Inconsistant Starts and idles...

[Dre]

Hey everyone,

I have been looking through the starting posts but have not seen anything quite like what is happening with my bike (1981 GS 650 GL Stock)

Once every odd number of rides even when it is warm it does not idle very well and kind of struggles until I bring her on the highway for a good little run, then things are better but sometimes idles up towards 1500 or so afterwards for a short while.

This past weekend I had ridden about 60 miles with a couple stops no problems. Went to start it up in the morning and nothing, tried varying choke levels and eventually ( after an hour or so I got it started by running and letting the clutch out. then revving it high and riding for a while and then it has been fine until this morning. Fine last night all of yesterday and this morning it would not start. pulled choke out same as every other day and tried to pop for about half a second and then nothing, still turning over but won't pop. when I tried pushing it and jumping on and starting it I got a low rumble like it was starting but when I gave it gas no revs and when i pull the clutch back in after that point it just kills whatever low rumble I had had. Both mornings this has happened it has been in the mid 60's and a bit humid not sure if I should be doing a different start procedure for this type of weather or not. If anyone has had this sort of problem any advice or knowledge would be much appreciated...

[BassCliff]

Hi Mr. Dre,

The usual suspects include:

1. Air leaks in the intake system
2. Low voltage at the coils (too much resistance in the wiring? bad charging system?)
3. Dragging starter
4. Mis-tuned/dirty carbs
5. Air filter (Clean? Over oiled?)
6. Valve clearances
7. Spark plugs, plug caps

I'm sure there are other causes for the symptoms you describe. Sometimes it's a process of elimination. Will the bike turn over until the battery drains, but just not start? Have you tried jumping it from a car battery (with the car NOT running)? Have you thought about the coil relay mod? What shape are your intake boots and O-rings? When was the last time you checked your valve clearances? Check the "Odds and Ends" section of my website for an article called "Diagnosing slow cranking" by Mr. Steve. Keep us informed.

Thank you for your indulgence,

BassCliff

[Dre]

Hi Mr. Dre,



I'm sure there are other causes for the symptoms you describe. Sometimes it's a process of elimination. Will the bike turn over until the battery drains, but just not start? Have you tried jumping it from a car battery (with the car NOT running)? Have you thought about the coil relay mod? What shape are your intake boots and O-rings? When was the last time you checked your valve clearances? Check the "Odds and Ends" section of my website for an article called "Diagnosing slow cranking" by Mr. Steve. Keep us informed.

Thank you for your indulgence,

BassCliff

The bike turns over until the battery drains, just won't start. And again I would like to say this only pops up every so often. One time I had jumped it from a car battery and that worked.Spark plugs look a little rich on 2 & 3 but fine on 1 & 4 I replaced them about two weeks ago. Also the prior owner put a little seafoam in when he filled up, could that have caused these problems or made them not show up as much? I have somewhat looked into the coil relay mod but do not fully understand what it does. also is that like 180 bucks? ordered new air filter and waiting on the part, although it does not look too worn. Also I have an air horn that seems to work oddly, is it possible for an air leak to be in those hoses as they sit closer to the engine? intake boots are still flexible, ordering new o rings today, what is the easiest way to get access to them, i'm sure you guys have a guide out there. I have not checked valve clearances yet as I do not have a garage until about three weeks from now and am limited on funding. I will definately take a look at the slow cranking guide you pointed out. Thanks so much and any other ideas/info are very much appreciated.

[Hoges]

Dre, It sounds like it is running rich to me esp if 2 & 3 are black sooty looking. Check your mixture screw settings on all first. I think the standard setting for your mixture screws are at 2 & 1/2 turns out. I know it's a pain, but pulling the carbs partially off and blowing through the jets and passages wouldn't hurt either. One of your throttle cables isn't getting caught on something is it like under the tank causing tightness etc.

[doctorgonzo]

"I have somewhat looked into the coil relay mod but do not fully understand what it does."

