Chinese generators

Scrubcadet10

Scrubcadet10

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Staff member
It's been a bad year for the off brand (Non Generac,Briggs, Honda etc) generators. or at least for me it has.
I've had several come in with issues and i finally have to throw in the towel, and more than a few are surging issues that i can't pin down.
I've got a DuroMax i'm working on now, my fresh gasoline, new fuel line, new carb from duromax, all new intake gaskets, surges for about 4 seconds on initial cold start, then goes away, begins to surge once i put about 3000 watts on it. unit idles down good. (10,500w rated). surge Goes away with choke, so i slightly oversized the main jet... i'm talking slightly... and it went too rich. had to swap the main jet from a junk duromax i have, same carburetor.
carb spray around the intake doesn't change anything so i know im sealed up good. Fuel flow stays consistent.
had a similar story with a champion several months back.
I've hooked my spark tester up and that stays consistent blue spark.

But i've not had a single issue repairing any Storm Responders or older powermates etc.... weird.
 
Restriction in idle circuit likely. Currently it is an unknown model so looking it up is hard. I know in some Nikki and clone they put in a too small of idle mixture jet even though they have an adjustable idle mixture.
 
Hi Scubcadet10,

This problem happens especially with clone generators because these companies mass produce them, but they are not test ran for quality assurance. Any problems later are simply pushed off to a warranty repair company, or the buyer just lives with the problem.

The air bypass jet is undersized or leaking past the O-ring, and the carburetor cannot balance the ideal air/ fuel ratio.

James Condon (Mr. generator) on You Tube has lots of details about this problem and how to correct it by using really fine pin drills to size up the air bypass jet orifice gradually until the engine runs correctly under load. Also, the tiny O-ring on the idle air jet is known to go bad or crack which will contribute to this problem.

Aftermarket clone carburetors often claim that they will "fit" but that does not mean they will work correctly in all altitudes. Even new generator units are subject to have these problems.

We are in an age where production in mass for profits far outweigh quality.
 
Hmmm, didn’t really consider the idle side on this DuroMax since it idles fine. But definitely something I will try.
It’s frustrating because every Briggs or Honda that comes in I can get running like a top in no time but these off brand suckers give me trouble
 
StarTech said:
Restriction in idle circuit likely. Currently it is an unknown model so looking it up is hard. I know in some Nikki and clone they put in a too small of idle mixture jet even though they have an adjustable idle mixture.
Click to expand...
It’s their 13000EH (gasoline only) model 20Horsepower.
That’s the only identification on it other than the epa sticker
 
Scrubcadet10 said:
Hmmm, didn’t really consider the idle side on this DuroMax since it idles fine. But definitely something I will try.
It’s frustrating because every Briggs or Honda that comes in I can get running like a top in no time but these off brand suckers give me trouble
Click to expand...
Hi Scrubcadet10,

It is often called an "idle air bleed" but it is literally the carburetor air bleed orifice that works the entire time at all engine speeds. I guess people associate it with the idle because it is held in place using the side of the idle stop screw adjustment.

Study the carburetor machining carefully and you will notice there is a small air inlet hole placed at a right angle to the removeable air bleed orifice. That orifice is what allows atmospheric air to enter the fuel bowl as the engine consumes the fuel out of the bowl.

When the air orifice is restricted by being undersized or dirty, the engine tries to "gulp the air/fuel mixture" as the load demand is increased. This is when "surging" occurs and it can also be contributed to a wrong governor tension "sensitivity" setting. The carburetor and the governor spring tension both play and important part in finding the right engine load "balance".

The actual low idle circuit has fine holes drilled into side of the throttle plate bore just past the throttle blade on the engine side. Being that it is a generator the low idle circuit is hardly ever utilized, but these carburetors are made for various applications and not just generators that run at 3600 RPM (with no load).

As I mentioned before, watch some of James Condon's videos. He goes to great lengths to correct engine surging problems on many models of generators.

As for generator brands and designs, practically anything portable are produced as Honda "clones" these days. They are just different colors with pretty stickers and maybe a different control panel configuration. If they all were painted one color and had a simple sticker that says "generator" no one would likely buy them.
 
Took the carb off this DuroMax today, stripped it down, soaked it, blew it out and cleaned it with a capital K, KLEAN… actually seems to be doing better.
Put it up to 1/3 capacity which is about all I can do right now wattage wise with what I have… if I have it on auto idle, load hits, the governor pulls back, speeds up to speed, it’ll bounce about 3 to 4 times then maintain speed under load fine……
 
Hi Scrubcadet10,

It sounds you are getting close to what will make this thing run happy and behave.

I have a few space heaters and a portable room AC unit for my shop that I use for testing when needed to pull at least 10,000 watts.

Most portable generators I ever see are in the 8K range or less.
 
Hi Scrubcadet10,

I failed to ask earlier if this is a dual throat carburetor or a single throat. A picture of the carburetor would help.
 
Auto Doc's said:
Hi Scrubcadet10,

I failed to ask earlier if this is a dual throat carburetor or a single throat. A picture of the carburetor would help.
Click to expand...
Single.
I’m not at the shop right now but if you want to look it up on DuroMax it’s a DMXP 13X part number
 
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