1977 GS750B - my long awaited first bike!

[Chuck78]

Another photo from the WV trip, loaded down and covered in dirt, grime, and limestone dust. We got rained on for at least 1-2 hours every day out of the 6 day trip. Not always while riding, but we we able to work around it.

[Chuck78]

Got a Hayabusa grade gold RK 530 o-ring chain for my birthday, figuring out gearing now so that I can swap this GS1100E aluminium swing arm on while I still have a borrowed motorcycle lift. 15-41 was stock (with 630 chain), which in a 530 equates to an 18-49 as far as ratios go. It's necessary to keep at least a 17 in front when converting to a modern 530 setup, as the sprockets are smaller than the same teeth in a 630, and a 15 on the bigger bikes will be too close to the swing arm. I'm going for a 17-48 (GS1000 equivalent gearing but GS1000 gearboxes are a little different on the primary drive gears). The 17-48 is a bit faster accelerating than original, but will spin at 5345 rpm's at 70mph vs 5135rpm's @ 70mph if I kept the stock gear.

I'm going with a really cool looking drilled/hardened GSF1200 Bandit/GSXR "Vortex" brand front sprockets that are a direct fit with the typical 6mm outside spacer added, going with a really awesome looking SuperSprox lightweight aluminium/steel black and gold setup for $89 to top off the drivetrain.

[steve murdoch]

Looks like all your hard work paid off.
Great pic of the bikes at rest.

[Young and Reckless]

A little carb trouble

Very nice. I have replaced the airbox with k&n pods. I just had the carbs rebuilt and its bogging down when I roll the throttle. Do you think I need to rejet ? I was told that on those carbs I would not need to but now I'm not so sure. Any advice would be helpful as I'm a noob to carb issues

[Chuck78]

Yes, definitely rejet. Look up Vance & Hines exhaust install instructions for recommended jet sizing for your year/model. Maybe the filter manufacturer offers similar jetting info.

[Chuck78]

Well I got that GS1100E swingarm installed, thanks again to Norm for machining me some custom hardened steel needle bearing inner races so that I didn't have to drill out my frame to the GS1000/1100 pivot shaft size!
EDIT - Here's a photo of the new spacer that I turned down to an hourglass shape to be much lighter than stock, as well as Norm's custom hardened steel races to fit the GS750 on the ID with the GS1100 bearing size for the ID


Did the 530 chain swap, soooooo much smoother wrapping around the front cog, coasts better in neutral, rides better, wow! That SuperSprox 48T is trick! very light! I dropped probably 8-10mph off my extimated top speed assuming the 9000 rpm redline (although it would probably go higher than that, I have hit 11000-11500 many times and it still had power in 3rd gear or so). The acceleration is slightly improved but the highway rpm's are slightly increased, but I think that combo (17-48) is pretty perfect. 1000cc+ modified engines maybe go a little steeper, but sub-1 liter I think that's a perfect gear if you want a little more acceleration

Rode WV and KY again last weekend and rode SouthEast Ohio last night 4pm-10pm, bike corners SOOOOOO great! Despite heating up and bending my exhaust however, I still scraped my muffler TWICE in a half hour last night on hard right hand leans!

The Shinko tires grip PHENOMENALLY WELL, WOW, but I have to say that I have 2500 miles on them in 6 weeks and they are definitely at the halfway point on the tread, ouch! I may have to go with an Avon AM26 rear and Shinko 230 front from now on, although the extreme grip is very awesome.

Carb rebuilds, K&N dual pod RC2222 filter install, and upsizing the jets is next on the list. modify rear brake stay length and mounting point to use this gold GS1150 rear caliper since I already have the rotor mounted and have a proper set of pads for the rotor height with that caliper. dropped from 295mm to 275mm on the rotor and proper length matching caliper hanger axle bracket. the piston in the 1150 caliper is larger, so I am wanting that to give me a little spongier pedal feel for more modulation of the rear brake with my master. If I don't like it, I have a matching master to go with it, but I think what I'm going for will be pleasing.

