bike is stranded at a friends house...

[shadowfist]

OK, this is going to be a bit of a long post because there are a lot of elements that COULD be involved but I'm just getting my feet wet (or hands greasy as the case may be) for the first time. and i don't know what is going on.

ok, first off, my bike is a 1978 GS750 which was running just fine. About 2 weeks ago i got the bike off an acquaintance for 500 clams when he sold it to me he said that it has a 'charging problem and i need to replace the stator' but it runs ok 'after a few hours the headlight will go pretty dim'. (which i now know to be the r/r problem that is always blamed on our poor stators.)

While i was waiting to get into my class to get my motorcycle endorsement i passed the time changing the spark plugs (which it originally had the wrong plugs in it, they were to short) and oil all the while starting it up daily because he informed me that if it hasn't run in a few days the only way he could get it started was starter fluid into the air filter. never had much problems getting it started. also in the meantime i bought myself a battery tender to keep it charged up because of said stator r/r issue.

starting Tuesday last week i started driving my bike almost exclusively driving it to work etc.. wasn't having any problems with it aside from it running a bit rich (you can smell the unburnt gas) I drove it Tuesday evening, Wednesday to and from work, Thursday to and from work, and Friday to and from work, Saturday i took a drive cause it was a nice day (probably about an hour or so). after this drive i thought it would be clever to adjust the carbs a little and see if i could get it to run not quite so rich (i did this while it was running). it seemed to be running a little bit better and not quite so rich (it seemed to puff more visible exhaust out of the right side pipe, and after adjusting a little it seemed more even). Stupidly i didn't stop the bike and start it up with this new carb settings.

in the evening I wasn't thinking about how cold it gets at night, and at six or so drove it over to a friends house for a get together he was having. now, at about 4 or 5 am when i went to leave, (there was frost on the seat that i had to scrape off) surprisingly (not) it wouldn't start. and within about 4 cranks i had drained the battery.

now, I thought it was just a combination of A: dead battery and B: its stinking-cold out. (wouldn't kick start either)

so i came back the next day and plugged in my battery tender to get it all charged up nice for me. so Monday after work I dropped by to take my bike home... still wouldn't start. once again drained the battery trying to start it, and again STUPIDLY thought my carb adjustment could have made it start rougher and attempted to put them back to where they were before i adjusted them... (tried it on choke and off etc... i usually had to start it with choke open for a few minutes day-to-day)

Tuesday night (last night) I brought my tools and checked what i could (which with my limited mechanical knowledge wasn't much) but i did notice that the spark plugs were black and dry (carbon I believe?) which is the same as the old plugs looked like when they came out (yet it ran ok). I checked the spark plug cables and they were arcing to ground when stuck a screw driver in each one. and i also added more gas just to make sure that wasn't my problem.

PS: during the day when i have been going to start it its mid 50s out?
PPS: to put icing on my cake i finally got my leathers in the mail on Monday... and haven't gotten to go use them yet...

so now... I still cant start my bike, i have a friend with a bike trailer who is going to help me get it back home at least, but where do i go from here?
should i replace the plugs again just to be sure?
should I play with the carb adjustment screws MORE to see if that is the problem?
did the cold "do something" to my engine etc...?
am i just to mentally deficient to figure this out?
how will batman get out of this dastardly trap?

[terrylee2u]

My carbs was just completely redone late this summer and mine is a bear to start in the cold too.. a trait of the GS maybe, but I'm sure you have more issue's than that...

[mriddle]

I would suggest you get a new battery, charge it fully and install before you spend much more time diagnosing.

[jknappsax]

You really need to check your valve clearances; this is a common cause of cold-weather starting problems. Another critical item is that the rubber manifolds between the carbs and head, and the o-rings between the manifolds and heads. The valve clearances wear tight with the 1977-1979 shim setup, and can cause your valves to not close completely. The manifolds and o-rings let air leak into the mixture AFTER the carbs, screwing up mixture and causing cold-weather starting problems. Do searches for these items; they're pretty common. Also, for the charging problems, read the Stator Papers in the archives.

[shadowfist]

the thing that confuses me is it doesn't even sound like I am getting any sort of ignition aside from the VERY occasional backfire. (like maybe 3-4 times total during this multi-day fiasco)

i mean it should at least be trying to fire up right? Its bad enough that I would assume either there is no spark to light up the fuel or there is no fuel going in there. its like im cranking it and forgot to plug all 4 spark plugs back in. nothing happening...

[Steve]

Since you say that you know you are having charging problems, I am going to make a silly assumption that you might also still have the battery in there that came with the bike. You know there were charging problems before, but are using a Battery Tender now to top it off. My guess is that the battery is so wasted that it won't even last for four cranking attempts. When the battery is this far gone, the voltage while cranking the bike will drop, probably below 10 volts. This is not enough to fire the coils. Add to this the problem that many bikes have with dirty connections between the battery and the coils (this is why so many are doing 'the coil mod') and you have even less voltage at the coils.

In my opinion, a new battery and a valve clearance check will probably cure at least 90% of your starting issues.

.

[bonanzadave]

I would suggest you get a new battery, charge it fully and install before you spend much more time diagnosing.

Ill second the battery. If it were mine, and we know it has been running, Id get a battery Charger / booster. Ya cant F-up a F-ed up RR. Choke on, hook up the charger, go to boost and crank away. If that dont work get one of your, up all night, buddies and try to bump / push start it. Dump the clutch in second.

