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Bloody Thing Wont Start

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Ducked
Two Stroke Sniffer



Joined: 07 Jun 2024
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PostPosted: 06:05 - 04 Feb 2025    Post subject: Bloody Thing Wont Start Reply with quote

SYM Wolf as before

Its got what appears to be an OK spark

I think the valve timing and clearances are set approx OK

(I used a ballon to confirm compression stroke, in case I was somehow on't exhaust)

My compression tester may be knackered, having been flooded last typhoon, and I dont have a screw in adapter that fits so am restricted to the conical push-on, not good when kicking it, but it has generated quite high numbers a couple of times, it makes popping noises and displaces my thumb off the plug hole OK, so I THINK its got compression

Kicking it over with the air filter and carb throttle slider removed, the carb top blocked and a paper towel over the air intake it floods fuel into the cylinder, so AFAICT it is at least capable of fuelling

Out of ideas,, apart from trying fresh fuel , though that stuff has been in a sealed can so should be OK

Suggestions?
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Ducked
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Joined: 07 Jun 2024
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PostPosted: 09:51 - 04 Feb 2025    Post subject: Reply with quote

Started on fresh fuel, and would more or less idle. Wouldn't rev, but thats still progress.

Apart from the fuel possibly being a bit stale, I've been using tubing from scrap dialysis sets for my improvised testing fuel supply, and sometimes returning unused fuel to the can rather than leaving it in the carb.

I suppose its possible that this contaminated the fuel, though I havn't seen any visible sign of it.

These tubes eventually brown and harden with petrol exposure, but then so did the tube that came with the fuel can.
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slowasyoulike
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Joined: 17 May 2021
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PostPosted: 10:01 - 04 Feb 2025    Post subject: Reply with quote

How long was the fuel in that can? It was something that never really happened back in the day IME, but these days I've had regular Unleaded go rank in as little as three months.
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doggone
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Joined: 20 May 2004
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PostPosted: 10:57 - 04 Feb 2025    Post subject: Reply with quote

A sealed can will still have air bleed hole so it can expand and contract, it helps to keep can nearly full but E10 unleaded will be going off after 6 months E5 is a bit better but a year at most.
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Ducked
Two Stroke Sniffer



Joined: 07 Jun 2024
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PostPosted: 15:49 - 04 Feb 2025    Post subject: Reply with quote

Cant see any breather hole, or smell one, and its got pretty well sealed steel caps, deeply threaded with O rings. I suppose the fuel might have been in there for 6 -8 months though, so maybe not that surprising
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Ducked
Two Stroke Sniffer



Joined: 07 Jun 2024
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PostPosted: 14:04 - 05 Feb 2025    Post subject: Reply with quote

Put the air cleaner and anti-pollution plumbing back on it with the intention of trying to get it to run, put fuel in it, and it flooded the cylinder.

Took the carb off and flushed it, checked the valve was holding petrol inverted, and passing it when the floats were lifted, put it back on, and it did it again.

Was OK yesterday, but now the carb is once again pissing petrol.

Think I'm almost finished fiddling with it, and I dunno that I feel like buying another carb, so thats likely to be the end of the line.
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Ducked
Two Stroke Sniffer



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PostPosted: 04:18 - 07 Feb 2025    Post subject: Reply with quote

flushed with petrol - flooded again

cleaned rubber tip of fuel shut off valve and valve seat with cotton bud - flooded again

Repeated with carb cleaner - now very slow leak and started

Hooked up air cleaner and anti-pollution plumbing -started and would now more or less rev though hesitant

So progress, but flaky and quite likely to regress. I think part of the problem is quite rapid accumulation of deposits from petrol residues drying out.

Next move would be to refit petrol tank, but its got a very flaky vacuum controlled tap and so far I havnt been able to find a manual one locally, though I might be able to import one
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slowasyoulike
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Joined: 17 May 2021
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PostPosted: 11:08 - 07 Feb 2025    Post subject: Reply with quote

Ducked wrote:
...anti-pollution plumbing


I used to have a US import Honda Helix that had a load of spaghetti attached to the carb that was supposed to catch fuel vapour or something... I guess it must have been from California? It didn't run at all well until I removed and binned it all. Might be worth trying it again with the air filter on and the anti-pollution guff disconnected?
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Ducked
Two Stroke Sniffer



Joined: 07 Jun 2024
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PostPosted: 12:17 - 07 Feb 2025    Post subject: Reply with quote

Yeh, did that with my last car, a 1986 Daihatsu Skywing. Tried to understand it and it gave me a headache, plus my choke stopped working, so I took it all off and never thought about it again.

This isn't so complicated though, and I'll have to get reasonably consistent fuelling before I can really address anything else. Today it wouldn't hold fuel again, so its consistently inconsistent.

I spent a long time adjusting the float level earlier, and have polished the valve seat with toothpaste and cotton buds. It looks ok, but it just wont work reliably, and, short of buying another carb, I'm about out of things to try.
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A100man
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Joined: 19 Aug 2013
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PostPosted: 14:56 - 07 Feb 2025    Post subject: Reply with quote

Ducked wrote:
Yeh, did that with my last car, a 1986 Daihatsu Skywing. Tried to understand it and it gave me a headache, plus my choke stopped working, so I took it all off and never thought about it again.

This isn't so complicated though, and I'll have to get reasonably consistent fuelling before I can really address anything else. Today it wouldn't hold fuel again, so its consistently inconsistent.

I spent a long time adjusting the float level earlier, and have polished the valve seat with toothpaste and cotton buds. It looks ok, but it just wont work reliably, and, short of buying another carb, I'm about out of things to try.


Buy another float needle and fit an in-line filter to minimise crud ingress. Longterm give the tank and damn good claen out - many methods to do this from shaking with gravel to mollasses.
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Ducked
Two Stroke Sniffer



Joined: 07 Jun 2024
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PostPosted: 05:20 - 08 Feb 2025    Post subject: Reply with quote

Thanks. I dunno if a float needle is available separately. Probably wont be locally (in Taiwan) but maybe on't internyet.

I did have one from a scrapped Kymco Zing, which might be compatible, but seem to have lost it.

The rubberised needle tip looks ok under magnification

The tank didn't seem to be dirty. I got a new (oversized) fuel filter for it anyway, but Im not yet using the tank, but a test lashup with scrap dialysis tubing.

This has a plastic mesh inline filter in it, as it happens, but I suppose it might be worth adding another one, and/or using a coffee filter in the funnel when refilling, for belt n braces.

Found the kymco Zing needle (I'd wrapped it carefully in foil which I didnt recognise). Looked OK under magnification, but a bit greyer and less shiny than the other one. perhaps suggesting some surface corrosion.

Bench tested, the weight of the floats (i.e. with the carb inverted) on the valve holds fuel, but the right way up with the float bowl filling it leaks.

I could try cleaning it up a bit more (I just rubbed it gentky with foil for this test) and bending the float tang to apply more pressure, but I'm not optimistic.
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