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Albert Smith

2 Stroke Generator problem

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I was recently given a 750 watt 2 stroke generator that apparently had refused to run from new. It was bought new in 2005, filled with fuel (50/1), failed to fire and then stored ever since.

 

The first thing I did was to take the fuel tank off and clean it out, then refil it with fresh fuel. Set the choke, turned on the fuel........ but the thing would not start.

 

Next, I checked the spark on the plug, a good strong spark.

 

Off with the tank again to get at the Carburettor, I carefully removed the spring and rod that controls the throttle, this was moving ok, Then I went to remove the carburettor which is held on with 2 long bolts. They were both loose, I removed the bolts allowing the carburettor to come. There was only half a gasket between the carb and the manifold.

 

I made up a new gasket, refitted it and put everything back together. I pulled the starter cord and it fired into life without hesitation. An electric drill was plugged in and it worked fine.

 

Now the problem I have is that it doesn't run smoothly..... how do I describe how it goes :blink: ok, here goes......

 

brmmmmmmmmm pop, brmmmmmmmmmm pop, brmmmmmmmmm pop

 

and if you didnt hear it the first time.......... :lol: :lol: :lol:

 

brmmmmmmmmm pop, brmmmmmmmmmm pop, brmmmmmmmmm pop

 

and no, I'm not doing it again.

 

The resonance remains constant but I'm sure it should run at the same speed, rather than the undulating way it does at present.

 

My mechanical knowledge of petrol power is around 1 out of 10, diesels I understand :).

 

What I would like to know is if there is some sort of timing system that would allow the engine to run smoothly, or is this the way all 2 stroke engines run?

 

Thank you chaps (and chapesses),

 

Albert.

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I was recently given a 750 watt 2 stroke generator that apparently had refused to run from new. It was bought new in 2005, filled with fuel (50/1), failed to fire and then stored ever since.

 

The first thing I did was to take the fuel tank off and clean it out, then refil it with fresh fuel. Set the choke, turned on the fuel........ but the thing would not start.

 

Next, I checked the spark on the plug, a good strong spark.

 

Off with the tank again to get at the Carburettor, I carefully removed the spring and rod that controls the throttle, this was moving ok, Then I went to remove the carburettor which is held on with 2 long bolts. They were both loose, I removed the bolts allowing the carburettor to come. There was only half a gasket between the carb and the manifold.

 

I made up a new gasket, refitted it and put everything back together. I pulled the starter cord and it fired into life without hesitation. An electric drill was plugged in and it worked fine.

 

Now the problem I have is that it doesn't run smoothly..... how do I describe how it goes :blink: ok, here goes......

 

brmmmmmmmmm pop, brmmmmmmmmmm pop, brmmmmmmmmm pop

 

and if you didnt hear it the first time.......... :lol: :lol: :lol:

 

brmmmmmmmmm pop, brmmmmmmmmmm pop, brmmmmmmmmm pop

 

and no, I'm not doing it again.

 

The resonance remains constant but I'm sure it should run at the same speed, rather than the undulating way it does at present.

 

My mechanical knowledge of petrol power is around 1 out of 10, diesels I understand :).

 

What I would like to know is if there is some sort of timing system that would allow the engine to run smoothly, or is this the way all 2 stroke engines run?

 

Thank you chaps (and chapesses),

 

Albert.

 

 

Hello Albert,

 

2 stroke engines often give problems if they've been stored without having first emptied their carburettors, the petrol evaporates and the oil stays but will not look like oil anymore. This could block one or more of the fuel passages in the carburettor and create maybe the sort of problem you've got.

 

Give it a try by soking the carburettor in a special solvent, and give it a go with compressed air to clear all the jets and fuel passages.

 

Hope for you that it's going to work properly again after a little fight.

 

Peter.

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<snip>

 

brmmmmmmmmm pop, brmmmmmmmmmm pop, brmmmmmmmmm pop

 

<snip>

 

My mechanical knowledge of petrol power is around 1 out of 10, diesels I understand :).

 

<snip>

 

Albert.

 

Mine is about the same, however - it could be a dirty carburettor, or it could be a sticky governor. Some careful taking apart and cleaning of the control mechanisms may help

 

Richard

 

Good description

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Mine is about the same, however - it could be a dirty carburettor, or it could be a sticky governor. Some careful taking apart and cleaning of the control mechanisms may help

 

Richard

 

Good description

 

I agree with Peter and Richard, my 4-stroke gennie does the same thing, when the main jet is slightly blocked.

 

I've also had the float valve block up too, meaning it'll run for a while from cold, then stop mysteriously and refuse to run unless you turn it off for 30mins or so... :)

 

The jets, at least on mine, are absolutely tiny and require finding something *really* small if you want to poke them out, carefully.

 

I got so fed up with it happening, I've got a spare carb lying around now, which can get swapped on at short notice. (And that's a genuine Honda engine including fuel system, I've never found where the crud is coming from!)

 

PC

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My 2 stroke gennie does exactly the same. Cheap Chinese unit but bomb proof. 8 years old, generally hammered. Apart from changing the plug every other problem has been poor fuel or wrong fuel mix.

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I was recently given a 750 watt 2 stroke generator that apparently had refused to run from new. It was bought new in 2005, filled with fuel (50/1), failed to fire and then stored ever since.

 

The first thing I did was to take the fuel tank off and clean it out, then refil it with fresh fuel. Set the choke, turned on the fuel........ but the thing would not start.

 

Next, I checked the spark on the plug, a good strong spark.

