'77 GS750B, "Hahn" Tankenstine.

Brodie

Gold Coast, Queensland
DTT SUPPORTER
OK I was not going to start a build on this bike until I had got the engine free but now is a good a time as any.
When I was looking to upgrade from my SR250 I started asking around at work if anyone had a GS450 or the likes, one of the blokes mentioned that he had a 750 he was going to restore.
Being that I am still on my "restricted" license (can't ride anything over 650) I was not in the market for a 750, after a bit of thinking I decided I would ask him what he wanted for it.
After a bit of talking he decided he did not have the time or money to do the bike justice so he asked if I wanted it, well yeah of course. A week later I picked her up, all for the cost of a carton of "Hahn Super Dry" hence the name.

The previous owner lives on a farm and this bike was sitting in his shed for two years, but it had been outside for the past 6 months. As with any bike found under a tarp behind a shed I assumed the worst, surprisingly the tyres were still inflated and only a few critters had made it home. Seeing that it is winter here I was expecting a snake to be under the tarp at least but there was only a few large spiders and lizards.

Here is where she sat for six months, picture was taken after the tarp was removed.


After I wheeled her around to the trailer I decided to take a "before" photo. Not to bad considering.


It was then I decided to jump on her and see if she would spin. After putting her in neutral and looking down to see the starter motor was MIA I flicked out the kick and decided to give her a gentle push, which ended up with me standing on one foot in the air. That is when the project got a whole lot bigger.

After I got her home it was off to work so the cylinders were filled with oil to hopefully loosen the engine. after sitting for a day it had not helped so I decided to rip in to the engine as I would have had to anyway to get the cylinders honed and stick new rings on. Here is the progression of the tear down.




Well at least the head is nice and clean. On to the cylinders now to see which and how many are stuck


Cylinder 1 and 2 seem fine, full of oil but fine none the less.


Yep has to be one of these two milky b-tards.

So with a bit of persuasion with a BFH and a block off wood I find it is cylinder 4. I decided that a bit of inox might help to free her up as that was the only thing I could find that would help. So another day later and no go. VonYinzer suggested Kero so that is the plan after I clean up the ungodly about of rust that used to be the exhaust system.
 

Redliner

New Member
Re: '77 GS750, "Hahn" Stuck engine.

Hey here's an idea! Toss the pipes to the heap :D

Suzuki had to cut costs in some parts. The exhaust wasn't spared. Pretty much any GS you find from those early 4-stroke days will have aftermarket. If not, you'll notice they are blue blue blue!

Just get aftermarket and smile, you got a good one!
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Re: '77 GS750, "Hahn" Stuck engine.

My plans for this bike so far are fairly simple. Get the engine free, get the brakes working and get the electrics sorted. No point spending cash till I know I have at least a decent base to work from.

I will have to do a rebuild on both brake calipers and I plan on getting a new master cylinder for the front whilst I try to rebuild the back. All new stuff for me coming from a lot of no hydraulic bikes.

After that it will be all the standard "go fast" stuff.
Dyna S electronic ignition.
Dynatek 3ohm coils
Roc City Cafe "Manx" seat
Stretched tank.
Acewell 2853 Gauge
Rear sets.
Clubmans
K&N filters
4 to 1 exhaust
swingarm mounted fender
Small LED indicators
Small LED tail light
New sprockets and chain.

I have not decided on a colour scheme yet but there are two bikes that are inspiration for this.
My inspiration


Previous Owners inspiration
 

Big R

Heaven is so far away.
Re: '77 GS750, "Hahn" Stuck engine.

Signed up.

I'm sure you'll get the cylinders free, so I won't add to that. But keep an eye out for a GS850 top end - instant addition of 100cc's. That's one of the many benefits of Suzuki: so many parts interchange.
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Re: '77 GS750, "Hahn" Stuck engine.

Thanks Rich. A mate of mine has a 79 GS850 that is a project as well. I figure on my poor ass early 20s budget I won't do anything to drastic. I plan on keeping this bike so I will be looking at an 850 top end once I tame the 750 lol. Another benefit I noticed is that the order in which to torque down the head is cast into the metal. Bloody awesome idea I recon. Suzuki keeps on surprising me.
 

