1977 GS750e project

[jibledso]

I think I have a seal guide problem, that or a head gasket.

when I get the bike at temp it starts smoking, a lot

[jibledso]

Sorry, I don’t know what happened to the sound but that’s reving it to about 6,000 rpm

Here’s the compression test results:

Dry. Wet


#4 - 100 psi. 130 psi


#3 - 90 psi. 120 psi


#2 - 94 psi. 109 psi


#1 - 101 psi. 131 psi

What’s strange is that #3 had a little bit of oil on the spark plug last week after riding around the block, all other plugs were dry, so I thought maybe the #3 exhaust valve guide seal was bad and blowing the smoke out the exhaust. There’s a lot in the exhaust pipe, so much that it drips out, it’s loaded in there.

Now I’m thinking maybe the head gasket failed between #2 and #3

I’m going to take the cam cover off, recheck the valves, I shimmed them about a year ago, 7 valves were tight, then I’ll look at the seals, if all of that checks out it will be time to take off the head and look at the head gasket.

Another peculiar thing is that when I bought the bike a rode it for a month I never noticed any smoke rolling out like it is now. Since than I’ve shimmed it, put a v&a exhaust, pods, rejeted, raised the needle. The bike actually runs well acceleration wise. I’m second guessing my shim job even though I checked them multiple times, and then some.

[Chuck78]

Please do re-check your valve shim clearances, and make sure you have the cam lobes pointed at the correct angles. You do not position it so that the cam lobe is pointing straight up in relation to the valve stem angle and shim, or rather perpendicular to the shim; you have to position the cam lobe and the adjacent lobe on that corner of the engine so that they are both pointing up at an angle opposite each other, the same angle from each lobe down to the shim, otherwise you will have one lobe off of its base circle and pushing down on the shim, forcing the cam upward with the valve spring pressure, taking up any slack in the cam bearing journal clearances, and then you will have too tight f a clearance & too thick of valve shims if you were to go back & measure with the proper method. Understand? Sorry I don't have the time right now to dig up an illustration or draw one for you, but I believe it is illustrated in the factory service manual,but you can download those on bass cliff's (aka bike cliff's) website

As far as the smoking, how long has this thing been sitting? It could also be stuck piston rings, or perhaps even some rusty piston rings (from condensation forming in the cylinder, especially when stored in damp environments or when not ran for a long time and going through extreme temperature swings with humid air above freezing temperatures hitting the dew point) that are no longer sealing or gouged the cylinder out.

The valve stem seal could also be a good possibility. As far as I know, it is not very common to ever have a GS with a blown head gasket. Unless it is a poor quality aftermarket head gasket. and it would have to be blown between cylinders 2 or 3 and the cam chain tunnel. If the gasket was blown between an oil passage and a cylinder, that is only on the outside for corner studs which also serve as an oil passage in the cavity surrounding the studs, if it was blown in that area, you would probably also have a very visible oil leak on one of the outside four corners of the cylinder head and cylinder block mating surfaces.
It is also possible that perhaps maybe some moisture got on the valve stem on a warm spot and caused some minor rust to form, which also trashed the seal. It would be pretty unlikely though that moisture would make its way through the the bucket area from above, which is where that theory would most likely need it to come from.

I also wanted to chime in that I had great success one time with an engine that had low compression, just squirting a little extra oil in through the intake ports and spark plug holes, the way that you put some oil in the spark plug hole when you do a wet compression test. Then cranking it over and running it with a fairly excessive amount of oil in there, but not enough to cause hydrostatic lock up! Less than the combustion chamber volume minus the piston dome volume, or else you could do some damage. I'm trying to recall now if I used some automatic transmission fluid actually. But I may have been the case. Somehow doing that restored compression into this GS550 engine for quite some time. I was wondering if it helped clean up the valve seats, or if the bike had some stuck piston rings or carboned up piston rings that became freed up by doing this procedure. I also have theorized in the past and practiced setting the valve shim clearance on the loose side in an effort to make the valves close a little more firmly against the seat, in an attempt to try and mechanically force excess carbon build-up off of the valve and seat sealing surfaces.

