Freshly assembled XJ550 motor blows up, help w/post mortem

Thanks, it was pretty hard to accept at first, but I'm dealing. Hey, it's only money right? and time, and energy, and....

That's what the consensus certainly seems to be. It really makes me angry that he tried to fool me with that story. Thank god for you guys and the xjbikes.com forums!

My crap detector was certainly going off when he told me that.

 

I agree, but getting any money out of this person would be next to impossible and certainly not worth the aggravation and effort from my standpoint.

The crazy thing is that in his mind I still owe him money. He wanted $500 for pulling the cylinder head of my focus and doing this motorcyle "work".

What was supposed to be a one week job according to him took over two months and now my last set of wheels is toast. I have two other cars that need major engine work, and I have to move out of this house at the end of the month.

So I told him to go pound sand because he really put me in a bad spot.

Best just to sever ties and never deal with him again.

I have certainly learned the "If you want somethin done right, do it yourself" lesson the hard way in this particular instance.

The situation seemed hopeless at first until I decided to get on the forum and see what you guys had to say. You don't even know how much I appreciate all of your helpful comments and support.

I was about ready to give up, but I'm much more optimistic now knowing that I have you guys in my corner.

 

Re: Freshly assembled XJ550 motor blows up, help w/post mort

Good point. maybe it snuck through the gap created when the cylinder sleeve got pulled down?

 

Yes, pistons and rings are very hard to find, and if you do, they are big $$.

 

But wait, I thought I was SPECIAL. :mrgreen:

 

Ask rpgoerlich what he went through finding a set of stock pistons and rings for an XJ550.

And why do you think my '83 is named "Toxic Asset?"

 

You Can handle it you will need a manual. Man thats a serious bummer. On the oil issue I actually switched to the 5-40 synthetic rotella early this spring when it was about 25-30 *F out as my bike is my only mode of transportation. I have put well over 500 miles on the bike(work is only 2.5 miles away) even have had er revved up to 10K gettin into it with abosolutely no problems. The bike shifts smoother than with the 15-40. That being said I will be changing to the 15-40 or similar(May stay synthetic) when the hot weather starts to stick around. ALthough that may not make sense since the higher 40w is the viscosity of the oil when warm so ti really shouldn't hurt anything.

 

Re: Freshly assembled XJ550 motor blows up, help w/post mort

Shelly over at Speed and Sport should have 2 new pistons that I had returned to him once I found a set here locally. I got lucky and found a set after looking for a while.
There seems to be a couple cylinders with pistons on Ebay right now.

1981 Yamaha XJ550 Cylinder (s) / Jug (s) & Piston (s)

Yamaha XJ550 cylinders 1981

 

I don't suppose the guy might have not spaced the gaps in the rings properly when he put the jugs over the pistons. All the gaps at the same position would facilitate a non lubricated spot on one side of the cylinder, and maybe that melted/chewed the rings?

Just a thought, sorry about your experience bro, never fun to have an engine go like that, especially after you've just redone the hones etc.

I had a shadow 500 that we we did the valve seats, guides, cylinders rehoned, heads re shaved etc etc. Put it all back together and 2nd gear was screwed. I was so mad after all that time and money for the tranny to be weak.

 

The assembled gap is really about the size of the plug gap when running, or smaller, and rings spin very slowly while running.

I'll suggest a $200 tested "drop in ready" motor, and best of luck.

 

Hey srf21, I feel your pain. I found out after I bought my XJ650 that "it might need a valve adjustment" actually meant "it has cracked rings and some hard metal went through one of the cylinders". I felt like pushing it into Chesapeake Bay.

I got lucky though, and bought a really good running 750 engine for $99. I agree with the experts here (... I am not worthy...) that rather than tear your whole engine apart to check for bits of metal you just replace it. Maybe you'll get a good one like I did.

 

I've got the Clymer M387 manual as well as a 3-ring binder w/printouts of the manual on an XJ-cdrom from 7-8 years ago.

