Restoration of a Gpz 750 R1 (1982)

[Philippe]

Hello men

this time I'm going to try to restore a wreck of a Gpz750R1 from 1982.
I bought the wreck a few months ago in northern France.
It's the most horrible bike I've ever seen...and I've seen a lot of wrecks during the past ten years.
The rear part of the frame was cut off and one of the previous owners made a "bobber" out of it.
During the past months I bought some missing parts and yesterday I decided it was time to start the attempt of restoring it back to original...
Please wish me luck, I'll need it.
Just have a look at the "thing" I start from.

the bobber after a few hours of dismantling

It's terrible, I know but this will hopefully turn into this:

the Gpz750R1 in my collection

It'll be a long way.
Most of the guys I know would throw the bike into the dumpster and I couldn't blame them for doing that but I'm going to give it a try and restore it.
As you can see there will be a lot of problems to solve.
I'll share my solutions with you here.

Let's start with the frame.
The rear part of the frame was cut off and I managed to obtain a complete frame without papers in Germany.

the donor frame

The frame costed me a 7 hour drive and a few bottles of special Belgian beer. It was for free.
I intend to cut off the rear part and weld it on my frame. I'll have to do a lot of measurements and some good welding but I'll get there.

Have a look at the horrors I've encountered sofar.

When you cut off a part of a frame, you end up with an open steel tube. How can you fill that hole? With body putty ofcourse, what else?

You need an exhaust hanger? Just weld a metal strip to the frame, problem solved!

You have no mufflers? Put two steel tubes over the collector ends and you have a loud pipe.
Can you believe this guy rode the bike like this?
I don't think those "mufflers" would rot, it's thick pipe.

In the mean time, the bike is completely taken apart.
Now I'll have to sort out the missing parts and find them.
And then I'll open the engine. Who knows what horrors I'm going to find in there?
It's not seized, I can turn it over by hand...
More news next time.

GrtZ
Philippe

[marmck]

If anyone can Philippe, you can that I am sure off,will follow closely as usual,

[r3sc]

Looking forward to this one already!

[weaver]

looking forward to this resurrection!

[Philippe]

Hello men

today I started cleaning up the frame.
In the past a "bobberbuilder" (in my personal humble opinion a bikedestroyer), added several pieces of metal on the frame and cutted off the rear part.
I started by removing the added pieces of metal.
The exhaust hanger came first.

the home made exhaust hanger

Then it was time to remove the "bridge" he added in order to reinforce the rear part he removed first.

the "bridge"

There were also two big nuts attached on the front reinforcement plates, one on each side.

one of the "big nuts"

So I decided to put the grinder on them!
After a few hours of grinding and cutting the frame was clean.

After the cleaning up, it was time to take some measurements.
I used frame parts as a reference and taped off the lines where I decided to join the two frames together.

the donor frame

the original frame

It took me a lot of sweat to get it done but I think I succeeded.

The frame is strenghtened by a steel rod with a diameter of 22 mm.
This fits right into the frame tubes, it gives strenght, acts as a guide and I hope it'll prevent me to make holes in the frame tubes when welding them together.

a small part of the steel rod

Tomorrow it's D-Day for me, I'll make an attempt to weld the frame parts together.
Hopefully good news tomorrow...
GrtZ
Philippe

[moizeau]

All the best Philippe, you could just stick a brown saddle on it and go with.......

[Philippe]

Hi men

some more news, good and not so good.
This morning I was able to weld the frame.
The steel rods did what I hope they would do: they gave guidance and prevented me from making holes in the frame tubes.
After the welding I cleaned the frame tubes and I must admit that the welding is not perfect but I'm satisfied with the results.

the right hand side

the left hand side

the result

This afternoon I decided to open the engine.
All the bolts of the camcover came out very good and the gasket looked like brand new...
After removing the camchain tensioner and the camshafts I started with unbolting the cylinderhead.
It came off very easy and once again the gasket looked like new.
Then it was time to remove the barrels.
Once again it was very easy and ...yes, the gasket looked like new.
Then the little show of horrors began:
I couldn't believe what I saw...just have a look for yourselves.

piston 1 and 2

piston 3 and 4

all four of them

Pistons 1, 2 and 4 were mounted BACKWARDS, only piston 3 had the arrow pointing to the front!
Can you believe it?
I couldn't see any scoring marks of the valves on the pistons that were mounted backwards but when I remove the valves from the head I'll have to check them in order to see if they aren't bent.
That's for tomorrow or for next week.
Once again guys: if you buy a bike in France, take it apart, no matter how good or how bad she looks, just take her apart and have a good look at all the parts.
I'm convinced that some French mechanics got there degree with a lot of bottles of wine instead of study.
Pete (moizeau), this warning is for you, you live in France, you buy french bikes, TAKE CARE !!!!
And as far as the brown seat is concerned: brown is a nice colour but I prefer black and not an ironing board but a nice comfy seat.
OK men, more news to come within a few days.
GrtZ
Philippe

[GPZ592]

Great work as normal, Philippe - she's in good hands now

Unbelievable anyone could put 3 pistons in back to front - not even all 4 the same (incorrect) way !!