I suppose a warped head from severely overheating is a very slight possibility, but I have never really heard of this happening in over a decade of wrenching on air-cooled GS's and other motorcycles

[Grimly]

[ATTACH=CONFIG]57153[/ATTACH]

Will these GS850 front calipers fit on my GS750?

If you have them to hand, offer them up to the fork legs and check whether they will bolt up and cover the disc surface properly.
A gotcha to be aware of, is the L model uses the same calipers, but the mounting bracket is different, to accomodate the different positioning of the disc in relation to the centre-line of the forks.
If you examine those calipers and find they're low-mileage, they are definitely worth cleaning and installing. What makes the older OEM brakes bad is accumulated wear on the sliding pins - but especially the holes they bear in. There is no provision for wear, they either are worn or they're not, and when they get a bit worn you lose essential brake power because the calipers tilt on their pins before being useful as brakes.
I've successfully hunted down low mileage calipers and I'm really quite satisfied with my GS brakes. After a proper overhaul they're better than they've been for 20 years or more, and I'm not exaggerating. The wear happens gradually and you don't notice it until it suddenly hits you the brakes are crap.

What I will say with a high degree of certainty; the brakes on the '79 850 were the hockey-puck type and they always were bloody awful compared to the '80 bike. When I took the hockey-puck calipers apart I was aghast to find they were designed with a large hollow in their structure that fostered corrosion out of sight. When I realised the amount of corrosion they had internally I binned them as totally unfit for purpose.
The good part:
The later calipers fitted straight on to the earlier fork legs.

So, to answer your question; yes, use them if they fit and your budget dictates.

[jibledso]

Please do re-check your valve shim clearances, and make sure you have the cam lobes pointed at the correct angles. You do not position it so that the cam lobe is pointing straight up in relation to the valve stem angle and shim, or rather perpendicular to the shim; you have to position the cam lobe and the adjacent lobe on that corner of the engine so that they are both pointing up at an angle opposite each other, the same angle from each lobe down to the shim, otherwise you will have one lobe off of its base circle and pushing down on the shim, forcing the cam upward with the valve spring pressure, taking up any slack in the cam bearing journal clearances, and then you will have too tight f a clearance & too thick of valve shims if you were to go back & measure with the proper method. Understand? Sorry I don't have the time right now to dig up an illustration or draw one for you, but I believe it is illustrated in the factory service manual,but you can download those on bass cliff's (aka bike cliff's) website

I checked the valves at the shim and lobe when the pointy side was facing away from the shim, I would look at the engine case and look to see it made a 90 degree angle; (case _) (shim l). _|

that is how I did my CB500F

like I said I’ll check it again and get the service manual

As far as the smoking, how long has this thing been sitting? It could also be stuck piston rings, or perhaps even some rusty piston rings (from condensation forming in the cylinder, especially when stored in damp environments or when not ran for a long time and going through extreme temperature swings with humid air above freezing temperatures hitting the dew point) that are no longer sealing or gouged the cylinder out.

The bike was in a heated garage after I stopped riding it and even though Gothenburg is very moist I don’t think that’s a problem.

The valve stem seal could also be a good possibility. As far as I know, it is not very common to ever have a GS with a blown head gasket. Unless it is a poor quality aftermarket head gasket. and it would have to be blown between cylinders 2 or 3 and the cam chain tunnel. If the gasket was blown between an oil passage and a cylinder, that is only on the outside for corner studs which also serve as an oil passage in the cavity surrounding the studs, if it was blown in that area, you would probably also have a very visible oil leak on one of the outside four corners of the cylinder head and cylinder block mating surfaces.
It is also possible that perhaps maybe some moisture got on the valve stem on a warm spot and caused some minor rust to form, which also trashed the seal. It would be pretty unlikely though that moisture would make its way through the the bucket area from above, which is where that theory would most likely need it to come from.

