kelabar
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Post by kelabar on May 24, 2020 13:51:30 GMT 10
I have a few of the cheap 2-stroke 600W generators. One of them runs fine and generates power but makes a ringing sound when loaded up. The sound is loudest near the electrical end housing so I had hoped it was the bearing there. No luck. The bearing is fine. This would suggest that one of the engine bearings is worn or something has come loose or moved and is hitting the casing. Has anyone split the crankcase on one of these little gens? Any tips if you have? I am much more familiar with 4 stroke engines. I also have a couple of worn-out ones which are on the 'fix it somewhen' list. Attached a parts diagram and if anyone has a workshop manual could they attach that? Or a link to one that works! TIA. ET950 parts diagram.pdf (387.07 KB)
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Beno
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Post by Beno on May 24, 2020 14:03:48 GMT 10
You may not have a problem, they don’t call 2 strokes ring-dingers for nothing. It could be the pull start mechanism or the governor. good luck with it.
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frostbite
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Post by frostbite on May 24, 2020 15:56:01 GMT 10
I have a few of the cheap 2-stroke I also have a couple of worn-out ones which are on the 'fix it somewhen' list. There's your problem. You should have bought a 4 stroke Honda. Only need one, or maybe two if you get one big one and one little one.
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kelabar
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Post by kelabar on May 24, 2020 16:02:25 GMT 10
Thanks, beno. I hadn't considered the governor. That would explain why it will idle OK but makes a noise under load. Also why it runs at all! The noise is a metallic ringing and sounds like something hitting the casing every rev. I wish I knew how governors worked!
I'm fairly sure it isn't the pull start. I have had the recoil assemblies apart many times and heard just about every noise they make!
Also for any Yamaha dealers out there: is part no. 7CE–E5741–00, the plastic drive pawl for the recoil assembly available?
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kelabar
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Post by kelabar on May 26, 2020 12:47:06 GMT 10
I have got most of it apart. Need my pullers to get a bearing off though. Nothing seems out of place at this stage and everything feels tight. Anyway since I had the muffler apart I took some pics. Most of these generators don't have the separate intake tube on the muffler. They are one piece welded units. As can be seen the inlet holes aren't very big. It doesn't take much carbon and muck to close them up. The generator will get harder and harder to start as this happens. I throw them into the fire to burn out all the sticky oil. This makes the carbon build-up brittle and it can be scraped out with a bit of wire. For one piece units I tap the four corners of the exhaust with a heavy hammer. This loosens the carbon and it can be shaken out. Unfortunately this requires quite a bit of shaking. The two-piece exhausts are much easier! The second pic is the interior. It isn't a very good pic but shows light coming through the muffler outlet. The outlet is a metal tube honeycombed with holes. It isn't much bigger than a pencil. The inside of the muffler is a big open space. There is some steel mesh along the 'back', the outermost surface when mounted, which holds a fibrous mat against the back. I think it is fibreglass but this is a guess. This, I guess, deadens the sound. In the first pic the heatshield which is normally spot-welded on has come off. So I use a couple of big self-tappers in those holes (only one shown) to hold the mesh there. Note that putting the muffler in a fire drastically reduces its strength. The metal softens. This is why the heatshield came off. The metal around the spot-welds tore from vibration. A better way is to put the muffler on one of the butane canister stoves. Make sure the inlet or outlet hole don't point towards the canister as flames come out for a while. It may also drip oil out of the inlet (one piece mufflers) so do it somewhere where an oil stain won't matter. Initially smoke will come out and eventually when it is hot enough the smoke will catch fire. Once it stops burning and smoking the carbon inside is dry and brittle. It does take a while and uses nearly a full canister. Also don't burn the gasket. It can crumble if you do! Degrease it or wipe it down instead. If anyone has one of these and can't get it started I can post some info on how to get it going. It is usually a blocked exhaust or crud in the carb.
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kelabar
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Post by kelabar on Jul 20, 2020 17:17:37 GMT 10
Cool. I think I've had a breakthrough in understanding the damn things. There seems to be three adjustments. 1. A bolt which screws in or out to adjust the limit of the butterfly valve travel/rotation/opening. This seems to set the low idle so the gen keeps going at a certain minimum RPM. 2. A needle/jet which screws in or out to adjust the fuel/air mixture. A standard type design on most carbs I've seen. 3. Another bolt which sets tension, using a spring, on the lever that is connected to the governor inside. This is also connected to the butterfly spindle. There is another jet but this is fixed. It is screwed in and there is no adjustment.
I think what happens is the fixed jet supplies a base load of fuel to the engine. Not enough or just barely enough to keep it running. Then the adjustable jet adds to the fuel being used. This would be very little when the engine is idling. But once the generator loads up and the revs drop in response to this, the governor moves and shifts the spring-tensioned lever. I'm not sure how the governor does this yet. It might be changes in air flow or friction from the drive shaft. When the lever moves, this opens the butterfly a bit, so more air can be sucked into the engine and this also adds more fuel through the adjustable jet. If the engine still isn't running at a high enough RPM the butterfly valve, through the action of the governor, stays open trying to increase the engine RPM. Once the RPM hits the desired range the governor stops acting on the lever (or acts on it less), the butterfly stays open just enough to supply enough fuel/air and the amount of fuel/air stabilises at a rate that keeps the engine going at the desired RPM even though it is under more load.
Any mechanics understand that? Or is it a load of tosh! It could be that the butterfly affects the governor instead. Not sure.
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