Test Ride Failed

[driftcreek850]

OK

So today I went home for lunch and since I got the riding fever, I decided to take the bike out. If you have been following my story you know I have been going through my 79 GS850 all winter, getting it ready for a day just like today.

I have synced my carbs and gone through them and the bike starts good, runs good (real good) and all the electrics work and so I decided to go for about 20 miles to check it out,, I have been going 2 or 3 and felt comfortable on a longer ride.

So In a 10 mile ride, The bike died 3 times and on the 4th time I could not get it started and had to get rescued. I waited an hour the last time and it never fired up again. I have not tested anything yet.

In detail what is happening, is after about 2 miles the bike will shut down. I still have all ignition and lights the starter turns, but no fire. The first three times it happened only when I was DECELERATING. I can't say if it happened when I hit the brakes or not, but the first three times I was able to wait 10-15 minutes and she would start and go again like nothing was wrong.

At first I thought it was a fuel supply problem, but I ruled that out. It seems to be temperature related and so I am thinking the dyna ignition module... am i right? Should I test it? How? Ther charging system appears to be OK. I had a steady 13 volts on it. HELP!!

[BassCliff]

Hi,

13 volts is not a very healthy charging system. Have you gone through the Stator Papers with a known, good battery?

It sounds like you are very, very close. Keep up the great work!


Thank you for your indulgence,

BassCliff

[reddirtrider]

Why did you rule out fuel related? If the tank isn't vented properly, you'll starve the carbs until it draws in more air. Try another run, then when it dies open the tank cap. If it starts right away you've identified the problem.

[driftcreek850]

fuel cap OK

That was the first thing I tried. Did not help.

[reddirtrider]

That was the first thing I tried. Did not help.

Ok, pull a plug wire when it dies and see if you have spark.

[Nathan Daube]

Another Idea

I had a similar problem with my 81 GS850GL and it finally took a trip to the motorcycle shop and having the mechanic figure it out. His finding was that one of the 2 pickups on the crank position sensor was sticking. He managed to get it fixed and its been good since. I like you though could go out for a while and then BAM it would quit and not restart. Also take a look at the seals in the airbox because if they arent right and in place like they should be they will cause you a ton of headaches as well

[reddirtrider]

If it's temperature related it's easy to identify the problem. Long ago as a TV tech we used component coolant in a spray can (should be able to get it at Radio Shack) to find parts that were failing when hot. Get the bike warmed up and in failure mode, then spray various components one at a time until it starts again. Repeat to verify and fix.

[nisom512]

If it's temperature related it's easy to identify the problem. Long ago as a TV tech we used component coolant in a spray can (should be able to get it at Radio Shack) to find parts that were failing when hot. Get the bike warmed up and in failure mode, then spray various components one at a time until it starts again. Repeat to verify and fix.

Really? I guess it makes sense

[1978GS1000custom]

does it have points or electric ignition? did you check the coils for ohms (3-ohm i think) or for loose half broken wires/ dirty connections at the coils? when it does not have spark is it like that on all cylinders? what ever it is, its something really simple. if your thinking dyna ignition your gonna want dyna green coils anyway. and they will work with your present ignition which ever type you have.

[driftcreek850]

OK for NOW?

Well, I think I ran down my problem. After my little adventure yesterday, I found no spark at all, so I pulled the tank and started tracing wires. MY 1979 GS850 has a dyna electronic ignition conversion. The power wire running to the ignition module was connected to the wiring harness with one of those side crimp tap connectors, and was shorting out, causing the module to lose power.

I did a complete stator and rectifier test, and they passed HOWEVER, I am still only getting 13 volts on the system @ 4000 Rpm. I am not sure what the "diode test" setting on my multimeter is, but the rectifier passed the test on all the settings.

What next? Do I need more than 13 volts? The stator was 75 volts on all three tests. I am going to ride the bike ... I have been working on it for months now its time to ride.

[MrZig]

Try adding a better ground from the R/R to the battery. Before I did this, my voltage went crazy, from being 14-15 volts, down to just over 12 when revved up, then back to 13 after that.

Once I added a good ground, I have a steady 14.X voltage

[BassCliff]

Hi,

I agree, a good ground path for the r/r is vital. If you are getting 75vAC from each leg of the stator but only 13vDC from the r/r then I would suspect the r/r.

After you get a good ground to the r/r, don't forget to clean the ground connections of the battery itself. There is a ground strap that connects the negative terminal of the battery to the back of the engine. Hopefully, that will solve your charging issue. If not, continue with the troubleshooting procedure in the Stator Papers.

Thank you for your indulgence,

BassCliff

[driftcreek850]

Done all of that.... including brand new battery. Moved the r/r ground to battery post.. Cleaned main ground and all ground connections.. Still only 13 volts.

[DanTheMan]

Done all of that.... including brand new battery. Moved the r/r ground to battery post.. Cleaned main ground and all ground connections.. Still only 13 volts.

I wouldn't worry too hard about it. Mine charges regularly between 12.8 and 13.2 volts, ocassionally will increase to 14 when the battery has had a heavy discharge, but running down the road with normal lights on (head, tail and front markers), it's around 13. When I switch on the grip heaters and the driving lights though, it hangs in around the 12v mark due to the heavy load exerted on the charging system.
I installed a volt meter where I can monitor it all the time, and have ridden thousands of miles this way with no problems. That being said, I still carry lots of tools and a pair of jumper cables. When going on a long touring trip, my trickle charger has a place in my luggage as well.

[posplayr]

Thin ice

Mine charges regularly between 12.8 and 13.2 volts, occasionally will increase to 14 when the battery has had a heavy discharge, but running down the road with normal lights on (head, tail and front markers), it's around 13. When I switch on the grip heaters and the driving lights though, it hangs in around the 12v mark due to the heavy load exerted on the charging system.

I would stress this. It is not good!!

This is not charging the battery. Anything below about 12.8v and you are discharging your battery. You should have at least 14V at 4000 RPM. If you don't you have a bad ground or resistance in your positive lead from R/R + to Battery + (in the fuse box for example). This will cause your R/R to shunt more current back to the stator . The result is excess stress on your stator and R/R as well as giving you a lack of power.

The GS charging system only works as a balance of several factors and there is really not much tolerance or design margin specifically for bad connections (plus or negative side). You are riding right against the rail and from your quoted values probably only works because you are constantly on trickle charge (a guess). You can't drive around very long with the battery at 12v and expect there to be enough charge to crank over the engine.

Pos