• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

1982 GS650GL. Loud banging sound. Possible valve problem.

  • Thread starter Thread starter William Groebe
  • Start date Start date
W

William Groebe

Guest
Hello, forum.

I recently replaced the transmission on my 1982 GS650GL. You can see the thread here. http://tinyurl.com/ld86h63

After finishing the work, the bike ran great for about two weeks, then all of the sudden one day I heard a light "tang tang" sound under load. As I was 15 miles from home, I decided to turn around. During the ride home the sound got louder and louder until it got to the point that it was so loud it sounded like something was going to explode and I began to lose power to the throttle, so I pulled over and had to come back with my truck to get my bike home.

A mechanic is telling me a valve may be stuck in the down position and the sound may be the piston hitting the valve, which may explain the sound, and loss of power due to lack of compression. I'm going to take the engine off the bike again and take off the head to see what's wrong. Or I may just try to get the head off while leaving the engine in the frame. That would be less of a hassle, but I'm not sure if it would work.

I'll keep you all posted on what I find out.

 
It is very possible to remove the head (and cylinders) with the engine in the frame, but before you do that, check your valve clearances.

If you have a valve that is stuck open, there will be a LOT of clearance.

By the way, if the piston has been making noise hitting a valve, I would bet that the valve is bent, keeping it from closing on its seat, leaving plenty of valve clearance.

If all the valves have proper clearances, verify proper cam timing, then try a compression check before removing the head.

IMG_5391_zpscd5be745.jpg


.
 
Yes, verify cam to crank timing, maybe the cam chain tensioner failed (or couldn't move) and that " light tang ,tang" turned into more interference.
 
Thanks for the input, fellas.

I'll get back to it tonight and let you know what happens.
 
Didn't get a chance to do any work on the bike last night. I almost forgot that the NLDS game was on, and I had to watch my SF Giants take down the Nats. Or more accurately, I watched the Nats hand the game away to the Giants with some very odd and clumsy plays and pitches. But we'll take the win. Go Giants!

Back to motorcycle tinkering tonight.
 
'Tis a sick mind, indeed, that allows a silly NLDS (whatever that is) game take priority over some GS wrenching time.

At least have a TV in the work area, if you need to keep track of it.

.
 
I checked the valve clearances, many of which are too tight.
Ex - 1=(-.04mm) 2=(.06mm) 3=(.04mm) 4=(-.04mm)
In - 1=(-.04mm) 2=(-.04mm) 3=(-.04mm) 4=(.05mm)
(I typed -.04mm by anything that was under .04mm as my smallest gauge is .04 so I can't get an exact reading.)

I removed the head. I pulled out the shims and found a piece of hard plastic under the #3 intake valve bucket. This could definitely be messing with my valve clearance, right?




I'm tempted to replace whichever shims I can, put the engine back together and fire it up to see if the sound is gone now that I've removed the piece of hard plastic. But I may take the head to my mechanic to have him pull apart the valves and check inside for damage. I don't have a valve puller tool or I'd do it myself.

Here are some other pics just for reference.


 
Heard a rumor that a valve spring compressor can be made with an 8" C-clamp and oxygen sensor socket, both available from Harbor Freight. I have both of these but haven't put them into action yet.

A valve spring decompressor can be made with a deep-well socket and a hammer. :)
 
I was in a hopeful mood yesterday and decided to see if the bit of plastic was causing the valve to hit the piston, so I put the bike back together and fired it up this morning. Alas, the engine is still emitting a loud banging sound. I think the sound may actually be coming from the crankcase. Looks like I'll be diving back in to the engine. yippee!! (sarcastic exclamation)

Eil. Thanks for the advice on the home made valve spring compressor. I'll try your method out this week.
 
PVC works too and is easier to cut if you don't have the proper tools. Just glue a big washer on top.
 
I brought the head to the shop. They didn't take the valves out, but pretty much flatly said it isn't a valve problem. There are no indications of damage on the valves, nor are there any markings on the pistons from hitting the valves. I may take apart the valves later if I don't find any problems anywhere else.

So I am digging deeper. I took off the cylinder and pulled on each piston to see if there was any play up and down, which there shouldn't be, and found that my number 4 rod has up and down play in it. Each piston head has a little side to side play, but as far as I know there shouldn't be any up and down play in the rod. Not good. Gotta bust open the crankcase again. Yay

Side note. In pulling off the cylinder, I should've been more careful, as I tore the gasket. Oh well. I'm learning as I go. I'll keep you up to speed as I go back into the crankcase.
 
