i need more umph (85 gs 700es)

[Billy Ricks]

Haven't installed them yet. I was needing a set of rockers before I went back into the motor. I finally got a complete head off of Ebay that I'm going to salvage parts out of to finish the job. I have a set of Vance&Hines modified grind cams that I'm going to install with them. I already have RS flatslides installed and a Yosh Duplex exhaust from an air-cooled GSX-R. The carbs alone make a huge difference. The combination of everything I'll have in the motor should make a huge difference. Stock hp is supposed to be around 80. I wouldn't be surprised to end up with 110-120 hp. The cams aren't as wild as a full road race grind and I won't have Carillo rods, though I'd love to find a set, but apart from that it will be close to Superbike spec from the period.

I'm kind of waiting to go back into the motor to see if I can get my hands on an '83 GS750 crank and rods to make it a full 750, mine is a 700. If I can find a crank I'll send it to APE for lightening and balancing. People will argue you lose some low end grunt, but when you increase your hp that much it will still probably have more bottom end than it does stock.

[HiSPL]

Sounds good, I'm going to give these pistons some serious thought. I need to see what other mods are in the budget if I go with 750 pistons. I have been planning on the big bore route, but this sounds interesting....I'd like to hear from you when you get your engine built to see what kind of power you get from it.

Thanks

[Anonymous]

Thanks, you guys

I own a 1983 GS750ESD in pretty much stock (and mint) condition. After 19 years of ownership I was feeling pretty good that I personally just reconditioned the forks, including installation of Progressive Suspension fork springs. Based on some of the posts here, I now realize that what I did was minor and that the bar has been raised out of reach (turbo's, 920cc punch-outs and such). Thank's guys for for providing a dose of reality .

Simon Waters

P.S. The fork springs work great........also 212+ degrees is normal.

[Billy Ricks]

I own a 1983 GS750ESD in pretty much stock (and mint) condition. After 19 years of ownership I was feeling pretty good that I personally just reconditioned the forks, including installation of Progressive Suspension fork springs. Based on some of the posts here, I now realize that what I did was minor and that the bar has been raised out of reach (turbo's, 920cc punch-outs and such).

Simon,
Your bike looks pretty pristine for one that is 20 model years old. If I hadn't met up with Britt I probably would have never started modifying mine. Knowing him gave me a source for parts and great advice. For someone that had as much success racing as he did he is a very approachable guy with a great wife and kids. He has his own business going now printing shirts for Yoshimura, Dunlop, and quite a few other race connections. He also builds custom surfboards. He's never too busy to stop what he's doing and help a friend. One helluva nice guy.

[Anonymous]

Billy:

In case I didn't mention it before: thanks for your tips on seal changing and aftermarket fork spring installation......the plastic pipe connectors worked well as spring spacers.

I keep meaning to do a write-up on fork seal & spring work (when I have time!) but let me mention a couple of things now. The manual specifies using new inner (i.e. lower) "anti-friction" bushings when changing seals. This I did but they were in pretty good condition from the last seal change by my dealer 13,000 miles ago. What surprised me were the state of the outer (i.e. upper) bushings - they were really worn!! Since the service manual doesn't mention replacing these bushings as standard, I guess mine were the original items with 32,000 miles on them. Fortunately, I had new outer bushings as well, so this was not a problem. However, if your bike has substantial mileage, I would recommend to anybody that they be prepared to replace these items.

One more thing: I found that my bike's left, chrome (upper) fork leg had a couple of closely-spaced grooves/gouges. Since I thought that these might be responsible for the short seal life, I spent 2 hours with 220 through 1200 grade wet & dry taking them out. I never did remove them completely (now I really know why chrome is used....it's incredibly hard!!) but at least they no longer fail the "finger nail" test. I just didn't see the point of doing all this work just to leave a possible root of the problem present.

Simon Waters

[Anonymous]

Any of you guys familiar with JE Pistons of California? They specialize in custom pistons for motorcycles and automobiles. I'm having them make bigger pistons for my XN85 Turbo. Cost is about $650.00 and includes rings and wrist pins. Phone number is 714-898-9763.
Axel

[Anonymous]

im amazed at how similar the 85 700esf and the 83 750es look alike does anyone know whether or not the cylinder heads and pistons are interchangeable would they work if anybody has a clue let me know, because it seems like they still make alot of parts for the 750 vs the 700

[moto_dan]

im amazed at how similar the 85 700esf and the 83 750es look alike does anyone know whether or not the cylinder heads and pistons are interchangeable would they work if anybody has a clue let me know, because it seems like they still make alot of parts for the 750 vs the 700

The 85 700 and 83 750es are the same except for a few cosmetic changes and a different crank shaft. The cylinder, head, pistons and rods are identical. Suzuki shortened the stroke of the '83 750 via a different crankshaft to get the 85 700. There are not really any more parts for the '83 750e than the 700. One thing to be cautioned about is that Suzuki did make a 750T in '83 which is the left over physically larger 750(16v) first produced in '80 and parts from those engines are not interchangeable with the 700. Hope this helps.

