77 GS750 - First Rebuild

[tbell]

Hello All,

I have been following this forum for some time. I have wanted to learn a lot more about motorcycle mechanics, and I thought the best way to learn would be to buy an old bike and work on it. After following this forum for a while, I knew that I would look for a Suzuki because this forum would be a great place for assistance. About two years ago I purchased a 1977 750 GS (picture below). Although the owner said it was running with a degree of dependability, I have not had an opportunity to run it. I did do a compression check on it and I know that I have a problem with 1 cylinder. I purchased it in the winter and got a great deal on it so I was not too worried about its mechanical state. My entire goal with this project was not so much to get a running motorcycle (I already have one) but to get something I could work on and LEARN from. The bike came with a ton of extra parts, wheels, an extra frame and an extra motor. My plan is not a restoration, but rather to get it up and running. I will be posting the progress as it goes, along with looking for lots of advice. Based on the number of parts that the owner had, I am sure that this bike is a compilation of several different years and models. I am not too interested in bringing it back to a true 1977, but I would like to know what is from the 77 and what has been added/removed. It also came with a front fairing (not shown in the picture).

I have already downloaded some of the manuals and other documents. My first step will be to rebuild the carbs.

http://s1275.photobucket.com/user/tbell1961/media/suzuki_zps09ef643d.jpg.html

 

[tbell]

Here is the picture of the bike...

Here is the picture of the bike...

 

[btbarb]

.. but I would like to know what is from the 77 and what has been added/removed.

missing stock airbox
those are not '77 turn signals on front or back
front master cylinder not '77
missing mirrors

 

[tbell]

I am in the process of rebuilding my carbs from the bike. The bike was not running at the time I bought it. I have attached a picture of the carbs. I am using the VM Carb Rebuild instructions by Paul Musser. In the instructions My questions is this. The instructions tell me to remove the Pilot Fuel screw. There isn't one in any of the 4 carbs? What am I missing? Is this the correct set of instructions? Everything else seems to match up?

 

[Chris G]

So what's the slotted brass looking screw I apper to see on the RHS, now the LHS you rotated your pic

 

[tbell]

So what's the slotted brass looking screw I apper to see on the RHS

Pilot Air screw....They are all accounted for, its the fuel screw that's missing.

 

[Chris G]

Your fuel bowl drain plug is different to your exploded diagram, you sure what carbs you have, those drain plugs look identical to what's fitted to my 29mm Mikuni smoothbores !
im no carb expert but a number of carbs look very similar on the outside, but it's the internals that differ, here's a link to a exploded diagram of the smoothbores, note item 87 the Venturi block, does your carbs have this, my understanding of the large drain plug is because it gives direct access to the main jet, so they can be replaced without removing the carbs, some refer to them as racing carbs.
if they are smoothbores and there serviable, there worth big bucks.

http://www.allensperformance.co.uk/exp-vm29.html

 

[allojohn]

So you've taken the bowls off and there's no pilot fuel jets at all? Someone must have borrowed them! You should have VM26's on that thing which have different settings/jets depending on the model. It would good to find out exactly what model you have there.

 

[TeamDar]

Those are 29mm smoothbores.

 

[steve murdoch]

Those are 29mm smoothbores.

Yeah the 17mm nut on the bowl and the square box on the carb body just above the float bowl make them 29mm smoothbores.
Good score, tbell.

I forgot...tie up your boot.

 

[GSX1000E]

The 29 smooth bores still have the fuel screw in the same location. Have you checked to see if the camshafts have been changed also?
Perhaps even been bored?