Well, I've definitely got a loose rod. I don't know anything about crankshafts, so I'm going to have to do some research. I'm not sure how it became loose, or what happened. When I did my transmission repair, I left the crankshaft alone.

There is a bunch of metal shavings in the bottom of the oil pan. Looks like the rod was wearing down the round part of the crankshaft next to the rod, whatever that part is called. I'll call it the round wheel thingie. The round wheel thingie on either side of a rod is supposed to have a rough texture on it like this


But the sides of the round wheel thingie next to the loose rod is worn smooth like this.

I think this is where all the metal shavings came from.

This seems really bad. Like I said, I've got to do some research. Lame. I was all ready for the Indian Summer riding season.
 
What a drag! You'll need a new crankshaft as yours got damaged by failing rod bearing. Honestly, at this point, I'd consider a whole other bike. Not sure about your area, but in northeast, one can scoop a low mileage/low cost bike with simple problems like carbs and electrical - easy stuff compared to what you gone thru. I admire your persistence at digging away at this critter but I think she's not interested in helping.
 
There are many of these available on Ebay, especially from this guy. This is the configuration you want, with the rods still in place. It IS an 81, however, AFAIK, the only difference is in the bearings, if you look up 'crankshaft' page on Parts Outlaw, OR, better yet have the factory manual, it explains it all. Now you're gonna get into bearing clearances and the use of Plastigage, etc, a fairly involved process. The 'thingies' (HARrumph), lol, are called crankwheels, sometimes flywheels, etc. Watching your posts, and your lack of fear in taking things apart, something tells me you'll be fine, just maybe a little extra patience. In fact, if they had a yearly award on here for 'Best New Guy', you'd get my vote. Carry on!!

http://www.ebay.com/itm/1981-suzuki-gs650-gs-650-sm40-crank-/230525286197
 
tom203, thanks for the advice. I'm still thinking I'm going to try to fix this. My goal is to get this bike running, and learn whatever I need to learn to do it. I'm using this bike as my motorcycle school. I'm sure there will be a point when I will have to call it quits, but I'm still feeling motivated to get it running.

I found an 82 crank on ebay for $85 http://www.ebay.com/itm/290613867561?ssPageName=STRK:MEBIDX:IT&fromMakeTrack=true
I'll buy some plastigage and, if necessary, some new bearings.

One question I have though, is how did a rod come loose? Somehow there is play in the rod even though the rod nuts are tight. What gives?

Oh well, on to ebay. Hopefully I'll get it back together in the next week or two.

And thanks for the encouragement, recycled64.
 
Price bearing stuff before you go ebaying crankshaft- if you have had metal bits circulating around engine innards, lots of the plain bearings could be damaged, not just the one for rod #4
 
Also, the crank I referred you to has the rotor attached, FWIW, same seller, different stock #
 
Hard to believe that your rod machined that crank journal surface so precisely. Are there visible signs of where on the side of the rod? If not, then it's more possible that it was machined by Suzuki originally. The metal shavings could be from another source or from the rod bearings themselves since the rod did have more play in it then expected. Don't ignore the possibility of the transmission rebuild being the source of the damage and metal. Inspect everything again.

Personally I would either pick up a complete engine or part out that bike and use the funds to get another good example easy fixer-upper. Lots of good usable parts on that one and many older Suzi's out there.

If you're determined to get this one running again, then clean and flush the entire engine case of any metal shavings before you proceed with the reassembly. New oil, new oil filter are manditory.
 
tom203 said:
Price bearing stuff before you go ebaying crankshaft- if you have had metal bits circulating around engine innards, lots of the plain bearings could be damaged, not just the one for rod #4
Click to expand...

+1 On this.

You have to assume ALL bearings are suspect and failed, plane and roller. This is a complete overhaul of the motor job. Not just a "pop in a new part and off you go". Everything, EVERYTHING, that is exposed to the oiling system needs to be meticulously cleaned, and then cleaned again. Bottom and top end.

Sucks that you just went thru to work of replacing the gearsets only now need to replace the crank (your cases are seeing a lot of daylight).

Path of least resistance/expense is to buy a complete used engine somewhere. Hopefully close by, and hopefully in better condition. Then resale the salvageable old parts to recoup your costs. The much more satisfying and interesting path is to overhaul the motor yourself. Than means; new crank (probably), all new plane bearing shells, new gaskets & seals, and you might as well do a ring job while you are at it.
 
You must log in or register to reply here.
Back
Top