1977 Suzuki GS750: classic, minimal, with a hint of modernization

Hey my name is Josh, I picked up my first bike, a '77 GS750 about two months ago. Since then I have mainly been focusing on learning to ride. Thankfully I have my dad who has been riding for 20+ years who has taught me a lot so far. I have been thoroughly enjoying the bliss that is riding a motorcycle.

Here are some pictures of how she came.

jackbday-8-3.jpg by macbethpoe1, on Flickr

jackbday-6-4.jpg by macbethpoe1, on Flickr

jackbday-3-4.jpg by macbethpoe1, on Flickr

jackbday-1-3.jpg by macbethpoe1, on Flickr

It has about 10,000 original miles on it, and appears to be well kept. Since it is riding season now, my plans are mostly to ride, and learn how to do so safely. And also, I want to get it running as best as possible, without doing anything too drastic to take it off the road for too long.

The first thing I did do was take the carbs off, and completely clean them. I do have a question tho that perhaps someone can shed some light on for me. Since cleaning the carbs, it doesn't seem to run as well as before. Acceleration from a stop is pitiful, and I really have to baby it to get going and not putter out, and I don't really get any power until about quarter way through second gear. Secondly it seems to run a little rough in general, and feels like I have to top out my gears just to get up to cruising speed, I can't really cruise a long at say 30-40 in 3rd gear without feeling like the bike is being pushed too hard. Any ideas?

Later I will update with some plans, and perhaps get some ideas of what should be done first to get it running top notch. Thanks to everyone for all the information here, I have found the answers to so many questions already, and also have gotten great ideas!

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

Wow, that thing is clean for its age.

Sign up on the GSResources - they already have all the info to get the bike running like new.

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

Thanks Big, yeah it pretty amazing how well it's held up. And definitely will check that site out!

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

Can you feel all 4 head pipes getting hot when you start it up? They will run on 3 cylinders.
Also check for a vacuum leak since pulling the carbs. When you say you completely cleaned them, how far did you go?
Technically speaking, wiping them off with a shop towel is cleaning them.

Welcome to DTT and very nice bike!

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

I will do an exhaust check next time I start it up, that's a good thought. And i cleaned them pretty damned thoroughly I think, completely disassembled off the rack, broke each carb down, kept all parts separate and organized, cleaned every tiny orifice, new o-rings and gaskets, bench synced and put me back on. Have tried tuning with the air idle screw to no avail yet, I think these carbs have a fuel and idle air screw, is that normal?

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

wow that thing is super clean!!! Are you planning on modifying it? I wouldn't do anything I couldn't put back to stock, just my 2 cents. There aren't many clean originals out there, but there are plenty of project bikes that can be radically changed.

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

Yeah I do have plans to modify, but no crazy mono shock conversions, or GSXR front ends or anything, and I plan to keep all the stock parts, just in case.

I think today I am going to pull the carbs off and check my bench sync, I adjust the air idle screw a little more and got decent results. But after riding a bit after cleaning the carbs, the plugs are pretty white so I think it's running on the lean side.

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

Btw godsilla, that's a pretty damn clean GS you got there too, can't wait to see where it goes.

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

Damn that is a clean GS. Looks amazing and even the exhaust is still intact.

Welcome Mac.

As for the carb problem, did you change the air filter when you cleaned the carb? Sometimes all it takes is a small bump for the old ones to turn into carb clogger.

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

As far as I could tell the air filter looked new, it's a UNI filter, will post some pics tomorrow of the carbs, a completely random rain storm blew in while I was riding today and put a damper on everything.

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

check to see if you have an air leak between the carbs and the head by spraying some engine start spray around the inlet manifolds while the motor is running
if you have a leak the revs should change as you spray
the motor will run lean if you have a leak and you could hole a piston like I found with the GS550 I'm building at the moment

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

Thanks firsty, will do the leak check tomorrow. I didn't take any pictures today as there really wasn't anything that exciting going on haha. But I got the carbs synced, my last since job was pretty pitiful, and it seems to be running much smoother now, with much better acceleration.

