Splitting the Crankcase on my 1971 T500

[T500_Brandon]

Hey Guys

The good news is that I (long time lurker) inherited a "barn find" 1971 T500 from my grandfather. The bad news is that, as far as I can tell, it has been run in the past 30 years. The right side piston is locked up in the barrel, and it looks like the easiest solution is another piston and barrel from Ebay. I'm betting that it will also need new oil seals. In order to accomplish this, it looks like my best bet is to split the crank case. Toward that end, I have removed all of the necessary bolts on the crankcase, pulled the screws from the sprocket collar and the crescent shaped plate (forgot the name) behind the clutch, and removed the alternator. I'm having an issue getting the halves of the crankcase to start separating. Does anyone have any tips on this?

I'm also planning on fabricating a puller for the cylinder barrels like the one here viewtopic.php?f=2&t=6731&hilit=t500+crankcase&start=15 Failing this, is it acceptable to split the case and have everything remain in the top half? Is it even possible?

Thanks in advance. Build thread to follow when I get round to it.

[T500_Brandon]

So it turns out that with the proper amount of force (BIG breaker bar), penetrating oil, and fire, the piston will move. Not happily, and it tried to bust my knuckles, but it moved.

I really should make a thread for this.

[Alan H]

Take PLENTY of picrures for when you rebuild it.

[akendall1966]

Once the crank case halves are free to part there is no reason you should not be able to lift of the top half with the crank / cylinder traveling with it. might be easier to press out the piston with the crank able to drop and not have to roate.

If it got damp enough in that bore to sieze, you want to have a look at the crank and assess its state. Its sounds like your close enough to having the whole thing torn down that it would be false economy not to have a peek inside at the crank and transmission.

[T500_Brandon]

AKendall: Basically you described my plans. So far the crank seems to rotate freely, but since I'll have the bottom end opened up anyway, I want to reseal everything and take a look at the crank, and replace the oil seals. I'm also going to fix the oil capacity in the transmission if it hasn't already been done. Right now I'm trying to figure out how to get the piston out of the jug. Right now I plan to replace the formerly seized jug and piston, as the other moves freely and its bore measures within the service limit and looks clean. My current thought is to drill a 1/2" plate so that it bolts to the jug where the head bolts do, then drill and tap holes over the studs for the barrel and use four bolts to walk the jug up and off the piston.

Alan: I have been taking photos and videos all along. This is my first restoration, so I hope that if I go overboard on the notes and information, I'll have an easier time putting it back together.


I've started making a stand for the motor out of a bunch of lumber that I had lying around. I'll post pictures and plans if anyone is interested when I'm done.

[T500_Brandon]

So I'm looking at the crankcase again, and then I decided to check the service manual. I have all the needed bolts out, and the front of the crankcase has freed up some, but it seems like something is holding near the alternator rotor (have the alternator removed). Is there anything that I might have forgotten?