OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions on Other Engines Scorpion 6.5hp generator

Hi, I am trying to get running a Scorpion HM-169 6.5hp generator. Things i have had to do so far is changed spark plug cleaned carby and new airfilter. Problem is it will only run for up to 20 seconds then cut out. Have double checked carby and fuel hose/tank, I am getting a constant supply of fuel. Spark is also good. The only time it will run properly is if the throttle screw is screwed all the way in (photo 1) but then it actually pumps out to much power, it will hit 300 volts (photo 2). Photos not showing what i explained as i have readjusted them.Everything looks right, just cant put my finger on the problem. No doubt it is right under my nose. Any help or advice appriciated. Paul.

Hi Paul. Let's start with clear identification of what we are working on. Because it is alleged to be 6.5 hp, I'm guessing the engine will be a chonda version of either the GX160 or the GX200, but we need some pictures, especially of the carburetor and rocker cover, plus various bits of cylinder and crankcase that we might be able to recognise. We also need supporting information, such as any numbers cast into or stamped onto the cylinder casting. Then we need some more detail on the exact symptoms. When it starts to falter, does it recover if you partly close the choke? Can we see a picture of the spark plug, so we can see the colour of the side electrode?

Hi Grumpy, there is no exact time it will cut out, sometimes it will run for approx 5 seconds other times i have counted to approx 25 seconds. It doesnt matter if partially close off the choke, I have even tried to gently hold governor open to half throttle, it will cut out.I even tried force feeding some fuel from a babys panadol syringe as soon as it started to cut out, didnt work. Each time it stops I take the spark plug out , its usually a bit black (as in photo ) give it a clean, have tried tweeking mixture screw on side of carby, have had it out to 2&1/4 turns,just to try, same thing, cuts out. It should be set on 1&1/2 turns shouldnt it, correct if wrong please.
The numbers on side casing are XY168FBY *7090718*, incase my photos arent clear enough. The spark plug is a BPR6ES. Let me know if more photos are needed.

OK, it's a chonda with a Ruixing carburetor. I'm not really familiar with the GX200, but that is Honda's 6.5 hp engine, so I'd guess that's what it is copied from. Hopefully someone will confirm this for us. It doesn't look like a GX160, which is only 5.5 hp in any case.

Because the plug is black, indicating rich running, and applying the choke doesn't help, I don't think a carburetor or fuel supply fault is the most likely cause of this problem. I suggest you start off by looking for an ignition fault, and move from there to an internal engine fault if necessary. That means finding a way to check for spark. How long is it after it flames out, before you can restart it? If it restarts immediately, we are going to have to use an in-line spark tester to check the ignition system, but if it takes a minute or more to recover after flame-out, you can quickly remove the spark plug, then do a spark test, immediately after it stops.

Hi Grumpy, Have just had a play with generator and it started 4 times, cut out and started first pull each time. Did check for spark by holding spark plug near to valve cover and pulling over motor, had good spark. I guess what is happening is the spark is dying or going somewhere else, am i on the right track? What exactly is a in-line spark tester and can i make one with shed equipment or will i have to buy one.

Hi Grumpy, Have just had a play with generator and it started 4 times, cut out and started first pull each time. Did check for spark by holding spark plug near to valve cover and pulling over motor, had good spark. I guess what is happening is the spark is dying or going somewhere else, am i on the right track? What exactly is a in-line spark tester and can i make one with shed equipment or will i have to buy one.

Try a bit of aerostart spray when it starts to die and if it keeps running, it's a fuel problem, if it still dies it's a spark problem. Also check your oil level and make sure it is full since the low oil cut out may be kicking in. If it is full, try disconnecting the cut out wire, the float may be stuck in the sump. If it keeps running on the aerostart, check the needle and seat for a possible bit of crud stuck in it. If all else fails check the valve clearances, they should be 2 and 3 thou I think from memory for the Chondas.

You could make an in-line tester that will work well enough for this job Paul, they are very simple. Here is one that will give you the idea:

http://www.ebay.com.au/itm/RyTool-I...arts_Accessories&hash=item2a47e91f54

All you need is a non-conducting body, with a screw in each end, and a hole in the side of the body so you can see the spark between the two screws. One of the screws needs to have its head filed down so the spark plug cap will fit over it, and the other one needs to have a strong clamp that can be connected to the spark plug without falling off when the engine runs. You screw the two screws toward each other until the gap between them in the center of the body is about 0.060". Then start the engine and watch that gap. If the sparks across it stop when the engine stops firing, the fault is in the ignition system.

If that isn't clear, please tell me and I'll get into more detail.

Hi Grumpy and Aussietrev, guess what, it running perfectly. Sorry Grumpy forgot to mention it had a low oil level cut out on it, and that was the problem. Diconected the wire kicked it over let it run for about 1 min, then connected wire back up, cut out straight away. Started again, ran for approx3 mins,i switched it of, started again and let it run for approx 20 mins without any problems. Hooked up a 2000 watt heater and it just kept going. Now i just goto pull it apart fix the problem and put it back together, should be easy for here onwards. If something else crops up will let you now, or if there is something i might of forgotten please let me know. Am still going to build a in-line spark tester, will send photo when its finished.
Thank you heaps Grumpy and Aussietrev, much appriciated.

Well, the spark tester would have told you it was an ignition failure, but not why it was failing. You'd have disconnected the kill wire and found the problem was gone - then you'd have had to trace out the kill wire circuit to find where it was happening.

I think a low oil sensor is an important feature for a medium-sized generator like that: people use those in holiday shacks or camp sites and leave them running until they run out of fuel, then refill the tank without checking anything else.

Unfortunately the oil sensor will probably be one of the chonda bits that is not an exact copy of a Honda part, and it may turn out to be troublesome even after you fix it.

I'll close this thread.