Running Honda EU generators re-jetted at high altitudes.

I was forced to screw around with prime movers including gasoline for many years in the high sierra. Even at 11,200 feet I failed to notice a significant improvement in power by rejetting and at the time I had an assortment of .045" jets and a number drill set. I tried decreasing orifice size until the engines quit running.

Perhaps for long service times, Robert at Honda's advice is sound. Reduce combustion chamber deposits, plug fouling and oil dilution.

But to gain power - I remain thoroughly unimpressed.

SPARK TIMING on the other hand is another subject entirely. Some engines like Wisconsin and 4-cyl Onan's, saw readjustment of initial spark timing eight to ten degrees BTDC.

Your mileage may vary...

Niner,

When drycamping ... the Onan is for air conditioning anywhere anytime, a microwave oven anywhere anytime, electric heating, cooking, and refrigeration anywhere anytime should the propane system ever run low on propane or otherwise fail, and to run the 120V AC compressor to pump up a tire or a balloon. The last time I checked, I noticed that life is unpredictable.

The little Honda is for everything else ... if it'll run at 9,600 feet with the jets that came in it. :B :



By the way and for what it's worth, I bought my first and only scrambler motorcycle brand new in Utah and rode it at their altitudes for four years - including high up on ski trails in the summer. It was a great bike and ran great as delivered by the dealer. I brought it back to Central California and did not change it's jets. As a result, I burnt a hole in one of it's pistons and gave it away with parts of it in a box. From that experience, I learned a valuable negative lesson about running lean (this applies to internal combustion engines, not my body weight). ;)

pnichols wrote:
I wonder how Onan is making it so convenient on their built-in RV generators: I just turn a knob on the generator to the various altitudes we might be camping at. The knob is marked in feet. This sure is an easy way to do it.

Wait, I thought all you ran was solar panels and your Honda EX650 that is so heavy, quiet, and self contained, that was gifted to you?

Do you rejet your EX650?

I wonder how Onan is making it so convenient on their built-in RV generators: I just turn a knob on the generator to the various altitudes we might be camping at. The knob is marked in feet. This sure is an easy way to do it.

The thing I have noticed with genneys at high altitude is usually you do not need the AC and for me that's the big draw. So if I can charge batteries and run the micro now and then, I am good. My eu3000 has worked fine at higher altitudes. Or should I say good enough for me.

Thank you to all of you! Your replies were exactly what I was looking for. Thanks so much for your input.

Chingo your WRONG you can BUY the jets for YAMAHA 2400. Bought them in Alamosa Col and Monroe,La for my 2400

robert_at_honda wrote:
A little off-topic, but maybe some of the aviation-types/pilots out there can describe how the mixture control works on small aircraft with carburetor-style engines? I'm guessing it allows for manual control of the amount of fuel flow to best match the altitude?

- - -
I work for Honda, but the preceding is my opinion alone.
Robert@Honda

In a nutshell, yep. However, you want to really stir up a hornet's nest, argue running LOP (Lean of Peak) or ROP (Rich of Peak). :)

Assuming small 4-6 seater general aviation - Most A/C Pilots Operating Manual (POH) or equivalent or Lycoming/Continental engine manuals advocate 50-100° Rich of Peak - lean to find best power or max Exhaust Gas Temperator (EGT) and then richen 50-100°

With good individual Cylinder Temperature Probes and engine analyzers, there's a school of thought that one can run the engines Lean of Peak for better efficiency, at the risk of burning up pistons and/or valves from running too lean.

1950s technology still going strong.

Changing the jet size as you go up in elevation helps to maintain the correct fuel/air ratio, so the engine does not run too rich. With the rise in elevation comes less dense air (less combustible oxygen) being drawn into the engine. Without a jet change, the engine would flow too much fuel and possibly foul a spark plug or have other running problems.

Modern fuel-injection systems use an oxygen sensor to provide feedback to a computer that can adjust the amount of fuel on the fly, and maintain the proper fuel/air ratio.

There will still be power loss on pretty much any engine with an increase in altitude, but by adjusting the fuel flow, the engine can at least operate with the proper fuel/air ratio.

A little off-topic, but maybe some of the aviation-types/pilots out there can describe how the mixture control works on small aircraft with carburetor-style engines? I'm guessing it allows for manual control of the amount of fuel flow to best match the altitude?

- - -
I work for Honda, but the preceding is my opinion alone.
Robert@Honda

srt20 wrote:
I don't have a horse in this race, I don't own either, but my snowmobile partner has a Yamaha gen 2k or whatever it is. We have used it in January at 10,400 ft in the Snowy Mtns with no issues at all. We use it to power his trailer as a mobile work shop for when we break stuff. His 42k RV furnace also works great at this exact altitude. I forget what brand furnace it is.

Whether it "worked" or not isn't really the issue ... any gas engine with a carb is going to run rich, consume more gas, and run less efficiently at higher elevations if it hasn't been rejetted regardless of what label may be on the genset. That chart post by Robert is telling. :E