Normally, the power that goes from the battery to your coils runs through various connections and parts of the harness before it gets to the coil. Old wiring, switches, connections, etc can suck voltage so that by the time it hits the coil it's not the 12.5 coming off the battery it's lower, often much lower like 8 or 9 volts. The "coil relay mod" runs a fused hot directly from the battery to the coils so they get the full 12.5 volts. The relay is used to switch the juice off and on like the stock system while bypassing the harness. Not saying it is related to your problem, but a thumbnail explanation of why people do it.

[Steve]

... Went to start it up in the morning and nothing, tried varying choke levels and eventually ( after an hour or so I got it started by running and letting the clutch out. ...

The bike turns over until the battery drains, just won't start. ... I have not checked valve clearances yet as I do not have a garage until about three weeks from now and am limited on funding.

Well, it looks like you might have to give up riding for three weeks until you can get into your garage and adjust the valves.

If you have indeed searched the starting topics you would have found that one of the classic symptoms of poor starting is improper valve clearance, most likely tight valves. Tight valves can quickly lead to other problems, so get them adjusted before you ride much farther.

.

[Dre]

Damned Battery Got Me...

So I got home from work last night and was trying a few things and got it goin by bump starting it. drove it around a while to get the battery back up came back and measured voltage at 11.7 Running. bumped her up to 4 or 5 grand and it came close to 12 volts. from off pushed starter and watched her dip to about 8 or 9. turned it off, same thing but about seven volts. turned her off and tried pushing start again, no voltage. So.... I ran and got a new battery and she starts great and is running a lot better in many areas. I had previously somewhat ruled out the batt as it seemed like intake/carb/valve issues which it still may have but she's running pretty good now. The P.O. had said it was a new battery at the end of last summer so I am not sure what the deal with that is. I am still planning on redoing carbs and valve clearances within a month or two. Anyone have any ideas of other electrical system problems I should be checking if this has happened or if she is running better it probably was just the battery? And thanks again to everyone here, I have already learned a lot from all of you on this forum and through the guides and walkthroughs...

[Dre]

Thanks.

"I have somewhat looked into the coil relay mod but do not fully understand what it does."

Normally, the power that goes from the battery to your coils runs through various connections and parts of the harness before it gets to the coil. Old wiring, switches, connections, etc can suck voltage so that by the time it hits the coil it's not the 12.5 coming off the battery it's lower, often much lower like 8 or 9 volts. The "coil relay mod" runs a fused hot directly from the battery to the coils so they get the full 12.5 volts. The relay is used to switch the juice off and on like the stock system while bypassing the harness. Not saying it is related to your problem, but a thumbnail explanation of why people do it.

Thank you Gonzo, that was exactly what I was looking for as far as an explanation.

[Dre]

Mixture screws...

Dre, It sounds like it is running rich to me esp if 2 & 3 are black sooty looking. Check your mixture screw settings on all first. I think the standard setting for your mixture screws are at 2 & 1/2 turns out. I know it's a pain, but pulling the carbs partially off and blowing through the jets and passages wouldn't hurt either. One of your throttle cables isn't getting caught on something is it like under the tank causing tightness etc.

I should check those, I have not taken my carbs out at all yet and I am not quite sure how. I have the guide on cleaning and reassembling them but do I have to take them completely out to change the mixture screws? are they on the engine side of the carbs? Anyone have any tricks to this or easiest way to pull the carbs out? tank off? And I should turn 2 & 3 in if they are running rich correct? leave 1 & 4 where they are at if they look good on the plugs? Throttle cable is not getting pinched as far as I can tell but that was definately a goood thing to check...

[Nessism]

Your charging system is not working; voltage should be 14+ volts when the engine is rev'ed up. Check the stator papers on the GSR homepage for more info - there is tons of info in the archives as well so please use the search function.

[Dre]

One other thing

The only other thing that really seems wierd is this sound others have talked about but it is always over 5000 rpm's and it sounds like tin pans like rattling back and forth really fast and it sounds like it is coming from underneath the tank... any ideas? cam chain?