Page 1 of 6

1973 T500 cafe build

Posted: Sat Sep 23, 2017 5:29 pm
by jabcb
Had absolutely no need for another project but got one anyways.

The bike is a T500/GT500 combo. T500 frame + a GT500 front end. Motor VIN is for a GT500. Spare motor is the 73 T500 motor without a top end.
Imagecafe-T500-0685 by jabcb, on Flickr

How do I tell if the motor has the T500 or GT500 top end?

Re: 1973 T500 cafe build

Posted: Thu Sep 28, 2017 3:01 am
by dollydog
according to the parts book, there is no difference between the 73 t500 heads and barrels and the 76 gt500 heads and barrels :D
i know some of them had weird pistons, but memory aint what it was :D
cheers, dd.

Re: 1973 T500 cafe build

Posted: Thu Sep 28, 2017 5:44 am
by jabcb
Thanks. I usually check before asking. The design change was between J & K models, and I thought it was later.

Am targeting a look similar to our GT250 cafe project, except for the bars & pegs. No rearsets & I might stick with the drag bars that are on it.

Re: 1973 T500 cafe build

Posted: Fri Sep 29, 2017 4:33 am
by dollydog
talking of handlebars - now the old back can't cope with clip-ons :D i normally use plain straight bars. get some 22mm o/d aluminium thick wall tubing - 16mm i/d - about 750mm long is perfect. grips and throttle fit perfect and with a good polish they look ace. and save weight :D oh yes, they are about a quarter the price of shop bought straight bars.
cheers, dd.

Re: 1973 T500 cafe build

Posted: Tue Nov 21, 2017 11:51 am
by jabcb
Split the cases today.
Good news is that the crank feels ok. Didn’t notice any rough spot. And the tranny gears look fine.
Imagecafe-T500-0735 by jabcb, on Flickr

But there is also some bad news. One of the topside crankcase bolts was rusty and snapped off.
A few other topside crankcase bolts were rusty — I’ll replace them.
Imagecafe-T500-0736 by jabcb, on Flickr

One of cylinder studs is rusty too. Should I have that replaced or just clean it up?
Imagecafe-T500-0737 by jabcb, on Flickr

Re: 1973 T500 cafe build

Posted: Tue Nov 21, 2017 2:46 pm
by dollydog
looking at the photo, the bottom of the stud looks like it's being eaten away? i would definitely replace it and smear some copper grease on the studs when you replace the barrels - makes them so much easier to remove in the future :D
cheers, dd.

Re: 1973 T500 cafe build

Posted: Wed Nov 22, 2017 7:45 am
by sportston
dollydog wrote:looking at the photo, the bottom of the stud looks like it's being eaten away? i would definitely replace it and smear some copper grease on the studs when you replace the barrels - makes them so much easier to remove in the future :D
cheers, dd.
Clean it well then, soak well with duck oil or plusgas. Use some heat (not so much that you will melt the casing!) to help avoid snapping it off when you remove it.
Nice bike. Looks like a good base to start from.

Re: 1973 T500 cafe build

Posted: Thu Nov 23, 2017 4:06 pm
by titan performance
Looks like a nice find. The T 500 pistons had thick rings with a light groove running around the centre of them, and the piston had a series of grooves in it below the rings. A change came with the GT. Thinner rings, and no piston grooves. Although they look different, they are interchangeable, and as I understand it, the later ones are better/stronger.

Re: 1973 T500 cafe build

Posted: Thu Nov 23, 2017 5:14 pm
by karl pa
titan performance wrote: The T 500 pistons had thick rings with a light groove running around the centre of them, and the piston had a series of grooves in it below the rings. A change came with the GT. Thinner rings, and no piston grooves.
? My 76 GT500 has the oil grooves on the pistons and rings, although it is early in the model year, maybe later ones changed.
I replaced the pistons and rings in my 75 T500, with 750 ones with thinner rings and no oil grooves.

Re: 1973 T500 cafe build

Posted: Fri Nov 24, 2017 2:29 pm
by titan performance
I would think the pistons in you GT had been changed along the way Karl. I've never seen a GT with T pistons from original, and I have seen a few !

Re: 1973 T500 cafe build

Posted: Fri Nov 24, 2017 6:00 pm
by karl pa
My GT500 was bought used in 1980 by my father in law, so it is possible, however my spare GT500 engine also has oil grooves on piston and rings, both engines are standard bore, so I am not sure why both would have replaced pistons.

Re: 1973 T500 cafe build

Posted: Mon Nov 27, 2017 11:10 am
by jabcb
Didn’t know about variations in T500/GT500 pistons.
I needed 2nd OS pistons & ended up getting Wisecos. (2nd OS Wossners were out of stock in the US. 2nd OS NOS are NLA & weren’t listed on eBay.)

Sent the crank out & am hopeful that the verdict is that the bearings are OK.

The guidance on replacing the cylinder stud reminds me about the old Clint Eastwood / Dirty Harry quote about knowing your limitations.
So I will take the crankcase to a shop to replace the bad stud & to remove the broken bolt.

Re: 1973 T500 cafe build

Posted: Sat Dec 09, 2017 5:25 am
by jabcb
Had a bit of luck. The bearings were ok & I got the rebuilt crank back.
Maybe I should buy a lottery ticket.

Re: 1973 T500 cafe build

Posted: Sat Dec 09, 2017 3:28 pm
by sportston
Well that is good news. How have you got on with the studs?

Re: 1973 T500 cafe build

Posted: Sat Dec 09, 2017 4:11 pm
by jabcb
Planning on taking the crankcase to a shop next week.

Made up for good luck on the T500 with bad like on the GT550. (See pics in that topic.)