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1981 Suzuki: elctronic ignition, turns over but wont start

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1981 Suzuki GS550T with elctronic ignition, turns over but won't start.

Getting fuel-new petcock, new coils, white spark at plugs, plugs wires on properly

Brian :

Good day and welcome to Just Answer. My name is XXXXX XXXXX I'd be happy to help you with your problem today. Is that a vacuum or gravity petcock?... are the plugs wet or dry?... when were the carbs last gone through?... when were the valves last adjusted?.... & what is the engine compression?..

JACUSTOMER-oqci3wn0- :

Last tried starting it last night. Just pulled plugs...#1 wet, others more of damp. Has electric start and cranked it without plugs 20-30 seconds to air out, Wiped off plugs and put back in.

JACUSTOMER-oqci3wn0- :

Petcock has 'prime' mode that is gravity fed, when running supposed to switch to 'on' which is vacuum fed.

JACUSTOMER-oqci3wn0- :

Tried starting in 'on', no go, then 'prime', no go.

JACUSTOMER-oqci3wn0- :

When turning it over without plugs was getting strong air out of plug holes. Recently bought bike and carbs had recently been rebuild, not sure if by owner or shop, and coils replaced by owner. Not sure when valves last adjusted, nor compression.

JACUSTOMER-oqci3wn0- :

Da...hit accept by mistake

Brian :

great, thanks for the info... sounds like you may have lost a vac line. What I would like you to try is to remove the fuel hose from the fuel valve & run it or another short hose into a gas can. Put the valve on prime, does fuel flow?... put the valve on & crank over, does fuel flow?...

JACUSTOMER-oqci3wn0- :

Getting fuel thru prime, no fuel with 'on' and cranking it over.

Brian :

is that a vacuum petcock?..

JACUSTOMER-oqci3wn0- :

Yes, once running you switch to it after using 'prime'.

Brian :

sort of. You can really leave it "on", because once the engine cranks vacuum pulls fuel to the carbs. Leaving it in the prime position gravity feeds the carbs & often on older bikes like that flood out the engine, as seen by the wet #1 plug & damp 2, 3, & 4 plugs.

Brian :

If when cranking there is no fuel flow there is a loss of vacuum to the petcock.

Brian :

Either a bad hose, or it is not connected to the right spot, which should be carb 2.

Brian :

white spark is actually hotter than blue, which will look white in daylight, spark does not appear to be the issue.

Brian :

I would get fuel to the carbs & see what happens

Brian :

I would also quickly check the oil for any fuel contamination for futher evidence of carb flooding & change the oil/filter if needed.

Brian :

And then, I really be interested in a compression test.

JACUSTOMER-oqci3wn0- :

It appears to be a new hose and is connected to carb 2. But, when I checked for flow from 'on' no hose was connected to carbs. Should I connect the prime hose and try it, or does the main hose need to be on and draw vacuum?

Brian :

no only the vac hose needs connected, the feed can go anywhere, well, best if hooked to carbs or directed into a fuel can..

JACUSTOMER-oqci3wn0- :

there is no vacuum hose, only the prime hose and the main one

Brian :

but since we are trying to check flow I'd run it into a fuel can & make sure the vac hose is run

Brian :

There is no "prime" hose. Of the 2 hoses connected to the petcock. The smaller is vac, the larger is fuel feed. Fuel only ever comes out of the fuel feed. The vac hose needs connected to draw fuel to the carbs.

JACUSTOMER-oqci3wn0- :

still, this thing is supposed to start with the prime on.....When I crank it over I can hear the small hose sucking ????

Brian :

you need gas flowing properly before it will ever start, that is issue 1, then we get to move onto the no start issue, which I suspect is related, & it sounds like it is not breathing properly either...

JACUSTOMER-oqci3wn0- :

But, when I first disconnected the hoses, there was fuel in the main hose but not the small one.

Brian :

There is never & never should be fuel in the smaller hose, if there is there is a carb over flow or petcock issue.

Brian :

that is only a vac hose.

Brian :

If fuel ever gets that high in your carbs you have bigger issues.

JACUSTOMER-oqci3wn0- :

Good to know. How much more time do we have?

Brian :

I'm not sure you understand how the system works & that maybe a starting point.

Brian :

As much as you need

Brian :

this thread stays open for 24 hours

JACUSTOMER-oqci3wn0- :

U the man

Brian :

although wrapping this us quickly is better for both of us, I'm here as needed. If you need to step away just let me know

JACUSTOMER-oqci3wn0- :

I regapped the plugs a little wider and pulled air filter out. Running now. What do you think?

Brian :

if it runs without the air filter I say there is a flodding issue from being left on prime. Removing the ait filter lets more air , if it now runs that means there was a rich condition.

Brian :

The plugs should always be gapped at .032", what did you open them up to?...

Brian :

you can get away with .040" on oil/air cooled motors & if they spar white they are a hot plug. What is the number on the plug?

JACUSTOMER-oqci3wn0- :

Plugs are NKG B8ES. Specs says .024-.031. They were at .025 and I raised to .027. Put air filter back in and runs, and restarts. Raise the gap to what you said??

Brian :

what spec says .024 - .031"?, I've never known import plugs to be anything other than .032".. I would start there.

JACUSTOMER-oqci3wn0- :

from the bike operating manual

Brian :

a suzuki manual?

JACUSTOMER-oqci3wn0- :

Yes, and the Hayes repair manual says .024-.028 (?)

Brian :

ok. I use .032" & have for many, many years. I would set them @ .028" for your oil cooled/air cooled engine.

JACUSTOMER-oqci3wn0- :

but manual does say you can switch to B7ES if running wet

Brian :

you do not need that. If they are wet you need to asses plug color & adjust jetting fuel mixture not plug heat range.

JACUSTOMER-oqci3wn0- :

Thanks for all your help. How do I give you a tip?

Brian :

when you click on accept you will be able to do so. Thank you.

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