Suzuki GS850 1981 american import

[Charlie G]

That's not checking for spark ...

Ya can't get away with anything around here. Your headed in the right direction. Cheers.

cg

[vinnie461]

miked

That's not checking for spark ...

haha no i realise that, i have checked for the spark, just thought id mention that there is also a higher voltage in 2nd and 3rd...but yeah checked the spark

[miked]

haha no i realise that, i have checked for the spark, just thought id mention that there is also a higher voltage in 2nd and 3rd...but yeah checked the spark

prob a good idea to put a bit of effort in to help us help you... Like pulling teeth here --- ok, and what did you find? Did you check all 4 cylinders? What was the result of checking for spark on each cylinder?

[sparki]

may want to check the voltage to the coils while you're there... old wires may well be causing quite a bit less than 12v arriving at the coils

[vinnie461]

sparki

may want to check the voltage to the coils while you're there... old wires may well be causing quite a bit less than 12v arriving at the coils

How would i go about doing this? if its elsewhere on the forums simply pointing me in that direction would be more helpful then you know bloody hate computers

[vinnie461]

miked

prob a good idea to put a bit of effort in to help us help you... Like pulling teeth here --- ok, and what did you find? Did you check all 4 cylinders? What was the result of checking for spark on each cylinder?

Sorry, yeah pulled all four cylinder cables individually, placed the individual spark plugs up against the engine and found a consistent spark on all four plugs when turning it over...my dad can even vouch for the voltage going through the cables haha

[miked]

Ok. So then your original explanation that the first cylinder isn't firing is off target, first cylinder is firing but its running poorly. Did this come on suddenly or did the performance slowly fall off?

To check voltage at coils you'd pull the tank and using a multimeter measure for ~13vDC on the feed wire going to the coils while cranking/running. The 2 coils have the same color wire as the 12v feed on 1 of the 2 lugs on the coil and each has a diff color wire on the 2nd terminal/lug as the trigger wire that tells coil when to spark based on points closing or CDI signal generators being triggered. You want to measure the feed side. But if the other cylinders are running fine I'd doubt that the issue is low voltage, you'd see the impact of low voltage on all cylinders, not just one.

To isolate/eliminate the coils as the culprit you can swap the wires on cylinders 1 and 4. If the coil is producing weak spark then the problem should move to cylinder 4.

The other option is to swap the coils moving the 1-4 coil leads onto 2-3 and 2-3 onto 1-4. youll need to swap the trigger wires as well to keep things in sync.

While a cam prob can happen overnight it's pretty unlikely. And the shim/bucket design elimantes things like collapsed lifters. The valve train is pretty solid on these bikes.

If you've got spark and compression (you did a compression check on cyl 1 right?) then I'd be figuring out a carb solution. Suck, bang, blow - will it suck in a fuel/air mixture? Will it bang/spark to ignite mixture? Will it blow spent gasses out? If it will do all of that it should run.