Bike dying when using turn signals

[Guest]

Hi All,

At first I wasn’t really sure where to post this since it seems to be a fuel/electrical combo situation.

I just got my 1977 GS400X running again after it was sitting for a few years. I live in the city and don’t have a place to work on it so I ended up taking it to a shop to bring her back to life. The guy that looked at it said it was still in pretty good shape so all he really had to do was :

1) Carb cleanup
2) Dress and adjust points
3) Set timing
4) Check valves (0.003)
6) Change oil
7) New battery
8) Clean plugs
9) Replace air filter (installed pods, see below)

The bike runs pretty nicely however I noticed a problem when the bike is ideling.

The bike typically idles comfortably around 1300-1400rpm however, when I put on a turn signal the idle begins to dip (like a hiccup) and in some cases it will cause the bike to die (requiring a fast kick start in traffic).

If I put the turn signals on and then turn them off when the idle beings to dip, it returns to normal (his is very reproducible).

I understand that these bikes have some stator issues however I’m not super, super familiar with them. I did check the battery and it holds a charge. When I rev the bike the voltage rises. The bike functions normally during higher-speed riding.

Okay, here’s the second part (the part that made it hard to decide which category to put the problem in):

A few years back when I was riding regularly I put shorty pipes on the bike but didn’t reject the carbs (this didn’t seem to make much of a difference). However, my mechanic now installed pods and insisted that I didn’t need to rejet my carbs. This seems a little odd to me since it seems to be a rule of thumb than when you mess with air/fuel mix you usually need to rejet.

Do you guys think this an electrical problem, a fuel/idle problem, or both?

Any insight would be greatly appreciated.

[Cipher]

is lectrical is stator or regulator related.
I have had this hjappen to me when a battery was marginal due to a weak charging system.

You have a meter? Dont need a fancy fluke just about anything will do.

[Redman]

Sounds like turning on the t/signals is enough of added load to drop the voltage to where the ignition is barley working. But that should not happen if the charging sysgtem is working enough to keep the battery at a good charge.

And... as with most eletrical problems, you need a volt meter (multimeter) to check out the charging system.

Check battery voltage with key off, then with key on, then bike running at idle, then again at mid rpm (like 4000).
List the results here.

[mcquillr]

That makes sense to me as well. I will check these volatages tomorrow and post em up. Thanks!

[Redman]

Here is a better description of the "Quick Test"

https://www.thegsresources.com/_forum/showthread.php?164993-Charging-System-QUICK-TEST&p=1272192#post1272192

as developed by Posplayer

[mcquillr]

The test results are in:

Key Off (Pre-start): 12.57V
Key On (w/lights 10s): 12.25V
1500rpm (idle): 13.76V
2500rpm: 13.39V
5000rpm: 13.52V
Key Off (Post-test): 13.36V

[Cipher]

the battery is somewhat depeleted at rest.
You should check the bulb sockets mine love to corrode being madde of a chromated cheap metal
also check the connectors to the harness the bullets are evil and get loose with repeated removals
they build up a thickish layer of tarnish as well
if a check and or clean of connections and sockets makes no difference well then clean the switch. AN amazing amount of dust can get packed in there giving you three contact points of cumulative resistance overall.

[Redman]

The test results are in:
...........

Charging system is working, could be a little better, maybe some bad connections here and there. But good enough to mostly charge the battery and keep the bike running. Not bad enough to explain the bike stalling when use the turn signals.

Bike stalling when use the turn signals sounds like low voltage to the ignition.
Try measuring voltage at the coils (the org/wht wire). Will have to have the tank off to get access to that.

[mcquillr]

Okay good thinking!

Redman: I will test the voltage at the coils this weekend and report back.

Cipher: I will check the bike up-and-down this weekend for loose and/or dirty connections & switches and report back.

Thanks for the advice!

Question: Should I think about changing out my R/R to a series R/R as a preventative measure? Also it was suggested in the Top Ten Newbie Mistakes thread that you should re-route the headlamp switch leg back to the R/R to prevent stator overheating. I imagine this is referring to the day/night paths in the pre-1978 charging system diagram in the Clymer manual?

[Uncamitzi]

I would suggest that you check the fuse box and make sure the contacts holding the fuses are clean. feel for heat on the fuse box, this will tell you if you have a bad connection in that circuit.

[OldVet66]

Hi All,
A few years back when I was riding regularly I put shorty pipes on the bike but didn’t reject the carbs (this didn’t seem to make much of a difference). However, my mechanic now installed pods and insisted that I didn’t need to rejet my carbs. This seems a little odd to me since it seems to be a rule of thumb than when you mess with air/fuel mix you usually need to rejet. Do you guys think this an electrical problem, a fuel/idle problem, or both? Any insight would be greatly appreciated.

If he installed pods you need to re-jet but only after you fire your mechanic. Exhaust is not so bad but pods change everything! Your bike should idle at 1,000RPM. It seems you have more than one problem.

[Redman]

Good that you have reviewed the Top Ten Newbie Mistakes information.

............
............... should re-route the headlamp switch leg back to the R/R to prevent stator overheating...............

That is a recommendation for 1980s and after bikes (dont have the headlight on-off switch). I think your 77 will have the headlight swtich, and if you do want to retain the headlight swtich you will want to keep the wiring in the stator circuit up to the headlight switch and back.

[mcquillr]

Good that you have reviewed the Top Ten Newbie Mistakes information.


That is a recommendation for 1980s and after bikes (dont have the headlight on-off switch). I think your 77 will have the headlight swtich, and if you do want to retain the headlight swtich you will want to keep the wiring in the stator circuit up to the headlight switch and back.

Actually, I don’t have an on/off switch either—only a hi/lo switch. There seems to be a hard piece of plastic that acts as a placeholder for where an on/off switch would be.

[mcquillr]

I would suggest that you check the fuse box and make sure the contacts holding the fuses are clean. feel for heat on the fuse box, this will tell you if you have a bad connection in that circuit.

Added this to the list!

[mcquillr]

If he installed pods you need to re-jet but only after you fire your mechanic. Exhaust is not so bad but pods change everything! Your bike should idle at 1,000RPM. It seems you have more than one problem.

You are correct that it will not hold an idle at 1000rpm. I currently have the idle set between 1300-1400rpm (I though I saw this as the correct range in the owner’s manual, but I don’t have it in front of me to check that).

Okay so if my limited intuition is right, pods would increase air flow and lean out the mixture so I should be jetting up to increase fuel? Is there any rule of thumb with re-jetting or is it simply trial and error?