1978 GS750 Model B, C, ?? What do I have?

[Skao777]

I recently purchased a GS750 and am trying to get some history on model designations. I have been purchasing replacement brake parts and some of the diagrams have me confused as to what model I have. The bike is titled as 1978, built in 1977 has spoke wheels, single disk up front, disk brake rear, non-stepped seat.
Parts diagram for the gauges and rear brake master indicate it is a 'C' model.
Front brake piston size seems to indicate it is a 'B' model.
Z1 enterprises model listing by VIN seems to indicate it is a C.

So, does anyone know the difference between B and C? Was a B model sold as a 1978? Maybe my front caliper was swapped for a B model? Are the master cylinder Pistons different sizes on dual vs single front brakes?

 

[Big T]

The letter designates the year, not the model

C is 1978, so if yours has wire wheels and one front disc, it actually lacks a model designation. If it had cast wheels and 2 front discs, it would be an E model

Confusing? you bet

 

[Skao777]

The letter designates the year, not the model

C is 1978, so if yours has wire wheels and one front disc, it actually lacks a model designation. If it had cast wheels and 2 front discs, it would be an E model

Confusing? you bet

Thanks for the reply. So is there any guide for interpreting the parts diagrams? I guess all 78's are C and then the E is added to that as CE? But what is a B? Is that a year or a model? Would mine be a CB?

 

[Guest]

77's were manufactured from (approximately) 8/76 to 4/77. They were designated as GS750B's. Spokes and single disc front, single disc rear. The most obvious way to tell, sitting on the bike, is that the ignition switch is mounted on a flat plastic mounting surface, in between and slightly below the gauges, slightly to the right side of that panel. The 78 750's, in that area, incorporated the steering lock, a redesign for that year, dead center and between the gauges, right above and between the handlebar clamps. The 78 GS750C also had single disc, front and rear (except for the English and Euro model, double front disc), but still spoked. The 78 GS750EC had cast alloy wheels and double front discs, so there were, basically, 2 '78 750's offered, a 'plain' C, and a 'deluxe' EC, as I described. I know-I sold them, sold parts for them, worked on them, and owned a 78 C.

(The only 750A in '76 was the 2-stroke triple, GT750A)

 

[Sandy]

A GS750B would be a 1977 model. 750A would be a 1976 and the C is 1978. For some unknown to me reason in '79 the year designation went to N and didn't really follow a pattern after after '78.

 

[Skao777]

Thanks for the help. So how should I interpret the parts diagrams listed below? For instance, the front brake caliper shows a 'B' and an 'EC' option. Single disk is the 'B'? Obviously there are issues with the descriptions based on all of the spelling errors. Or are they showing other year options even though I have filtered on 1978? This is common to all of the websites I have viewed.

 

[Bevo]

Howdy, Skao777 - you've gotten some helpful info from Forum already, but I don't read that your master cylinder question has been answered, completely, and I am wondering if anyone CAN answer it correctly, as I have had a similar head scratching going on about this for my 1978 GS750C. It has the spoke wheels, the single disc front and I ended up ordering BOTH front MC kits from Babbitt's Online. I thought the "EC" would be correct for my bike, as it was a "C" and not a "B." There was no mention of "C." The piston was too big in diameter. So, I ordered the kit for the "B" - it was the right diameter, but other parts were not matching what had come out. I assume I had an original setup, but I could be wrong. I imagine double disc front M/C have a larger bore and single disc have smaller. It does seem, also, that the new kits have a different arrangement/design and in my kits the boot for pistons were not set up the way the originals were, per the shop manual. Mixing/matching, I ended up using parts from BOTH kits and the thing works! Ha! Good luck!

 

[chuck hahn]

And youll note the 77 B and C started with just GS 750- XXXXX The 78 E had the VIN starting with GS750E​-XXXXXXXX

http://www.ozebook.com/compendium/suzi/engine-nos/engnos.htm

 

[Guest]

Per the VIN you have a 1978 GS750. With the year code of "C", its also referred to as the GS750C.
See:
http://www.suzukicycles.org/countries/index.html?Canada-imports_1970-1979.shtml~isoraami

 

[tkent02]

And to make matters worse, a lot of early owners put dual brakes from the later E model on the earlier bikes. My '77 B model has these, and it still doesn't stop worth a damn.

 

[hannibal]

Howdy, Skao777 - you've gotten some helpful info from Forum already, but I don't read that your master cylinder question has been answered, completely, and I am wondering if anyone CAN answer it correctly, as I have had a similar head scratching going on about this for my 1978 GS750C. It has the spoke wheels, the single disc front and I ended up ordering BOTH front MC kits from Babbitt's Online. I thought the "EC" would be correct for my bike, as it was a "C" and not a "B." There was no mention of "C." The piston was too big in diameter. So, I ordered the kit for the "B" - it was the right diameter, but other parts were not matching what had come out. I assume I had an original setup, but I could be wrong. I imagine double disc front M/C have a larger bore and single disc have smaller. It does seem, also, that the new kits have a different arrangement/design and in my kits the boot for pistons were not set up the way the originals were, per the shop manual. Mixing/matching, I ended up using parts from BOTH kits and the thing works! Ha! Good luck!

I have done some head scratching of my own about the differences in 8valve 750 models. As for brakes, my understanding is that the 750E models with dual discs have a 5/8" front master cylinder, while the single disc models had a 14mm MC. I was not aware that there was single discs models in 78 and 79 until last night. I was emailing with an Ebay seller about stainless lines and he mentioned he had measurements for a 79 single disc. After some research I learned that the single disc models did continue in 78 and 79 (along side the dual disc E models).

It's weird to know that the 1978 single disc MC is a combination of the single disc and dual disc parts.

 

[tkent02]

If you are interested in stopping, check out Saltymonk's twin pot brake upgrade. It really works.

 

[Skao777]

Howdy, Skao777 - you've gotten some helpful info from Forum already, but I don't read that your master cylinder question has been answered, completely, and I am wondering if anyone CAN answer it correctly, as I have had a similar head scratching going on about this for my 1978 GS750C. It has the spoke wheels, the single disc front and I ended up ordering BOTH front MC kits from Babbitt's Online. I thought the "EC" would be correct for my bike, as it was a "C" and not a "B." There was no mention of "C." The piston was too big in diameter. So, I ordered the kit for the "B" - it was the right diameter, but other parts were not matching what had come out. I assume I had an original setup, but I could be wrong. I imagine double disc front M/C have a larger bore and single disc have smaller. It does seem, also, that the new kits have a different arrangement/design and in my kits the boot for pistons were not set up the way the originals were, per the shop manual. Mixing/matching, I ended up using parts from BOTH kits and the thing works! Ha! Good luck!

So far I have ordered both part numbers and neither was correct.
I found this thread and ordered the recommended part number (59600-45821):
http://www.thegsresources.com/_forum/showthread.php?210413-What-part-Front-MC-KIT-1977-GS750-Help

I have yet to install it but it looks close though not quite the same (slightly longer). Apparently Suzuki used a mix of Nissin, Asco and Tokico parts and they all have different part numbers.

Looking at ebay listings I found this text:
Suzuki part number is 59600-45821 for Tokico brand master cylinders only(Look on the bottom of the master cylinder for identification).
Suzuki also fitted ASCO and NISSIN brand master cylinders to some of these bikes so please make sure before purchase

 

[Skao777]

I found info on the piston here:

http://www.thegsresources.com/_forum/showthread.php?160009-GS750-front-brake-caliper-piston-help

I'll look up the part I ordered that worked and post it later.