Question about engine

[Blackhearted]

So I just acquired a 1978 Honda Goldwing GL1000. The story was it was riden for 46K miles over the course of its life, put into a barn at the end of a season and when they took it out the motor wouldn't turn over. When I received the bike it was partially taken apart etc. Well the question is when I got it he told me the engine was seized. I took the heads off and I do know engines but this one is puzzling me. I looked into the cylinders and there is no rust the crosshatch looks beautiful the piston heads aren't terribly burned. I put a wrench on the crank and can turn it for one * up to down* or visa versa stroke and then it locks up, as if the crank wont allow me to fully spin the engine. The pistons move pretty freely but wont do one full revolution. I cant figure it out why it wont go any farther than this. My next step is to tear apart the engine just thought I would get opinions before I go any farther. And yes the bike is in neutral and when I rock it back and forth it turns about the same as by hand. Everything seems to be moving ok just cant figure out why it wont go full revolutions .

[WingAdmin]

Well normally I'd say "broken valve" but seeing as you have the heads off, the next obvious thing would be something broken inside that's jamming the primary chain or input cluster.

Oh wait, you said the rear wheel also jams up, and it's in neutral?

Hm. That's a little more mysterious. Can you get it into any other gear and see if it still does the same thing?

[scootsx2]

These are interference engines. Check for a broken timing belt. That can cause a valve to remain open. Piston hits the open valve and game over.

[WingAdmin]

These are interference engines. Check for a broken timing belt. That can cause a valve to remain open. Piston hits the open valve and game over.

Except he said that he had taken the heads off, which means the valvetrain is no longer attached to the engine. So that's definitely not what is going to be stopping it.

[scootsx2]

These are interference engines. Check for a broken timing belt. That can cause a valve to remain open. Piston hits the open valve and game over.

Except he said that he had taken the heads off, which means the valvetrain is no longer attached to the engine. So that's definitely not what is going to be stopping it.

Yep, I missed that. I wonder it it really is in neutral. I would also be tempted to remove the back cover to see if the stator is hanging up or if there is an issue with the primary chain. I don't recall if the '78 model year still had the kick start. If so then it might be a good idea to see if the kickstart mechanism is hanging up somewhere.

[Blackhearted]

No they didnt have a kick start. That was going to be my next step was to remove the back plate and see if there is anything in there

[terryt]

When you turn the engine over do all the pistons move. may have dropped a conrod.

[Blackhearted]

Yes all pistons move for about 1/8 to 1/4 of a stroke. The starter chain moves as well.

[kndw]

If you have the engine out already, take off the back case. It's not that much work, and then you can simply see what the problem is...

[terryt]

The starter motor my by jammed

[dingdong]

The starter motor my by jammed

A good possibility. Broken gear in starter could cause this.

[Blackhearted]

Starter isnt in, I can see the chain and it moves and doesnt "lurch" like its getting hung up as a chainwould

[Blackhearted]

The things that are taken off of it currently are
1. Heads
2. Starter
3. Timing Belts
4. Back plate

[Old Fogey]

the bike is in neutral and when I rock it back and forth it turns about the same as by hand.

This statement doesn't make sense to me. If you mean rocking the bike back and forth, if it really is in neutral that would not move the crank in any direction.
It sounds to me like the engine is still in gear.

[AZgl1800]

the bike is in neutral and when I rock it back and forth it turns about the same as by hand.

This statement doesn't make sense to me. If you mean rocking the bike back and forth, if it really is in neutral that would not move the crank in any direction.
It sounds to me like the engine is still in gear.

Picky picky picky, you meant the Transmission is still in gear, it definitely is NOT in neutral.

[Blackhearted]

I meant to use two different statements. When its in Neutral it free turns the wheels. I put it in 5th geat it turns the wheels to make the pistons a little in each direction as well as the crank. When Its in Neutral it doesn't turn the engine but rolls. It IS in Neutral....

[Old Fogey]

In that case I don't see an alternative to pulling the engine out. Start dismantling at the rear. You may find that the Plate B in the clutch has disintegrated and the bits are jamming the scavenge pump. It would not be the first time! But it's a relatively simple fix compared with splitting the crankcases, which will be the next step if there is nothing to be found in the rear case.