[Billy Ricks]

The cylinder, head, pistons and rods are identical.

Actually the rods have to be a bit shorter and the crank pins moved out on the crank by the same amount. This allows the piston to end up at the same point TDC and be drawn down into the cylinder by that amount to increase the stroke.

[moto_dan]

The cylinder, head, pistons and rods are identical.

Actually the rods have to be a bit shorter and the crank pins moved out on the crank by the same amount. This allows the piston to end up at the same point TDC and be drawn down into the cylinder by that amount to increase the stroke.

Yep, sounds reasonable. Thanks for clarifying. I mainly wanted to communicate that many(including myself) intially reason that the differences between the two is the bore size when as you pointed out to me years ago it was the stroke. Another good example of why you were missed from the forums.

[Anonymous]

I think the new GS bike of the month proves my previous theory, you can fit an 1100 into the 750ES frame! I am more than excited after seeing that bike and teh info on it.

Thanks!
Mike

[moto_dan]

I think the new GS bike of the month proves my previous theory, you can fit an 1100 into the 750ES frame! I am more than excited after seeing that bike and teh info on it.

Thanks!
Mike

It appears that it was more than a weekend project and I would love to see more details on this project myself. It looks great!

[Billy Ricks]

I think the new GS bike of the month proves my previous theory, you can fit an 1100 into the 750ES frame!

It also means air-cooled GSX-R750 or 1100 motors can be made to fit. The Kat motors aren't as high strung as the Gixxer motors.

[Anonymous]

Hello. I am new to the board and saw everyone talking about the 85 gs700. I just happen to have one but with a few cool tweaks ending in a super responsive 96HP street monster. I went to AIM in Daytona Beach were I had the chance to really do some nice stuff to the bike and had some good help too. It has 767cc using a Falicon crank and Wiscoe pistons. Comp. is 12.8 to 1. Cams are custom Yosh. stage two setup with 5 angle vavle job. Head was ported. Piston, valves and head were of polished by hand to a mirror like finish (took me weeks to do it, had blisters to prove it, hehe). Rotating part were all balanced by hand. A gsxr oil cooler was used to keep this cooler. Carbs are 36mm but were tuned by the owner of Dynojet personally (he is kind of a jurk but a really smart jurk,LOL) using some wizbang nylon jets, new springs and neddles and four K&Ns on a Dynojet dyno of course. Exhuast was a custom Vance & Hinse with a Rat Trap baffle/tip that was run off the choke lever (thoery was you could close it up coming out of a corner for more torque, could not really say it worked. I used it when I saw a cop as the open baffle of the Rat Trap was quit loud).Trans have all been undercut. Frame was redone for added streinght and to be lighter. Many parts of the bike were drilled to save weight. Progresive front springs and a Kolien?? in the rear. I am sure I am missing some things here but you get the picture. The end product of this labor is awesome. It produced 96HP at 12,500rpms and wieghed in at 396lbs dry. It runs a little on the fat side down low but it is really responsive. On the back curvy roads it a real treat.

This was all done about 10-12 years ago when parts were more available but most could still be done.There is always a way to improve on a motor, it all about how much money and time you want to spend. I am the same guy that has a 250+hp ford escort, hehe, turbos are fun too

[Anonymous]

Re: mods

I'd like to hear more about this. What sort of homebrew efi kit did you get? Where did you get it from? Same questions for the turbo.

The efi is cobbled together from gpz750turbo throttle bodies, injectors, plenum chamber and pressurized pipework, and tps sensor, a aftermarket fuel pump, homemade adjustable pressure regulator and im in the process of replacing the (unreprogrammable) gpz efi computer with a megasquirt.

http://www.bgsoflex.com/megasquirt.html

Turbo wise, I was using a hitachi ht10b, again from a gpz turbo, but ive taken my gs out to 850 since and the lil ol hitachi doesnt reliably flow enough air for the bigger motor, so ive moved over to a garret t2, headers are homemade based round the gpz turbo ones but with the fittings to suit the t2. Most of the problems are from low oil pressure. Hope to solve this finally with a morgo crank driven gear pump for a ariel square four dedicated to pumping and scavenging the turbo......
http://fluffycentral.com/photos/GS850DB-pic2.jpg

Any updates? Hows the megasquirt treating ya? A friend of mine is working on getting his palm setup to tune a megasquirt (that he's adapting to a 200cid ford inline six). At first he's going mild N/A then planning on ~15psi(rail the 2bar map sensor). Should be an interesting project.


-=Whittey=-