me, my friend, and our 1978 GS750

[schwalbewurger]

Hi all,

I'm Bennett and my friend and I are currently in the process of making this bike run again. The person who owned this bike before us tried to convert it to a cafe racer - left many of the wiring unfinished.

Here's a list of things we did and are currently in the process of doing:

-Changed to new oil and oil filter
-Changed to new spark plugs and spark plug caps
-Changed to new R/R
-Need to buy new lead acid battery because the old one from previous owner turned out to be 6v - we charged it back up to 12.18v but not enough to start the bike
-Rewired the ignition system
-Currently rewiring the lighting system
-Made a new seat out of fiberglass and foam (need to sow leather on it and final touches)
-Cleaned out gas tank from rust and coated it with Red Kote Fuel Tank Liner/Sealer
-Tried to start the engine and it runs (though with many things needed to adjust like valve adjustment, putting in exhaust, cleaning carbs, adjusting idle screw, possibly rejetting the carbs)
-More to come!

I've been involved in engineering projects like solar powered vehicles, RC airplanes, and PC boards but I've never fixed a motorcycle before. Willing to learn as much as possible In this post I'm including some pictures of the incomplete bike as well as a video of us trying to start the engine run again yesterday.

Thank you for reading my post!

Link to video of us running the engine:

 

[schwalbewurger]

Exhaust pipes for the bike

 

[schwalbewurger]

Prepping for making the fiberglass seat

 

[schwalbewurger]

Carbs with pods

 

[schwalbewurger]

Seat with foam (just need leather to finish it off)

 

[Grimly]

Those 'exhaust pipes' are a pair of engine / crash bars.

 

[rphillips]

Your comment, willing to learn as much as possible, caught my eye. You're at the right place. And Grimly has given you a good start.

 

[schwalbewurger]

Those 'exhaust pipes' are a pair of engine / crash bars.

I see...my bad - thank you for teaching us more!

 

[schwalbewurger]

Your comment, willing to learn as much as possible, caught my eye. You're at the right place. And Grimly has given you a good start.

Thank you for your comment! I will be posting more pictures and progress of the bike. Right now we are in the process of cleaning up the carburetor and tuning it. So far the engine still stops while on idling rev.

 

[Rich82GS750TZ]

Have you set your valve clearances yet? If not, just bench sync the carbs. Tune the carbs after valve clearances, or waste your time. I’m assuming, by “tuning It”, you mean using a color tune or other carb tuning apparatus to tune each of the 4 carbs while the bike is running.

 

[schwalbewurger]

Have you set your valve clearances yet? If not, just bench sync the carbs. Tune the carbs after valve clearances, or waste your time. I?m assuming, by ?tuning It?, you mean using a color tune or other carb tuning apparatus to tune each of the 4 carbs while the bike is running.

No, we have not had the chance to set our valve clearance yet, but we haven't turned on the engine too before adjusting the valve clearance. What do you mean when you said bench sync the carbs? We decided to rebuild and clean the carbs (will take no shortcuts here) because even though the previous owner said that the carbs were cleaned, we wanted to make sure of it.

 

[schwalbewurger]

We also have a question regarding the serial number of the engine and frame. The number on the engine is: GS750-44811 and the number on the frame is: GS750-33577. I tried to look up engine and frame serial numbers but have had no success yet because I wasn't sure how to decode the numbers. I found the numbers for GS750 online but am not sure if these numbers are the starting production numbers or does it have to be exact with our engine?

The reason I am asking this is because we realized our left sprocket cover does not fit with the engine - the previous owner must have bought a different model year cover. But we want to make sure that the engine is 1978 GS750 before buying the right sprocket cover for it.

 

[Rich82GS750TZ]

.....What do you mean when you said bench sync the carbs?

I’m going to take a “teach a man to fish” sort of approach here and give you something much more valuable than a direct answer. You’ll appreciate it more in the long run. That is how to make the most of this site’s search function:

Under the search box at the top right of this page, click on Advanced search. On the resulting page, type your search words. Change the search criteria to Titles Only (this is the important part). Then click search.

 

[schwalbewurger]

I?m going to take a ?teach a man to fish? sort of approach here and give you something much more valuable than a direct answer. You?ll appreciate it more in the long run. That is how to make the most of this site?s search function:

Under the search box at the top right of this page, click on Advanced search. On the resulting page, type your search words. Change the search criteria to Titles Only (this is the important part). Then click search.

Thank you for the tip! I appreciate it. It has been helpful to some extent.

 

[Steve]

On July 12 you posted this:

... we haven't turned on the engine too before adjusting the valve clearance. ...

However, on June 23 you posted a video of the bike (sort of) running. Which is it?

I watched the video. First things first, get an exhaust system on there.

While you are rebuilding the carbs and waiting for the carb bodies to soak overnight in the carb dip, check your valve clearances.

Get something on the intake side of the carbs. When there is nothing there, you can get the engine to start, but then it will act just like it did in your video. Turn the grip and NOTHING happens. To illustrate the point, take a shop rag, fold it in half, drape it over the carb intakes. Repeat that throttle grip twist and be amazed at the difference.

Good that you are willing to learn, but please ask questions BEFORE making serious mistakes. Yes, the search function can be a bit frustrating at times, but there is a LOT of information here.

.

 

[Big T]

We also have a question regarding the serial number of the engine and frame. The number on the engine is: GS750-44811 and the number on the frame is: GS750-33577. I tried to look up engine and frame serial numbers but have had no success yet because I wasn't sure how to decode the numbers. I found the numbers for GS750 online but am not sure if these numbers are the starting production numbers or does it have to be exact with our engine?

The reason I am asking this is because we realized our left sprocket cover does not fit with the engine - the previous owner must have bought a different model year cover. But we want to make sure that the engine is 1978 GS750 before buying the right sprocket cover for it.

On your side cover, the 77-79 motors are all the same.

The frame numbers and the engine numbers never match.

 

[schwalbewurger]

On July 12 you posted this:

However, on June 23 you posted a video of the bike (sort of) running. Which is it?

I watched the video. First things first, get an exhaust system on there.

While you are rebuilding the carbs and waiting for the carb bodies to soak overnight in the carb dip, check your valve clearances.

Get something on the intake side of the carbs. When there is nothing there, you can get the engine to start, but then it will act just like it did in your video. Turn the grip and NOTHING happens. To illustrate the point, take a shop rag, fold it in half, drape it over the carb intakes. Repeat that throttle grip twist and be amazed at the difference.

Good that you are willing to learn, but please ask questions BEFORE making serious mistakes. Yes, the search function can be a bit frustrating at times, but there is a LOT of information here.

.

Yes, the June 23 video was before you told us to not turn the bike on. So we have not turned the bike on before adjusting the valve clearance until now too.

 

[schwalbewurger]

S

On your side cover, the 77-79 motors are all the same.

The frame numbers and the engine numbers never match.

Sounds good! We bought a new side cover for 77-79 and it fits well - turns out the previous owner installed the wrong side cover.

 

[Big T]

OK, but you need to document your progress in the Projects forum