'77 710...ish

[80GS1000]

Thank You.
which year rotor mount did you use? '06/07?

Rear caliper bracket on mine is from an 05/06 GSXR 1000, same as the swingarm. Since you have what looks to be an extended 02 GSXR 600/750 swingarm, you should be able to use the stock caliper bracket, the 06 GSXR 600 wheel with its 220 mm diameter rear rotor (same as the 02), and then fab up a custom torque arm. You'll need to center the wheel in the frame first, measure to find the spacers needed to keep it in that position and then measure how much front sprocket offset you need. From my experience the max offset you can run in a GS frame is about 5/8" even with a 520 chain before the chain rubs the inside of the frame.

Yes on the wheels.
There is a lot on this subject floating around the forums. The lengths people have gone to make it true amazes me.
Funny thing is quality control in the 70's wasn't shall we say, evident lol
So as you know things will have to be adjusted for every frame with the parts being used.

True story. There's a general recipe for these kind of mods but every bike is slightly different.

I have spacers (commercial lawn mower spindle washers/spacers fit perfect) and have set it up with the sprocket strong to the outside like yours.
Lined up pretty good.
But nothing is bolted down yet so changes are to be made...!!!

If you need an offset front sprocket, give PBI Sprockets in Oregon a ring and ask for Randy. Great machinist who can make any size offset front sprocket you need including the 520 I use.

[unfocused]

Wonderful and thank you for the information.

I will put it to good use.

I'm not there yet and I'll add more photos and updates as the build moves along.
Steer bearings are showing up Thursday so this weekend is getting the front fascia in place

Goal is to safely ride it to Bike Week 2020 with my buddy on his '72 750 Commando.
His is on the lift and as you can see, we both have a steep goal LOL

stretch 8.jpg

[unfocused]

I've built plenty of drag race cars in my time.
Very few race bikes but several fast runners.

Never had to tuned the suspension on crotch rockets but I've read enough in the past years to be understanding of the process.
Now I am into processing the data I've amassed and apply it to this build...
Your information makes sense and just running numbers through my head and it's working.

I am looking at everything and making sure it's right. The days of farm built hot rods aren't over but this is going to be used on the streets so safety is paramount.

FYI:
I've looked over your valve spreadsheet and can't wait to use it. I've yet to touch the 750 head as the 1000cc mill jumped into my lap.


Thanks for that!!!

[unfocused]

Spent my weekend installing fork conversion bearings so those 2002 GSXR USD's would play nicely in the '77 GS750B frame. I couldn't be any happier. The only way it was going to be any easier to install those forks, was to have someone else do it LOL...

Now the steer stops, stabilizer, brake hose connector... let's not forget the headlight, turn signals, and all that damn '77 wiring... ugh.
All the brake hardware, light brackets and more are on there way. Thankfully so is a 4 day holiday

forks 10.jpg

[unfocused]

Here she is staged, so I could see what lock to lock is going to look like and engineer a replacement... OK so my mind is wondering around the subject lol.

Did realize after staging her that the rear shock length is going to change drastically. Good thing for drive chain/swing arm.
Still have decent room for the header.

front 10.jpg

[unfocused]

...when the toys are put to bed.

projects 3.jpg

[80GS1000]

Looking good...

A couple things to keep in mind when using late model upside down forks on our GS bikes:

1. Fork springs on late model GSXR forks tend to be too soft for installation on a GS. You'll likely need around 1.0 kg/mm springs to get it right. Check the Racetech website for recommendations on spring rate https://racetech.com/ChooseVehicle.aspx and factor in the weight difference between the GSXR and GS in your calculation.
2. Check your rake and trail to make sure the bike will be stable and handle decently with a calculator like this: https://www.rbracing-rsr.com/rakeandtrail.html Trail is very important and you don't want to go under about 3.8" of trail for stability. Given this is a dragbike, more trail is better to keep it stable in a straight line at speed.

[unfocused]

Thanks GS,

I'll put that info to good use

Not that close yet LOL

[unfocused]

Mocked up at shock height.



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[unfocused]

Challenging build. As I am sure some of you are aware, you go backwards as fast as you go forwards.

Here I've finally added the rear brakes, centered the wheel in the swingarm, to check for center in the frame... only after this do I have a chance to work with the chain alignment... ugh

During this garage visit I also installed the front rotors and calipers. I've ordered an experiment off of flea bay since the '77 front master cylinder is large for the clip on's causing issues with my old school headlight. It'll be a $20 mistake if it fails. I'll look smart if it doesn't

No matter what, I'm keeping those off kilter, round dated mirrors!!!





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[80GS1000]

Something that may be helpful...try using a laser level to check if the center of the rear wheel is aligned with the center of the backbone of the frame. It's a lot easier and more accurate than using string.

[unfocused]

Ok, clicking wrong buttons... duh huh.

Took some time to start the engine. She runs, and well I might add. Lucky purchase !!!
Front brakes a fully functioning in the garage. Road test eventually.
Working with the headlight/front signals/wiring.
Fixed side stand... it's short. Shud-up!!!
That jeep needs a heater core.
Brought home welder, lazer level, and enough parts to hopefully at least find first gear and some tire spin



phase2-3.jpg

[unfocused]

I will be doing this over the long weekend LOL.
Among other things. A bunch of parts and time :-)

Something that may be helpful...try using a laser level to check if the center of the rear wheel is aligned with the center of the backbone of the frame. It's a lot easier and more accurate than using string.

[unfocused]

During my time fixing everything I own, twice

... I was coerced into this... ugh

v-rod 1.jpg

[Chuck78]

Confusing title at first, I kept thinking of what size GS650 piston would make 710cc, or what you could do to destroke a 750!
Then I saw the clutch cover linkage... Then the 710 started making sense! Not quite as talked about as the 7/11 swaps... A hyphen or backslash would make 710 (7-10 or 7/10) a lot more self explanatory!

I think you're going to be searching for shock springs for a while, but you may want to look into ATV and snowmobile shocks. Something of a laid down angle on one of those heavier machines could be closer to your range needed? Then you'll need different valving as well vs standard bike valving... There's likely going to be a lot of trial and error involved unless you enlist someone like Racetech to plug everything into their computer formula for a valving answer, or if you know someone with a shock dyno and you find some online calculator tool that gives you valving/damping rate targets based on suspension geometry...

Personally I would shorten that swingarm A LOT, to maybe 2.5" or 3" longer than stock if I was only looking for higher hp straight line performance.
Are you going with a 16v 1100E clutch basket? Or custom making a H.D. backing plate for the 1000 clutch basket?

Suzuki Performance Spares sell a spacer kit for the clutch cover to be able to run an 1100E clutch basket without loosing any clutch discs (as the basket has to be machined down to fit in a 1000 otherwise).
Welded crank will be VERY necessary, from the rear tire choices alone... A lot more traction than a 79 GS1000 had available back then, & hard use/abuse could twist a crank on those even!

What pistons? MTC had some bargains on some old school 74mm GS1000/1100G pistons a year or so ago. They are pretty old school though, NOS, heavier than a modern Wiseco or JE by a fair bit.
Would require 1100G cylinders, 1000 base gasket trimmed, block decked a fair bit (.020"?)

What carbs? Can't make out in the pics. Sticking with the small port head?

Best of luck.