79 GS750E Clutch Issue's

[Neveragain55]

Ok Gang,

I own a 1979 GS750E that I restored about 17 years ago and have meticulously maintained all these years.

The internals of the engine are all original and I have never changed the clutch, although I did put a new clutch cable on about ten years ago.

I also put new chain spockets on the drive end and the rear wheel but I used lock-tite on everything and I periodically check everything for tightness at the begining of every riding season.

The clutch is due to be changed which I plan on doing this summer because my adjustment at both the clutch lever and clutch case ends have no more room for adjustment.

Here’s the problem, that never happened before until last summer at the tail end of the summer riding season.

She would slip and just unexpectedly rev like crazy during hard acceleration in the upper gears.

I’ve seen some of the write ups on this but it seems like a lot of people have different opinions.

My bike never did this before and I’m really miffed by it. I’ve never wheelied on the bike or abused her in any way, no hard launches or anything, any ideas?????

[1980GS1000E]

Your clutch is worn out.

[hjfisk]

Pull it apart and measure everything if all is in spec and looks good order a new set of springs , and a new cable put it back to gether and ride it another 15 years or if it is not within spec order a OEM clutch, with fibers and steels, new springs and a cable and be good for another 34 years

[tkent02]

Get a Suzuki cable this time, and new clutch springs. The plates are not likely to be worn out unless you slip the heck out of it every time you ride, do a lot of very hard drag racing type starts, or you have 200,000 hard miles or so... It doesn't sound like you do.

The springs on the other hand have been compressed for 34 years, they are shorter now and can't provide enough pressure. Use stock Suzuki springs, they are the best and are dirt cheap.

Look for wear in the perch and in the lever, where the cable goes into the lever. Also check the helix thing where the cable goes into the sprocket cover. These parts get messed up sometimes. Make sure the adjustment screw on the helix is set correctly too. Grease everything that moves, especially where the cable end goes into the hole in the lever.

[1980GS1000E]

Or your springs are worn out.

[gssteve]

Clutch

Just out of curiosity what type of oil are you using?

Synthetic oil can also cause the clutch to slip.

[tkent02]

Synthetic oil can also cause the clutch to slip.

More likely to make it slip is modern thin car oil with "energy conserving" on the label.

Synthetic in the correct type and grade won't cause any slipping.

[Neveragain55]

Thanks for all the reply's guys.

I thought you guys would point me in different directions like the dog shifter or the nut that holds the front sprocket or the groove that the sprocket key slides onto.

I use dinosaur oil because everybody I know that uses synthetic oil in these old bikes have nothing but problems.

I've used the same oil over all these years since I built the bike.

The clutch does need to be changed, but not because she slips, I just like to do preventative maintenance. I'm changing the clutch because of the age of the bike.

She doesn't slip really in any of the gears normally; it's just when I goose her hard at speed - in gear - around 70 miles per hr. And like I said in my original post, she's never done that before.

She's ll just momentarily rev like crazy and then catch again after I back off of the throttle.

It's very strange and doesn’t seem like a slipping clutch.

[Agemax]

She doesn't slip really in any of the gears normally; it's just when I goose her hard at speed - in gear - around 70 miles per hr. And like I said in my original post, she's never done that before.

She's ll just momentarily rev like crazy and then catch again after I back off of the throttle.

It's very strange and doesn’t seem like a slipping clutch.

well, if you goose it hard while it's NOT in gear then it would rev wildly.
if it doesn't seem like clutch slippage, are you sure its not wheel spinning?

[blowerbike]

lol@ wheel slip on a 750...
WORM GEAR ADJUSTMENT!!!!!!!!

[Neveragain55]

Agemax,

Thanks for the reply but you misunderstood.

Let me try this again....

While I'm cruising down the road with the bike (in 4th or 5th gear) and I want to accelerate very quickly (from a running roll in gear) I lose drive action to the rear, and the engine will rev really high.

It doesn’t feel like the clutch is slipping as much as it feels like the whole system just disengages momentarily.

It's not wheel spin, it’s not because I have the clutch lever pulled in, and it doesn't feel like the clutch is slipping, it feels more like something inside, somewhere it causing everything to disengage momentarily.

Understand what I'm trying to say?

