metallic tapping noise

[Dave_17954]

tapping solved maybe!!

while reshimming the #4 exhaust which seem to be where this noise is coming from I happened to take an upclose pic of the shim bucket without the shim in it. it looks to me if you look real close that the end of the valve is protruding ever so slightly through the bucket casuing a bulge in the center. this it would seem to me cause the shim to actually rock back and forth similar to a teeter totter as the cam lobe passes over it. is this this mysterious valve noise ive been looking for? does anyone out there have a good used shim bucket for a 1980 gs650gl? I want to replace this one and reshim to spec and cross my fingers .

[Dave_17954]

well it looks like a false alarm on my shim bucket. removed the exhaust cam and took out the bucket in question yesterday and everything looks fine. looked over the entire area there and couldn't see anything out of the ordinary. guess its time to learn to live with it

[waterman]

What does your cam chain look like? I am probably way off base but I had a cam chain rattle around from a suspect tensioner that made a horrible racket around 2500 rpms. Bike ran perfect but sounded horrible. Eventually have rebuilt and replaced chain, tensioners and guides. This bike currently has a slight rythmic knock at idle that I think is clutch related. I may check it out this fall.

Just to clarify, the 650 shaft models were plain bearing lower ends not the roller bearings like the many other gs. The 650e has roller bearings.

Keep digging, something will show up eventually.

[Dave_17954]

hi

actually i have a pic of the cam chain. it looks like new. just sounds like that noise is coming from the #4 valve shim area. the bike runs perfect, idles great no other problems. I ride it everyday and this noise has been there ever since i got it. it has 31,000 miles on it and i change oil religously (20w-50 castrol) run 87 octane and correct heat range on the plugs. the plug color looks excellent. i can find no lose nuts or bolts or anything out of place. the rest of the motor is quiet. only this one area and i can only hear it at speed not at idle. the noise is intermittant at highway speed. i did the bearing check with pushing down on the pistons (all 4) and they are all tight. i've cleaned and rechecked the tensioner no difference. ive disconnected the tach cable no difference.

[bwisted]

I don't think there is a problem in the valve train here. Taking the spark plug wire off doesn't change a thing in the valve train. I would be looking towards detonation. With no more combustion pressure or temperatures, it sounds like detonation. Detonation can be caused by many things. Lean mixture, carbon build up, poor fuel, oxygenated fuels, spark plug heat range, etc. With 30K miles, I may not lean towards bearings, unless you have specific reasons to go that route.

[Dave_17954]

I was suspecting a fuel issue at first to. I've played with the air/fuel mixture screws with no results. they are set at 2 1/4 turns out all the way across. I regularly use shell gasoline its the best brand around here (no plug intended). I figured if it were fuel related I'd hear in the other cylinders as well. going down the road it has power to spare. very smooth and stable idle. starts right up everytime. how far out can i turn the air/fuel screws without hurting it? I was thinking lean to but the plug color shows normal burning.

[bwisted]

Maybe a little more info on the noise. A bearing knock typically sounds like knuckles rapping on something and comes from the bottom end. wrist pins are slightly higher pitched and come from the cylinder area. Detonation is a metallic sound, like you explain, that almost sounds like rattling, when the engine is under load. Idling and cruising are usually not enough load to make it audible. The mixture must be good if changing the mixture screws has no effect on the noise. You right on with saying a fuel problem should result in all cylinders having the noise. Have you looked in the cylinder with a boroscope?

[Dave_17954]

the noise sounds like if you would take say a screw driver and tap it against the side of the case. although it is slightly metallic in sound. it comes from higher up in the motor specifically the valve/ shim/exhaust area of the #4 cylinder. no i havent looked into the bore except with a small flashlight. i can only see the usual carbon build-up on top of the piston. i have tried different octanes of gasoline but it runs the best on 87 unleaded gas and standard d8ea plugs. you can hear it very plain as you bring it up through the gears or even if you ride in a lower gear at a higher rpm say around 3500-4000 rpm. leaving the bike in nuetral and revving it you can hear it briefly not under a load coming from the same area. the noise is definately higher up. no doubt about that for sure. its not a ticking noise but also not a knocking noise either. somewhere in between those two. also i have noticed when riding down the road at say 55mph i can pull the choke on and it has no affect on the bike. i would think it would choke itself and bog the motor down but it doesnt. might try pulling the exhaust off and looking behind where the pipe sits in the cylinder. i do have new exhaust gaskets in also. it averages right around 50 mpg when cruising. i know aluminum can transfer sound rather easily but this noise i've never noticed come from any other area.

[catbed]

i have a metallic tapping noise from the #4 cylinder of my bike too. i can only hear it at idle. i dont worry about it.

[Dave_17954]

well since its raining today i decided to pull my clutch and exhaust off to give everything a good look. I put in a newer (approx 1000 miles) clutch on this bike when i first got it and done everything according to the manual but again i'm just revisiting areas that maybe will give me a clue. the same with the exhaust area. darkness has settled in so tomorrows another day. any suggestions on what areas to look at while i have the clutch out?

[49er]

Could it be just an excessive cam endfloat knock?

[Dave_17954]

found everything to be in good shape in the clutch area. everything is assembled correctly and torqued to spec according to the service manual. also checked the exhausts for anything touching the frame clamps especially and there is good clearance all the way around. also after reassembling everything the noise is still there. the noise will start around 3,000 rpm and is intermittent at cruising speeds. also noted when I disconnect the #4 spark plug and ride it at highway speeds there is no noise. reconnect the wire and the noise comes back. also noted that the #4 plug looks to be running hotter than the other 3. adjusting the air/fuel screw on #4 carb doesnt change anything as far as noise goes. I also took out the plugs and rolled the #4 piston just past tdc and push down on the piston with a dowell rod and found it to be tight with no play. also went from a 20w50 castrol oil back to a 10w40 pennzoil with no change. probably just continue to ride it as there not much left of the riding season and i have no major rides planned. maybe do a top end tear down this winter and maybe carb kits to. give me something to do to while away those cold winter nights lol. i'm gonna figure this thing out if kills me. LOL

[Flaggo60]

....You are dealing with roller bearings, not plain.....

A GS650L is a shaft drive machine, isn't it? If so, it has, for some strange Suzuki reason, plain bearings, not rollers. Could never figure out why we 650G and GL owners were so blessed with that feature ...

[flyingace]

A GS650L is a shaft drive machine, isn't it? If so, it has, for some strange Suzuki reason, plain bearings, not rollers. Could never figure out why we 650G and GL owners were so blessed with that feature ...

Looks like a case where we're both wrong. I was wrong in assuming the GS650 engine has roller-type engine bearings, which it does not. In looking at the parts fische, I see that only the larger GS engines (850 and above) have roller bearings regardless of model.

[Bribird]

With out hearing the noise it is very hard to rule things out. Wrist pin is what comes to mind for me. Bad wrist pin sounds almost like detonation but more hollow sounding.
The other, and I only mention it because I had this happen on my 650, is a broken valve guide. Now I did not hear any noises, but did have smoke at start-up and a little when it was wide open.

Bri