4 Stroke Generator help

[DCM]

Right, I am at me witt's end with this generator. It keeps running hot, has popped a couple of spark plugs and, right now, won't run off the choke. As soon as you try letting off the choke, the engine leans out and dies.

I have checked fuel flow to the carb, and that don't seem to be a problem. I have popped the carb off and I can't see any blockage in the valve etc, but it is getting starved of fuel, I don't think I got an air leak either.

OK, it is a Chinese generator, so not the best of quality, but really could do with some 'helpful' suggestions??

[mark christopher]

dont supose it has a mixture screw?
does it run of with the fuel cap off?
what model is it?
is it fresh fuel?
is the inlet manifild tight/cracked, no air leaks?

[DCM]

Generic generator with a Honda copy carb.
Mixture screw, yes, tried it in all position, unless there is a blockage between the float bowl and mixture screw (after the throttle butterfly?)
Fuel is fresh.
Not seen a crack.

[cjm_2008]

overheating = mixture too lean.

does it have an inline fuel filter steve? have you had all the jets out of the carb & given them a blast with carb cleaner?

sounds to me like gunk in a jet somewhere.

[badger5]

It does sound like it's running lean, any chance of an air leak between the carb and the engine?

[luniemiester]

If its a copy of a Honda then under the carb is a round cover. Undo the cover and remove and inside you will see the jet (you have to look upwards from underneath). Check it's not blocked by undoing and removing. Clean it all out and reassemble.

The screw on the carb doesn't really adjust the mixture to much its an idle air screw which doesn't do anything above 1200 rpm or so

Also try putting in a plug from Hondas recommended range (a colder one if you can get it)

Out if interest are you running the full foam/paper air filter?

[DCM]

I resealed the carb to engine today, still the same. I will pull carb off again and have another look at fuel channels.

I get good flow from the tank to the carb, so fuel filters fine.

[DCM]

Foam filter.

Had the main jet out, couldn't see a blockage there.

There was a NGK BPR5ES in there, put in a 6ES (hotter), do I need to go to a 4ES?

[luniemiester]

Pretty sure the higher numbers are colder plugs in Ngk but might be wrong

What size was the main jet

Have you checked the valve gaps are ok (engine doesn't try and pull the starter rope out your hand when trying to start)

If you can get it running with the choke on try spraying gt85 or similar around the carb area. If the revs suddenly go up it will point to a leak somewhere drawing in air

Also check the black rubber breather hole from valve cover to carb isn't blocked or leaking air

Does it actually burn the tip of plug away

[DCM]

I may have gone the wrong way with the spark plug, should of gone to a 4 not a 6.

Don't think there was any size markings on the main jet.

[luniemiester]

According to Ngk chart below higher number is colder so I think a 6 is right

http://www.ngksparkplugs.com/docs/te...bols_plugs.pdf

Did you try mark Christopher's suggestion about the fuel cap.....

[DCM]

First thing I tried, loosening the fuel cap.

[DCM]

Re-reading the NGK pamphlet, the lower the number the hotter the application, so I have gone the wrong way, should of gone from 5 to 4 not 6, BPR4ES is stock on a honda engined lawnmower....

Still, won't stop it running lean?

[mark christopher]

Originally Posted by DCM

Right, I am at me witt's end with this generator. It keeps running hot, has popped a couple of spark plugs and, right now, won't run off the choke. As soon as you try letting off the choke, the engine leans out and dies.

I have checked fuel flow to the carb, and that don't seem to be a problem. I have popped the carb off and I can't see any blockage in the valve etc, but it is getting starved of fuel, I don't think I got an air leak either.

OK, it is a Chinese generator, so not the best of quality, but really could do with some 'helpful' suggestions??

Sounds like you have a fuel restriction, or an induction air leak, has it been stood with fuel in? Kipor recommend a drain down if stood as the fuel can gum the carb
I allways use brake cleaner to test round manifolds as it evaporates and leaves no mess
Plugs have to be pretty knackered and would norm missfire than run hot.

[DCM]

Not stood for long periods, week, maybe two but then run all day too.

If I spray and got an air leak, will it bubble or draw in the brake cleaner/change engine sound?

If there is varnishing in the carb, remedial action?

[luniemiester]

Ngk plug info for you! With karts we always run a number 10 in dry and then a hotter plug for the wet which is a 9

http://www.ngksparkplugs.com/tech_su...k_plugs/p2.asp

The varnishing is from the blowbuy from the rocker cover so is normal

Have you checked the oil level or changed the oil?

When you spray stuff around the carb the revs should increase if you do have an air leak - this will highlight the area to look next

[mark christopher]

as above if a leak it will alter engine note
a good carb cleaner will remove gum.

[DCM]

Right, tried spraying brake cleaner over the carb, no engine note change, so it must be internal.

[spud31]

Base gasket leak where barrel meats case