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Time to rebuild my old GPz

Work in Progress

Moderators: KeithZ1R, chrisu, paul doran, Taffus

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Kwackman
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Location: Belfast

Re: Time to rebuild my old GPz

#16 PostAuthor: Kwackman » Sat Mar 10, 2018 12:59 pm

chrisw1 wrote:I think I would use the standard swing arm ....... that one looks a bit too bulky for my eye

Agreed.
Also, the braced one looks taller where the chain goes over it at the front?
It's hard to tell from the photo though, so could be a red herring!
Good luck anyway, I'm watching this thread with interest!
2006 ZRX1200R
1982 Z400J project

ex owner of Z1100R
GXI 2752 are you out there?

Philippe
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Re: Time to rebuild my old GPz

#17 PostAuthor: Philippe » Sat Mar 10, 2018 5:30 pm

Hi GPZ592

the alloy swing arm looks way too heavy to be ment for a GPZ550.
Try to replace the bushings or bearings from the original swingarm with new ones, I think that will be an improvement.
Replacing original parts with aftermarket parts seems tricky to me if you're not sure if those parts were designed for that specific bike. I think you need a lot of experience and better tools than a disc grinder to keep it safe to ride on the road. Don't forget that an insurance company does no charity in case of a severe accident.
No offence ment! Keep it safe!
GrtZ
Philippe
the differences between a little boy and an adult man is the price and size of their toys!

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GPZ592
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Re: Time to rebuild my old GPz

#18 PostAuthor: GPZ592 » Sat Mar 10, 2018 9:33 pm

I think I would use the standard swing arm ....... that one looks a bit too bulky for my eye

Agreed.

Chris/Kwakman - if I'm honest I had my reservations as well. I think it's the under bracing is just overkill for a 550. it would probably look great on a physically bigger bike like a 1000 or 1100.

No offence ment! Keep it safe!

None taken, Philippe. Part of the reason for this thread is to get feedback and ideas from other people.

Anyway, I thought I'd try to get a feel for how it would look and managed to temporarily work around the clearance issues, but then run into the next problem. The top shock rocker would not line up to the frame mount. It took me some time to fathom out what was going on, but I figured it out when I compared the 2 swingarms. Look at the previous picture of the 2 arms side by side. You can see that the lower shock mount is formed by 2 plates bolted onto the lower side of the swingarm. the ally one uses the standard plates, but because the main beam of the arm is deeper, they are lower by about 15mm so it pulls the shock down and alters the angle of the top rocker arm. Remember what I said about this looking like it wasn't built around a bike - I reckon someone has taken the dimensions of a standard arm without reference to the frame. How else would you get all these problems ?

Here it is, temporarily fitted

IMAG0320.jpg


I did check the chain run with a piece of ally on the sprockets to see if it would clear and it would, but I did use a 17t (+1) front sprocket. However, thats a moot point now.............

IMAG0323.jpg

IMAG0321.jpg



So if I really wanted to use it, I would get the under brace removed, then I'd need to make up new lower shock plates, then remove part of the footrest mounting, which in turn means changing footrest mounts, etc, etc. It's a shame because an ally arm was part of the look I was going for on the completed bike. Never mind - maybe, I'll just spray the standard arm in ally paint :shock:

So now it's time for plan "B" :D
"Racing is life. Anything before or after is just waiting" - Steve McQueen

Philippe
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Re: Time to rebuild my old GPz

#19 PostAuthor: Philippe » Mon Mar 12, 2018 4:22 pm

Hi
go for plan B! Paint the original swingarm in an ally color so you won't change the wheelbase nor the ground clearance of the bike and with new bushings and/or bearings the steering capacity of the bike doesn't get worse anyway. You allways have to wait and see when you change the original swingarm with one of another bike.
Good luck
Philippe
the differences between a little boy and an adult man is the price and size of their toys!

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GPZ592
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Re: Time to rebuild my old GPz

#20 PostAuthor: GPZ592 » Thu Apr 19, 2018 1:47 pm

So, It's been a few weeks since my last post and progress has been slow :(

I did re-visit the ally swingarm and spoke to couple of people about modifying it, but their considered opinion is there is too much that needs changing to make it viable. Oh, well - it's headed for ebay, hopefully someone can use it and I'll get something back into the kitty :D

So, I looked at plan "B" and re-fitted the original swingarm. Whilst it wasn't too bad, it just looked a little flimsy against the new wheels/forks -

IMAG0326.jpg


So I started to experiment with the possibility of getting an extra piece welded onto the bottom of the main arm to beef it up a bit. Using a cardboard template & duct tape, I reckoned a 1/2" "U" channel welded onto the bottom will achieve the desired effect -

IMAG0333.jpg


The other thing I noticed was that by being black it "disappeared" into the frame. That's to say you didn't notice it as it was the same colour as the frame. Maybe I'll spray the swingarm black instead of ally - that might work, but I'll see what the arm looks like once modified.

So the frame/forks/wheel & swingarm are now away being modified to suit.

The electrics have also gone away for refurbishment, so it's time to look at the engine. Once again I have some modifications planned and I'll update as things progress. :)
"Racing is life. Anything before or after is just waiting" - Steve McQueen

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GPZ592
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Location: Surrey/Sussex Border

Re: Time to rebuild my old GPz

#21 PostAuthor: GPZ592 » Tue Apr 24, 2018 8:26 pm

The first modification I wanted to do on the engine, was to replace the "H" GPz ignition plate & bob weight for the advance retard, with the later "A" series static pickup plate & CDI box. The newer CDi has the advance curve built in and also has a rev limiter, which the standard "H" ignition doesn't. I've done this successfully on the GPz750 motor in my P&M and that was a straight swap - not so with the 550 ! When trying to fit the later pickup plate it was fouling on the webs used for the original plate.

Original "H" series plate

IMAG0257.jpg


Newer "A" series plate fouling on the crankcase web

IMAG0267.jpg


As it happens, I had a set of the later "A" 550 crankcases and I could see the casting for the pickup plate was different - the lower left support had less of a web on it.

"H" cases

IMAG0266.jpg


"A" cases

IMAG0265.jpg


So, a good mate took them to work and using a 90 degree drill, took away part of the casting. They came back like this

IMAG0455.jpg


Ignition plate now sits true :-)

IMAG0458.jpg


I'll have to get the loom modified to accept the newer "A" series CDI and find somewhere to mount it as it's larger than the standard "H" item, but I like the fact it has the advance curve & a rev limiter built in. :D
"Racing is life. Anything before or after is just waiting" - Steve McQueen


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