Burn fuses - regulator rectifiers? GS750 -77

[Warlock]

Hi.
My master fuse will blow as soon as I place one in the holder with key off or on.
Some say its the regulator rectifiers that I have to change. But if it's the regulator rectifiers, shouldn't the fuse hold until I try to start the engine?

It's a -77 so I only have one fuse.

[André]

I think you got a short circuit somewhere follow the wiring from the main fuse look for open connector or exposed wire that can touch the frame or engine, but you can disconnect the r/r to see what happen. Good luck.

[BassCliff]

Greetings and Salutations!!

Hi Mr. Warlock,

Start by checking and cleaning every electrical connection and ground in the entire wiring harness. Yes, it's tedious, but necessary. Look for any melted or worn insulation that is shorting to ground. Once you start digging around, it should be pretty obvious if you're blowing fuses with the key off. You should be able to find some useful documentation for your bike on my website.

Anyway, I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", the Carb Rebuild Series, and the Stator Papers. Now let me roll out the welcome mat for you...

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[Warlock]

Thanks for the welcome .

This is my first GS bike and I'm new to old bikes...

I will check all the wires, but I'm not 100% sure about the fuse. I bought the bike with a empty fuseholder and I can't find any information about how many A it should be. I guess it's a 10A fuse?
On -77 there is only one master fuse.

Former owner said it was the regulator rectifiers that was broken but I'm not so sure anymore

[fatnfast]

The single fuse is rated at 15amps for the 77 GS.
You may still have the original seperate regulator and rectifier on your bike. The fuse will pop, even with the ignition off, if the rectifier has a couple of short circuit diodes.
To check this, locate the rectifier behind the side panel (square object with cooling fins). You will see that it has a red wire. Disconnect this wire (trace it back to find the connector) and try again with a new fuse. If it pops again, you have a fault elsewhere.
Although in the UK, my bike is a USA spec machine the same as yours. I fitted a new combined unit suitable for a Honda CB250 Superdream (not sure if you guys had these bikes). I bought a brand new chinese copy for $30, and it works just fine.
Your regulator is fitted below the battery box.
Hope this helps,
Phil

[BassCliff]

Hi,

Mr. fatnfast raises a good point. Many here have simplified their wiring by installing a combined r/r unit and doing away with the separate regulator and rectifier. A member here, duaneage, sells upgraded r/r units for our bikes at a very reasonable price. I buy his units rather than Electrosport units. Or you could go with a new high-tech Compu-fire unit.


Thank you for your indulgence,

BassCliff

[Warlock]

Thanks for all the answers,,,, I found the problem .... I started to look at the cables and found one that was touching ground, I rewired that one.. Now I can try to start. the bike have been standing in a garage for 2 years so it will not start the engine. It will fire up with motor starter and then die, it seems that it not getting any gasoline.

So I guess the next step is to learn everything about the carburator... any suggestions?

[cowboyup3371]

Go to Basscliff's site he listed in your mega-welcome...everything you need to know is there.

[BassCliff]

It will fire up with motor starter and then die, it seems that it not getting any gasoline.

So I guess the next step is to learn everything about the carburator... any suggestions?

Hi,

Good work finding your wiring problem.

Now you'll need to read through your "mega-welcome" and follow the maintenance lists. Here's an excerpt...

***********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.

What I have noticed at the rallies is that very, very few 850Gs are actually running right. Make VERY sure it's actually running the way it's supposed to before busting out the modifications.

Brian's E-Z and fun plan for GS850 happiness:

1) Seal the airbox and air filter with weatherstripping.

2) Ensure no intake leaks. Spraying WD-40 or water doesn't tell you much, since very small air leaks can cause problems even though they won't suck in enough WD-40 to make a difference. Replace your intake boot o-rings and boots if needed, and seriously consider spending the lousy $28 for new airbox/carb boots.

3) Ensure clean carbs with correct settings, new o-rings, and original OEM jets. No, not just squirted with something. I mean completely disassembled.

4) Check/adjust valve clearances (Manual calls for every 4,000 miles. This is not optional.)

5) Ensure healthy electrical system.

6) Seriously consider upgrading coils and plug wires.

7) Install new, stock NGK B8-ES plugs gapped to .031".

8 ) Fine-tune float height and idle mixture screw to ensure best off-idle transition.

9) Clean air filter and reinstall with only the lightest oil mist -- over-oiling and/or letting the filter get dirty is a common and critical mistake, and will make the bike run funny at low speeds and run rich. This may take a few tries.

10) Make sure the exhaust seals are sealing.

11) Ooh, much better now, huh? You're gonna need upgraded suspension - Progressive or better fork springs and shocks. Set suspension sag appropriately.

12) Upgrade brakes with new pads and stainless lines to deal with all that extra speed.

13) Install new petcock, since I'm going to head to the roof with a rifle if I have to read about yet another #2 plug fouling and failed hillbilly attempts to rebuild the petcock and/or deny there's a problem.

14) Oh yeah -- check compression somewhere in there to ensure the valves and rings are reasonably healthy.

15) You'll probably need new OEM clutch springs -- the clutches last forever, but the springs get tired after 20 years or so under pressure. E-Z and cheap.
Carburetor maintenance:

Replace the intake boot o-rings, and possibly the intake boots. Here's the procedure:

http://bwringer.com/gs/intakeorings.html

Here's an overview of what happens with this particular problem:

http://cycleorings.com/intake.html

You'll also want to examine the boots between the carbs and the airbox. There's a good chance these are OK, but check them over.
And finally, if things still aren't exactly right, you'll want to order a set of o-rings for BS carbs from the GS owner's best friend, Robert Barr:
http://cycleorings.com
Once you receive these rare rings of delight, then you'll want to thoroughly clean and rebuild your carburetors. Here are step-by-step instructions that make this simple:
http://thegsresources.com/gs_carbrebuild.htm


There's lots more GS lovin' on my website. Please feel free to have yourself a heaping helping.



Thank you for your indulgence,


BassCliff

[Warlock]

Fixed the wiring, changed battery and blow the carburator. Now she's up and running

starts easy but the idle can get stuck at 2300 rpm and the go down after a while to 1200 and then go up again.

Today... new plugs and take her out for a ride

thanks all for your help