help me with my '82 GS750T

[Anonymous]

Hello All,
I bought my '82 GS750T 6months back. It was lying unattended for almost 1 yr. I bought a new battery, cleaned the carbs, bleeded the brakes and added new oil, cleaned the gas tank and the waterworks and then it was ready to roll.

I have been riding it for 6months now. (Yes In Atlanta you can ride even during the winter months !!) My bike's acceleration from 0-60 is unbelievably good. I'm always the first one to leave the lights when they turn green. But the acceleration is really bad after i cross 60mph. It takes almost a full minute to reach 75mph. and at75mph the engine is so busy, I have never tried to push it any further. and My speedometer has markings only upto 85mph. So I thought it was normal behavior. Until I started researching to buy a Honda Shadow.

The honorable members in Honda were horrified when I said that my GS750T doesnot go over 75mph. I was overwhelmed by what i heard from them. They urged me to spend some time and investigate what is wrong with my bike. They said GS engines are legendary and they can easily pass 100mph.

They were the ones who directed me to this site. And Here I am soliciting your help to realise the full potential of my GS750T. Where do I start from ? What do I look for ?

Here are some things I have laready done. (1) I have found that my rear tires are smaller than the tires that ought to have been used for this bike. (2) I also have starting problems on winter days, when I take the bike out after 2 weeks of inaction. The machine doesnot start until I spray some Starter fluid into the engine !!! (just choke doesnot help) (3) I have difficulty rolling my bike after 2 weeks of inaction. I hear squeaking in the front tires. But once I take it out for a ride, it smooothens.

I just though this information might help you guys understand the condition of my bike. I would highly appreciate any help/advise/comments that you can guys can give me. Thank you all.
gforce.

[Mastiff]

'mI glad you decided to came over here, Gforce. I'm not the guy to help you on this, but I am sure these guys can definitely sort out how to fix your bike.
When you say you cleaned your carbs, what exactly did you do? Did you just spray some carb cleaner through them, or did you take them off, dissassemble them and blow out the passages? What does your fuel filter and air filter look like? What is the waterworks you cleaned out? Just a few questions to get started.

[Anonymous]

hi mastiff,
I gave the bike to a machanic and go it cleaned, He charged me $150 for it. God knows what he cleaned or how he cleaned ! Havent seen the fule filter, but I see the sir filter regularly, when i open it to spray starter fluid to get my bike to start.

I am not familiar with motorcycle repair until I bought this bike. Am learning and am very interested in knowing the internals. I changed the cltuch wire on my own, the side-stand indicator switch, I tightened the chain and installed a new tachometer chord. These are my only experiences with motorcycle repair.

I'm an engineer, so am curious to know what is wrong and I am determined to get this bike back to its old glory, with help from you guys !
gforce.

[80gs1000e]

When I got my 80gs1000e it was the same way almost. I had to hold on for my life until I got to about 70mph where it would bog and stutter. Only after I took the carbs off did I find that somebody was in there tinkering and had basically destroyed one of my carbs and mashed up the wall making it inoperable and limiting my fuel flow. I got a replacement, dipped and rebuilt them with a little help from a friend and whooooosh.....full power up to 100mph where I backed off fearing for my safety. It was wanting to go faster but I don't need to go there. You've got a fuel flow/delivery problem....perhaps a vacume problem. Check your carbs!

[HiSPL]

What is the tach telling you? Can you easily rev the bike to 9-10K rpm? Or is it sluggish as you get the revs up? When your doing 70mph in fifth gear what is the rpm showing?

Maybe this will shed some light on the subject.

As far as I'm concerned, there was nothing wrong with the T model save for the brakes. But that can be fixed. The engine is identical to the E model of the same year..... And it was very powerful indeed.

[Anonymous]

My tachmeter cable is broken. I'll work on getting it fixed .. so i can answer ur questions

gforce.

[Anonymous]

FYI -
1) My rear tire is 130-70/17 .. I guess this is smaller than what ought to be on that bike

gforce

[HiSPL]

Nope... Thats exactly right. The T model had a 17 inch rear and a 19 inch front. The E model used a 18 inch rear, thats where the confusion lies I bet.

My gut is telling me that your clutch is shot (which is an easy fix BTW). When you get the tach working we'll be able to determine a whole lot more.

[Anonymous]

Hi HiSPL,
I put on a tach cable today and checkedthe RPMs .. Here are some observation :
1. It idles at 1500RPM
2. I tried reving up the machine to 6000RPM at idling.
3. When i was doing 80 mph the tach show 6500rpm ...
4. Today i pushed her to 85mph (that is the max it wud show on the speedometer). There is a small plastic piece inside the speedometer which stops the speedoeter arm from going further. Can i drive any faster than that, without damaging my speedometer ?

Here are 2 things i plan to do from my side :
My front brake pads are worn out. And are rubbing against my front disc. which might be slowing down the bike too. ( ??) I am getting new pads on tuesday. Once i replace that I'll know if there is any improvement in performance.

