Head start, getting a 'new' gs750

[Anonymous]

I am about to aquire a GS750 (1984?) that hasnt seen the road in at least three years. Most all the repairs have been made but I still need to clean up a few loose ends. Dont have the bike yet but I just wanted to throw out the problems that I have in case you guys have any sugestions, I want to get up and running before I run out of nice days.

The battery was just replaced, everything works fine but the battery goes dead after sitting for about two and a half days. I plan on checking the stator and rectifier per the faq on this site, I am guessing thats a likely cause.

The carbs were just disasembled and cleaned by a motorcycle mechanic, bike still hasnt been ridden but it idles fine and revs fine except that the rpms take a long time to slow back to idle. Aparently the diaphrams in the carbs were put in poorly by the last guy to work on it and some were pinched or folded or something? He straightened them out best he could and put it together, I dont have all the details about this yet.

Once I get the bike in my garage I will be able to check it out personally and start troubleshooting, just figured I would post this in case somebody has anything they think I should know. This is my first bike and I look forward to learning to ride.

[Billy Ricks]

Check and make sure the throttle cable has some play in it and that the manifolds don't leak. As for the battery discharging it may have never been given a full charge. You should go ahead and do a stator and R/R check. Also make sure you have a good ground on the engine and go through and clean all the connections and make sure they are tight.

[Mastiff]

You probably don't have an 84 GS750. Canada got the GS750, but we got the GS700 because of the Harley Davidson tax. Before 84 they were 750's. Take the MSF course. It will be worth it. The GS 750's are OK as a beginner bike, although I would prefer something smaller with less power for beginners. I started riding bikes when the biggest non-Harley you could get was a 750. People generally started with a 350 or smaller. Just remember not to get too deep into that throttle. This is a very powerful bike. Suzuki redesigned the 83 GS 750 motor to oil/air cooled, made more power at a lower weight. They are great bikes.
Clean all the electrical connections, and put a dielectric grease on them before you put the clean connection back together.
Where in Chicagoland are you located? I'm down by Oak Park at Harlem Ave and the Eisenhower.

[Anonymous]

I know its a 750 but dont know the year for sure. I live way out in batavia (next to aurora), I think all of northern illinois is a chicago suburb.

[Anonymous]

Hello, I bought an 83 GS750ED about 2 months ago, my first bike, it had sat for about a 1 1/2 yrs. I was unaware of this site when I bought the bike. I was unsure about the model year, the frame was stamped 82', the title said 83'. A member got me straight on the model and year. There was a minor electrical problem - directional flasher. The bike runs fine, although I had to rebuild all of the calipers, found most of the parts on Ebay. Another source for parts is bikebandit.com. I had to buy the factory service manual for this bike, for some reason Clymer and Haynes skipped the 83' model, and none of the service manuals include a parts lists, they are available on Ebay.
I have limited mechanical ability, but this site and the members have provided me the know how to do most of the work myself.
I agree about the MSF course, I took the course Oct 2-3, glad I did.

Good luck.

Bob
83 GS750ED

[AOD]

hey tmoreau, i'm in N. Illinois myself...actually NIU. g'luck with the bike...maybe i'll see you on the road soon.

~Adam

[Anonymous]

OK, just got the bike home and in the garage. Its an 81 GS750 with an indicated 6658 miles. The problems are a little different than I had thought.

First, you can start the bike with the petcock in the on position and it idles fine (normal rpm)... but touch the throttle and it dies. Also it will rev up to about 3k rpm and then drop back down from time to time on its own.

You can start the bike in the reserve position and it revs to about 5000 rpm and stays there. Throttle works as expected. Occasionally it will drop to around 1k rpm but then rev back up after a second. If you let it run for a few seconds and shut it off a couple times, it will leak gas out the airbox drain when you turn it off. I am guessing it would leak while running but I havent let it run at those rpms for more than a couple seconds.

The carbs were disasembled and cleaned (twice!) and aparently the last guy to work on them was a bit of a lunatic, hardware was missing or inapropriate and things were not assembled very well... as if it was thrown together as quickly as possible. A couple of the slides were sticking but were cleaned and polished (twice) and the float levels were adjusted so that they all matched although the mechanic did not have a manual so they may not be at the correct level.

I am thinking that the best route might be to get a rebuild kit and rebuild all the carbs, and replace the fuel petcock. Do carb rebuild kits include a new diaphram? From the sound of things the diaphrams may be damaged. I will be trying to find a service manual as well.

Thanks for reading this far, if you can help I certainly apreciate it.

[Anonymous]

correction: With the fuel valve in the on position it will only run for a minuet then run out of fuel and die. While running though, it idles right at 1000 rpm.

