Loud BANG! then problems...ideas please!

[maparker]

1981 GS450T 17,000 miles: I was on the highway running about 70 on the way to the office when I heard a loud bang. I thought my rear tire had blown so I got to the right lane but no wobble, weird. I pull onto the shoulder and the bike dies, uh oh. Won't start with the starter. I notice there is oil coming from the top of the right side cover like maybe the gasket blew? (This may have been here previously though as I have a bad fork seal that pretty much has everything covered in crap!)

I can't start it with the bike in gear, but I do get it started once in neutral. Putting it in gear kills it again so I push it down the on-ramp and onto the sidewalk. I put it on the center stand and cannot even begin to turn the rear with the bike in gear? Pushing it just results in the rear tire sliding, double uh oh. Looking in the oil fill I can't see much, but no obvious hunks of broken metal. I get to a downhill section and get it push started in 2nd. I can keep it running, but any compression breaking or low throttle it tries to die like it doesn't have the power to keep running unless you are giving it some gas.

I made it the last mile or two to work and it died again pulling into the parking lot! I can't find anything obvious, but notice that all of a sudden my chain is VERY loose. It was not like that before. I really need some ideas as I need to figure out whether to try and nurse it home or hitch a ride as I don't want to trash something if I haven't already.

[Pacman]

1981 GS450T 17,000 miles: I was on the highway running about 70 on the way to the office when I heard a loud bang. I thought my rear tire had blown so I got to the right lane but no wobble, weird. I pull onto the shoulder and the bike dies, uh oh. Won't start with the starter. I notice there is oil coming from the top of the right side cover like maybe the gasket blew? (This may have been here previously though as I have a bad fork seal that pretty much has everything covered in crap!)

I can't start it with the bike in gear, but I do get it started once in neutral. Putting it in gear kills it again so I push it down the on-ramp and onto the sidewalk. I put it on the center stand and cannot even begin to turn the rear with the bike in gear? Pushing it just results in the rear tire sliding, double uh oh. Looking in the oil fill I can't see much, but no obvious hunks of broken metal. I get to a downhill section and get it push started in 2nd. I can keep it running, but any compression breaking or low throttle it tries to die like it doesn't have the power to keep running unless you are giving it some gas.

I made it the last mile or two to work and it died again pulling into the parking lot! I can't find anything obvious, but notice that all of a sudden my chain is VERY loose. It was not like that before. I really need some ideas as I need to figure out whether to try and nurse it home or hitch a ride as I don't want to trash something if I haven't already.

Loud BANG, clutch cover suddenly leaking oil, chain suddenly loose and unless the motor is putting out good power (higher revs) the bike dies. Sounds like serious transmission issues. You are going to have to take off the clutch cover and the left sprocket cover and post your findings. I have a feeling your clutch basket blew up and cracked the engine case in back allowing the drive sprocket to move around thereby slacking the chain.

Or it could be rear axle and the clutch cover leaking has been going on for a long time.

Do some more checking and let us know what you see.

Chris

[maparker]

Chris,

Thanks for the quick reply, so you are thinking its a definite "don't ride it" ? The clutch seemed to work OK once I got it started again, would this be the case if what you descibed happened?

[rcp]

Chris,

Thanks for the quick reply, so you are thinking its a definite "don't ride it" ? The clutch seemed to work OK once I got it started again, would this be the case if what you descibed happened?

I have a hard time coming up with a scenario where I would advise someone to ride a bike that made a loud bang then started leaking oil.

Call a friend with a truck/van/trailer or a service and get someone to cart that thing to were you can open it up and inspect.

Best of luck.

- Richard

[Pacman]

Chris,

Thanks for the quick reply, so you are thinking its a definite "don't ride it" ? The clutch seemed to work OK once I got it started again, would this be the case if what you descibed happened?

I definitely would not ride it until you know what is wrong. You can do some very basic work to find out more information which will help you to determine what the issue is.

First, take off the sprocket cover and see if the front sprocket shaft will move around. If the hole the shaft goes through is normal and the shaft doesn't move then move on to the rear axle. Basically, find out why the chain is loose and tell us what you find.

You said the bike runs normal in neutral so we know the problem is from the clutch back.

Chris

[maparker]

I have a hard time coming up with a scenario where I would advise someone to ride a bike that made a loud bang then started leaking oil.

When you put it that way I feel kind of stupid that I even aske!

[duaneage]

If it were an airplane would you take it up in the air?

I consider motorcycles in the same vein as airplanes. They need to be 100 % safe and ready for the road, for at 70mph if something goes wrong you will find out how merciless the nurses in the ER can be with those brushes.

[doug g]

Sounds to me like the rear axle is the issue at hand and the oil leak has been there. If the rear axle moved forward in the swinger than maybe the wheel is locking up in the swinger which would make it not move and also why the chain is suddenly loose. I may be wrong ut the first thing I would look at would be the rear axle before pulling off any engine/sprocket covers. If all is fine at the rear end then move to the sprocket cover and check to see if the output shaft is loose in the cases. If so then you have major issues at hand.

[tkent02]

Need a hand? Or a truck?
I'm bored and curiosity is getting to me.

[maparker]

Need a hand? Or a truck?
I'm bored and curiosity is getting to me.

I would love to meet another GSR member and get a hand! I'm close too I work in Littleton just off Broadway between Mineral and County Line! If you are serious PM me and I'll give you my contact info. I usually knock-off at ~3PM, but exceptions can be made with the offer of free help!

Mark

[maparker]

If it were an airplane would you take it up in the air?

I consider motorcycles in the same vein as airplanes. They need to be 100 % safe and ready for the road, for at 70mph if something goes wrong you will find out how merciless the nurses in the ER can be with those brushes.

Isn't that what the armored jacket and fullface helmet are for?


KIDDING! I've been down easy twice and never ever want to go down hard. I am feeling more and more like an a$$ for even asking about riding it home.


What sucks is I just put an new Jasper engine in my Jeep so I thought I was done with major engine work for a while at least!

[journerr]

Am curious to know how this all turns out.
Please post to let us know. ???

[maparker]

Well nothing solid yet except praise for the GSR community. TKent02 offer his assistance and I gladly took him up. Its amazing the people will step up on this sight, Kudos Tom.


We loaded the bike in his truck and drove it back to my house. Pulled the sprocket cover and the clutch cover and can't find anything. I'm begining to think (hope) that as embarsing as it may turn out that it was a combinantion of hitting something I did not see underneath the bike with low fuel. It will run just like I descibed when it is ready to go on reserve sometimes. The loose chain could just be neglect on my part. I adjusted it last fall, but maybe it is so worn that the few hundred miles that I've ridden since last adjusting it loosened it significantly

I won't know for sure without more work, but I think that it may be half weird confluence of events and half my stupidity. (I will make the excuse that sleep deprivation and cold medicine may have played a part, but I don't know if that counts!)


Thanks all and I'll post more as I dig deeper into the motor!

Parker

[80GS750]

well if your leaking oil and the chain is loose...

i second the thought of serious tranny issues...

with the motor not wanting to run with it in gear it sounds like part of your tranny is providing more resistance than necessary and killing the engine..

the bang. who knows. worse case you shelled something out inside your tranny. hopefully it didnt damage the case, cause that would be some serious cash there.

-nate

[rapidray]

I'm thinking it is VERY possible you lost the output shaft bearing with the symptoms you are describing. The noise, oil leak, trans issue, & LOOSE chain all point to that bearing. The clutch hub would have NO effect on play in the trans unless it took out a bearing. Ray.