Help diagnosing a craigslist GS650 G

[Guest]

Hi all! Wanted to make an intro post about my old 1982 GS650 G I bought from someone on Craigslist two days ago but it's already stopped working : /. Poor bike is now sitting out on the side of some street unable to start or go. I'm wondering if the sages here could help me figure out where to look. It ran perfectly fine the day of purchase and this morning. Rode over 100 miles over the course of two days. Here are some symptoms today which may or may not be related at all:

-Upon cold start the bike spits out a good amount of white smoke which goes away after warming up.
-Suddenly afternoon today, maybe two hours into the ride, I notice on two occasions phantom revving from just pulling in the clutch (while moving). Adjusted choke, and it seemed to be fine after that.
-Evening time, while moving, throttle suddenly stops giving the bike any go (at all). Pull over to the side, turn off bike. After a minute, try turning back on. Starter doesn't get the engine running.
-Sometimes the starter needs some throttle to start the engine, but throttling doesn't rev the bike at all
-Abuse the starter button a little bit, and it gets weaker and weaker and eventually stops making any noise whatsoever
-Try pushing bike up a hill and bump starting it. Pop the clutch and bike starts perfectly, but the engine gradually starts chugging slower and slower until it sputters out (within 3 mins).
-Bump start it three times, each time the engine sputters out a little faster.
-Come back 45 mins later, and the starter sounds like it's alive again. Still no engine start or throttle response though.
-Battery seems fine the whole time as the lights are all bright

I'm thinking there are two issues, one with the starter (it's not normal for it to die from repeated use and vaguely work again after 45 mins right?) and one with the actual getting the engine to stay running, since bump starting removes the need for a working starter.

I was really hoping it would be a gas issue. I'm pretty sure I ran out of gas because the (probably uncalibrated) fuel gauge is reading about empty, and there's been over 100 miles ridden on the last fill up, and throttling induces sad, minimal revs if at all. Shaking the bike does reveal some sloshing gasoline noises though. I tried bump starting on with the tank set to reserve and the engine still sputters out.

What do you think could be the issue? Where should I look first? Thanks so much for your help this is my first street-legal bike!

[tom203]

Since "It ran perfectly fine the day of purchase and this morning. Rode over 100 miles over the course of two days" I think the bike gradually grew to dislike your approach to maiden voyages on pre owned vehicles . Did previous owner offer any maintenance history or warn you about "minor" issues? Driving around on empty gastank is good way to get any tank debris to carbs- keep it sorta filled, until you know more. Petcock needs to be checked before you conclude that it has a reserve position.
youll get less than 3 minutes of cranking starter before a fully charged battery gives up....unclear how your lights stayed bright. These bikes have lots of charging issues that need fixing
Get this thing running right - your life depends on it.

[steve murdoch]

Welcome to the site, TT.
Unfortunate that your first post is about a breakdown but given all the pertinent info you provided the smart guys here will probably have you back in action shortly.

The starter is probably 45ish years old and they indeed can get too hot from repeated use, get too hot and slow down/stop. Cool down and start working properly.
Any chance you have an in-line fuel filter that might be preventing fuel flow?
Could also be the filter on the petcock inside the tank is getting clogged with debris.
Not sure about your particular tank but some tanks have a small air vent in the cap that can get clogged and pressure in the tank builds up after a long ride and the gas will not flow. Wait on the side ofthe road for a bit and the pressure abates and the bikes runs fine. Was there a "whooshing" sound when you popped the cap to check for fuel?

[Steve]

Congrats on the 'new' bike and welcome to the forum.

Since this is your first bike, I will suggest that the first thing you do is put some gas in the tank. Or at least move the petcock to the REServe position. On a FULL tank, you might expect about 125-140 miles before switching to REServe. Unless you filled the tank and reset the trip odometer, you will have to trust the fuel gauge that you already suspect. In this case, it's probably not lying to you by very much. On re-reading your post, I see that you DID switch to REServe, but since the bike did not run, it did not have a chance to fill the carb bowls. Try switching the petcock the other way, to PRIme for about a minute, then trying to start the bike.

