GS750 back to nice.

[Drummert]

Hi Guys,


I'm new here. Decided to, finally, make some work of the old GS. I've been driving it for about 2,5 years, bought it in a not so good state, and had to buy another motorcycle at some point because I didn't believe this one to be very reliable anymore. Long story short, the older one wins when it comes to getting me to smile. The problem these last few years has been that I don't really have a lot of space to tinker away, nor a lot of money. So it will have to be a 'one-at-a-time' job mostly. Still, I would very much like to see it back to a reasonable state again.

Work to do for as far as I know (newbie at motor-mechanics):

• Fix/replace exhaust (Hole in the left exhaust), blue discoloring
• Replace headgasket (heard a loud bang whilst riding, after which it started to leak oil. Happened right after its last servicing at a shop)
• Clean the carburators
• Fix/replace seat (not the original anymore, but done for)
• Check the suspension.
• Get a new rear tire ^^

The motorcycle doesn't have to ride at the moment as I own a GSR also, but it can't be in parts for a long time either, due to space. With that in mind, what would be my best starting point? What are major problems I have to look out for? I already came across BikeCliff's formal welcome, but just starting without a good idea of what I'm doing seems a little daunting at the moment. I would really like to learn how to keep these machines in a good condition, but unfortunately I don't know anyone close to where I live who could help me with it.


Some photo's for you guys:

 

[Weasel]

Welcome Drummert. I picked up a '78 GS750 a few months ago. Chuck78 is a wealth of knowledge on these bikes and should be along here shortly. He got me on the right track with a plan on what order to work on things along with the best parts and where to source them. You can click my link below to read his input. Good luck, I'll be following along.

 

[Buffalo Bill]

Your list does not have to all be done in one episode. It's really about one thing at a time when it needs to be done and you have the time to do it.
I usually choose the easiest thing first, and the most difficult for last.

 

[Drummert]

Allright,

So I decided to start with the carbs for now. They are the vm26ss ones. Got myself an o-ring kit and new boot o-rings from cycleorings, new top cover and float bowl gaskets and some aluminium crossovers and tees.
Luckily, the bolts at the boots to the cyllinders have already been replaced by some allen head screws.


And now we wait for parts...

 

[dorkburger]

Welocome to the GSR. Regarding the seat, it looks like it may be a Guiliari seat. They seem to be somewhat rare and coveted.

 

[tkent02]

The one thing that is often neglected that will cause expensive damage is valve clearances. The valves normally get tighter as they wear, if they are allowed to get too tight the valves will burn.

Patch that old pipe and keep it on there until you know everything is working correctly as far as carburetion, it would be a shame to buy a shiny new pipe and turn it blue from running lean for some reason.

Check the charging system, and clean up every electrical connector in the whole thing. Corrosion causes resistance, resistance causes heat, this heat causes the plastic connectors to melt, melted connectors allow the wires inside to short out, then very expensive parts go poof.

The corrosion need not be visible to be harmful, even slightly tarnished brass connectors will cause resistance and heat.

Welcome to the forum, the old 750s like yours are one of my favorites.

 

[rudeman]

Love those first gen GS750s. Their motors are absolute tanks. If you use a bit longer shocks it'll steer much quicker. I saw a pretty cherry seat on FleaBay a couple of weeks ago.

Where is it leaking from??

 

[Drummert]

Thanks guys,


Dorkburger: That's the name I couldn't find anymore! I found it at some point, a year or so ago. It's not an original though, but a remake (no logo, and probably was never there). I'm still between getting myself a new seat or taking this one to an upholstery shop. I like the look of it.

tkent02: Would the valve clearances be a possible thing to check myself, with my (at this moment still existing) lack of knowledge? I'm not afraid of taking the engine apart, more of damaging something in the process.

Funny thing, I always thought this was a 2nd gen GS750, because of the wheels.

 

[Drummert]

And I do plan on changing the suspension. Read some nice things about that on this forum. Fork is pitted, so I'll probably do that all at once.

 

[tkent02]

tkent02: Would the valve clearances be a possible thing to check myself, with my (at this moment still existing) lack of knowledge? I'm not afraid of taking the engine apart, more of damaging something in the process.

Easy do it yourself stuff. You need a feeler gauge, 10mm and 19mm wrench, a few shims, a new valve cover gasket and something to scrape off what's left of the old one. Also requires a special tool which costs about $20, but some folks like to use zip ties and a slightly more cumbersome procedure instead. Either way the hardest part will be removing the old gasket.

 

[Drummert]

Ok, seems doable allright. That's gonna be step 2.

 

[Drummert]

Where is it leaking from??

It seems to be leaking from the gasket between the cyllinders and the top.

 

[rudeman]

Did you just start riding it? Had it been sitting for a while prior to you buying it?

It seems to be leaking from the gasket between the cyllinders and the top.

 

[Drummert]

Bought it 2,5 years ago. Unfortunately I don't know what happened before at the PO. I know the shop I bought it at did an engine revision, but I do not trust it that much anymore.
Leaking started about 1,5 years ago, after which I bought a second bike and this one only came out occasionally. Leaking started after a bang whilst driving after it just got back from a shop.

 

[Drummert]

Allright, so I checked it today with a bit more light. Oil is leaking from the head gasket. It's not much, but still. Also, I can't read the oil level, the oil inspection window is dirty. Can you clean that one or should I just replace it? Already found a way to put in a new one somewhere.

 

[rudeman]

You should be able to clean the oil sight glass. Don't forget to clean the metal reflector as well.

 

[fred smailes]

Thought I'd throw this out there.
I was on a road trip with my 81-850g and it started leaking oil. It got quite bad soaking my gortx pants but made it home.
Upon inspection I found the vent tube from the top of the motor to the air cleaner blocked. A closer look reveled the distribution panel in the air cleaner housing was rusted closed creating a lot of pressure in the crank case.
After fixing the problem the oil leak was much reduced but the seal on several gaskets was broke so it still had small leaks.
Fred

 

[Zagg]

Bikecliff's website has most of the info you will need including manuals, vendor info, and tutorials on pretty much everything you need to do to the bike. The manuals will have valve clearance adjustment instructions as well. I think you are heading in the right direction... Get the engine cleaned up, adjusted, and running right before spending time and money on comfort and cosmetics. Good luck, brother! Sounds like you're on the right track.

 

[Drummert]

Yeah, that one has been really helpful already.


So I made some room to work at my grandmothers ^^ (my grandfather had two workbenches there, and a lot of other stuff I will have to have a look at at some point in time), so there's enough space to work on the first parts.

I figured it doesn't really make sense to clean the carbs and not clean the tank, so I'm doing that one also.
For now I ordered gaskets for the carbs and valve head cover+breather and for the clutch and points covers, O-rings for the carbs, intake boots and oil filter cap, some aluminium crossovers and tee for the carbs, a new oil filter and a valve shim tool (didn't want to mess with tie-wraps). That should get me started for now. I also ordered some evapo-rust for the tank.

Now for another problem: They don't sell the Berrymans'/GUNK here in the Netherlands. They do sell some carb cleaner, but either it's a spray or something you should add to the gas. I figured I could buy a few cans of spray and just drain them in a container. Would that do the trick? Otherwise: anyone living in Europe who has tackled this problem in another way?


It's already been a great learning project. Just tracking different parts is already helping me understand how everything works.

 

[Guest]

Our European carb cleaner works ok as a spray, but is no good as a dip, as it evaporates quickly. Personally I use an ultrasonic cleaner, and then verify that I've cleared all the passages by using an aerosol carb cleaner.