Starting Issues with my '83 GS750T

[brienc]

Hello GSers,

I am Brien and I got a 1983 GS750T about 4 months ago as my first motorcycle. The PO did a good job of restoring it and it was running great for the summer months. The bike is not a daily driver for me I usually go for a 30 min ride 2-3 days a week.

Troubles for me began when I went away for two weeks and when I got back the bike wouldn't start only turn over but not fire up. I borrowed a buddy's battery charger

http://www.amazon.com/gp/product/B000CITK8S/ref=wms_ohs_product

and after a night's charge all was well it fired right up and worked well for the next couple days. Then a week went by and again the same issue of just the starter motor going but no start. I bought one of the above 750 mA "smart" chargers and that time it took a couple days of trying and charging to get it to start. I would charge it overnight and the first time I would crank it would sound like it was firing but would quickly die out and subsequent start attempts would just sound like the starter motor going. Eventually after three nights it started up, then a few days later it was doing the same thing.

This weekend I had no luck at all after several charging attempts. I pulled out the battery and it was a lead-acid type and the fluid level was extremely low, so I opted to replace it with a new AGM one. The new battery didn't fix the issue. It still won't start.

The troubleshooting steps I have tried so far are to start the Stator Paper tests but I didn't get very far without it being able to start.

I started going through the electrical section at BassCliff's site and this section had me worried

http://members.dslextreme.com/users/storagecliff/images/electrical_odd-n-ends.html#A17

When I hook up a multimeter to the battery I have 12.8-9 on a freshly charged new battery, with the key and lights on it drops to about 12.4, the first crank I see about 11.0 volts and it tries to fire up, then on the second and later attempts the voltage when pressing the crank button go down to 10.5, 10.0 then 9.5. After the start it goes back up to 12.3-4.

http://www.mtsac.edu/~cliff/storage/gs/GS750_schematic_color.pdf

I have traced through as much of the wiring as I can see without taking the tank or controls off and I don't see anything obviously corroded or burned.

Tonight I pulled the spark plugs and when grounded I saw a small blue/white spark on each one, but having no frame of reference I am not sure if that was weak or not.

I suspected that it was an electrical short issue since it seemed to start better
on warmer dry days then dew covered mornings or rainy days.

I was hoping that this kind group could try to point me in the right direction to try to help me find my issue(s). Thanks for your time and patience with a newbie.

Brien

Pic below

[tkent02]

Go back on Cliff's site and find the list of neglected maintenance, do it all.
Adjust the valves, replace the o rings, go through the electrical system. All of it.
Then it will be as reliable as it was when it was new.

Turning over but not starting could be anything.

Since it was better in warmer weather could point to carburetor circuits or tight valves.

[tom203]

You need to take gas tank off and check voltage at coils (orange/white wire) during cranking- if it drops too low some ignitors won't fire decently. This will also let you clean these connections. I suspect this is an electrical issue, but lots of maintenance issues need to be checked, despite any PO's assurances. Maybe your starter motor is tired and your new battery can't satisfy its needs.

[yasser]

Yours sounds a lot like mine and they need a great charge to start. It really really really likes fresh batteries not just charged. I take the battery out and trickle over winter, but even at that once I hit ~ 3 years it is time to start thinking about a new battery. Amazing how long they will spin like something is going to happen and then nothing and you think it cant be the battery. Then the slightest of bump start and it pops right off. I quit asking why and just replace the battery sooner then I think I should have to, rather than starters. I did smoke one starter and have had better luck since replacement.

Also day to day it starts right off but if it sits a week + she gets difficult to start also despite the spinning, I figure it to be a passive aggressive ploy after neglect. Something my wife taught it, to encourage more riding - not a bad trait once understood and adhered to.

[cowboyup3371]

As Tkent02 said, go back and do all the required maintenance to start with. Once that is done and you can start from a solid baseline, break out your multimeter again and run through the stator paper tests on the main site under the In The Garage heading.

Also, when leaving the bike for as long as you did, the carburetor bowls are dry. Put your petcock on prime for about 30 seconds to refill them and place back to run. Try to start it from there making sure your vacuum line is still attached.

Finally, AGM batteries are a good replacement for lead acid but are not always the end all be all to your issues. Take a methodical approach and you'll get it running correctly.

[brienc]

You need to take gas tank off and check voltage at coils (orange/white wire) during cranking- if it drops too low some ignitors won't fire decently. This will also let you clean these connections. I suspect this is an electrical issue, but lots of maintenance issues need to be checked, despite any PO's assurances. Maybe your starter motor is tired and your new battery can't satisfy its needs.

Thanks everyone for the help. I was finally able to get her started tonight. I think this was the main issue. I was able to move the tank to get at the ignitor coils and there was some white chalky stuff in the connectors, after cleaning them it sounded more hopeful.

I know that I need to do the baseline maintenance to the carbs and valves. I think I may have induced a flooding issue by getting confused about my petcock and leaving it in PRI for too long. I drained the screws on the bottom of the carbs and what seemed like a lot of fuel came out and some of it was brown so a strip and drip of those are my next project.

I had one question to prep for this on this site...

http://cycleorings.com/intake.html

There are two options for the intake O-ring sizes, with out taking off the cylinder head is there a way to search for which size my bike will need?

Thanks again everyone. I still think I have an underlying charging issue that is the likely cause of cooking my last battery and the quick battery discharges when left for a few days. When at idle the voltage across the battery went up to 16-17V and even higher with revs. I know that I need to run the rest of the stator paper tests to isolate it to possibly the R/R or Stator. Anyone have opinions on the likely culprit?

I am trying to take the bike to my second MSF course tomorrow so I can be legal to drive it to work, then I know I need to buckle down and test the electrics, clean the carbs, and adjust the valves.

These forums are great, thanks again for the help, advice, and knowledge.

Brien

[tom203]

I don't think your 750 has orings at head interface.
Overcharging is likely a faulty R/R (regulator), but could be just bad connections between R/R and battery- you have to test! Many maintenance issues await you- ignore them and you might not need a motorcycle endorsement on your license!

[brienc]

Thanks very much again for helping me get my bike running. I did some more troubleshooting today and tried to put together a picture tutorial of my attempts as a new thread here. I think I proved the RR is bad.


I also got my O-rings in today, so that will be the next project after the RR.