High Altitude Jetting

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High Altitude Jetting

High Up
I recently purchased an EF2000IS.  I live full-time in my trailer at 8,000ft +\-.  Although, the generator does run, I understand it should be properly jetted for this elevation.  I'm not about to pay a Yamaha shop to do what is a simple calculation and replacement process.  Problem is, I cannot find specs to determine what size the current jets are.
Anyone know the sizes of the main and pilot jets out of the box?
Thnx
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Re: High Altitude Jetting

CycleRob
This post was updated on .
EF2000iS parts diagram. Copy-n-Pasted from https://www.shopyamaha.com/parts-catalog/lines/generators

JET, PILOT (#35)
JET, MAIN (#86.3)

If you have a California model, an EF2000iSC
JET, PILOT (#37.5)
JET, MAIN (#67.5)

I would go 2 sizes smaller (lower numbers) if they are available. The Yamaha dealer in that area should be familiar with which jets to use -or- make a phone call to these Denver Yamaha dealers (the Mile High City)

www.coyotemotorsports.com   "Yamaha dealer with a 5 star certified gold service department".

www.gforcepowersports.co

www.copowersports.com

www.vickerymotorsports.com

Good Luck !

Talent, On Loan, From God  --Rush Limbaugh--
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Re: High Altitude Jetting

Lawlietisnear
In reply to this post by High Up
Did you ever figure out what jet to get?
I just got the same generator, and haven't had any luck trying to figure out what jet to get for similar altitudes.

Thanks,
Sam
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Re: High Altitude Jetting

High Up
I feel really stupid when I discovered it was nothing more than the oil level being just slightly low, but enough that when jiggled the auto shut-off would kick in.  Since then I have been successfully running the generator at 8,750ft (600+hrs of operation).  And I mean it really runs well at this altitude.  Surprised that Yamaha doesn't advertise just how well it does operate at higher elevations.  Bottom line-- I never changed the jets!

Sent from my iPad

On Nov 20, 2015, at 9:21 AM, Lawlietisnear [via Yamaha Generator Fan Club] <[hidden email]> wrote:

Did you ever figure out what jet to get?
I just got the same generator, and haven't had any luck trying to figure out what jet to get for similar altitudes.

Thanks,
Sam


If you reply to this email, your message will be added to the discussion below:
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NAML
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Re: High Altitude Jetting

CycleRob
High Up,
  Your Genny runs so well because it is effectively running a richer fuel mixture than the EPA mandates and Yamaha is legally allowed to set it. The thinner air at high altitudes does that. If the Genny was jetted correctly at Sea level it would run way too rich at 8,750 feet. The sparkplug porcelain would be black and it would emit black exhaust smoke when the throttle motor yanks open the throttle for an electric motor start-up. It would also deliver poor fuel economy.
 I bet it needs very little choke, if any at all, to keep a really cold engine running just after starting it. Take a look at your sparkplug porcelain and tell us what color it is.
Talent, On Loan, From God  --Rush Limbaugh--
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Re: High Altitude Jetting

LeftyS7
I'm very surprised it runs well, I have two hooked parallel to run my 4WD Motor Home A/C and at 7000' they did not provide enough power to start it.

I was VERY disappointed with Yamaha. The local authorized repair shop said there was no need for a jet change, even though my owner's manual says on page 26 that a "High Altitude Kit" is necessary at elevations over 4000'. The owner's manual they looked at did not have the warning. He asked for the part number of my manual, looked it up, and was surprised to find the warning there. Reno is at 4500', yet he had no idea a jet change was necessary. Even worse, I called Yamaha Corp and the Customer Relations person had no idea, either. I finally found one who was somewhat helpful who told me to call Coyote Motorsports in Denver to learn what they did. I called them and they also said no change was necessary, only a float level adjustment. Calling back to my helpful Customer Rep at Yamaha, she told me that Yamaha does NOT sell jets but that I should contact Mikuni who makes the carbs for Yamaha. I did, and eventually a representative from Sudco.com called and gave me the necessary info, he said I only needed to change the main jet and that a 65 was what I needed so i bought two. They haven't yet arrived.

As you say, carbureted engines are adjusted for sea level, and if anything, a little lean so as to produce less pollutants. Running richer at higher altitudes does not make for better performance but, you are right, it needed NO choke to start and would stall if given choke.

However, once you have the proper jets for your higher elevation DO NOT run the gen at significantly lower elevations for any length of time as it will run too hot and burn out your exhaust valve.

Been there, done that, on a '55 BMW motorcycle jetted for the Alps and run at sea level. My introduction to gas engine repairs.
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Re: High Altitude Jetting

LeftyS7
In reply to this post by CycleRob
Where did you get this information from? A rep from Sudco, the Mikuni Distributor, told me no need to change pilot and 65 main for 4000 feet, 62.5 for next higher altitude (I forget what range he said).

A parts guy at Coyote told me that there was NO need to change jet, only adjust float level. Seemed weird to me.
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Re: High Altitude Jetting

Colorado Stryker
In reply to this post by High Up
I live in Colorado and have had an extremely difficult time trying to get ANY factual information for rejetting the EF2000iS generator as well.  After exchanging a couple of emails with Yamaha technical support, they finally admitted they don't have a "high altitude kit" for the generator even though their owner's manual references that one should be installed for extended use above 5000 feet.  I looked at the Honda generator site a found that they reference 3 different sizes that can be used in their 2000 watt generator based upon elevation.  One for under 5000 feet, one for 5000-8000 feet, and one for 8000 and above.  Unfortunately they didn't state the size of each of these jets.  I talked with every Yamaha sales/service dealer in the Denver area and got conflicting information, including one dealer that said they merely readjust the float.  I understand carburetors and have rebuilt several, that answer didn't make sense to me.  Needless to say, I got extremely frustrated and quickly lost confidence in the dealerships.  I decided to try once again and this time I asked to speak with the service person that does the jet replacement.  Some dealerships would let me talk with that person, some wouldn't.  Armed with what I knew about carburetors, I quizzed them to see if they actually knew what affects carburetor performance and how they work.  Eureka!  I found a very knowledgable person at Colorado Powersports and that's where I took my machines to have the swap done.  Even though I could have done the rejetting, I just don't have the time and was more than willing to pay them.  Here are the specifics regarding the jets put into my two EF2000iSV2 generators.  Only the main jets were replaced, the pilot jets were left alone.  My machines are not the California models, so they came with the standard size non-California jets used for 5000 feet and below.  These are size number 86.3.  I use my generators primarily at 8000 feet and above and had them jetted for use at that altitude.  The jets installed are size number 62.5.  I asked them what jets they would recommend if my use was primarily in the 5000-8000 elevation range.  They said that they would still have installed the 62.5 size jets as the difference in that lower elevation range wasn't significant enough to warrant a slightly larger jet.  There are a lot of factors that have to be considered when considering the optimal jetting size - altitude, temperature, humidity, barometric pressure, carburetor bore size.  So, selection of jet size is a compromise as all of those variables (except bore size) can change from day-to-day.  I'm happy with the result and feel that the rejetting was done correctly.  
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Re: High Altitude Jetting

CycleRob
In reply to this post by LeftyS7
LeftyS7 asked: Where did you get this information from?

https://www.shopyamaha.com/parts-catalog/lines/generators

Navigate to the model and then the carb listing.
Talent, On Loan, From God  --Rush Limbaugh--
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Re: High Altitude Jetting

LeftyS7
Thanks, but that only shows the stock size as 67.5. It shows no options.