Your "phantom revving" is likely due to air leaks. Primary suspect here is the o-rings between the intake boots and the cylinder head.

Since you will have the carbs off to replace those o-rings, you may as well rebuild the carbs. Oh, since the bike is new to you with an unknown history, you better check the valve clearances, too. In fact, click HERE to see what we refer to as the "Top Ten Newbie Mistakes".

A good source for the intake o-rings and the o-rings necessary for the carb rebuild is cycleorings.com. No need for "rebuild kits", just these o-rings and a can of carb dip, and you will be good to go. If you don't feel comfortable splitting your carbs into 300 pieces, there are a few of us here that are willing to do it for you, for a modest fee.

Any chance you have taken a safety course on how to ride properly?

.

[Redman]

TT, Welcome to TheGSR.

Good that you have found GSR. But too bad your first post is a "dead on side of the road" post.

You have mentioned many things, some of which I am not sure what you mean, some maybe not related.
But, overall, most of what you say seems like you are dealing with a battery that started out okay and over time an useage has been run down because it is not being charged by the charging system.

QUOTE//////////////
-Abuse the starter button a little bit, and it gets weaker and weaker and eventually stops making any noise whatsoever
-Try pushing bike up a hill and bump starting it. Pop the clutch and bike starts perfectly, but the engine gradually starts chugging slower and slower until it sputters out (within 3 mins).
-Bump start it three times, each time the engine sputters out a little faster.
-Come back 45 mins later, and the starter sounds like it's alive again. Still no engine start or throttle response though.
////////////ENDQUOTE
That all sounds like weak battery from not being charged. Maybe the charging system has not been working and the PO had it on a battery charger, or maybe charging system has failed right after you got it.
WHile it was running before it quit, did you notice the turn signals flash slow and then not blink?? that is another sign of charging sytem not working and battery voltage going down.

THen later you said the lights were brite. That is sometimes hard to tell.
Which leads into something I often say "Can not troubleshoot electrical problems with your eyeballs, you need a voltmeter (multimeter)."
And the other thing I often say "YOu have a 35 year old motorcycle, you could use a voltmeter. You have an 80s GS, you need a volt meter."



QUOTE/////////////////
-Suddenly afternoon today, maybe two hours into the ride, I notice on two occasions phantom revving from just pulling in the clutch (while moving). Adjusted choke, and it seemed to be fine after that.
ENDQUOTE////////////////////
You say "adjust" choke. If you had left the choke on, well, that was the problem for the engine reving. (but not related to why not stasrt).



QUOTE/////////////////
-Evening time, while moving, throttle suddenly stops giving the bike any go (at all). Pull over to the side, turn off bike. After a minute, try turning back on. Starter doesn't get the engine running.
ENDQUOTE////////////////////
THat sounds like running out of gas. You say you rode 100 miles. Seems like you say there is some gas. You did say you put on RESereve. But even in reserve it takes engine vacuum to open the petcock (same as ON), so would have to crank alot before get any gas. Once the carbs do run out of gas, you can put on PRIme to get gas to the carbs without the engine running.

Note: if do put on PRIme, dont leave it there for more than a few minutes when not running.


So, tell us more about if you have gas. Tell us more about the battery voltage.
Maybe find a friend with a voltmeter.

Note: if you try jumping it from a car battery; have the car engine off (or else probably then you WILL have problem with your bikes charging system).

[unfocused]

I had a similar issue with my fuel system. I rebuilt it with new petcock/adapter plate, all new fuel lines and filter (lawn mower style - white) and rebuilt the carbs.
The vacuum style petcock is known for issues that you can search for. The "new" ones from eb*y are questionable at best.
The phantom idle issue is can be caused by several things, up to and including running out of fuel ( running lean does bad things )

Put fresh gas in the tank, turn the petcock to prime and see what happens.