I also checked all the headers on start up and they were all getting warm so that's a good sign. I have clip-ons that will hopefully be here tomorrow, and am ordering new grips as well, so will post pics of the install.

A quick question, I was looking at the passenger peg mounts for possible rearset mounting, but am wondering if people mount them directly to the peg mount, or do you use some sort of bracket? The biggest problem I see with it, is that I don't see any room to get a nut between the peg mount and frame to secure the rearsets. Any input? Can get pictures of the pegs if needed.

Was looking at Tarozzi sets specifically for my GS, but they mount to the stock locations, and don't look very "rear" if you know what I mean.

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

So from one problem to the next. Bike was running decent, I was out riding enjoying it and suddenly it died, no warning or puddering, just cut out. I tried to restart it and nothing at all, no headlight, turn signals, nothin. I was close to home so got it back and started tracing all the wires with a voltmeter.

It led me to the headlight bucket, pulled the light out and found this.

image by macbethpoe1, on Flickr
Obviously that's not how that's supposed to look. If I wiggle it and ask it nicely it will make connection again and I can start the bike, but will lose connection randomly.

So this, coupled with knowing the GS models are notorious for poor electrical has prompted me to make this my priority upgrade.

Plan:
Contact Sonreir and start planning out a new harness, going to buy it through Spark Moto
Upgrade stator, R/R, and battery
Possibly upgrade to all LED lighting
Lastly, figure out electronic ignition/eliminating points, not sure on how this works, lots of research left to be done

Basically, I want to simplify the entire electrical, and make it much more reliable.

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

Dyna DS3-1 or DS3-2 depending on if it is a KD or ND factory timing plate...

"Dyna "S" Electronic Ignition for Suzuki Part No. Item Price Buy Option DS3-1 1977-78 Suzuki, 550 /750 four cylinder (KD) DS3-2 1977-81 Suzuki, ..."

Click to expand...

http://www.dynaonline.com/skins/products/sportbikes/dyna_s/

http://www.dimecitycycles.com/vintage-cafe-racer-caferacer-bobber-brat-chopper-custom-motorcycle-electronic-parts-dyna-suzuki-gs550-gs750-high-performance-ignition-suzuki-21-7532.html


and a set of their coils... I think 3.0 ohm "Green" is what you need but may want to verify with Dyna,,, ???

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

Hoosier, thank you so much! Just eliminated at least two hours of research haha.

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

Be sure to check the grounding on all those wires. That has been the only thing that has completely killed the power on my GS. I have blown fuses and lost individual lights, but the only thing to ever kill everything has been issues with the grounding. I nearly replaced all the wiring, and I did buy a new R/R (which I never used). But the only issue to cause total power loss was a bad ground. That was easily fixed with some sand paper and a little dielectric grease. Try the cheap option before some of the more expensive ones, unless you just want to have a new harness from Sonreir. Can't fault you for wanting upgrade the electrical system on a GS ; )


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Re: 1977 Suzuki GS750, first bike, first post, no name yet.

I have been searching for a page I used to have bookmarked that has more GS info on it then I know what to do with. Once I find it I will post up the link.

Luckly I have a habit of saving any info I think might even be the slightest bit useful.

Here are two PDFs you will want to have a look at if you are going to Electronic ignition.

And this wiring diagram might help as well

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

Lovingthecle - thanks for the info, that is the first thing I will do is check the grounds. I have to at least temporarily fix this so I can still ride it, cause it will take a while to collect all the parts needed as budget allows. Thanks again.

Brodie - I appreciate those links so much man, I looked everywhere for a schematic, and couldn't find it. Those will all come in handy later. Btw love your build, very awesome bike, I read from start to "finish" the other day.

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

The parts collection begins! Ordered these before I realized my electronic woes.


image by macbethpoe1, on Flickr


image by macbethpoe1, on Flickr

Nothin fancy, just the steel ones from DCC, but I really can't wait to be into my bike more taking corners, they should do the job just fine.

Re: 1977 Suzuki GS750, first bike, first post, no name yet.

Have you registered over on theGSResources yet? They have a "must read" in their garage section called "The Stator Papers". Several documents that start about half way down here http://www.thegsresources.com/gs_garage.htm