Newbie: 1978 GS750E Starting Issues

[jots77]

Hi All,

Last summer I purchased 1978 GS750E with ~30K miles. The bike starts when used regularly (say every 2-3 days) yet is a bear to start when it has sat a bit. The battery drains after ~5 days. I can usually get it started with a battery charger or by 'busting my hump' for 10+ minutes with the kickstarter but there must be something wrong. I realize I shouldn't believe the PO when he told me that the battery was relatively new, but it doesn't look very old either. I have replaced the spark plugs which were, and still are, coated in a dry black film. I am a complete novice with respect to both maintenace and repair, but I have the Clymer manual, the vast GS resources, and the willingness to learn. My theory is how bad can I screw up a 30 year old bike? I guess I am looking for a road map of sorts; should I clean the carbs, have the battery tested, ect...

Additional questions:
How does one know if their bike is running on all four cylinders?
How does one clean the contacts?
How does one perform a spark plug test?

Thanks in advance! I still can't believe that I stumbled across a bike with such a dedicated and knowledgable following.

[Dave8338]

Congrats...you've found one of the best websites on the net! \\/
Now, on to your issues, as they relate to your bike. When you do get it started, does it idle fine, how about the road trip, does it pull hard through all the gears? Do you notice a flat spot at any point through out the RPM range? Have you checked all the connections on the electrical side of things? All the connections...and pay special attention to the various grounds. These are just a few issues to check first, then on to the more detailed points that are most likely to ensue.

Again, good to have you aboard.

Dave

[Billyboy]

Hi All,

Last summer I purchased 1978 GS750E with ~30K miles. The bike starts when used regularly (say every 2-3 days) yet is a bear to start when it has sat a bit. The battery drains after ~5 days. I can usually get it started with a battery charger or by 'busting my hump' for 10+ minutes with the kickstarter but there must be something wrong. I realize I shouldn't believe the PO when he told me that the battery was relatively new, but it doesn't look very old either. I have replaced the spark plugs which were, and still are, coated in a dry black film. I am a complete novice with respect to both maintenace and repair, but I have the Clymer manual, the vast GS resources, and the willingness to learn. My theory is how bad can I screw up a 30 year old bike? I guess I am looking for a road map of sorts; should I clean the carbs, YES have the battery tested, ect...

Additional questions:
How does one know if their bike is running on all four cylinders?
The pipes are hot.
How does one clean the contacts?
Nail file
How does one perform a spark plug test?
Chop test: Run it in 4th at 35mph and kill the engine. Pull plugs, check for a nice tan colour. Black - rich. White - lean.

Thanks in advance! I still can't believe that I stumbled across a bike with such a dedicated and knowledgable following.

Comments in red.

[tomo]

Both my GS750`s and my CX500 are pigs to start unless I use this old trick. Pull on the choke, then blow a couple of times into each of the two carb breather tubes. Chances are if the problem is`nt electrical, the bike will fire up. I guess it pushes a bit of extra gas into the jets. Sounds daft, but give it a try, has always worked for me. See my posting in tech tips.

[tkent02]

If the battery drains after four days, there is a problem....

Disconnect it, and see if it still drains. If it does, replace it. If it does not, you have something on your bike drawing a little bit of current, find it and fix it.
A properly set up bike should start easily until it sits a long time, the battery should last a month or so too depending on ambient conditions and it's age.
Not good for it to sit but it should start.

[jots77]

Thanks for the quick replies!

Dave, I generally get it started on full choke which once it starts is backed down to say 1/3 choke. The bike idles a bit fast for say five minutes then I can back the choke down to zero and it idles fine. The bike seems to run fine (this is my first bike so it is hard to say what a 750 should feel like) but one day I was riding and the bike seemed especially strong. I mean that I literally thought 'wow'! This is why, along with the spark plug issues (I replaced the NGK boot on one of the plugs becuase it did not seat well), I am concerned that the bike is not always running on all fours. With the winter in Buffalo I haven't ridden in about three months so I can't really comment on any flat spots. I was reading the hayes (not clymer) manual last night and I will have to begin to cleaning various connections.

Billyboy, thanks for the quick answers!

Tomo, I've read of the breath trick at multiple places on this site and will certainly give it a go!

Tkent, yeah I guess that's a bit of a no brainer but I haven't tried it. I will fully charge the battery and see what's going on there. I have this 'citylights' small balck box thing (I'll call it a relay) that connects via two small wires to the battery and has a second wire package leaving towards the front end to somewhere. I don't know if this relay is part of some display lights or what. I've always been concerned that this unit might be part of the problem. Basically, I need to disconect it and see what happens.

[Steve]

Another thing that will cause very hard starts...

Valve clearance, or the lack thereof. Check the valves. Normal clearance is only about the thickness of a piece of paper, .002-.004". As valves wear, the clearance gets LESS. With no clearance, the valves might not be closing all the way, making it difficult to obtain compression. Makes for very hard starting and poor (usually rich) running, evidenced by your black plugs.


.

[thekegk]

i have a gs 750en 79 and i had a battery drain problem at first i thought my stator went out but i found one of my diods was bad on my rectifier. tosee if your bike is chargeing correct run it above idle amd see if the battery reads above 13volts

[Matt Vann]

When I know my 1100 is going to be in a cold-natured mood (especially when it's been sitting for a while,) I pull the choke and remove one carb pod. I then cover the carb air intake with my hand for a couple of cranks and it lights right off.

[bradleymaynar]

I stated this earlier in a different thread. If I know I'm going to be off the bike for more than a few days (unheated garage), I plug in the battery tender. If the amount of time the bike sits is more than 5 days, I spray a bit of non-ether starting fluid into the filter box. I then pull out the choke and hit the starter button. It may take a few tries, but it generally starts. I have a throttle lock (can be purchased for less tha $10 at most bike shops) so that I can up the throttle a bit for idling. I generally wait a couple of minutes and the take-off. I push the choke in while I'm riding away.

And as a note, the longer my bike has sat, the longer it runs on less then all cylinders.

Brad bt

[jots77]

Success!

Hello Again,

Thought that I'd update the thread with the results. I tried charging the battery and after a few attempts and error messages determined that the battery was shot! Either the PO misinformed me about the whole 'relatively new' statement or I fried it when over using the charger as a jump starter. Either way I purchased a new battery, added some Stabil (couldn't find Seafoam) and after a few 'puffs' on the carb breather tubes the bike fired up! Seemed to be running pretty strong too. I took it up and down the street (it is ~20F outside) and it lives. Now to work on cleaning out the carbs properly and trying to do a bit of a repaint. Thanks for all of your help and suggestions.