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Post by stoo on May 21, 2020 2:45:11 GMT -6
Ordered a new reed valve. Cant do any harm, especially as teh bike's been sitting for a while. Hopefully that'll sort it. Updates to follow. :  |
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Post by stoo on May 20, 2020 14:19:40 GMT -6
Petrol in float chamber. Tried it today with an external auxiliary fuel tank and no joy. Carb just ovrflowed. Still no bang! The 2 stroke oil and the petrol aren't premixed but the oil seems to be added direct to the crankcase by means of a pump which appears to be activated by a wormwheel off the crank and a vacuum pipe from the inlet manifold..... All the jets are clear. The manifold is tight. Now tending toward the reed valve assembly. will investigate further.
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Post by stoo on May 19, 2020 14:35:48 GMT -6
It's this vacuum issue that's puzzling me know. I'm wondering whether the 2T ol pump which is connected to the carb by a tube could be at fault or whether there is an issue in the reed valve block. Although when I checked it the other day, it all looked fine... I've blown out all the fuel lines so that doesn't seem to be a problem..... Put new O-rings in the inlet manifold faces. As i said new vacuum petcock. Again compression seems good but I can't measure it by meter as there isn't enough space to use it. Like you say, ellpee, it's not likely to be electrical now but I'm absolutely stumped as to why it won't suck in any fuel. Ah well, tomorrow is another day....
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Post by stoo on May 19, 2020 7:38:00 GMT -6
Progress! But not yet Success...
Faulty safety cutout on brake lever repaired so now, Starter button working. Headlamp and tail light working when engine cranks over. But still not the slightest whiff of a bang in the combustion chamber. I've installed a new vacuum petcock already. So the two things that I think it could be are 1. dodgy CDI unit? Got one coming from a piaggio that is supposed to improve performance anyway or 2: some vacuum-related issue that isn't pulling fuel into the carb -> cylinder. Will investigate further. Hopefully getting closer. Should run for another fifty years with the amount of new parts that I'm buying !! $$$$$
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Post by stoo on May 19, 2020 3:33:41 GMT -6
Thanks ellpee, I've stripped the carb and cleaned it to within an inch of it's life. Still no joy. I've put a new starter relay in - no joy. Tested the autochoke on the bench, which is working fine. I've got a new cdi unit and regulator on the way. Diagnostics are difficult as I can't get a wiring diagram for it anywhere and the diagrams offered as alternatives seem to vary quite a bit and only add to the confusion. Weather permitting, I'll get out and have a look at the brake/stand cut-out switch possibilities. This was my next port of call. Having old '50s brit bikes, we rarely have keys, never mind any kind of safety features - apart from brakes(which more often than not don't brake!) 4 of my bikes don't even have brake lamps. Anyway will poke the multimeter around, look for shorts etc. The annoying thing is that the guy I bought it from mananged to get the starter switch going by jiggling the battery terminals! After transporting it - nada! Keep the faith : Stewart |
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Post by stoo on May 14, 2020 15:57:15 GMT -6
Hi all, just taken delivery of a '97 SGX50 in reasonable condition. BUT it's a non-runner :-( Gets a good spark and has good compression. Only 4000 miles on the clock. My suspicions are taht it's something to do with the auto choke? I've got a load of old brit bikes from the 50s n 60s where everything is manual and easily fixed. These sealed units befuddle me as they're so tough to diagnose. As I say the engine turns over fine, shows a good steady spark but will not draw fuel into the combustion chamber. Checked the reed valves - all seems fine. Replaced the vacuum petcock - no improvement. After turning over the plug is still dry.... One other thing is that the engine won't turn over on the start button. I have to run power direct from the battery to the starter relay. Can't find a wiring diagram anywhere. The alternative diagrams seem to miss a few components. I've tried getting the auto choke to activate by connecting power across the two wires - nada. The little needle does push in and sring out by finger pressure. I have poured fuel down the plug hole and it still won't start. Tried filling the float chamber and it won't fire. Poured fuel down the manifold and it won't fire. So....... does the auto choke cut out the fuel supply? Is there a fuel vacuum issue? Does the fact that the starter switch doesnt work have some bearing? Could someone perhaps give a basic description of how this fuel system works ? Any and all help very gratefully received :
Cheers,
Stoo |
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Post by stoo on May 14, 2020 15:41:00 GMT -6
Hi all, great site. Just got my hands on a '97 Honda sky SGX50 non-runner. I'm more used to old British bikes of the 50s n 60s so this wee thing seems massively overengineered for what it is. I've also still got my own Yamaha Fs1-E from when I was a teenager - and that wasn't yesterday. Kept it for 40 years in boxes under beds and on top of wardrobes through many house moves. Still love it. Half restored at the moment. Anyway,,, the SGX has an issue with fuel delivery but I'll address that in the relevant section
Cheers for now and stay safe,
Stoo
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