Just how common are heat siezures?

Finally got into junior's '86 fz600 to determine what actually happened to the thing as it died on the hiway...after it's 5th or so hour of running.. Heat Siezure .. of all 4 cyls, equally damaged even? No broken bits, no oiling probs, Just a simple stupid 'too hot' situation.
Very strange tho, as the Ambient temps were in the high 20's (low 80;'s F)
No running lean issues,, ign timings?.. wewre spot, on before and even now

Ignition modules have been known to go 'erratic' under higher temps... just a wild guess.
Any one else ever have a similar 'unexplainable' heat sieze issue...?
Unlikely that this is the only one to meet this particular form of death... just trying to figure out why

 

I did with my coils years back. Run the Accel coil set now. Problem went away.

 

Really?? and yours did not need : new bores, new pistons/rings?
Err.. that's like $500/600 in bits alone... according to my friendly Yamaha partsman. Obviously yours was a far milder event. ..any siezure is serious stuff though. Motor ran reasonably well considering it's damage but the smoke screen was something to behold.
With this bike, it effectively means a replacement (used) motor.

 

My apologies, I was refering to your question about heat exposure and the ignition modual. "Ignition modules have been known to go 'erratic' under higher temps... just a wild guess". I'm sorry to have caused any confusion. Heat can cause parts to stop working, but I confess I've no idea why your engine siezed up, though I'm curious as to what weight and type of oil you were running. Run too low a viscosity number in high heat, viscosity (protection) will suffer. Just throwing out some ideas. No broken parts? Just some scuffing on pistons and cylinder walls? Humm...

 

If this bike was brought-in for me to evaluate ... the first thing I'd look for would be the possibility that engine was run on AvGas or Funny-Car fuel.

I'd investigate an Oil Pressure failure; anyway. Without a sufficient oil sheen getting on to those bores ... disaster awaits. Particularly, if the bike was run in heart of the power band.

An extreme lean situation, with no oil pressure problem, would have melted a piston or burned right through its crown.

The standard ignition modules are incapable of the amount of advance needed to be destructive.

I'd stick a feeler gauge between the oil pump's impellers and housing after checking it for no rotational issues.

Put the tape up all around the motorcycle until we solve the case.
I'm investigating this as a "Yama-cide."

 

Great deductions Rick, I can't wait to see where the culprit is hiding.

 

Danilo,

I'm sorry, but I don't understand how great the damage is. Have you taken the head off? How do the pistons/cylinders look?

I can't answer your questions. I wish I could provide a solution though; I mentioned it before, I have a spare engine, whose head I replaced on my bike. I wanted to use the bigger bore pistons/cylinders from the spare engine, and in the process I broke one of the rings (stupid me did not get a ring compression key). So I had to put the old pistons back in, and now I'm trying to source a replacement ring, without any success. I'd give you my original pistons and cylinder head (good shape) if I had that ring and if you indeed need these parts. So, let me know if you do when you assess the damage to the engine.

I'm really lost as to where to get a ring that would fit this piston.

Best regards,
Relu

 

Oil drama , it would have to been really lean and on all pots....

 

Id say an oil problem too.
Was this engine rebuilt and did the parts go to a machinist, say for boreing or anything?
Were new rings put on the pistons, and were the ring grooves cleaned? (that could throw the tollerances off)
Was the head shaved? (could have changed the compression)
Any fuel additives?
The possibilies could be numerous.

Please let us know what you find so history dont repeat itself.

Good Luck
Mike

 

is that bike water-cooled? maybe something in the cooling system failed ( thermostat,water pump,etc.)

 

It's not water-cooled.

 

Well ... now we have to pull the Oil Filter and have a look for particulate. Just to see if something got chewed-up. The bypass should have kept the circulation and pressure up ... but, there might be a clue if there's shavings or excessive foreign matter in the filter, itself.

Pull the drain plug and get all of the oil out of there, too. Go "fishing" in the oil that drains-out with a magnet, to see if there's anything the magnet picks-up.

Look at the magnet on the drain plug. A very small amount of particulate is usually picked-up by the drain plug magnet.
If it looks like magnet has a hair style right-out of the '70's ... well, something was worn-down from not being oiled.

I'm confused as to the sudden onset of this problem?

It seems to me that the bike must have had the oil pressure fail to cause the seizure. But, if the oil pressure suddenly quit ... you'd have heard some pretty unfamiliar noises, louder than normal.

Then, you should have felt (and maybe even smelled) something getting so hot as to contribute to a pending catastrophic failure -- [ And this IS a catastrophic failure ] -- do to the kind of heat generated to cause ALL FOUR holes to lock-up.

The list of probable causes gets smaller when you take into consideration that all four holes sustained damage.

All matters related to a mechanical sudden oil pressure failure. (Pump)

Fuel and mixture. With the carbs set-up to run with Gas within the 87>93 Octane rating -- (And I'm being generous on the 93) -- some form of fuel far above 93 was introduced.

Additives. The possibility of mistakenly adding far too much performance or cleaning additive to cause the combustion on the power stroke to be so highly volatile that it exceeded the designed limit for air cooling. (Which, by design, is engineered to withstand high-temps from running at high rev's for some time.)

