help please Coil resistance question.

[Seana23]

Hi All.
Ive been having problems with my GS850 (WITH CDi) running on 3 cylinders...
Ive cleaned the carbs about 30 times so im pretty sure its not that so i decided to test the coil resistance...
They appear to have about 5ohms resistance across the wiring terminals...
Shouldnt it be about 3 ohms?
Would this cause the bike to run badly and foul the plugs?
I have some other coils that have a resistance ov about 3.1 ohms... Would these be better?
Please ask if ive missed sumat.
Thanx all.
Xxx

[Seana23]

Ive borrowed some other coils from another 850 and they have resistance ov about 5 ohms too!
Xxx

[2BRacing]

It's important to know what voltage reaches the coils, so measure that as well. If voltage is more than 0.5 to 1.0 V lower than battery voltage, you should clean connectors or consider coil relay mod.

However, because you say your bike is running on 3 cylinders, I suspect that the plug cap of the 4th cylinder's plug wire could be faulty. Unscrew the cap from the plug wire and cut off a short piece of the wire so there is a nice fresh end, and screw the cap back on. If still a problem, swap out that cap with one of the others to check if the cylinder now fires, with the other one being dead.

[spyug]

I think 2B is right it is a plug cap problem. They do go bad too so you might need to change it out. In my experience and referring to what a professional bike mechanic told me, coils rarely go bad. In the case of our 4 cyclinders if the coil were dodgy, you'd have 2 non firing cylinders.

Luck,
spyug

[hampshirehog]

Try swapping the leads around 1 and 4 share the same coil so do 2 and 3. So if it's #2 that's fouling swap the lead with #3. If #3 now fouls it's the lead (or the cap).

[Seana23]

Ok thanx. Food for thought there...
I.dont think.its likely to be the wiring/ connectors as they seem clean, tight and free from rust...
However, on swapping the coils over i felt the ht lead ov my coils spin round in the coil housing...
I looked and they seem to be Coils, and seperate leads.... So i trimmed to some fresh coil and screwed.them right in...
It was pitch dark and absolutely freezing by then so i hope.to try the.old girl again on Saturday.
Ill let you know.
If no better, i reckon it might be something like the valves or an oil ring on the piston...
Gulp.
Oh well, ive got time.to do it as im off work til early spring...
thanx all.
Xxx