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Spark plug gap problem...

  • Thread starter Thread starter Tiny
  • Start date Start date
T

Tiny

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So i have t recieved my clymer manual yet...

i have an 81 gs 750 lx (or so it says on the title)... I looked online and found a place that says ngk plugs should be .028 and champion should be .032

when i took the plugs out they were closer to .030... Theyre ngk plugs ...

i tried gapping them to .028 and it wouldnt start... I tried .032 and it wouldnt start... I put them back to .030 and it wouldnt start... My response? WHAT THE HELL???

it ran before but backfired in deceleration... Can someone tell me what the gap should be for ngk plugs?

and anyone got any thoughts on what could have happened to make it not start?

occasionally i do get a massive backfire out of it if i crank it for too long... Pretty sure i almost lit my shoe on fire...

in any case... Heeeeelp!
 
Since it ran before plug playing, make sure you put plug wires on correct spark plug as it's easy to mixup. As you sit on bike, the ignition coil on left fires 1 and 4 plugs (1 being the plug under the clutch lever ).
put your location in your signature,as there might be a member close by to lend hand.
 
tom203 said:
Since it ran before plug playing, make sure you put plug wires on correct spark plug as it's easy to mixup. As you sit on bike, the ignition coil on left fires 1 and 4 plugs (1 being the plug under the clutch lever ).
put your location in your signature,as there might be a member close by to lend hand.
Click to expand...

Welcome to the site Tiny,

Mixed up plug wires could do that, also check to see if you are actually getting spark through the plugs by grounding the plug to the case and crank the engine over. New plugs can be bad, it happens, it's also possible the plug wire end caps are not getting a good enough connection to the wire. They screw into the end of the wire and may not be getting good contact. If there is enough length in the wire you can cut them back a 1/2" to get to clean wire(non-corroded wire strands).

If you check the plugs, see if they're wet and smell like gas, then at least you'll know if your getting fuel to that particular cylinder.

Like Tom said you'll get spark at plugs in pairs(1-4, 2-3), so if you find that 3 out of 4 are sparking, it's not going to be the coils, but the wire, end cap or plug.

Now if your not getting anything, then it could be the signal generator(off right side of crankshaft under the cover with screws-older bikes were points). It has two wires that may have come disconnected or it may be the CDI(little black box) Both of these items need to be working to tell the coils to fire and when.
 
Once you get that Clymer manual, you can toss it in library donation box because here's an electronic copy of the official Suzuki service manual for your bike: http://www.mtsac.edu/~cliff/storage/gs/GS750_16valve.pdf See page 2-8 (page 27 in the PDF) for spark plug gapping instructions. Don't forget to do all the other maintenance specified in that section as well.

And go here for way more Suzuki GS information than I can possibly summarize: http://members.dslextreme.com/users/bikecliff/

Welcome!
 
To sort of answer the question, these bikes aren't really at all sensitive to spark plug gap, so you'll need to find the real cause of the issue.

It's common if you've worked on 4-cylinder cars recently to get the firing order wrong. 1/4 are on one coil, 2/3 are on the other. I don't know how many times I've screwed that up, so that's why we mention it.
 
Thank you all for the information!!! Ill go tomorrow and check some more of those things...
 
And if your gap is getting larger for no apparent reason the plug caps may be bad.
 
Thanks guys... I put in new plugs gapped at .026 and it fired right up... Still sputtering and backfiring a lil but i think that is a carb issue... 8)
 
Tiny said:
Thanks guys... I put in new plugs gapped at .026 and it fired right up... Still sputtering and backfiring a lil but i think that is a carb issue... 8)
Click to expand...

I have my doubts. Best guess is a low voltage level going to the coils.
 
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