bad night out

So I decided to take out my fiance's 82 550 maxim tonight to see what kind of mileage it gets. We have a road trip coming up and I thought it would be good to know.

I topped up the tank and hit the interstate running 70mph. I got about 15 miles and things went to ****. It started losing power, so I kicked it down a gear or two, and itkept slowing up. I pulled the clutch and let off the gas and it quit. Best I could tell it cranked hard, but I was rolling at about 50mph and couldn't really hear. I popped the clutch and got it going again and turned around at the next exit. About 3 miles later it is leaving a blue smoke trail. I shut it down and, since I was on the exit for a small town, push it to the gas station. As I was trying to contact her for a ride, I let it cool some. I started it and it ran a few seconds, coughed and smoked bad again. After a bit I got it going and found if I unhooked either of the outside spark plugs, it would nearly die. The two inside ones made no difference. Great spark though as it was flying all over the place. I can also here the cam chain buzzing, that happened on the ride out.

So, am I looking at valves or rings? I am going to set the cam chain tomorrow night and see how it runs then.

Thanks,

Matt

 

I've heard this story story before.
The tale don't end with a happy ending.

First things first.
Do a Compression Test.

Rub a Rabbits Foot if you got one.

 

Sounds like it might be lean and it overheated badly. Hope not if it did rings possible boring cyls if they not round anymore cracked head ect. Lets hope not see what the plugs look like.Hopefully it did not jump time and valve kissed the piston If its blowing smoke checking compression is not gonna help much. Hopefully it was full of oil. Wish you the best of luck and keep us posted

 

If you were to wheel your bike into any reputable shop, ... the FIRST thing the Foreman or Lead Tech would expect to be done ... (after hearing it was "Blowing Smoke") ... would be a check of Compression.

That is my recommendation, too.

You need to know what those numbers are ... across the board.

Hopefully, ... you'll HAVE Compression and this fundamental diagnostic test will provide you with some good news.

Blowing plumes of smoke is a very scary symptom after a dramatic loss of power.

A quick compression test reveals the condition of your engine's head gasket, valves, valve seats, piston crowns, piston rings and indicates if those parts have failed or sustained damage.

 

Sounds like holed piston to me.

 

i had a similar problem after a honing and a complete rebuild on my rd 350, new piston/rings, i hit the gas too hard, and didnt give it the break in time it needed, make a long story short, smoke, bogged, died,, took head off to find a massive hole in the forged piston i had just installed over the winter, on a positive note i had a great parts bike!

 

Your problem with the rd was incorrect timing lean condition. That is the only thing on an rd that will hole a piston in an rd. If you were not running the heck out of it. Also if you put a forged piston in it without having a cyl punched over you clearances are to tight since you have to set them up much looser then non forged. Std wisco piston is actually .20 bigger then convectional piston. They will fit in the bore but when they get hot they stick to the cyl walls causing heat then you melt a hole in the piston

 

The bike that possibly blew up wasn't an RD, it was an XJ550.

Start there. Don't keep running the motor until you do, you could just make a bad situation worse.

 

What good is a compression test going to do? You already know its broke, maybe a leak down test but a compression test just tells you what you already know. It doesn't say valve, rings, piston or gasket, just broke.
Start taking it apart

 

The following issues are commonly suspected after completing a preliminary diagnostic Compression Test rendering unsatisfactory results:

Yes / No
Yes -- Relax
No -- $$$
NO Comp on Hole -- Piston Crown Holed
Rapid Comp Loss -- Burned Valve
Low Comp ~ Adjacent Holes -- Gasket
Low Comp Dry -- Rings / Valves
Low Comp Dry ~ Good Comp Wet -- Rings
Low Comp Dry ~ Low Comp Wet -- Valves

 

A hole in 2 pistons? I put a hole in a sportster(rear cyclinder of course) and the motor was toast bottom and top end Pieces floating in the oil make great shrapnel. Pray it didn't get that far. Goodluck on the teardown. I'm lost at that point, but sure there are experts here that can help you out.

 

We had a forum member that bought a beautiful, clean XJ550 Maxim with only about 5500 miles on it and both #2 and #3 pistons were HOLED. Melted.

It's certainly possible. The man of few words is ultimately right, but I'd still run a compression test before pulling it down. What's to lose, 15 minutes?

It done blowed up*, that much is rather apparent. How badly is yet to be determined.

Don't run it any more and diagnose. We love a good disaster.


*thank you NASCAR and DW

 

I'm surprised it didn't show symptoms before losing power, on a 15-minute ride staying steady at 70mph, it seems like it would start behaving differently enough before the damage to indicate a problem. Unless it was just a sudden failure I suppose.

I agree totally with the comp test, it will show what Rick detailed and usefully it can even show to what degree each pot failed. The fact that it will still run at all is at least one bright spot, the lower end is still intact and it's possible the top isn't toast, just warm bread.

Also the most likely pistons in ANY air cooled engine to get too hot and fail are the ones that by design receive the least amount of cooling from the air...a like the two in-board ones on an XJ or #3 on a VW Bug.<--..sadly been there