Looking forward to seeing her brought back to her former glory

[rickm]

That piston story is just amazing
Not a lot you can say really !

[gray]

you think you've seen it all... all the more reason to carry on and inspect it all. Best wishes

[Philippe]

Hi guys

some more news about the restoration and the amazing discoveries I'm making concerning french craftmanship...
If you thought that mounting the pistons backwards was bad, have a look at this:

the french "snap ring"

the piston bolts were secured with this on one side.
I take no risks and I'm going to change all the 8 snap rings, even those still in the grooves.

So far for the engine story.
I decided to disassemble the carbs. They looked dirty and greasy on the outside. A cleaning with thinner would solve that and also partially dissolve the old black paint. I was going to repaint them anyway.
After the separation of the carbs, I removed all the parts I could and soaked them in cellulose thinner.

the four musketeers

This is how three out of the four looked like after 15 minutes of soaking in cellulose thinner.
The fourth was kept "original" to take some pictures.

The inside of the float bowl was dirty, greasy and very sticky.

All the important parts on the inside were stuck, it was nearly impossible to remove them so an additional hour of soaking in thinner was required.
In the end I managed to get the parts out with a lot of effort and patience.

before cleaning

I used carburettor cleaner to soak these parts in and afterwards they turned up rather clean.

after cleaning

I'll have to use some parts of a previous restoration (Z1000R2) in order to get the carbs working again...
That's why I never throw old parts away, sometimes they can be used again.

Next time more news of the carbs and perhaps about other parts.
GrtZ
Philippe

[moizeau]

Good luck with carbs, I had a nightmare with my CV's off the Zeph and they looked clean. Yes I know French 'mechs', remember this

Found in the sump that was replaced by a bit of allthread

[Philippe]

Hi men

it's been a few weeks but there's some progress.
I've been degreasing parts and removing the old paint and rust.
To remove the old paint I use ant acid. Very dangerous stuff so protect yourself with goggles, gloves, etc when using it!
Before I put the parts in the acid, I have to degrease them. I use cellulose thinner to do that. It has the benefit of dissolving the old paint and it certainly dissolves the old paint from a spraycan.

The old paint was allso removed as much as possible from the oil cooler. Take care when removing paint from an oil cooler, the fins are very thin! Mostly a lot of them are bent and distorted. I use a very fine pair of pliers to straighten them. It takes quite a while but the air has to be able to pass through the fins in order to cool the oil.

the oil cooler

The wheels were the next parts. I removed the old bearings and stripped the wheels completely.

As you can see the front wheel is partially cleaned, the rear wheel is as I got it.
Because thes parts are too big to soak in the ant acid, I use a masons' tub with cellulose thinner. It takes about 10 litres of thinner to soak one side of a wheel. The plastic of the tub isn't affected by the thinner.

the mason's tub with engine parts

After about one hour, I turn the wheel so that the other side can soak.
This is the result after a few hours.

the rear wheel after soaking in thinner

Not completely clean but half an hour of using the nylon bristels on a drill, this is the result

Now I only have to polish the rims and then I can degrease the wheels, tape the parts off that need to stay bare aluminium and spray them in firecracker red.
That's for a next episode.
GrtZ
Philippe

[Philippe]

Hello guys

the wheels were cleaned and the rims polished.
They were both degreased in aceton and then the taping off could begin.
It takes me about two hours to tape the wheel rims off and to make sure they're ready to paint.

the taped off rear wheel

They were sprayed outside because the temperature was OK and I didn't have to cover everything inside in order to prevent the spraydust getting on other parts.
I sprayed quite a few wheels in the past and sometimes the paint was damaged when I turned the wheel upside down in order to spray the other side.
This time I inserted four bolts in the holes where the disc rotor bolts go in so I could turn the wheel without damaging the fresh paint.

A simple solution but very effective. The wheel rests on the bolts and not on the rim. No damaged paint anymore.
The results are satisfying for me.

Another step taken in the restoration of the Gpz750R1.

The frame parts of the previous episode were sprayed in matt black.
Other parts will be sprayed in gloss black but I have to wait for the paint.

In the mean time I've started to clean up the engine parts.

the cam cover

As you can see there's a lot of work to do, the camshaft cover is partially cleaned, there was a lot of white oxidation where the old paint had lifted off in the past.
Since there are a lot of covers to clean and to paint I'll do the spraywork in two sessions.
First the parts that need a gloss appearance . Those need a black, heat resistant paint and afterwards a gloss varnish. The cranckcases need no varnish and the'll be done afterwards.

Something for the next episode.
GrtZ
Philippe

[Garry.L]

Fantastic work as usual Philippe.

Does the R1 have the Crinkle finish on the cover or Smooth?..