I cannot express how happy I am at the way this bike handles at present! Maybe at some point I will have Hagon 2810 adjustable dampening rear shocks or Ikon rebuildable adjustable dampening rear shocks. For now, I am very very pleased!

[Chuck78]

I drove the bike over the scales today, 640lbs bike+rider, bike w/3 gallons of gas = 500lbs!!!!!!

Looks like the diet routine I had strategized for the bike has worked out!!!
I figure the scale weighs in 10 or 20 lb increments, but that seemed pretty darn accurate! I noticed that I had dropped from 150 lbs to 143 on the bathroom scales recently, too much stress, not eating enough, no time!

I think if I can upgrade ignition to Dyna or similar and rebuild the carbs asap, I may ditch the starter, gears, and battery to drop another 23 lbs or so. Then I think the bike will be the ideal weight that I'm looking for to be able to more easily throw into turns when riding in the twisties of SE Ohio, but still enough mass to not get blown all over the highway at high speeds. The 1100E swingarm's added 1-1/8" length really made it more stable at high speeds. wow. As in you might not notice you are doing 110+mph because it's so much more stable

Photo is taken in the beautiful little canyon that makes up Clear Creek Rd/Clear Creek Metro Park south of Columbus 50 minutes. It's a very very nice ride. very scenic little river valley like a smaller scale version of smoke hole canyon. The road is rough in parts in the middle but the scenery makes up for it. lots of pedestrians due to it being a great fishing spot and so darn scenic, so not something you want blaze through anyway (the middle section mostly). Beginning and end is more desolate and the pavement is better. nice turns!

[Hone101]

Who is this Norm and would he make some races for me?

[Chuck78]

A machinist guy who rides & lives NE of here.

[T8erbug]

Well I got that GS1100E swingarm installed, thanks again to Norm for machining me some custom hardened steel needle bearing inner races so that I didn't have to drill out my frame to the GS1000/1100 pivot shaft size! Did the 530 chain swap, soooooo much smoother wrapping around the front cog, coasts better in neutral, rides better, wow! That SuperSprox 48T is trick! very light! I dropped probably 8-10mph off my extimated top speed assuming the 9000 rpm redline (although it would probably go higher than that, I have hit 11000-11500 many times and it still had power in 3rd gear or so). The acceleration is slightly improved but the highway rpm's are slightly increased, but I think that combo (17-48) is pretty perfect. 1000cc+ modified engines maybe go a little steeper, but sub-1 liter I think that's a perfect gear if you want a little more acceleration

Good info and great work! You lucky bastage! I can't believe you managed to figure out how to get a hardened needle bearing race. Ha after all the work I went through to perfectly align my frame in a huge drill press TWICE to drill out both sides of the frame. Well, either way we both got our desired GS1100 swingarm on right? Glad she's handling well! Not that it matters anymore for me but just out of curiosity how tough was it for your buddy to lathe up those races? How much did it end up costing you when it was all said and done?

[Chuck78]

My new Suzuki/BMW ridin' machinist buddy took care of all that for me, gave the stuff to me basically for cost of materials and tool wear and tear with just a little on top!

I spent some time with a toothbrush and carb cleaner, stripping all the gold paint off of the 83-86 GS1150E rear brake caliper, and installed a new K&L seal kit in it. The originals looked really good but I was hesitant to reuse the little round rubber gasket that gets sandwiched tightly between the two halves of the caliper. Glad I tore it apart to clean, I've seen worse, but all well-used but functional brakes DEFINITELY need to be torn down and cleaned and reassembled with Permatex Ultra Disc Brake Caliper (& piston) Lube.

Re-using a decent stock set of pads for now, but contemplating standard organic vs HH rated sintered pads. Seems they will gouge the rotors out more rapidly but stop better in constant hard braking use. The lower grade GoldFren Sintered Ceramic Carbon "AD" street compound pads might be a middle ground, as their S3 race is probably going to wear more on the rotors, same Sintered Ceramic Carbon base, but a lot more copper and iron in the pad I believe.

