GS850 running poorly - troubleshooting igniter and coils?

[Chuck78]

Yes the 81 engine has had the original mechanical advance replaced with all electronic advance parts, the pickups and ignitor.

 

[GSOH]

I tested the ignition system tonight to try and whittle this down. Here is what I found:

battery: 12.52v (new AGM battery)
voltage to coil wires (coil relay mod installed on both coils, key on): Left: 11.74v Right: 11.73v
coils (both were same when testing): primary: 4.5 ohms secondary (no plug boots): 12.5k ohms
signal generator: green-black: 169.3 ohms, black-yellow: 168.7 ohms

Ignitor test: well, I tried Mr. Bill Ricks method and the service manual for 82 1100. left #3&4 in, pulled #1&2, ground to (gulp) painted engine. with key on, connected + blue and - yellow on boot going to ignitor to try and spark #1. nothing. connected + green and - black for spark at Cyl#2. No dice.

I've taken a few photos to try and better illustrate (and troubleshoot). I wanted to test ignition system before checking needle jets and fully tearing carbs apart (again) and get some opinions.

 

[GSOH]

Ok. It's been a while since I have posted on here (and tore back into the bike). I'm still having issues, particularly with the idle and cylinder 1. It is driving me bat shvt crazy and I'm hoping someone on here can help me nail this down.

completed thus far:
sealed tank
new plug boots & chopped wire ends
carbs thoroughly cleaned
New intake boots & o-rings
new float needles (and required oil change due to gas in oil) with new o-rings
Dyna S DS3-2 installed (12.9v at battery. 11.6v at coils with relay mod)

Also, there is an aftermarket gravity-fed petcock on this. The vacuum port on carb 2 is sealed with a cap.

I started with idle fuel mixture screws at 2.5 then 2 and they are out at 3 in this video. I've set the idle screw at 1300 rpm but it wont stay near it, often diving to 500. I was wanting to get this taking care of before setting timing (perhaps that is a bad idea?). I was under the impression after reading kool_aid kids CV idle mixture steps, a hanging idle indicated a lean mixture, which is why I back the screws at to 3 turns. Maybe its a high idle caused by something else?

Another issue I am having is very intermittent nearning non-existent spark (at least based on hardly any light with timing gun) on cylinder 1. 2-4 all flash solid with gun.

video link
http://youtu.be/ic0NwtXD3z0

 

[cowboyup3371]

I don't see on your list that you replaced the orings behind the carb boots as that's one cause of it.

Also, try clipping off about a 1/4" of the end of the number 1 spark plug wire and then put the boot back on. Sometimes you might just have a bit of corrosion on it and need to trim it. You can also try swapping coils (swap the connectors I believe but do a search on it) and see if your spark problem follows. That can tell you if it's a coil issue or not.

 

[GSOH]

I don't see on your list that you replaced the orings behind the carb boots as that's one cause of it.

Also, try clipping off about a 1/4" of the end of the number 1 spark plug wire and then put the boot back on. Sometimes you might just have a bit of corrosion on it and need to trim it. You can also try swapping coils (swap the connectors I believe but do a search on it) and see if your spark problem follows. That can tell you if it's a coil issue or not.

I forgot to include both of those in my list [updated below). Next step was going to be swapping could & connectors to see if that causes it I run any different (better).

 

[cowboyup3371]

Hey GSOH, I just realized you tagged onto Chuck's issue here.

If I may make a suggestion, please make your own thread about your issues so we don't take away from Chuck's. For one, it can confuse people as to who we are talking about and two, yours could overshadow his since they may not be the same thing.

 

[GSOH]

Hey GSOH, I just realized you tagged onto Chuck's issue here.

If I may make a suggestion, please make your own thread about your issues so we don't take away from Chuck's. For one, it can confuse people as to who we are talking about and two, yours could overshadow his since they may not be the same thing.

I guess I should clarify, Chuck started this thread for my bike.He has been helping methe last few months on my 'project.'

 

[GSOH]

I swapped plug wire 1 to cylinder 4 and vice versa. PRIOR to the swap, timing light was intermittent on cylinder 1 and very strong continuous on cyl 4. After swapping, cyl 1 has no timing light & cyl 4 is erratic at best.

Any ideas? Bad coils? Bad plug wires?

 

[Guest]

was this problem ever resolved ? i have the exact same problem with my 81 gs850gl

 

[Guest]

Can anyone say with 100% certainty that the igniter unit test recommended in the service manual works for diagnosing weather or not it's good or bad ? I've owned quite a few gs850's with not very good results !

 

[Nessism]

I don't think the manual procedure is foolproof. I'm not an expert on such matters though.

 

[salty_monk]

It certainly caused a similar problem on my 801000G. Chased it through the carbs for ages before finally trying a Dyna S....

 

[Guest]

This is a old post but i have the same problem ! Did you ever find out what the problem was ?

 

[Chuck78]

The original bike owned by GSOH (Alex) who chimed in above in 2013, got sidelined due to him starting a family. I parted out an 850 since then and saved the carbs for him, but he hasn't gotten back to bikes other than refusing me every single time I try to get him to sell me his '79 GS425!
The original bike in question was a GS850 engine in a GS1100G chassis, and what I was suspicious of was the GS1100G carbs with GS850 jets and I believe slide needles, but I was really suspicious of the needle jet size and air jet sizes... Also found a lot of corrosion that had been cleaned off of the needle jets and other areas by previous owner that looked to potentially have altered the size of the air jets and needle jets...

Had a friend's DR-Z400E that I looked at which did very similar.
"Runs great, just needs jetted for the aftermarket pipe and airbox mod" said his friend who sold it to him.
Ran awesome up to half throttle, but no matter what jet size I put in it, which I went the full range of jets available, same problem, above half throttle, it just bogs...
He put that away for the winter, and next summer I revisited it, noted that it was low or out of coolant...
Filled, ran, checked, low...
Drained oil. There's the issue... Tan creamy sludge... Oil and coolant mixing.
Haven't gotten back to that one as I spent my efforts after that to get his WR400R running good. That's an awesome trail bike or dual sport conversion, not too heavy at all considering it's got 2 strokes too many for off-roading in my opinion!