[chuck hahn]

Look at the steels for any wear marks, bluing, and lay them on something dead flat like a sheet of glass to see if they all lay flat and no warpage.

Measure the fibers..or just replace them and check the steels thickness as well.

New springs will also help.

If you have the adjustments at the bars and the lower end as far out as they will go, then i would also replace the cable..its probably stretched some.

[allojohn]

Agemax,

Thanks for the reply but you misunderstood.

Let me try this again....

While I'm cruising down the road with the bike (in 4th or 5th gear) and I want to accelerate very quickly (from a running roll in gear) I lose drive action to the rear, and the engine will rev really high.

It doesn’t feel like the clutch is slipping as much as it feels like the whole system just disengages momentarily.

It's not wheel spin, it’s not because I have the clutch lever pulled in, and it doesn't feel like the clutch is slipping, it feels more like something inside, somewhere it causing everything to disengage momentarily.

Understand what I'm trying to say?

It can only be clutch slip causing this issue - nothing else. Get in there and fix it.

[Nessism]

Agemax,

Thanks for the reply but you misunderstood.

Let me try this again....

While I'm cruising down the road with the bike (in 4th or 5th gear) and I want to accelerate very quickly (from a running roll in gear) I lose drive action to the rear, and the engine will rev really high.

It doesn’t feel like the clutch is slipping as much as it feels like the whole system just disengages momentarily.

It's not wheel spin, it’s not because I have the clutch lever pulled in, and it doesn't feel like the clutch is slipping, it feels more like something inside, somewhere it causing everything to disengage momentarily.

Understand what I'm trying to say?

What you describe IS clutch slippage.

Have you ever adjusted the clutch mechanism helix drive? If not, look in your factory Suzuki service manual and do so. Lube the helix while you are at it too, if you haven't lately. Needless to say, you should adjust both ends of the clutch cable inward as far as possible (adding slack) before adjusting the helix.

Properly adjusting the clutch mechanism may solve the problem. If not, you will have to crack the cover and inspect all the clutch parts per the service manual procedure. Most of the time the friction plates will be plenty thick and simply replacing the springs will solve the problem. In some instances the clutch friction plates will get hard and petrify, and fresh stock plates will grab better. What to do comes down to money and time.

Oh, and hope you are not using dino automotive oil. The formulas have changed over the years and a good deal of the high pressure additives that reduce wear have been removed. Diesel engine or motorcycle oil is far better for your bike.

[Steve]

Just out of curiosity what type of oil are you using?

Synthetic oil can also cause the clutch to slip.

Synthetic oil will not cause slippage.

Using the wrong viscosity or wrong additive package will, though.

I use dinosaur oil because everybody I know that uses synthetic oil in these old bikes have nothing but problems.

They they are using the wrong synthetic oil. What kind of problems are they having?

The clutch does need to be changed, but not because she slips, I just like to do preventative maintenance. I'm changing the clutch because of the age of the bike.

Evidently you have more money than I do.

And, based on your description, it's not "preventative" any more, you are squarely into the "repair" phase.

She doesn't slip really in any of the gears normally; it's just when I goose her hard at speed - in gear - around 70 miles per hr. And like I said in my original post, she's never done that before.

She's ll just momentarily rev like crazy and then catch again after I back off of the throttle.

It's very strange and doesn’t seem like a slipping clutch.

Well, if it's not a slipping clutch, it has to be stripped gears or a spinning tire.
Since it hooks up again, we can rule out the stripped gears.
Since it's a basically stock 750, we can rule out the spinning tire.

If you have paid any attention to all the responses, hopefully you will have caught on by now, but your most-likely culprits are cable/mechanism adjustment or the clutch springs.

It costs virtually NOTHING to adjust your cable and release mechanism. It only costs just a little bit more (about US$30) for a clutch cover gasket and a six-pack of STOCK springs.

If you have ridden the bike as carefully as you say, the clutch disks are probably just fine, but if you want to spend over $100 to replace them, go ahead.

Just out of curiosity: you say you are changing the clutch due to its age. When is the last time you changed the brake hoses?
In the service manual, Suzuki recommends checking/changing the clutch when you experience problems (as you are, right now), but recommends changing the brake hoses EVERY TWO YEARS, and there is no mileage criteria. Just wondering if you have done that or maybe even replaced the stock hoses with stainless lines?

.