I was thinking the same thing, once the engine is warmed up, the synthetic oil should be the same viscosity/thickness as the dino multiweight.

 

Bummer. For some reason cliffs and bodies of water come into mind during episodes like these. If I lived in Hawaii I might also consider hurling it into the magma of an active volcano.

That's a great deal. If I could get a decent low mileage engine for under $200, I would be a happy camper.

 

Re: Freshly assembled XJ550 motor blows up, help w/post mort

Thanks for the links and suggestions. I'm going to pull the cylinders off today, and see what the piston and crankcase look like. My fear is that there will also be plenty of metal in the case, and I'm not sure if this motor is worth repairing. Such a waste after all the time work and $$ put into this one, but oh well.

I think the most cost and time effective route at this point is try and find another used motor as others have suggested.

 

Sorry Time i meant the spacing relative to each ring to eachother, not the "gap" in one ring end.

Like you would space them 8, 4, 12 o'clock between the top two compression rings and the oil ring.

If they were all 9 o'clock there would be a quick way for oil to shoot up to the combustion chamber, and a touch less compression, bad lube at 3 o'clock.

 

Re: Freshly assembled XJ550 motor blows up, help w/post mort

tried looking at your Engine Damage Photos but without success No matter.
Interestingly that motor as seen apart in the photos I did manage to see was Junk.. Is this the "new" motor from the Wrecker that was errr.. 'rebuilt'??
IF SO.. you Bought Junk Mate.
I've dissasembled motors with 75k miles on them that showed better cyls/chambers. condition. Rings are likely Shot as well as Valve Guides in my estimation.
Gawd knows What? the rest measures out as.

Add in an incompetent 'reasasembler" and you get a 10 minute ride

Junk yards are Legend for being Pure BS .. All ..their motors are Low Miles driven by an Old Lady.
Buy NO motor unless you either See it running, Have it apart for inspection or in the V least witness a comp test. Get a warranty in Writing.

Unfortunately nicely painted is just Lipstick on the pig.. Until.. it runs like New.
G'luck

 

Agreed, a spanking new motor needs the rings offset, as per all instructions.
A little off topic- - but I meant to also say that once the motor is running, the top ring spins one way, and the second ring spins the other, and in ten minutes, all rings are in various orientations relative to their perfect starting positions. 2 stroke rings are pinned to prevent rotation.

 

I can't be absolutely sure without examining the engine and measuring a few things.

It appears, from the looks of what appears to be a fracture in the Cylinder Liner at the Top of the Liner ... just below the Cylinder Head ... that you had Piston which was too small for the Bore.

You might have needed Oversized Rings or an Oversized Piston.
The Piston "Slapped" and a chunk of Ring broke-off and began doing the damage to the Crown and Combustion Chamber.

After you Honed the Block you should have Measured the Inside Diameter of the Holes.
Following a High Mileage Honing you would have needed either Oversized Rings or Oversized Pistons.

Having too large an Inside Diameter after a Honing lets the Piston Skirt "Rock" side-to-side.
You hear a soft Knock.
The Rings are stressed and crack.
A Fragment breaks loose and does the damage that appears in your photographs.

Find a Ring and place it in the damaged Cylinder.
With the Ring level ... measure the Ring Gap.
That's going to tell us part of the story.

 

I was present and helped when the piston and rings were inserted into the cylinders. I actually set the initial ring orientation myself, so I know that it was done correctly.

The motor was warmed up definitely running for a total of more than ten minutes before I took it on the fateful last ride.

 

Good idea. I will perform this test when I finally do get a chance to pull the cylinders off the pistons.

Btw, where should I position the piston ring in the cylinder in order to perform the measurement...top, midway, or the bottom?

My understanding is that cylinder sleeves are usually tapered, which would affect the measurement depending on how far down the cylinder the ring is positioned.