As for the starter, if the bikes not going to start, don't keep beating on it. Not cheap

[Steve]

The vacuum style petcock is known for issues that you can search for. The "new" ones from eb*y are questionable at best.

Yes, there are "issues", but most of them are related to neglect, not use. Of all the GSes in this stable, my wife's bike has been here the longest. It came to us in early 2005. The petcock was a bit stiff, so I cleaned and lubricated it, it has been absolutely trouble-free since then. 14 years and about 35,000 miles.

No doubt the units from eb*y are questionable. Units from eBay are considerably better, but OEM units from Suzuki are a treat. They fit perfectly and work perfectly, and are likely to last another 20-25 years or so. Stop shopping on eb*y (wherever that is) and get OEM.

.

[T_T]

Hi all,

Thanks a ton for your answers. I had no idea that I had to turn to PRIme before REServe. I definitely just ran out of gas, and the battery just got weaker and weaker in my attempts to start the bike a few days ago. What a complete rookie mistake. Never again!

Actually I was on the side of the road yesterday with my bike looking a bit confused, and some guy comes up to me and goes "I used to own a motorcycle repair shop what's wrong" and literally diagnosed everything. He came to the same conclusion as you all. How do you guys know so much?! He jump started my battery and turned the petcock to prime then reserve, and my bike started right up as if nothing was ever wrong.

I'm going to replace the battery immediately. Previous owner didn't seem to have much maintenance history, so I'm for sure going to get this thing running right. I'm going to replace the brake hose and fuel line and intake boots and o rings, and also clean the carbs and get them tuned. As for possible leaks, I'll try the propane tank trick.

That roadside magical motorcycle mechanic told me my bike is in great condition. I was scared I purchased a dud from CL but I am so relieved! Hopefully running out of gas and having the engine sputter out after bump starting it those three times didn't hurt my bike too much.

Thanks again guys for your kind help.

[Steve]

I had no idea that I had to turn to PRIme before REServe.

Maybe it will help a bit to learn how that little device works.

Normally, you will have it pointing down in the RUN position. In that position, it draws gas from the top of a tube that is about three inches from the bottom of the tank. As the level of fuel in your tank (AND ON YOUR GAUGE) drops to that level, you will "run out" of gas. You will experience a feeling of running out of power and slowing down. If you catch it reasonably quickly, you can turn the petcock lever clockwise, so it is pointing forward to the REServe position. In this position, it is now drawing fuel from the bottom of the tank. There is about a gallon available, but you don't want to count on much more than 25-30 miles. There is no need to turn it to PRIme before going to REServe.

However, in the situation you just experience where you ran the carbs completely dry, or if you have not ridden the bike for several weeks and the fuel has evaporated out of the bowls, you DO need to turn to PRIme to fill the float bowls. In the RUN and REServe positions, it is necessary to have vacuum applied to the petcock to pull the diaphragm back, allowing fuel flow. The PRIme position pushes the diaphragm out of place mechanically, so the engine does not need to be running.

One major caution here: do NOT leave the petcock in the PRIme position for more than a minute or so, just long enough to fill the bowls. The float valves in the carbs should be able to hold back fuel flow, but sometimes fuel will leak around the valves (not through them) and flood the carbs, and likely the engine. Not leaving the petcock in the PRIme position will stop fuel flow when the engine is not running.

.

[Wingsconsin]

Prepare to learn a LOT
Be open to the challenges - take advice with grace -
Strive for understanding - Ask good questions -
The information stored in the archives here and among the members at large is immense
There is not a problem this group can't help you figure out with patience and willingness to get dirty
There will be frustrations and difficulties along the way and your character will be revealed.
But this forum is the BEST place on the planet to acquire the knowledge you need to own a vintage motorcycle

"There is no such thing as a cheap motorcycle"

[Admiral Beez]

I have the same bike. When I bought it I took it to my local vintage Japanese bike shop and had them certify it and go over the entire machine. Cost me a few hundred bucks but got everything fettled, fluids all round, brake cables replaced, air filter, all electrical connections cleaned and greased, etc. That way I started with a clean sheet.