Hi, I have just reconditioned and cleaned my carby, decompression valve and cleaned out the fuel tank on my Victa Mustang Series70, 2 Stroke, Mark 4 lawnmower and it started first go however it stopped after about 30 mins and would not start again. Can anyone out there provide me any advice on what I can do next to get my Victa Mustang to start and run more reliably? Also when I replaced the diaphragm in the carby it only had a small circlip washer holding the diaphragm to the end of the poppet valve (see photo) whereas the videos I have watched show that there should be a larger metallic diaphragm retaining plate! Would it be advisable for me to replace the small circlip with the larger metallic diaphragm retaining plate to provide better support to the rubber diaphragm? Any advice or help would be greatly appreciated. Lecky23
Hi Lecky, Small clip is fine, it is only to hold the poppet. Silly question, didn't straight fuel it did you? It does happen. Checked the spark plug? Put in another one just to check. Also check for spark. . If all check out then start looking at fuel and that often is a problem with the float needle and I hate them with a passion
Hi NormK, Thank you for your reply. I put 2 stroke fuel mixture into the fuel tank and not straight fuel so I can discount that theory. The fuel had been sitting in the can for a couple of weeks whilst I waited for parts to be delivered and installed, however I did shake the fuel can to mix the fuel up. The spark plug was new and I ensured that it was sparking before I actually started the mower after the reconditioning. The mower started first go and ran for 30 minutes before it stopped. I will test the spark again. With the mower suddenly stopping and failing to be restarted have anything to do with the cutout Stop/Start wiring as I put on a brand new rubber boot and plug as part of the carby rebuild! The poppet valve that is in my carby had a round flat disc on one end but the poppet valves I have seen in videos show that they have a little prong on the base (see photo) that is used to change the way the poppet valve is secured so that it can be rotated to increase or decrease the revving of the motor. Is this correct? If so should I change my poppet valve to the one shown in the photo?
Hi Lecky, Yes disconnect the wire through the side of the kill switch, they are a problematic design, I find they are near impossible to get to work with the aftermarket parts. I don't use the poppets without prong on them so I don't know how well they work
Hi NormK, If I disconnect the wire through the side of the kill switch, this would disable the Stop mechanism so how do I shut off the lawnmower’s motor? If I turn off the fuel tap and turn the throttle to Stop, will that stop the motor? In regards to the poppet valve, my cap on the diaphragm end of the carby has a plastic round dial that can be turned to Slow, Idle and Fast so does this dial in fact control the revving of the engine? (See photo) If I replace my poppet valve to the one with a prong, will that still work with the dial on my cap on my carby? Sorry to keep bothering you but I seriously want to get my lawnmower working for sentimental reasons and not throw it away.
Hi NormK, I followed your advice and found that the kill switch was the problem preventing my Victa from starting. I found that the rubber plug that goes into the side of the carby through the rubber boot was jamming inside when the cam was moved with the throttle cable. As you said the the kill switch mechanism has been poorly designed and problematic so I decided to by-pass the kill switch mechanism by connecting a Narva micro push button switch connected to the two wires that normally go into the side of the carby. After installation, my Victa started first go and has started without any problems since. Fingers crossed 🤞it will continue to start with every mow to come! Bye bye the poorly designed old kill switch mechanism.🤬 Thank you again for your advice.
Hi Lecky, Good to hear you have fixed it. Yes I have always said that the kill switch idea was drempt up over a very long lunch at the pub. Over the years it must have sent thousands of Victas to an early grave
I think a lot of people have a problem with the kill switch because they turn the mower off and leave the throttle control in the off position.
Pushing the throttle control to full speed while the mower is off can help ensure that the kill switch wires do not become distorted or touch each other. This practice helps to keep the throttle poppet fully open and can prevent the wires associated with the kill switch from being bent or damaging the rubber grommet. .
Leaving the throttle in the off position also compresses the poppet spring and after time that spring stays compressed and you loose high rpm unless you stretch the spring again.