I also wanted to chime in that I had great success one time with an engine that had low compression, just squirting a little extra oil in through the intake ports and spark plug holes, the way that you put some oil in the spark plug hole when you do a wet compression test. Then cranking it over and running it with a fairly excessive amount of oil in there, but not enough to cause hydrostatic lock up! Less than the combustion chamber volume minus the piston dome volume, or else you could do some damage. I'm trying to recall now if I used some automatic transmission fluid actually. But I may have been the case. Somehow doing that restored compression into this GS550 engine for quite some time. I was wondering if it helped clean up the valve seats, or if the bike had some stuck piston rings or carboned up piston rings that became freed up by doing this procedure. I also have theorized in the past and practiced setting the valve shim clearance on the loose side in an effort to make the valves close a little more firmly against the seat, in an attempt to try and mechanically force excess carbon build-up off of the valve and seat sealing surfaces.

I suppose a warped head from severely overheating is a very slight possibility, but I have never really heard of this happening in over a decade of wrenching on air-cooled GS's and other motorcycles

thanks a bunch for the info!

[jibledso]

If you have them to hand, offer them up to the fork legs and check whether they will bolt up and cover the disc surface properly.
A gotcha to be aware of, is the L model uses the same calipers, but the mounting bracket is different, to accomodate the different positioning of the disc in relation to the centre-line of the forks.
If you examine those calipers and find they're low-mileage, they are definitely worth cleaning and installing. What makes the older OEM brakes bad is accumulated wear on the sliding pins - but especially the holes they bear in. There is no provision for wear, they either are worn or they're not, and when they get a bit worn you lose essential brake power because the calipers tilt on their pins before being useful as brakes.
I've successfully hunted down low mileage calipers and I'm really quite satisfied with my GS brakes. After a proper overhaul they're better than they've been for 20 years or more, and I'm not exaggerating. The wear happens gradually and you don't notice it until it suddenly hits you the brakes are crap.

What I will say with a high degree of certainty; the brakes on the '79 850 were the hockey-puck type and they always were bloody awful compared to the '80 bike. When I took the hockey-puck calipers apart I was aghast to find they were designed with a large hollow in their structure that fostered corrosion out of sight. When I realised the amount of corrosion they had internally I binned them as totally unfit for purpose.
The good part:
The later calipers fitted straight on to the earlier fork legs.

So, to answer your question; yes, use them if they fit and your budget dictates.

i 100% agree on the short comings of the hockey puck design and after seeing all of that sand fall out I’m not thrilled about using them again but money dictates a lot. I actually don’t have those in the picture in hand, they’re in Germany. There is one more guy in Sweden I can call and hope has one for a decent price.

I got a free rear caliper from a guy on a Facebook page here in Sweden, it came off an 83’ GS model of some sort and it works very well compared to the old rear caliper. This one has no stabilizer bar to the swing arm.

[jibledso]

i Looked at the manual just now and yeah I think I measured it at the wrong position, gonna check tonight

[jibledso]

Got the correct shims and measurements, but haven’t started the bike. I did get a nice new shiny oem front caliper that looks great and at a good price.

before I start the bike I need to tighten the clutch spring bolts, because when I rode the bike last it was slipping which it never did before.

I’m just not sure how to tighten the bolts to 3.5~ without turning the clutch plats? I tried holding the rear wheel and using my torque wrench but I can’t hold it.

Tomorrow I’m going to take the basket out because I need to see what’s going on with the shift linkage. When I rode it last it will go into all the gears but they are not shifting solidly into place. For example when I put it into first I have to lift up a little on the shifter before putting more force to go into 2nd, pretty much all the gears are like this. Back home my 03’ 1200 bandit did the same thing. I’m assuming it’s the linkage has something wrong with it.

also I noticed my kickstarter does absolutely nothing when coming down, it just turns the inside of the clutch basket and not the motor.

should I loosen the clutch cable and the nut and screw on the left side before jumping into the right side?

[Chuck78]

It's not a primary-kickstart like enduro/woods/trail off-road bikes. If you pull the clutch in, everything spins EXCEPT FOR the crankshaft & outer part of the clutch (the basket).
You are either pulling your clutch while trying to start, or you have no freeplay in either your clutch actuator or the cable or both, and your clutch is always slightly disengaged.

