• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

85 mph speed restriction in early '80's bikes?

  • Thread starter Thread starter robinjo
  • Start date Start date
R

robinjo

Guest
As of yesterday I have a 1982 GS750T in my workshop who needs it headgasket replaced, this is an US import with the 85 mph speedo. Now the owner tells me that it is restricted to that speed also and can't go faster! 8O Since the bike is now in pieces I can't try this for myself. Also when I rode Karen's 81 or 82 550L (papers say it's a 82T but the bike is an L and the frameplate says 81) I took it on the Highway and it ran very well upto about the speed mentioned above and then cut out, sortof felt like fuel starvation, weird... It is also an American import with the 85 mph speedometer.

Anybody know any more about this phenomenon?

How does it work? The slides on the 750T can be fully opened, I checked that.

Or is it bull :?:
 
Wrong!!! The bikes with the 85 speedo go just as fast as the others, the 85 mph speedo was found to be very dangerous, cause the rider didn't have a clue how fast they were going when above 85, especially dangerous in curves. The law was removed in 1983, and all went back to reasonable speedos. Speedo had no affect on how fast the bike would go
 
Its only the speedo that is limited to reading up to 85 robinjo. Nothing else on the bike is different.

Earl
 
The law was put in place in the late 70s (read fuel crunch) to try and prevent people from going real fast, IE: using a great deal of fuel. This theory worked for cages with 4bbl carburators, but really didn't mean much for bikes. This was also the reason 55 was required to be highlighted on the speedo, because the government wanted everyone to stay below the double nickle. I have the 85mph speedo on my '81 450L and I know I have done better then 85 on it because it was just bouncing off the peg and a friend tailing me said we were above 90. Hope that helps clear some of that up.
 
Found this bit of info on www.suzukicycles.org

"The GS750T was a budget model aimed for the North American market, available in the beginning of the 1980's. It had the 16-valve 750cc engine but its power output was restricted for maximum speed of about 80 mph (130 km/h) making more simple brakes adequate for the model (seemingly borrowed from the GR650, along with other details like the alloy wheels). At front, the GS750T had a single disc and the rear brake was a mechanical drum brake. The color scheme was similar to the GR650 and the larger 8-valve inline-four shafties GS850G, GS1000G and GS1100G."

http://www.suzukicycles.org/visitors-bikes/visitors_GS750T_page1.shtml

The one I have here now is Ard Bisschop's bike.
 
I believe Tim (HiSPL) had one at some time in the past...check with him...I find it hard to believe that they would limit it to 80 mph.

Hap
 
80 MPH

80 MPH

I'm not an expert mechanic but it seems to me that the only way to limit the speed (other than gearing and horsepower) would be to put a rev limiter on it. If it had one of those, the gifted mechanics in our group would know about it and point it out...so it seems like a myth. :?
 
Re: 80 MPH

Re: 80 MPH

chuckycheese said:
I'm not an expert mechanic but it seems to me that the only way to limit the speed (other than gearing and horsepower) would be to put a rev limiter on it. If it had one of those, the gifted mechanics in our group would know about it and point it out...so it seems like a myth. :?
Click to expand...

I have PM'd both Tim (HiSPL) and (Mark) Shaftzuki about this, I hope I get a reply. I knew I shouldn't have taken the bike apart right away :roll: Would the owner be pleased if the top speed of his bike have been increased with 40 mph? :twisted:
 
shaftzuki said:
Robin - the bike will well exceed 85 mph - before I tore mine apart, I rode mine "hard" a few times - well past the mark. As far as I can tell - there is nothing different from the T model motor and the standard E model motor. My carbs are the same, the ignition is the same - I haven't actually measured valves, etc. - but I don't think there is a difference.

I have noticed, however, that things like gasket sets, manuals and other stock items are under different part numbers.

I have a spare 81 750e model motor - I need to make some comparison measurements between the two.

Let me know if I can help - I don't have a manual for the bike (yet) but I can probably put my hands on what ever you need!!
Click to expand...

