"
    Weight: 30#

Spark plug: NGK #6535 CR5HSB or Denso U16FSR-UB


    Using propane after the single or dual stage regulators will be 11" W.C. or 1/2 PSI.  Or using natural gas which is the same pressure.  The on demand regulator then allows the engine to "sip" the correct amount of fuel using the "load block" as an adjustment for air/fuel mixture.  


            Everything is in this link for the basis of my modification, except for the load block, and other small details.

            Remote primer or use as an idea for internal mount with this mechanical idea.

            Exhaust extension

            Load block how to


Fittings and adapters:

Replacement parts:

My Notes:


    It took me a long time to figure out how to make my own 'load block' as I just could not find one to buy.  Impco makes them but I can't seem to find a dealer.  Found some smaller regulators but realized the reason why to use the bigger KN was for sensitivity as this is a small engine.  Mean while I can't help but want to make this run on propane only.  I hate gasoline in something that is a '"standby" device.  with all the gumming up and extra maintenance.  If I did this, I might be able to install the regulator where the gas tank is and use the fuel cap as an inlet.  yet somehow I would have make a way to press the prime button.  I found a pic online of someone using a solenoid to do this with a hinge.


    It seems it would be better to mount the regulator on the outside of this machine.  But I then came into the problem of how do I mount it on the side.  I would like it to be removable since It may not be needed.  The current idea is to use JB weld and mount nuts behind the side panel that bolts can ankor to.  But by doing this how to make the removable assembly hold itself together and not have washers and spacers fall off.  Right now the idea is to use faucet washers as a retainer and have foam mounted on fender washers for a anti chatter/noise guard.  Since this is such LOW pressure the gas disconnect will be a standard 1/4' industrial quick disconnect mounted with a 90 degree elbow on the top near the front of the handle to be out of the way.

    Load block problem has been solved in theory.  This depends how well the modification works.(link #5)  


    I think I might have finally solved the regulator mounting dilemma.  I had to figure out how to have bolts with spacers and washers and stuff not fall of when the regulator is removed.  I first thought E-clip, then I remembered that faucet washers come in a hundred different sizes and stretch a bit.  So next time I go to the hardware store I will see if they have e-clips to try otherwise faucet washers will be my solution.  To mount it to the side I'm am thinking about using fender washers with urethane foam rubber glued with super 777 adhesive.  Question is where do I get the foam I need for this.  if I use silicone rubber I am pretty sure I can't get an adhesive to make it stick.  Maybe rip apart an old mouse pad.


    Found that McMaster-Carr sells anything I could possibly want for self adhesive rubber.  So that problem is solved.  The E-clip idea just didn't work.  But the faucet idea did, so I bought those.  Exhaust extension is something I am also trying to solve Research #7.  i think mine is too small for this exact modification.  I think welding a 3/4 close 316L SS nipple should work.  Only problem is the threads are on the outside.  I dont think I can use a coupler as it's too big to fit between the plastic and where I want to weld it.  I also found some videos on YouTube that brand new had what i thought noisy valves.  Must just be from being a small engine.  Might still take the case apart for cleaning, Haven't totally made up my mind.  


    Decided to buy a SS 1/2" x 1" half thread pipe and use a reducer tee to attach an exhaust extension.  With that I also ordered a 1/2" half coupler,  If I decide to cut up the plastic This will fit otherwise I will used this as a thread saver for the other piece.  With this 3/4" pipe that will be pointed up or sideways, I can use a lawnmower sausage muffler as a secondary.  Since this is quite a bit larger it should not cause any restriction losses.  This might or might not actually help quiet the machine, but would be interesting to find out.  This secondary muffler isn't very big so I don't have to worry about stresses involved with this modification.  Decided to change hose and fittings to 1/4" as this will be easier to find and replace later as well as needed size for fuel shut offs.  