Shifting problems wuth engine running are often caused by warped clutch steel discs. Running them slightly slipping (caused my the afforementioned mis-adjustment) will warp them

One quick thing to check, if you have a huge amount if freeplay or just had it apart & put back together, the cable housing may be hung up on on the end of the adjusters barrels/ferrules, sitying on the rim of them under tension, and not seated down into them.this woyld also cause the exact kickstarter symptoms you mention.

[Chuck78]

Oh wait I just re-read your full post, sorry was distracted/conversing/multitasking previously....

If your 6 clutch springs are not torqued, nothing will happen between the front half and back half of the engine/gearbox...riding it or trying to operate the kicker.the kicker turns the transmission, which turns the clutch, which turns the badket if clutch is engaged, which turns the crank.
Torque them down & see if that fixes that issue.

Its like tightening car wheel lug nuts with the car jacked up. You have to have the wheel (lug nut on left side lower than wheel center) in the right position & the wrench at the right angle (from 2:30 to 3:30 or thereabouts?), & the clutch won't spin anywhere near as easy. I made up a clutch holding tool a whe back out of steel bar stock. Suzuki sells them, motion pro makes a cheaper one as well.

[Chuck78]

Shifting is mostly controlled by the shift drum, forks, & shift dogs on the sides of the gears. Riding the shifter pedal will cause excess wear on these parts
I think there is a forked/toothed detent shifter piece on the 750 that is to the rear of the clutch side on the opposite end of the shifter shaft, but I've never seen any of those go bad. Perhaps the shaft is bent and it is causing it to hang up and fight against the shifter 2-way spring.
Most of the junkyard engines I scored all have bent selector shafts sadly, most from mis-handling when apart, some from crashes.

[jibledso]

Thanks for the info Chuck

Yeah, I never was holding in the clutch when pushing down on the kick-starter.

the strange thing about the shifter is I never had a problem before when I bought it and rode the bike initially. I suspect when the bike was being transported to it’s current garage it must of bumped up against something on the shift lever. That’s initially why I took off the clutch cover to see what was going on, because it wouldn’t shift at all. After taking off the cover the return spring was off the shifter and the teeth (dent/fork/teeth you’re referring to)were not meshing, so I put the spring back into place, placed the teeth in the correct place going into all the gears and thought the problem was solved but after putting everything back in I could go into every gear, but like I said, it’s not as smooth as before. Like I said something must of happened when transporting the bike. It was in an enclosed box truck strapped to the floor, my XTZ was strapped next to it. We could hear some moving around while driving, I thought maybe the bikes were bumping into each other but I never heard anything that sounded like a shaft being bent, but that’s the only thing I can think of.

It still goes into all the gears so I’m not going to be splitting the case anytime soon, it’s actually not that bad, and after riding that Bandit for three years with a similar problem I’m use to it.

But maybe after taking the clutch basket out again I can see what’s up with that spring and teeth and make it smooth again.

[jibledso]

So, I finally got around to playing with the shifter and what I gather is when I up shift there’s not enough pressure from the return spring to put back into its original place without physically moving it with your foot, then it clicks into place. However, it does function normally when downshifting, there’s enough spring pressure to put it back into its original place on the meshed gears.

here’s a video, you can see it when I up shift, it just hangs there.

[jibledso]

I noticed one end of the spring is shorter than the other, the top one where it pivots. I’m starting to wonder if that is affecting the pressure of the spring, or it’s not catching the pivot on the back of the shifter arm.

if you notice in the video when I up shift the top of the spring where it pivots does not move away from the pivoting point, unlike the bottom one that does move down and returns the meshed gears back into place, ready to shift again.

Does it make a difference how you put the spring on the pivot? Should you do it with the shifter arm aligned with the other teeth?

136A4CAC-2C11-4D1C-A73F-128C22065FB6.jpg It

[jibledso]

Btw, it goes into all the gears, just takes a little tlc with the upshifts

C9AA5F6A-68AA-41D7-959B-A5BCBFD5F8E7.jpg