These XJ Engines are modeled after the same engine that powered Yamaha to be dominate on the racing circuits in the decade that the XJ-Series bike's were introduced. These engines -- quoting the motorcycling press reviews -- are supposed to be "Damn near bulletproof."

So, we have to find the magic bullet that killed your bike!

 

Lotsa good guesses Some quite good. sad truth is None appear correct.. Including my own .
Oil was/is fine, was changed the day before it died, when removed, it was(albeit a bit darker) than when it went in 24 hours earlier, no sediment, no floaters, no sparkles and absolutely nothing onna Magnet.
Cam lobes are perfect, these in my experiences show oil issues almost instantly. Hell even the plugs are burning properly.
Have located a 'new' motor an '89 ..victim of a hiway crash a few years ago.( Steering pulled full lock to the right apparently.. resulting in a spectacular crash, Rider survived.. Bike did not) It has the large (improved) alternator on the left crank end which means I can only use the engine for parts. Will be picking it up this weekend.

 

Have you pulled the cams and examined the bearing surfaces? Odd to hear of a lock-up with little or no obvious damage. Did the oil smell burnt? Need more details.

 

It's too bad we all don't live close enough together to bring-over a few tools and do an Old School D-Day invasion on the whole project. With everybody handing each-other preloaded right sizes ... we'd probably be done, cleaned-up and home to in time to let me catch Katie doing the New CBS News format.

With two air lines going, some good light, enough cooks stirring the broth with ten, twelve and fourteen millimeter sizes, and an officially designated Duncan Donut Runner that MUST write-down everybody's order, I'd say we'd be done with the whole sha-bang in a few hours ... provided we don't stop when Big-Papi's up. His chasing an ages-old, homer's in Fenway mark.

Sorry; I'd have to peek.

 

Oh how I'd love to be party to that Rick. Not too many opportunities to throw a wrench with the "guys" anymore (family man now you see). I'd wager we could pull the motor, strip it and diagnose the issue in three hours tops. Another two hours to put it all back together (gotta clean everything before reassembly) if the problem is simple enough and parts are available. Another hour to punch it back in. A day, with plenty of time to spare. Lemme at it!

 

How do you want your coffee? I'm ready to write it down!

 

Hate the stuff, yech! Wish I was born with a silver spoon so I could afford to go running around the world to wrench...sigh, not in the stars. I'm hopeful that the issue on this bike did, in fact, little damage and will allow for a swift repair. Just the same, a fine toothed comb will be necessary, you never know where the problem might have been from. I was able to rip through a motor by myself in about three days (pulling it with no machining needed) but I have yet to reinstall the bugger. Shouldn't pose to much trouble to get it out.

 

Guys like you make this forum great. I learn so much only from "listening" to you... in fact I wouldn't mind getting a real XJ if only to join the ranks of the likes of you.

 

You ought to write a nice letter to Yamaha and tell them that you'd really like to have a new XJ-750 Special Edition; so please start making them!!!

There has got to be some committee deliberating what they should build for the new generation of transportation-needing public, facing high-priced gas, and looking for a fun-machine to save some money.

Your letter might light the bulb over the head of some Marketing Genus who would recognize that Mega-Cruiser's, modeled after the company bike's they saved from swirling down the drain, appeal to a very limited market segment.

Not entry-level motorcycle buyers who are shopping all the makers showroom's looking for a bike to buy that would be more like the old Chevelle SS, than these Cadillac Escalade's.

Don't want a STAR Motorcycle? How about one of these high-tech, fully plastic-wrapped bullets? You see the Bullet-Rider's pulling-off at the highway rest stops, very frequently, for a "Vibrating Butt and Back-ache Break."

When I hit the road on my Max, all I want to do is keep going!

 

I'm with ya Rick, those leaking, vibrating popular bikes that are status symbol only!!
Gimme an XJ that runs like a swiss watch, one that I dont have to stop to pick up parts on, one that doesn't cost a fortune to ride because the "factory authorized mechanics" are so far and few.
Anyway my XJ suits me just fine! This coming from someone whos last bike was a Goldwing.

I DO still want a new Star though!!! I just prefer big bikes

 

Some ponderings from my brain.


Question Danillo.

IS the damage limited to the bores and pistons?

Was the bike rebored with new pistons rings etc.

If it seems like only the bore is affected then I'm thinking ring clearances or reboring has left it a bit tight creating a bit much heat in the bores.

Maybe needed a bit filed off the rings if new.

Maybe run in revs were ignored. Did you run it in yourself?



Cheers
HG

 

Not writing anyone off yet just the obvious reasons don't seem to fit. Woulda been easier to understand if the cause was immediately apparent.
Will be taking the thing to bits soon enough, 'replacement' motor will be stuffed into my pore car's trunk tomorrow.. not looking too forward to it as those things are damned heavy.

 

"He ain't heavy. He's my brother."

"That ain't heavy. It's your motor!" : )

 

Just be careful with the back, once you blow it out, your done for life!! Use help and/or a hoist if you can.