New Project: 78 GS750

[Guest]

So today I went and picked up my bike, a 1978 GS750. Eventually I plan on doing some light modifications both for appearance and performance so I figured I may as well start a build thread for the bike. But first I want to start with some maintenance items here's what I've found from my 10 mile ride home with the bike and the associated questions:

Front tire - needs replacement due to the early stages of age cracks, thinking of going with the Dunlop D404
Check brakes front and rear/new fluid
Clutch - has an extremely hard pull to it. Is it common to put aftermarket springs in these bikes? Also which cover is for the adjuster?
Oil change
Front brake light switch doesn't work - has a non factory master cylinder so unsure of where to start on this
Headlight side adjustment screw is missing
Clean & lube chain
Very extreme handle bar shake at certain speeds if I let go of it
Mount tank - What is supposed to be there? See picture
Fix original fuel petcock - The previous owner said it didn't work, and there's an inline aftermarket petcock, are the original ones still available?
New plugs, check timing - possibly new points
Lube all cables

Anything I'm missing in the list that you think should be done? Once I complete the list I'm going to move on to replacing/repainting parts that have rust on them.

 

[Guest]

Gas tank mount

Gas tank mount

This is the picture of the gas tank mounting bolt. Obviously there should be something else here but what is it?

 

[GSXR7ED]

Subscribed!


Ed

 

[gwyon]

Follow the clutch cable down to a small cover on the left side. The tank parts you need are a couple of rubber cushions and a steel spacer. Fiche is your friend.

http://www.suzukipartshouse.com/oemparts/a/suz/50d3fecff8700230d8b4dcc3/fuel-tank-gs750c

 

[cowboyup3371]

So today I went and picked up my bike, a 1978 GS750. Eventually I plan on doing some light modifications both for appearance and performance so I figured I may as well start a build thread for the bike. But first I want to start with some maintenance items here's what I've found from my 10 mile ride home with the bike and the associated questions:

Front tire - needs replacement due to the early stages of age cracks, thinking of going with the Dunlop D404
Check brakes front and rear/new fluid
Clutch - has an extremely hard pull to it. Is it common to put aftermarket springs in these bikes? Also which cover is for the adjuster?
Oil change
Front brake light switch doesn't work - has a non factory master cylinder so unsure of where to start on this
Headlight side adjustment screw is missing
Clean & lube chain
Very extreme handle bar shake at certain speeds if I let go of it
Mount tank - What is supposed to be there? See picture
Fix original fuel petcock - The previous owner said it didn't work, and there's an inline aftermarket petcock, are the original ones still available?
New plugs, check timing - possibly new points
Lube all cables

Anything I'm missing in the list that you think should be done? Once I complete the list I'm going to move on to replacing/repainting parts that have rust on them.

Stay away from the Dunlop 404 in my opinion as they get real nasty towards the end of their life. The Shinko 230 Tourmaster is a much better tire with better life all the way through at about the same or less price

They do make a hydraulic brake light switch that you can get from Z1 Enterprises. It uses a banjo bolt to screw into your MC and connects into your wiring. The biggest issue with them is that you have to pull on the brake lever a short distance before it activates the light so it's harder to just "flash" your brake lights at someone.

I would look at replacing the bearings both in the steering stem and in the wheel. That with new tires will help you immensely

What kind of condition is the chain in? You might want to replace it and when you do, you must replace the sprockets at the same time as they all wear together.

For some parts, like the headlight adjustment screw, use your favorite Suzuki dealership but remember that most parts counter folks don't know or care about your aged bike. I recommend using the parts fiche to record the numbers and give them to the parts counter. They will still get most everything though it can take up to two weeks as they have to order from their warehouse. The forum's favorite dealership though is Parts Outlaw (www.partsoutlaw.com) in Florida as they have the best service and prices.

Z1 also sells a very good petcock for the bike and their customer service is top notch. You'll get their parts in about 3 - 5 days.

Please do a valve adjustment and clean the carbs from the beginning so you have a solid base to start with. If you start the process at the same time you order the parts you need (gaskets, O-rings from www.cycleorings.com, etc), everything can be finished about the same time.

 

[DirtDiver]

Good to know about the Dunlop as thats the rubber currently on my ride..

 

[Guest]

Well thanks for the suggestions so far. Tire is planned for tuesday, still haven't decided on it and open to suggestions but a shop near me has most of them in stock. The next thing I want to tackle is the clutch that way it'll at least be safe to test ride a little until everything gets done. So far I've lubed up the connection at the control lever and the mechanism at the engine side and it's still super hard to pull. Not sure if this is normal, but it seems as if the shaft to the clutch moves up slightly before it starts to rotate and I think this might be the problem but any advice is appreciated. Is there a bushing behind the mechanism? I'm going to order a new cable just because of the age but it seems to be moving smoothly. Anything else to check on this?