 

Off with the tank again to get at the Carburettor, I carefully removed the spring and rod that controls the throttle, this was moving ok, Then I went to remove the carburettor which is held on with 2 long bolts. They were both loose, I removed the bolts allowing the carburettor to come. There was only half a gasket between the carb and the manifold.

 

I made up a new gasket, refitted it and put everything back together. I pulled the starter cord and it fired into life without hesitation. An electric drill was plugged in and it worked fine.

 

Now the problem I have is that it doesn't run smoothly..... how do I describe how it goes :blink: ok, here goes......

 

brmmmmmmmmm pop, brmmmmmmmmmm pop, brmmmmmmmmm pop

 

and if you didnt hear it the first time.......... :lol: :lol: :lol:

 

brmmmmmmmmm pop, brmmmmmmmmmm pop, brmmmmmmmmm pop

 

and no, I'm not doing it again.

 

The resonance remains constant but I'm sure it should run at the same speed, rather than the undulating way it does at present.

 

My mechanical knowledge of petrol power is around 1 out of 10, diesels I understand :).

 

What I would like to know is if there is some sort of timing system that would allow the engine to run smoothly, or is this the way all 2 stroke engines run?

 

Thank you chaps (and chapesses),

 

Albert.

Do`s it misfire or whatever when it`s on load ie, with drill plugged in & running?, some constant speed 2 strokes are set to run rich with out load, so that they don`t lean out when loaded, If it do`s the same loaded it`s probably carb trouble If it `s ok under load it`s probably a sticky governor

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it sounds like you have a chinese copy of the YAMAHA ET500,the yamaha was an 80's design with few faults.

once you are sure that the carb. is clean,make sure that the oil/petrol mix is correct.

too much oil in the mixture will cause the generator to "hunt" when it is off load

clean the jet(s)with acetone(nail varnish remover),or carb. cleaner

dont let the cleaning solvent come in to contact with any of the plastic or rubber components.

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Try running it with a full load on for a good while. they seem to like that. I have had a couple over the years and they run better when loaded up.

 

Also you can get a 2 stroke bomb from the likes of Skil. The oil in these seems a much better product. It's to blend with 5l of petrol. My strummer runs better in it.

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you have missed out,catweasel,they have a smell that is reminiscient of a LAMBRETTA or VESPA.

I had a CZ 250 mate, now that is a smell !! :) I have a seagull outboard too :)

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Are you using the correct 2 stroke oil? There were before synthetic oils two types of 2 stroke oil, one used in air cooled engines and the other type used in water cooled engines. The need for the different types was due to the operating temperature of the engines. I would think the same must apply with synthetic oils, but I honestly don't know.

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Try 2mm BTDC all my yamaha m/c's were either 2 or 1.8. However I remember the 250 was a bugger as if you got it slightly out you burnt a hole in the top of the piston. You also needed a special gauge not the pencil and fag paper which used on my old triumphs

 

Bob b

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Most of the small 2-strokes I have used require critical adjustment to the carburettor.

Typically they have two adjustable jets - high and low.

 

Having ensured that all fuel/airways are clear and the fuel is good, as above:

At full throttle with no load the engine should be just 'four-stroking'

- ie. rich, burble, burble; if it is too lean rpm will increase beyond the normal.

Quickly opening the throttle from idle the engine will die if the low setting is too lean.

 

The 'low' and 'high' jets must be adjusted alternately until both conditions are met.

 

'brmmmmmmmmm pop' sounds like the engine is running too lean.

 

Alan

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I can give you one tip ..if you overload it and it stops working then you have blown the diode INSIDE THE ROTOR ..you need to pull it all ...the gen bit is on a morse taper to the engine ...no front bearing very long bolt down the centre of the shaft ...and the diode is visible in the middle of the rotor .....Mapling 1n54 I think it was or fit two in parallel.

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Whilst running under load, spray carb cleaner into it, it will smoke like the plague, but should clear any dross. As others have said, these things run better with a heavy load on. light/no load seems to make many of them kinda 'pop' even old villiers types !!!

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Whilst running under load, spray carb cleaner into it, it will smoke like the plague, but should clear any dross.

 

<snip>

 

Go on then, how does that clean out the fuel passages in the carb?

 

Richard

Edited by RLWP

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Go on then, how does that clean out the fuel passages in the carb?

 

Richard

 

On the assumption its already been cleaned, carb cleaner will lossen any crud on the inlet side, and also exhaust port. As carb has itself been cleaned, it is a pain free way of making sure the rest of the system is clean. Though it ought to be spotless if the unit has never run.

 

Someone in the workshop here did also suggest changing the plug in case of partial failure, apparently its common, don't see it myself though.

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you have missed out,catweasel,they have a smell that is reminiscient of a LAMBRETTA or VESPA.

 

Yes I've got a 1kw one that I keep as a spare but I like to run it because it sounds and smells exactly like the Lambretta J125 I had in the sixties. I suspect that the one being discussed here is from the same family as mine (Powercraft/Omega/Wolf), which has a little fuel shut-off tap so that the carb can be run dry after use, which helps keep it clean.

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Thanks everyone for this wealth of information, my apologies for not responding to the individuals giving specific advice. Unfortunately Mrs Smith was taken into hospital and is undergoing major surgery as we speak, she went in at 0730 this morning and is still in theatre (1715), I await news. My son is with her and there's not much I can do at the hospital.

 

Nonetheless I will divert my attention to the troublesome genny and work through what advice has been given. Under load it does seem to run better and there is no 'popping' every 3 or 4 seconds, this possibly points to a dirty carb, old fuel in the carb or both so thats where I will start. Thanks again for the advice.

 

Albert.

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