[AOD]

sounds like the vaccume line going into the petcock is either not connected, or the wrong line is connected.

having the floats at the correct level is probably causing the fuel overflow problem...that's just my guess at it.

~Adam

[Anonymous]

OK, I ordered a clymer manual but wont get it for a week or so. I pulled the carbs and checked the float levels, they were at 28mm and I moved them to about 25.5-26mm (dont know if this is right or wrong, but figured if that was the problem this would help).

I checked the fuel petcock, flows freely in prime and when I sucked on the vent line (half expecting a mouthful of fuel) there was resistance and then fuel flowed throught the fuel line. As I understand it this means its working properly.

I put the carbs back on without the airbox so I could better see whats happening, I also didnt bother to connect the throttle or choke cables.

in 'prime' position the float bowls fill up then fuel pours out the air passage hole on all four carbs simultaneously.
in 'reserve' position when I start the engine the same thing happens. in 'on' I seem to get no fuel flow, it will run for a while on whats in the bowl then die.


I am still very new to carbs and I dont understand what is causing this. Sorry for all the questions, its scary jumping into this kind of project with limited knowledge and I want my GS to run! Thanks for the help.

[mdole]

Re: Head start, getting a 'new' gs750

I am about to aquire a GS750 (1984?) that hasnt seen the road in at least three years. Most all the repairs have been made but I still need to clean up a few loose ends. Dont have the bike yet but I just wanted to throw out the problems that I have in case you guys have any sugestions, I want to get up and running before I run out of nice days.

The battery was just replaced, everything works fine but the battery goes dead after sitting for about two and a half days. I plan on checking the stator and rectifier per the faq on this site, I am guessing thats a likely cause.

The battery going dead after two or three days sounds like a current drain with the ignition off. These can be very hard to find. I have had things like defective relays cause this and the only way I found it was checking resistance on the relay and finding something like 50 0hms closed and 2k ohms open on the relay showing that when it was open it wasn't really opened only presenting enough voltage drop that whatever the relay was connected two would not function. The last relay I found this problem on was a starter relay on a Cavalcade. The other big place I have run into this sort of a problem is with add on accessories and wiring mods to the stock wiring where some one inadvertently put in a high resistance path to ground. Some accessories work like this so that they are on with a low resistance and off with a high 30k resistance but over time break down and the high resistance drops to the point that you get a small current flow even when the device is off.

The other likely problem is just a bad battery. I have occasionally picked up a battery that just didn't work from day one. The last on I picked up that was like that had an intermittent short in a cell that would allow the battery to partially discharge over a week?s period or time. The battery would also charge up to 12.3 volts one day and the next only charge to 10.2. This was just a bad battery but I have seen things like this happen on a good battery that was charged at too high a current.

I saw on just a few months ago where on of my sons friends had picked up a nighthawk and bought a new battery for it. He knew he needed to charge the battery but only had an automotive charger and wanted to try the bike out right now so he put the batter on charge in the starting position on the charger and charged it at 50 amps for the next 2 and 1/2 hours. This blistered some cells boiled off most of the water and ruined the battery.

Mike

[mdole]

sounds like the vaccume line going into the petcock is either not connected, or the wrong line is connected.

having the floats at the correct level is probably causing the fuel overflow problem...that's just my guess at it.

~Adam

Another possibility is that you have leaky float valves but because of all of the carbs overflowing this doesn't seem that likely. I only wanted to mention it because on a bike you just bought that you don't know the history of it's a possibility.

Mike

[Anonymous]

I plan on opening the carbs up again and taking a close look at the needle valves, odd though that the problem is with all four. Thinking maybe somebody left a peice out someplace so the fuel is not shutting off?

Does anybody know what the float height is supposed to be set at? I will leave them at 26mm until I get some solid info.

Not worried about the battery anymore until I can stop the fuel from pouring out! It hasnt gone dead on me yet so we will see... there are a few places where the wiring is butchered that I will have to closely inspect.

[first timer]

if you are playing around with cleaning the carbs and petcock, i would install a fuel filter as soon as possable so you don't have to re clean your carbs. about your petcock if you have written the old one off you may want to try to take it apart and clean it. if that doesn't work you can always get a new one. about your carbs you need to poke around here and get some info from fellow gs750 owners about mixture screw settings, float heights, and main jet sizes. you can also sync your carbs to but i would look into the petcock first it seems you have a fuel delivery problem. once you know the stock setup you can go thru your carbs and check to see if you have all the right stuff. oh yeah don't wory about takeing your carbs apart, they are pretty simple especially if you know all the setting for everything.

ryan