4-banger GS issue...constant electicity flowing through #2/#3 coil

[makenzie71]

If the ignition is on there is electricity flowing through the #2 and #3 plugs.  This is not "when the motor is turning over".  It is constant.  It still arcs crazy big when it's supposed to fire the piston, but it's got a lot of juice the rest of the time, too.  I've replaced the coil and wires with no change. 

[laserred97gt]

Here's how a coil works...

A power source (battery+charging system) runs power through a switch to the coil.  The switch in this case is a rotor under the cover on the side of the engine.  When that swicth reaches a certain point, it closes and allows power to go to the coil.  This creates a large magnetic field in the primary side of the coil.  When the switch reaches the right position, it opens, and the power is shut off to the coil.  When this happens, the magnetic field collapses and the collapsing of that field imparts the charge to the secondary side of the coil, which amplifies the voltage, and that electricity tries to find the path of least resistance, which (hopefully) is the sparkplug.

On all coils I have seen, it should NOT have power when in the dwell time (off time).  However, if you were checking the coils when the switch happens to be in the saturation time (on time), then it will show voltage.

You can try bumping the engine over with the starter quickly without letting it start, and see if it still has power.  Do this a few times to lessen the chance that it is in the same position.

Good luck!   

[makenzie71]

does it at all times, any crank position.

[GeeP]

Points or "ignitor box"?

[makenzie71]

it was a points bike to begin with but someone has installed a dyna III digital igniter.  I'm going ove rthe wiring now to make sure they put it together right.

[sledge]

Mak,
I really do admire you for taking these "Modern classics" on mate. Sorry I havent got a clue what to suggest other than ripping the after-market unit out and going back to stock, that way if there is still a fault you have got some backup. Alternatively you could ask the question in here.......  http://www.suzukiownersclub.co.uk/forum/search.asp?KW=GS750&SM=1&SI=TC&FM=18&OB=1 .........

[makenzie71]

thanks sledge. I did figure out the issue, though...coil was shot.  Shorted out on the inside and allowing constant 12V current through.  It was still firing pretty good on time, though.  Just odd.  I got that figured out and now I'm working on figuring out the carburetors and next the valve clearances.

Anyone know the valve clearances for a 1979 750E?

[sledge]

Mak,
If you are not already a member, join this forum http://www.classicbikeforum.com/search.php?s=1&q=GS750 Someone in there will have the answers you need.

[makenzie71]

I'll hit it up...anything's better than GSResource right now.  Those guys are wound up so tight and flipped out over me saying my GS is 30 years old and that I "might" rebuild the top end...actually I had just asked if anyone sold an all-inclusive kit to redo the top end...nuts...