If that dont work then Id get the new Battery, RR, and become acquainted with the stator papers.

[Larry D]

get one of your, up all night, buddies

That's funny. Sounds like my girlfriends teenage boys...Up all night, sleep all day. I try and make as much noise as possible when I get home in the afternoon !!!

[shadowfist]

Since you say that you know you are having charging problems, I am going to make a silly assumption that you might also still have the battery in there that came with the bike. You know there were charging problems before, but are using a Battery Tender now to top it off. My guess is that the battery is so wasted that it won't even last for four cranking attempts. When the battery is this far gone, the voltage while cranking the bike will drop, probably below 10 volts. This is not enough to fire the coils. Add to this the problem that many bikes have with dirty connections between the battery and the coils (this is why so many are doing 'the coil mod') and you have even less voltage at the coils.

In my opinion, a new battery and a valve clearance check will probably cure at least 90% of your starting issues.

.

well, after charging it up the battery lasts quite a few starting attempts, could i test this theory by hooking it up to a car battery (known good) and see if it fires up? if it doesn't next thing to check would be valve clearance, right?
and it seems like no one thinks i should try new plugs?

[salty_monk]

Doubt it's the plugs. You can check anyway... plug out, in the end of the lead & hold it near the head, you'll see the spark jump.

Good jumper cables from a car battery without the car started is a safe way to start a bike with a flat battery.

Sounds like you need basic overhaul that all these old bikes need.... New battery, valve clearances, follow the stator papers to sort your charging issue & give the carbs a clean & replace all the O rings.

Dan

[BassCliff]

Hi Mr. shadowfist,

Perhaps you've already seen these, but I like to remind all the new members. In addition to the carb rebuild series, I recommend visiting the In The Garage section via the GSR Homepage and check out the Stator Papers. There's also a lot of great information in the Old Q&A section. I have some documentation on my little BikeCliff website to help get you familiar with doing routine maintenance tasks (note that it is 850G-specific but many tasks are common to all GS bikes). Other "user contributed" informational sites include those of Mr. bwringer, Mr. tfb and Mr. robertbarr. And if your bike uses shims for valve adjustments, send an email to Mr. Steve requesting a copy of his Excel spreadsheet that helps you keep track of clearances, shim sizes and other service work.

These are some edited quotes from one of our dear beloved gurus, Mr. bwringer, with ideas on basic needs (depending on initial condition), parts, and accessories.

***********Quoted from Mr. bwringer************
Every GS850 [and most other models] has (or had) a set of well-known issues that MUST be addressed before you have a solid baseline for further troubleshooting. It's a vintage bike, and it's quite common (as in, every single GS850 I have had contact with) that there are multiple problems that have crept up and slowly gotten worse over the years. It's not like a newer vehicle, where there's generally one problem at a time.

These common issues are:

1. Intake O-rings (install NEW OEM or Viton only - common nitrile O-rings will quickly deteriorate from heat)
2. Intake Boots (install NEW -- these cannot be repaired)
3. Valve clearances (more important than most people think)
4. Carb/airbox boots
5. Airbox sealing
6. Air filter sealing
7. Petcock (install a NEW one)
8. On '79 models, install new points or Dyna electronic ignition (or at least verify that the old points are working correctly)
9. On all models, it's fairly common to have problems with the spark plug caps. These are $3 or $4 each, and often worth replacing if you're keeping the stock coils/wires.
10. Stock exhaust with NO leaks or holes -- good seals at the head and at the junctions underneath.
*************End Quote**************


To add to Mr. bwringer's wisdom, I suggest cleaning every electrical connection and ground, from the head light bucket to the tail light. Replace bullet connectors with blade connectors (or better) as necessary.


Keep us informed.


Thank you for your indulgence,


BassCliff

[82Shafty]

My carbs was just completely redone late this summer and mine is a bear to start in the cold too.. a trait of the GS maybe, but I'm sure you have more issue's than that...

We need to work on yours then Terry,

Both mine and my dad's fire right up in this cold weather.

Adj valve clearances
New intake boot o-rings
carbs were dipped and robert barr kit installed on both bikes
synched
adj in 80 degree weather and they still fire right up in the low 40's.
plugs burn very clean
both have coil relay mods

[82Shafty]

Get yourself some Ether to spray to see if it could at least get it started. Don't go crazy with the stuff as it is hard on components.

Also, pull a plug out, hook the wire back up to it and crank the bike over to see if there is good blue spark. Or if you have a known good spare plug, you can use that without removing an arc plug.

See my post above, you will want to spend the time to thoroughly go through everything in a step by step process. the time invested now ensures many future reliable rides.

It could be something as simple as the vacuum line to the petcock cracked over night shutting off your fuel.

If you have good blue spark and the plugs are still dry, you are missing the fuel aspect. blow into your draft/vent tubes and throw the bike on prime.

Even if you get it running you still need to take the time to go through this beast and fix it right.

[shadowfist]

It could be something as simple as the vacuum line to the petcock cracked over night shutting off your fuel.

where do i find this? i know where the petcock is but which line coming out of it is the one i want to look at? and would i be able to start the bike in 'prime' if this was the problem?

[BassCliff]

I've got pictures

Hi,

If the vacuum isn't working, the PRIme setting will allow fuel to flow without a vacuum applied to the petcock. Click the link below for more information that may help.

Where Do These Hoses Go?

Thank you for your indulgence,

BassCliff