    Building begins!  Took a few hours to mark lines and get everything to fit to mount that regulator.  I used angled aluminum just like the research #2 showed with a few changes.  I found I have to dismantle the case to mount the gas inlet and fuel shutoffs.  As for the gas inlet I can't think of a better way to make the mount solid other than using JB weld on the inside when screwed together.  But I think it should be perfectly fine if not overkill.  Exhaust parts arrived and look like they will fit perfectly.  Test fitted fittings to make sure all needed parts are ready.  Small changes in mount, need more nuts and washers.  Possibly need different silicone sheet as this is far too hard to use for its intended purpose.  I am wondering if I should modify the original shut off as it also messes with the gas line.  Possibly adding a separate "Run/Stop" switch.  Will consult the shop manual.


    Decided to use the 1/2" half coupling to weld onto the muffler as the threads wont have a possibility of being damaged from being exposed.  Then using a close nipple, a reducer tee (1/2" x 3/4") with a another muffler helps with the exhaust noise.  Initial test of this was very slight change in noise levels but only barely noticeable.  But this mod did help with blowing the exhaust up which would help if you didnt want to blow it toward something.


    Finishing up the removable mount.  While doing this I've been thinking how I should do the fuel shutoffs and quick disconnect.  I think I have to take the case apart to put the quick disconnect in the way I would like.  As for the fuel shut off, I'm not quite sure I know how to make it fit.  I've been wondering if I should just use the fuel shut off and add a separate engine kill switch.  I think there is a hair bit of room on the front panel that would be quite convenient for installation and use.  

04/13/14        Getting back to it

    After much thought of where to mount the new RUN-STOP switch I think I will just end up putting it on the side near where the old one was.  This will make it 'right there' when pull starting and is easily mountable as this case is CRAMPED!!  

04/20/14        Wrapping up

    Finally had the courage to drill the carburetor took a very long time to set up the drill press and line that up just perfectly.   I used a 3/16" drill bit as shown in Research #1. But I will use 1/4" brass tube for the nipple.  I think I have figured out how I want to route the hoses.  With addition to the ignition switch I will not need to add a another fuel shutoff inside the case.  Which I looked at for so long and just couldn't figure out how to make it fit.  I also drilled and mounted the new ignition switch and gas inlet on the case.  The switch doesn't tighten to the case as well as I would like.  So I will JB Weld them like I did the nuts on the door.  Something I noticed too late was the switch is marked I/O.  Which in this application is backwards as when this switch is closed the engine will stop.  Maybe a red sharpie or paint marker will fix it.

04/22/14        Completion

    Installed the modified carb. hose fit just like I was hoping it would.  Hooked it all up and it started in a few minutes after adjusting the mixture via the load block.  Presto after it warmed up a but I did some final adjustments and locked it in place.  I think it starts easier on propane than it does on gasoline.  The smell.. there is hardly any noxious fumes like running on gasoline. This is the only way to run a generator.  Now I never have to worry about a clogged carb or stale gas!

08/08/16    Further notes from testing

    After 30 hours intense testing and use.  I found two things.  1.  I think I made a mistake on WHERE the propane enters the carb, I constantly had to adjust the mix dependant on load and rpm.  This also made it hard to start and loss of power when demand ramps up.  2. As my need to use this for quite extended periods of time, the current cost of propane is 2.5x the cost of gas for whatever reason when using small 20# tanks even though propane is $1.09/gal, anyway. When i changed the oil it was still just as dirty as it was with gasoline.  Meaning it might not make the engine last longer as originally thought due to burning cleaner thus having less soot in the oil. so that's 2 strikes. Now I noticed that it seemingly needed to run a bit rich to run smoothly and not sputter.  I do not know the reason for this.  My guess is it needs higher compression to burn correctly.  This lead to needing the spark plug to changed where 30 hours before seemed to run ok.  But it was not a new plug (should have been) but it might have just been the hours and needed to be replaced.  Now that this generator has had so many hours and the valves need to be adjusted, propane wouldn't prolong or create any benefit for this heavy maintenance.  

So in conclusion it does run and it did run very well when under a constant load.  But for total practicality this setup isn't ideal and may be discontined.  This was a great experiment, but does leave me a bit disappointed.

And when I get the 2000i
electric start:
Starts at, view of the starter:

11/01/13 - 04/22/14