GT Reassembly Issues

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Bomber
Cucciolo - the Lil Pup
Posts: 8
Joined: Tue Nov 03, 2009 6:33 am
Location: Ontario, Canada

GT Reassembly Issues

Post by Bomber » Tue Nov 03, 2009 7:58 pm

On cleaning and assembling this 74 GT I have come across some problems, not sure if they're typical. Oil leak from porous casting on a case bolt hole that was somewhat repaired with epoxy at a prior teardown.Crankshaft shimmed on both ends.Shims need replacing as they're split in two. Sludge traps almost full.Oil pump installed with silicone.All this done by a reputable dealer/race shop.But it did run this way 15 years.Can't wait to tackle top end.Any idea of piston clearance?
Tom

GT Pete
Diana
Posts: 71
Joined: Mon Aug 20, 2007 6:17 pm
Location: Walworth, NY

Post by GT Pete » Thu Nov 05, 2009 5:30 pm

Back when I had my 750GT, it had a porous case on the back of the engine. The dealer repaired it with epoxy back then. I ran it for another couple of years with no problems. Also, when I rebuilt the engine, the crank shims were destroyed.

Bomber
Cucciolo - the Lil Pup
Posts: 8
Joined: Tue Nov 03, 2009 6:33 am
Location: Ontario, Canada

Post by Bomber » Thu Nov 05, 2009 7:29 pm

Thanks GT Pete,
Glad to know the shim destruction and porosity are not unique.Back when I first picked up this bike early nineties it was a dog and when pushed hard it would destroy the forward sparkplug.Turned out the previous owner had both carbs being fed by one tap and the front cylinder bore the brunt of leaness.When I tore it apart a couple of seasons later the front piston compression ring was in 22 segments,but all held in a rather damaged land.No scoring in barrel!As the bike has come back in my possesion with new pistons I have a one standard used Mondial sport piston donkey'y for trade.Looking for a std. piston for my Monza.
Tom

Bomber
Cucciolo - the Lil Pup
Posts: 8
Joined: Tue Nov 03, 2009 6:33 am
Location: Ontario, Canada

Post by Bomber » Thu Nov 05, 2009 7:33 pm

Kinda cute the way assembly came up donkey.
Tom

Crashfangio
Mariana
Posts: 35
Joined: Fri Aug 15, 2008 6:48 pm
Location: Melbourne Australia

Post by Crashfangio » Tue Nov 10, 2009 4:22 pm

Tom,

These are typical, my '73 750GT cases have had some form of hard epoxy placed around the front bolt holes inside the cases, I suspect to address the same problem. My oil pump has also been assembled using clear silicone, both of these 'mods' from the factory. My cases had never been split up until now. I tore my motor down recently and discovered both mains shims split through the middle as well and yes, my sludge traps were full of junk.

I'm not woried about the epoxy or silicone. It beats having leaky cases. The sludge traps are doing what they are designed to do. The thing that does concern me a little is the split shims, I still haven't had any clear explanation given as to the cause.

Anyone who does know for sure feel free to weigh in.
73 750GT

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