Big TX500 project, any help appreciated!

[Made2care]

Hello everyone! New here! I hope I’ve joined the right forum.
I’ve just acquired a 1974 Yamaha tx500. I’ve restored many Goldwing and a 1967 yamaha 180 but this looks like a challenge as I’ve never rebuilt an engine. This engine is locked up! I guess I can fill the crankcase with some diesel and marvel mystery oil and soak for a week .
Thoughts??
Thank you for your help.

 

[gggGary]

Welcome aboard!
While primarily xs650 we're an open tent so post away.
Perhaps change your thread title so TX500 is in it will help attract the right eyes to your thread. There's several round here have messed with TX500 (not me)
@5twins

 

[5twins]

I'm afraid I won't be much help as I never worked on one. All I've done is strip three so far for useful XS650 parts, lol. In my opinion, that's about all they're good for. It's a rather obscure model and wasn't very popular. Finding parts will probably be difficult, and expensive.

 

[Jan_P]

Yes chemicals ..heat and patience
Winter coming up I would be prepared to wait 3 months even before increasing force .With the risk damaging things
Which happens now and then Patience saves money if not time
And in this case with few parts and expensive I would be extra careful

 

[Made2care]

Okay…. Thanks for responding

 

[Max Midnight]

I have read that a 50/50 mix of ATF and acetone is very effective.

 

[jetmechmarty]

Nice. Save it! The early TX500 was prone to a cracked cylinder head. The last models have a single piece head that fixed it if I’m not mistaken. @desmoman900 knows the details. Maybe he’ll see this. Upgrade time is now.
In one of these threads has a ho-made tool for pushing the stuck cylinder. That’s what you need.

Do those have a 180 crank?

 

[Kevin Werner]

Hello everyone! New here! I hope I’ve joined the right forum.
I’ve just acquired a 1974 Yamaha tx500. I’ve restored many Goldwing and a 1967 yamaha 180 but this looks like a challenge as I’ve never rebuilt an engine. This engine is locked up! I guess I can fill the crankcase with some diesel and marvel mystery oil and soak for a week .
Thoughts??
Thank you for your help.

Locked up likely means stuck rings. Pour your mix into the spark plug holes and let it sit with the drain plug open and a pan underneath. If the pan fills and it's still stuck your pistons and/cylinders will need some work.

 

[gggGary]

Thread title edited. ;^)

 

[jetmechmarty]

Locked up likely means stuck rings. Pour your mix into the spark plug holes and let it sit with the drain plug open and a pan underneath. If the pan fills and it's still stuck your pistons and/cylinders will need some work.

The head is off. Rings are stuck.

 

[Jan_P]

With the risk sounding like a parrot I would probably start use regular motor oil fill up above pistons and now and then heat up .. the oil
Hot air gun or electrical heater
Using a wood piece and hammer Gently knocking on the top of the pistons.
The oil can give some damage control . Patience and if not coming loose . Next stronger chemicals

 

[Jim]

Me personally.... that piston and liner are already toast. I'd beat the crap out of it 'till it gave up.
Seriously... what are we trying to save here? A junk piston? Nah..... stick a chunk of 2X4 in there and wail on it... but that's just me...

 

[gggGary]

Me personally.... that piston and liner are toast. I'd beat the crap out of it 'till it gave up.
Seriously... what are we trying to save here? A junk piston? Nah..... stick a chunk of 2X4 in there and wail on it... but that's just me...

Just make sure the crank is free to turn and isn't TDC OR BDC so you aren't hammering on rod bearings.
Yeah I was that guy, ONCE...........

 

[Jim]

Just make sure the crank is free to turn and isn't TDC OR BDC so you aren't hammering on rod bearings.
Yeah I was that guy, ONCE...........

Thought about that before I suggested it.
Left piston is off TDC... 'bout a third of the way down. Not TDC and not BDC.... so wail away.

And yes @jetmechmarty ... looks like a 180° crank.

 

[gggGary]

(Edit) Usually just one piston is stuck bad, if the piston you aren't hammering on is stuck, twisting loads on the crank/bearings can be very large.
On this motor it looks pretty obvious which is the stuck side.

 

[Jim]

Far as I remember, that engine uses a high pressure lube system. Means plain babbit bearings on the crank.
Hate to be the debbie downer here, but there's a good possibility that water intrusion went past the rings and down the con rod....

 

[Jan_P]

It is not so easy to get access for the big hammer .And a miss can get expensive
don't ask me how i know. But I understand what you are saying the well oiled routine can save the cylinder bores perhaps even if it is
unlikely .
I don't know this case but sometimes there are no parts available Say you smash up scratch the bores need a re bore .But no oversize pistons to buy nowhere ( for some machines obsolete )
Then we are talking scrap .. A scratched re honed bore with so so compression can still run a little

 

[gggGary]

Make and use a hardwood block so the force of your blows is directed out to the piston edges.

 

[Kevin Werner]

Make and use a hardwood block so the force of your blows is directed out to the piston edges.

Or an alloy pipe/tube roughly the diameter of the bore. Lay a 2x4 across the top of the tube and rap away, after soak, heat, soak, heat, soak.

 

[Wingedwheel]

I’ve been down the TX500 route. It was a pretty complex engine IMHO. I believe there are two or three chains with one of them operating the starter setup. I believe it was the 74-75 heads were a two piece setup and prone to cracking. They corrected the issue by going to a one piece in 76. Mine had a rusty crank like Jim mentioned so it ended up being a doner bike. I re-purposed or sold most of the bike but I still have a few parts lying around. Let me know if you need anything and if I have it, it’s yours for postage.