Very quick reply by Mark here :D

The plot thickens... :-k
 
Hap Call said:
I believe Tim (HiSPL) had one at some time in the past...check with him...I find it hard to believe that they would limit it to 80 mph.

Hap
Click to expand...

why would Suzuki produce a 750 that was slower than it's little brother, the 250??
I know the 81 GS 250 I had would pull past 85mph (135kph) to a top speed in the low 90's given enough room and tucked in good.
 
My 82 GS750T was NOT speed restricted in any way. It also had a 140 mph speedo on it. That however could have been put there by its first owner who was a Suzuki mechanic. It was then sold to my brother, then sold to me. It was run over in a parking lot in the summer of 1996. I still have most of the parts in boxes in my garage.

My T model actually seemed to have mored power than my current 81 GS750E. I know for a fact that the cam followers are different in the T. The cam is probably different too.

There has been some discussion about T models being speed restricted somehow. This has come up before and I answered lots of questions about it in the past, however I can't find the thread now. It must have been before Frank changed domains and it was lost.

If this bike truely is governed somehow, it shouldn't be too hard to reverse engineer the problem to provide a free running engine.

Good luck with your search.
 
cams

cams

I think the answer lies in cam timing, especially if the valve train parts are different.
The camshaft is known as the brain of the engine since it's profiles determine airflow at given speeds through the head.

The carb is a torque limiting device. It will provide progessively more fuel for a given airflow, carbs are seldom a limiting factor on engines like this. However a camshaft with close overlap on the intake and exhaust durations will purposely limit the amount of scavaging and charging that takes place at higher rpms. Reducing the intake duration will lower peak combustion pressures and prevent higher rpms.

Detroit did this in the early seventies to their muscle cars to lower combustion pressures ( and reduce NO emissions) before they stroked the engines and redesigned the combustion chambers.

my .02
 
My first GS bikes were two GS850GZ's, 1982 models. Both came with that silly 85 mph speedometer. Predictably, I took both of them past that 85 mark more than once. :wink:

No harm to either bike or to either speedometer.

Nick
 
My 82 GS1100E came with an 85 mph speedometer. I put the 140 mph unit in that came stock on the 83 GS1100E model. I can assure you the needle does not stop at 85. I think the top speed spec according to the magazines at the time was about 142 mph.
 
Also, my 81 1100e had the 85mph speedo. In top gear the speedo would hit 85 at about 6000 rpm, but the tach would keep climbing! I passed my buddy on his Harley once, he said he was maxed out at 110.
 
My 82 GS1100E has an 85mph speedo, it's useless after 3/rd gear :D :D

Same hold for the 80 GS1000S, 85mph buried in 3/rd gear

Useless speedo.........
 
My '82 GS750T has the 85 mph speedo, if I want to go faster than 85 I just shift out of third. :D My brother in law has a Kawazaki with the 140 mph speedo, I shut my GS down at 120. Like to go fast but not stupid. and 120 is more than fast enough for me. Guess I'm just getting old.
:?
 
I have a 83 750 T and I replied last time I saw this discussion. In mid september this year I had mine up to 100 mph, it was about 7000rpm and I decided that was fast enough and let off. Its possible the 85mph thing was fixed though since the bike's been around a while. I also checked my speedometer against a radar sign that tells you your speed and it was dead on at 60mph so I have decent confidence that the 100mph I observed was accurate enough to say that I was indeed going 85mph or more.
 
Allmost forgot to tell this, the bike was not restricted.
After retorquing the head I have had it up to about 110/115 or so guessing by the way I was passing cars. Speedo did stop because of the little needle that gets in its way, maybe that was why the owner was thinking it.
 
Like Pavlov's dogs?

Saw the 85 and called it a day???




robinjo said:
Allmost forgot to tell this, the bike was not restricted.
After retorquing the head I have had it up to about 110/115 or so guessing by the way I was passing cars. Speedo did stop because of the little needle that gets in its way, maybe that was why the owner was thinking it.
Click to expand...
 
You must log in or register to reply here.
Back
Top