Big R

Heaven is so far away.
Re: '77 GS750, "Hahn" Stuck engine.

Nice, huh? As long as it's clean enough to read the numbers......

You could skip the 850 top end and just work a GSXR motor in there.......nah, better hold off on that for a while. :)
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Re: '77 GS750, "Hahn" Stuck engine.

Now you are giving me bad ideas, I wonder how much a TSCC GSX engine is. Every time I start to think this bike is better as a parts I keep thinking "Well if I do replace most of the things at least I will know what has been done"

Just did some minor things thisarvo, removing stuff from the frame was the aim. Pulled the original lights and indicators and chucked on a set of clubmans. Also removed the gauges and sorted some of the wiring. The clubmans do not sit in the risers well as they contact with the bolts at the top of the fork legs. I will leave them on so I can move the thing but I think that clip ons with a bit of a rise are going to be the way to go. So much work to be done, but that is what makes the build for me, chipping away at problems slowly.
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Re: '77 GS750B, "Hahn" Stuck engine.

AND I broke the lobes off the spark advancer trying to turn the engine over using the crank. So lesson learnt, $50 lesson, but still learnt.

I have tried most of the simple things to free the piston, all but two, I am going to try patience before I resort to this "Fire" method.
I came home to find my Roc City Cafe seat had arrived, man that thing is sturdy! Sadly for me I ordered the seat to fit the SR not the GS, It will fit but it just looks a little small.
I would take a photo of it but I am trying to force myself to stay the hell away from the bike until kero has had a chance to work.
 

Hoosier Daddy

Earache my eye...
Re: '77 GS750B, "Hahn" Stuck engine.

Von is one smart cookie so not to take anything away from him but I mix in a little Automatic Trans Fluid with my Kero. OR better yet if you can get acetone down under ( I know your chemicle regs are more strict than here in the states) a 50/50 mix of ATF and acetone is rated at the top of many penetrating oils to free rusted bits.
Have you drain the crankcase yet? You'll want to see if any water made it past the rings and into the guts of that engine.

And just to keep you from getting discouraged here is a pic of the engine in my Zook the day I brought her home. ;)
 

Attachments

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Re: '77 GS750B, "Hahn" Stuck engine.

Ha thanks HD. Looks like I have about the same starting platform as you did. I have not tried ATF and Acetone yet, Catbird has been telling me to use that mixture also. I will have to give it a go then. Once I knock off work it will be off to the auto store.

As for the fuel tank I have heard that filling it with apple cider vinegar is the way to go for removing rust.
Once the rust has come free you then neutralize the acid with bi carb and water mixed.

The other thing I have seen is electrolysis which I was also thinking of trying.

I am going to pull the rear wheel this arvo as well so I can rebuild the caliper.
 

Redliner

New Member
Re: '77 GS750B, "Hahn" Stuck engine.

If I had something in that condition, it'd come down to nuts and bolts. Just not a good idea to ride on anything that has sat that long. As well you may come across some bodgy mechanic work and oh I dunno, find some stem bearings missing ::)
 

danejurrous

New Member
Re: '77 GS750B, "Hahn" Stuck engine.

Big rich and HD are great resources on the suzuki bikes. Fire method with ATF and Acetone is probably your best bet to free the engine plus you get a nice portable fire place in the process.
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Re: '77 GS750B, "Hahn" Stuck engine.

Yeah it is looking that way. A bloke at work just suggested pulling it apart from the bottom and dropping the cylinders off a two story verandah with a rope tyed to the con rod. I think I will light it on fire though.

I think Big Rich and HD are going to be big helps with this build, this is my first Zook and I love it so far. Apart from that 1 piston.

Ohh and Red. Yeah every load bearing bolt will be replaced. The engine mounts might even get 12.6 if I feel cashed up lol. I have already decided to re do the wiring harness. I will build one on the floor and stick it on the bike after.
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Re: '77 GS750B, "Hahn" Stuck engine.

So the Acetone/ATF mix is in, I got Dex3 because I remember reading somewhere yesterday that it was the best for mixing with acetone. I am not sure if the level went down or if I just tripped out but I have filled it to the top of the cylinder and in a few hours will look again to see if it has moved.
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Re: '77 GS750B, "Hahn" Stuck engine.

