550 Seca resurrection

Hi Group -

I just picked up an '81 550 Seca and I'm going to need some help getting this thing going.

When I came upon the bike, the p.o. had it in an unheated shed, out of the weather. I was told that the engine had been rebuilt by a shop and that there was an oil leak, but it ran.

Initial examination indicated a complete bike including all unbroken plastics, a tank not only unvarnished, but still shiny inside, throttle, choke and clutch cables operating as normal, no front brake, bent handlebars, bent front brake lever and bent rear brake pedal, indicating it had been down on the right side and a missing start button. Mechanical evaluation revealed that the chain was off the rear sprocket and the shifter didn't move.

Once I got it home, I gave it a bath and looked it over for obvious external engine damage (there was none). I gently tapped on the shifter and got some movement, but it was extremely stiff (as if the transmission were filled with glue). I checked the oil fill and it appeared to be dry. I stuck a finger in there and felt no oil. (I still need to check with a light.)

So, my question is, what is my next step? Do I hook up a battery and see if it cranks? Do I try to spin the engine by hand with the crank bolt? If so, where does the crank bolt live and in which direction do I turn it? (Waiting for the service manuals to come in.) This is my first resurrection and it doesnt help I'm going in blind, not knowing the bike's history. I'm concerned this engine might be ruined.

Heres a picture, after the bath . . .

Thanks in advance for your help!

Jeff

 

I would make sure there is some oil in it, remove the spark plugs then see if you can turn the engine over by hand. Remove the left hand side engine cover (ignition cover) and use a spanner / wrench on the end of the crank. From memory I think it's a 19mm or 3/4 inch. Turn it anticlockwise.

 

Perfect! Thanks for that. I'll report back with results.

 

I forgot to say, don't force it. It should turn over easily. Also see if you can spin the front sprocket to check it's in neutral.

 

Will do. Thanks for the guidance. I'll report back when I have more info!

 

19mm

 

This just might jam up the shifter, dont ya think?

 

Here it is, freed and cleaned up.

 

This part got damaged. It was on the shifter shaft. What is it?

 

And finally, here is why I think the chain got thrown. Look at the position of the adjuster!

 

Ok. Since I freed the chain, I can shift through all the gears, the main drive sprocket spins freely when the trans is in neutral and I can spin the engine freely with the plugs out. I can even feel compression!

So, other than a new chain and sprockets, is there anything else to do before trying to start it?

 

Spacer for the shifter pedal shaft.

 

Looks like the chain needs to have a link, link and a half, or two.....or more? Taken out.........but id’ check to see if a new chain is in order, too

 

I'm going to go with new chain and sprockets. Better safe than sorry.

 

Looking at that sprocket I would say that's a good call

 

Told you the same as my CB 750.

 

I bet if he holds that chain sideways it will have a big curve in it, better with an new one eh.

 

The PO was lucky the case didn't get damaged.

 

Looking at that rear sprocket, I understand why the adjuster is at it's limit. See the points on the rear sprocket? That shape means it's worn. I'd get new chain and both sprockets. (you really want those at the same time since they all wear together).

Here's an article with tips to help figure it out for yourself: https://www.revzilla.com/common-tre...cycle-chain-and-sprockets-need-to-be-replaced

 

Thanks! That's where I'm headed.

 

Greetings all -

Here is the latest update. I have gone a second round of degreasing the engine - it's looking SO much better! Still have one more session with the degreaser - then on to power wash!

Got the bike on the lift, started to strip it down. Plastics and tank removed, replaced the rear brake pedal, front brake lever and front right directional. then started the arduous task of cleaning the "greasy dust" off EVERYTHING under the seat and tank. It's beginning to look much better. Opened up the headlight to replace the right front directional, found evidence of tampering in the headlight bucket (cut wires, taps on wires, workarounds on others). Bought a battery and threw it in to test electronics. Directionals light up and flash, taillight works, brake light works (although the rear brake light switch need to be adjusted), horns work (boy are they LOUD!), no illumination from the headlight. As I got under the seat, there is the red/yellow wire to the fuse block that has been removed from the block and wired around with an in-line fuse holder. This circuit should have a 10a, currently has a 25a in the in-line holder. One circuit has a 20a but calls for a 10, one calls for a 10 and has a 7.5; just all over the map.

Bought some supplies - oil and filters, oil filter housing O-ring, tires (Dunlop 404's), shifter shaft bushing (got destroyed when the chain got thrown). Still need plugs, air filter, chain and sprockets, master cylinder rebuild kit, caliper rebuild kit, fuel tank mounting rubbers, side cover rubber mounts, front brake pads, rear brake shoes, fork seals. Not sure what to do about the wiring issues, because I HATE having any cuts in the factory harness, and one of the fuse holders has a broken tab, making it inmpossible to hold a fuse. Anyone have an extra fuse block?

Last thing I noticed - I stuck a probe down into the oil and when I pulled it out, it looked a bit "golden", and smelled faintly of gas. I plan on changing the oil before I crank the engine, hopefully the gas is from poorly adjusted carbs, or running short trips, or something else minor. Now, in full disclosure, the PO mentioned that a shop (Kucknicks in Bear Lake, PA) replaced the gaskets and there was a story about an oil leak, but it wasn't clear if it was before or after the shop did gasket work.

Any thoughts? My biggest concern are the problems with the wiring, but I'm open to all comments.

Jeff

 

Hi all -

Here's the latest. Continued the seemingly endless cleaning, but I think I'm to the point that it's just "dirty" now. When I removed the tank, I realized how far i DIDN'T get under the tank, so that was the nest area to clean. Then I got after the area that houses the taillights and got that all clean. I sourced the wiring harness that goes to the headlight, so that one is now fixed. I reverse engineered that had happened in the headlight with the cut and bypassed wires and replaced them with the correct type spade connector and color wire, so THAT'S fixed. I have sourced the original type fuse box and am waiting for them to come back in stock and then all the electrical modifications are back to original. Oil is drained, oil filter and oil filter housing O-ring have been replaced. Called the shop that supposedly worked on the bike, but he didn't recall doing any motorcycle work in the past several years. As we talked, he DID remember a bike coming in for an inspection, with the engine covered in oil, but he didn't do any work on it, as far as he can recall. Purchased plugs, tank mounting "pucks", side cover grommets, tires, chain and sprockets, front brakes (ceramic), caliper and master cylinder rebuild kits, fork seals and dust covers, air filter. Tires and forks are off the bike, new tires mounted and balanced, waiting for fork seals, caliper rebuild kit and rear sprocket to arrive so I can start re-assembly. Carbs are currently filled with K-100 and soaking the innards. Handlebars have been replaced, as has the start button. Once the bike can support it's own weight again, I'm testing for spark and putting some fire to it!

I have a few new pictures to add. I'll get them up asap.

Thoughts and comments are welcome.

Thanks.

Jeff

 

I wouldn't wait for the original style fuse box. Install a blade fuse instead of the glass type

 

did you replace the spring and washer on the oil filter?

 

I installed the spring between the housing and the filter. Is the washer under the head of the bolt that holds the housing in place?

 

there is a washer between spring and filter to keep spring from pushing through the gromet on filter. the washer tends to stick to filter when changed

part 10 in drawing
https://www.partzilla.com/catalog/yamaha/motorcycle/1981/xj550rh/oil-cleaner

 

Ok! Thanks for the tip, looks like it's coming apart again!

 

This concerns me. Filling carbs and/or soaking carbs will not do under any circumstances. They must be disassembled completely and meticulously cleaned and floats dry and wet set. There is no shortcut.

 

Just picked up the washer. Going back together tonight.