Need Help Addressing Damage After Crash

Hi everyone, I just joined so allow me to introduce myself.

I do not own one of these bikes but yesterday I went with my friend/ roommate to look at one. 1981 Yamaha XJ550 Seca. Bike looked great. He bought it and we rode home. Unfortunately, he didn’t commit to a turn and laid the bike down going about 30mph just 2 blocks from home.

Good news is he’s fine other than a small scrape and a bruised ego. But he learned a good lesson and the bike is repairable. Hence why I’m here. I’m the mechanically inclined friend and have been working on a vintage Honda. I’m going to help him fix up his bike and get back on the saddle.

The only part I don’t know about is the right crankshaft seal. I’ve circled the area of concern, it’s not leaking oil but some did dribble out initially. The engine was running till he hit the kill switch and the bike will still turn over, but we haven’t tried running it again just yet. It did sound like it wanted to start.

My question is how crucial is that area that’s crushed in? We will pull the engine and replace the lower crankcase at some point to make the bike look new again but is this something that has to be done right away or am I able to put some sealant over that area and run it? From what I’ve found it doesn’t seem too important, But I don’t know much about this bike specifically. I’m not afraid of engine work though.

We will be going through and making sure everything is fine before trying to start it again.

Any advice is greatly appreciated! Feel free to throw in any knowledge you might have too. I love learning about these old bikes and my friend shares the same interest.

 

Hi @Clure77

That really sucks. Glad everyone is OK, but sorry about the bike.

Good news is that parts are available. Looks like the crankcase part number is 4G0-15100. There are a few on eBay.

If you look at a cross section of the crankcase, it looks like that raised lip area where the seal goes is a good distance from the crankshaft itself.

My $.02: If it runs without any discernable problems, it's probably OK for the short term. Others may have better insight.

 

the seal that goes in there has a ridge to fit in a grove it seals off the end of crank
the replacment seal has no ridge so it can be replaced with out removing the lower case.
the seal is sealed with yamabond when replaced.

the part you have to be concerned with is the plug under the crank with the allen hole. which is sheared off.

 

Clean the area throughly apply JB weld let it fully cure for 24 hours make it neat tape it off with masking tape . I have fixed VW engine cases with JB weld . I will caution do NOT use JB quick this is not same as it sets up in 5minutes .