Engine Trouble New motor seized

[Captain Rainmaker]

Well, I thought I'd finally finished my first build, until I went to fire it up and noticed the clutch wouldn't engage no matter how tight I cranked on the star nut. I then popped off the magneto cover and tried to spin it by hand, and it wouldn't budge. So I pulled off the head and the cylinder and found the engine was seized up solid. (Talk about a ball-buster.) This engine was brand new and never ran before this, so I'm guessing it's one or several stray pieces of swarf that broke off and got jammed in the works; regardless, I plan to tear it down and see what's up.

Before I go ripping into it, what are some precautions to take and things I should keep an eye out for? If it turns out that is what happened, would it be safe to reuse the rotating assembly, or should I just go ahead and order new parts?

 

[Frogslayer]

Same thing happened to me. It was a piece of chrome plating i think that got into a crank bearing on mine. I disassembled, cleaned, got that debris out of the bearing, put everything back together and it still works.

 

[Chainlube]

You should try taking the clutch plate off first, it seems you have tightened it too much.

 

[Captain Rainmaker]

You should try taking the clutch plate off first, it seems you have tightened it too much.

I did kind of a bad job explaining: My initial problem was that no matter how tight I got the pressure plate, the clutch would slip and the engine would refuse to turn. After some troubleshooting, I pulled off the cylinder assembly and pressure plate, and even with a sizable helping of brute force and ignorance, I couldn't get the crank to spin.

Same thing happened to me. It was a piece of chrome plating i think that got into a crank bearing on mine. I disassembled, cleaned, got that debris out of the bearing, put everything back together and it still works.

Thanks for the input. Glad to know that this isn't a unique situation.

 

[Captain Rainmaker]

Alright, so I ripped it apart and cleaned it out as thoroughly as I could, and I found the problem. When the crank is fully seated in the right case half, it binds. There was nothing really obviously wrong in there, so I'm kind of at a loss. I'm thinking I might have to hit up a machine shop, which sucks.

 

[Street Ryderz]

The bearings should be removed from the crank and pressed into the case square to the crank,it helps to lightly sand the main(crank) journals so that the bearing can just slip fit the shaft,then when assembled the crank will spin freely right now your binding the bearings when the case half's are tightened.

 

[Captain Rainmaker]

The bearings should be removed from the crank and pressed into the case square to the crank,it helps to lightly sand the main(crank) journals so that the bearing can just slip fit the shaft,then when assembled the crank will spin freely right now your binding the bearings when the case half's are tightened.

I'll give that a try, thanks.

 

[Chainlube]

The bearings should be removed from the crank and pressed into the case square to the crank,it helps to lightly sand the main(crank) journals so that the bearing can just slip fit the shaft,then when assembled the crank will spin freely right now your binding the bearings when the case half's are tightened.

When he says sand, he really means polish, like 1000 grit or more.

 

[Captain Rainmaker]

Any tips for getting the bearings off the crank? They seem really jammed on there.

 

[Wrench]

Got a pic. I will recommend the correct bearing puller