Tore the original master cylinder off today. WOW was that thing FILTHY!!! The plunger assembly is getting swapped for a GS1100E setup, same guts but in an external reservoir master. That one was cleaner looking, not rusted to crap on the bottom, but practically seized. 100psi of air couldn't pop the piston/plunger out! I depressed it by hand with force, and 100psi would not return it and blow it out the end. Putting back together with original seals, still looking good but I will monitor.

On the fence about using the original GS750 line that is two short rubber hoses and a steel hard line section with flare fitting ends. This will be as stiff as braided stainless, but longer so I may have to cut the hard line section and re-flare it if I can find my double flaring setup. The GS1100E brakes used a long long rubber hose with a protective coil spring around the rubber. I didnt have the correct banjos for the front brakes to work with the Earl's fittings to run DIY stainless braided lines, so I still have the lines and banjos for that, thought about using them for the rear, but this 77 GS750 line is probably going to get re-worked.

Gotta get back to it, had to take a quick dinner break! Photos soon once I can figure out this MTP file transfer crap on my upgraded Android phone operating system, not working well with Linux PC operating system...

[Chuck78]

I've had the carb bodies soaking for DAYS AND DAYS AND DAYS now, while reading up a lot on jetting and needles. I looked down the plug hole at my carbon'd up pistons, and it looks like they are GS850 pistons, not the Wiseco's I was hoping for, but I may squirt some carb cleaner in there to get a better look at the casting vs machining - the Wiseco's valve reliefs will give it away for sure. The MTC 920cc pistons are going to wait until winter probably, unless I can get a lot of additional income this summer to pay for a good shop to bore these spare 850 cylinders, not to mention a complete set of mixed and matched Suzuki gaskets. GS1100E 73mm 5 layer s.s. MLS gasket, GS850 base gasket, and all the rest of a GS750 gasket/seal/0-ring set.

So I am hearing that with pods and a pipe on VM26 GS750's, people are saying start in the range of 120/122.5/125 main jets, and raise the needle one notch.

I was chatting with a really smart guy on here who used a wideband o2 sensor AFR setup and dyno to tune his custom big bore GS850 of similar displacement, and he was running the GS1000 5DL36 needles in his shimmed to 2.5 clip position with the best results. I have a spare set of nearly identical spec 5DL35 needles, and I am contemplating trying them out. They are a very very slight bit thicker at low throttle openings, but have a very aggressive taper at performance oriented throttle opening levels - ESPECIALLY in comparison to the big fat 5F21's that came stock. See photo


At wide open throttle, I believe the needles are still very slightly in the main net's needle jet bore opening (CORRECT ME IF I'M WRONG), so the tip of the needle may have a slight impact on the overall wide open throttle fuel metering, so I was theorizing that maybe with a much more narrow needle tip/taper, I could get away with a smaller main jet???

I was thinking that if I ran the stock 5F21 needle in the 4th position (1 richer than stock), that I would start out the tuning with 122.5 mains. If I use these 5DL35 needles, I might run then in the second clip position down, and try a 115 main for starters. Maybe I would be better off with a 120? Really looking for some guidance here to save me some jet and needle swaps!

[Chuck78]

Also jetting to install the long awaited K&N RC-2222 dual oval filters! They have so much more area, and will be far more consistent with the mixtures between all 4 carbs than what a set of pods would do. I think these and the old Abe Henry breadbox filters are the only BEST alternatives to the factory airboxes for the long term.

I am also looking at getting a Gunson Colortune setup, a special spark plug with a clear top that allows you to monitor the flame color. perfect blue flame means perfect air/fuel ratio. yellowish or orange flame, too rich. White-blue flame, too lean. This will really help dial in the tricky VM carbs since they have both pilot fuel and pilot air screws. I was looking at a wideband o2 sensor AFR gauge setup, but that's pretty costly ($200+)

[Hone101]

Those air filters fit properly without modification?

[Chuck78]

yes they are designed for VM26 carbs as found on the GS750/850/1000 and KZ900/1000, possibly KZ750, all of the late 70's before cv's were the norm. the carbs on all those bikes are interchangeable basically or at least have the same spacing just not the same jetting etc