One of my friends who took a look at mybike put his arms in front of the exhaust and askedme to rev the engine. Andhe observed that the exhaust coming out is weak. He thinks that the exhaust might be rusted on the inside and might be blocking the exhaust, which might prevent the engine to lose performance on the high end. any comments .. so next weekend i plan to remove my exhausts andtry and run the machine and see if there is any change.

Any comments/ideas will be welcome.
thanks.

[HiSPL]

Ok, 6500 at 80mph sounds about right... So its not the clutch.

Yes you can go faster than 85 without hurting anything. In fact I drive around at 85 all the time....

Get your brakes sorted out. the dragging pads are definately not helping the performance any. Just a note though. There should be some free running drag on the brakes in order for them to work properly. So when you put it back together and the rotor makes that slight grinding noise don't worry, its normal. Also don't forget to grease the two pins that the caliper floats on. These pins dry out and cause the static side pad to drag the rotor too much, causing worn pads and warped rotors. Also check, clean, adjust, and lube the drum brake. Sometimes if its too dirty or dry it won't retract like it should.

Its also possible that the exhaust is rusted inside the mufflers. I don't think this would cause any blockage, but it could make your bike run too lean. Which would cause a loss of power. Don't expect an overwhelming amount of air coming from the exhaust. These are very small motors by comparison. Besides, the stock exhaust has a crossover pipe, so if you block one side then all the exhaust comes out the other side.

If your baffles are rusted then you should hear some rattling or something coming from the muffler area when you rev the engine. It may also spit out small chunks of rust too!

Does the bike make little popping noises on deceleration? Or spitting? Or real backfiring?

What does the chain look like? Rusty or oily?


We'll get this figured out, just hang in there.... It really is worth it. 8)

[Pete Logan]

I got a '82 750E TSCC. It is redlined at 9500 rpm. If you are doing 80 at 6000, that would imply around 120 at redline which would be about right IMHO.

You won't hurt the speedo by going over what it says. You might break it though, which would be no bad thing, given that it won't tell you anything useful, unless you plan to stick to 85 mph. That was a joke

Different exhaust systems have different effects on hands held at the end of the mufflers. I would be more inclined to pay attention to actual performance.

Idles at 1500 is a little high. Maybe 1200 would be better. To be honest, on mine, it's kind of 'just a little bit the thick side of 1000'. Just on the idle screw if you want to.

OK - since you are riding it, here's the next thing I suggest you do:

Thrash it to redline in each of the first three (3) gears, note rpm and speed achieved. Let us know how it felt as you went up the rpm range and gear range. It should be pretty consistent, with a strong pull all the way up to the max in every gear.

Back off if you feel like it. I personally would not care to take mine flat out all the way up the lower gears, and I am a big, brave coward

Obviously speed readings will not apply to the higher gears, from what you have already said, so in fourth and fifth, just run it into fourth at the same speed as you come out of third, note the rpm reading, then run it into fifth at the same speed, and note the rpm reading again.

I'm pretty sure this will give us a bit more helpful information.

Oh, by the way, try and pick a reasonably safe road.

We don't want to lose you. 8) 8)

Pete

[Anonymous]

Pete,
>Idles at 1500 is a little high. Maybe 1200 would be better.
am sorry i had given u a rough figure .. actually it is around 1250rpm.

>You won't hurt the speedo by going over what it says. You might break it though, ...
Isnt it against the law to ride a bike with a broken speedo ? Do you think I shud change my speedo ? 'cos I plan to take it past 85 mph ...

>Thrash it to redline in each of the first three (3) gears, note rpm and speed achieved.
I will give u the results for this asap.

HiSPL,
Thanks for ur tips on break pad installation. I will keep them in mind.

>If your baffles are rusted then you should hear some rattling or something coming from the muffler area when you rev the engine.
No rattling sounds. or no solid particles coming out of the exhaust.

>Does the bike make little popping noises on deceleration? Or spitting? Or real backfiring?
NONE absolutely. She runs very smoothly and consistently. One observtion though. She decelerates pretty fast. Even when I'm on my top gear and am cruising at 60mph. If I cutout the throttle she slows down pretty fast. Cud this be 'cos of the dragging of the front brake ?

>What does the chain look like? Rusty or oily?
No rust. It is got black grease, but pretty dry. I apply chain lubricant once in a while. I am wondering if I shud clean it !

There is a noticeable change in the engine sound when i cross 80 mph. I dont know how to describe it. It is a hollow sound. I will buy a half helmet and then ride again to hear and describe the sound to u guys.

Anyway, thanks for ur help guys.
Lemme goahead try ur suggestions and get back to you asap.
I will be hanging around reading other replies that i get.
gforce.

[earlfor]

Ahh Haaa, howwlow sound eh? Sounds like you have a couple of carbs out of synch. Try synchronizing the carb vacuums, (should be 8-10 in hg @ 1250 rpm) and take a test ride.

Earl

[quote="gforce"]
There is a noticeable change in the engine sound when i cross 80 mph. I dont know how to describe it. It is a hollow sound. I will buy a half helmet and then ride again to hear and describe the sound to u guys.