Alright small update, I have had no luck freeing the stuck piston so it was on to the fire method. It is used to heat the cylinder sleeve and have it expand away from the piston to allow the rust bonds to be broken. All I can say is it did a nice job of cleaning the cylinder, I have topped it back up with ATF/acetone to let it soak in as it cools down. I will give it another go of beating the hell out of it tomorrow and if that does not work I will change my mixture to atf/petrol to try and get a bit more heat into the cylinder. The atf/acetone mix was slow burning and took quite a few goes to get a bit of heat into the engine.
Here is a lovely picture of my bike on fire.


Also just to confirm my suspicions this points plate is off a 450 right? My logic is that because it has 450 stamped in it and the PO had starting issues that this was the problem.
Ohh and you can also see where I broke the lobes off the advancer.


Here's to hoping that I can get this bloody engine free.
 

Redliner

New Member
Re: '77 GS750B, "Hahn" Stuck engine.

I believe the 450 does not denote displacement. Almost sure of it.
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Re: '77 GS750B, "Hahn" Stuck engine.

Yeah I thought it wouldn't to start with but was just jumping to conclusions. Doesn't matter anyway it is getting replaced with a Dyna S, WHEN I get the engine freed, not IF but WHEN.

EDIT:

Enter "Dad" advice. I asked my father for his opinion, he said "why don't you used the flywheel pull for your outboard to put pressure on it" Hmm gives me an idea. Block of wood to fill the cylinder and a metal plate over the top held down by the head bolts. Then a big bolt through the center of the plate to put pressure on the wood. I can just tighten it ever time I walk past and it should help to push the piston down over time. I will leave some ATF/Acetone in there with the wood to help soak in.

What do people think of that idea?
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Re: '77 GS750B, "Hahn" Stuck engine.

Alright here it is, the "Piston Press", specifically designed to put pressure on the piston in order to move it downward.


I am beginning to think that maybe this engine was mech seized and not rust. If I can't get it apart soon I will just strip it down and I might have to go looking for new cylinders, maybe some might fall off an 850 at some point.

I was given an Acewell 2853 today as a birthday present. Woo. Lucky I know what I want ha. So is where I will start building my new wiring harness from. I have the diagram for it and plan to mix a few together until I get a some what working model. I have never been the kind of person to plan stuff like that. Normal I just start building it and it comes together sooner or later. Now I just need to find a GS750E tank so that I can have the fuel sender!
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Re: '77 GS750B, "Hahn" Stuck engine.

Not much to update. I had a hectic weekend and did not get any work done on the bike, so yesterday before work I decided to start on the electrical as the engine still has not budged.
The previous, previous owner told me that he was having electrical troubles and could not get the thing to start which is why he passed it on. After a brief look I would change "electrical problems" to lots of dodgy wiring mixed in with a lot more melted wiring. I can't believe this thing ever ran with the wiring the way it is. there is just new bits added in the by pass the burnt stuff which was not even taken out of the circuit.

I will not be using this harness so it is now up to my minor electrical experience (I build a phono pre-amp for my record player and have wired up a few stereos and bike parts) to build a new harness. I think I will use the original controls but I am not 100% on that yet. I will be getting a new stator and a new rec/reg for sure as these old GS are know for problems with them. After that it will be a "Sections" harness. I will wire all the essentials into one harness and tape it up. I will then add another harness for all the nice to have things such as oil pressure light and gear selector and add that onside which will be wrapped in one. Well at least that is the plan.

No more to update yet but slow progress is still progress. Off to research wiring diagrams.
 

Brodie

Gold Coast, Queensland
DTT SUPPORTER
Re: '77 GS750B, "Hahn" Stuck engine.

Well I pulled the engine out this afternoon. That thing weighs a shitload. Still have a stuck engine but I plan to pull it completely apart now and get at it from underneath. If I can't get this piston out I will try a press at work, and if that does not work I might have to go junk diving for some 850 parts.

As for the wiring I started to look into it and there seems to only be a few things that can be improved upon. I plan to do the coil relay mod as well as fitting all new parts. I think the only old parts will be the controls. I will post some pictures of the engine removal soon.
 

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