 

[cowboyup3371]

It's possible someone put in heavy duty springs so you'll want to check them and replace at least half with OEM.

 

[Guest]

Any chance there is a marking or something on the factory springs? I was thinking of using a borescope so I know for sure before I pull it apart

 

[Guest]

Here's an update for today. Parts are on the way and I got the new tire fitted, unfortunately I did end up with the Dunlop but the rear is about a year old and when it starts getting low I think I'm just going to replace them as a set and after doing some reading I think the Shinko 230 is what that set will be. I planned on repacking the wheel bearings but it looks like someone has put in sealed bearings and they spin just fine so I put it pack together as is. I think I figured the clutch out, the lever arm that the cable goes to was not on the flat properly and the cable was way out of adjustment. Seems to be a little better but still slightly stiff, I'll know for sure after some more riding.

 

[Guest]

More problems

More problems



Finally got a better picture or the bike. I rode it to work yesterday, a good 50 mile round trip and found some more problems. First obvious problem is that it'll probably need a clutch replacment relatively soon. Noticed a vibration under braking in the front so I may have a warped rotor and can't seem to find a replacement online anywhere. Also, in typical GS fashion the battery does not go anywhere above 12.5 Volts at any RPM. Strangely enough I've done about 70 miles on the bike so far using only the electric start and lights on the whole time and have never had a dead battery. I guess I'll just start going through the stator papers to find the problem.

 

[jibledso]

Oh no, I didn't realize it was difficult to find another rotor, I'm in the same boat with my GS750 which I didn't even mention. When I was riding it last fall it had a definite wobble when braking, especially at low speeds.

I haven't gone through my charging system yet since I'm still waiting on parts to get it running correctly, but funny enough there is a parts dealer here in Sweden in Uppsala that sells new stators, it's nice to know if you have to go there.

Wow, your bike looks great cosmetically.

 

[Guest]

Exhaust

Exhaust

Just a quick update: I've been through most of the list with the exception of the brakes so far. I also painted the exhaust because I just couldn't stand the look of the rusted header pipes. It came out alright, definitly better than it was. While I'm here does anyone know what aftermarket exhaust this is? It came on the bike when I got it. I also put in new plugs as the old ones where the wrong heat range and boy did they make a huge difference. Now that I've got it riding pretty well I think i'm going to start doing some modifying. First thing to go is going to be the mirrors, but I'll give another update when I get to that.

 

[wymple]

Doesn't the 78 have points? I would upgrade to Dyna ignition either way. That includes coils. If the bike was made with points, get the 5 ohm coils, if not you can use 3 ohm coils. It's a coil life issue that's a bit argumentative, and the subject of a lot of back & forth on some forums. I have personally burned up 2 sets of green Dyna coils over the years by getting this backwards. Not looking to start anything, just google it for your own opinion.

 

[Guest]

V&H? It's hard to tell from this angle.

 

[Guest]

Here is a rotor on eBay.

http://www.ebay.com/itm/1979-Suzuki-GS750-GS-750-79-Right-Front-Brake-Rotor-/232089662644?hash=item36099f34b4%3Ag%3A8hUAAOSwIgNXkvsO

 

[Guest]

Yep the bike has points and electronic ignition is something I had in my head for the future. I'm a car guy and i'm really into engine tuning so if I could find a unit that would allow me to do a programmable timing curve that's probably what I would end up with. As for the exhaust I think I have figured out that it is a V&H header with some generic muffler put onto it. And finally the brakes I think I am going to clean up the calipers and see if that gets rid of the shake under braking and if not then I guess i'll have to try to find a good used rotor

 

[jibledso]

Well, I'll follow your step, take the caliper off and clean, maybe it will make a big difference.

I also have a a V&H but it's the full exhaust, maybe we can go back and forth while dialing in the carbs, or I assume yours are quite close already.

I put a K&N replacement in the factory airbox, so I'm going to have to change the needle height and maybe the mains, they have 105s now, and it rode quite nice with a slight hesitation when taking off with the throttle too open.

How's your bike run when running hard threw the gears?

 

[Guest]

I haven't even touched the carburetors yet. I set the timing (it was way off) and the plugs show that the bike runs pretty rich. That being said it pulls hard in every gear and all around runs great. My air filter is just about destroyed so I may go with the K&N as well but they are kinda expensive so I may just end up finding filter material and re wrapping the cage that's in there. I did pull one of the float bowls the other day just to see how dirty the inside of the carburetors where. To my surprise they are immaculately clean. One thing that struck me as odd is it had a plastic main jet in it. Is this normal?

Also forgot to mention that cleaning the front and rear calipers got rid of the shaking. I didn't even replace the seals just cleaned up the pistons and cleaned out all the old fluid

 

[Sam 78 GS750]

One thing that struck me as odd is it had a plastic main jet in it. Is this normal?

The jets are usually brass. I've never seen plastic jets on a bike carb.