metallic tapping noise

[Bribird]

Hey Dave, sorry to hear that did not do it for ya. Good luck in finding the problem. I hope it turns out to be something easy like carb adjustment or rebuild verses wrist pin or a broken piston skirt.

Bri

[TheCafeKid]

Still havent located the source huh? It certainly is puzzling. I wish I could have been more help, but you'd already suspected MY usual suspects. I kinda wonder about the wristpin thing. But then i still wonder about a possible head gasket leak, or an exhaust leak as well...

[Dave_17954]

I took the exhaust off last weekend and checked everything. my new exhaust gaskets still looking in excellent shape and checked for any exhaust rubbing or touching the frame aka clamps etc. but could find nothing out of place. I'm borrowing a friends timing light tomorrow and will check my timing here in the next couple of days. When i do find the source of this noise i'm having one hell of a party for sure.

[82Shafty]

We obviously have discovered that 4 is buring hot which would be lean.

Have you checked the float level--fuel level in the bowls?

This 3G knocking.... if you are at 3g steady cruising down the road in 3rd and you do 1/4 throttle does the noise get audibly louder or does it just increase its frequency?

3g crusing going to WOT... does it still knock?

A. you could try a 3 step colder plug to see if the knock goes away as a diagnositic measurement.

B. You need to determine why it is running lean on one carb? Have you double checked for vac leaks with soapy water in a spray bottle? Air box rubbers tight?

[82Shafty]

I took the exhaust off last weekend and checked everything. my new exhaust gaskets still looking in excellent shape and checked for any exhaust rubbing or touching the frame aka clamps etc. but could find nothing out of place. I'm borrowing a friends timing light tomorrow and will check my timing here in the next couple of days. When i do find the source of this noise i'm having one hell of a party for sure.

Did you peak in to inspect the color of the deposits on the valves? Was # 4 a lighter gray compared to a brown or black on the other 3 cyls?

Oil (carbon) could be built up on the back of the #4 intake valve as well soaking up the atomized fuel causing the CC to run lean. I would further explore what's going on with the #4 fuel delivery circuit.


I also didn't notice if you have installed a robert Barr o-ring kit yet along with intake boot o-rings; have you?

[Dave_17954]

I put new carb boot o-rings in the last time i had my carbs off. never made any difference. I'm going to post pic of spark plugs and i'm going to try and do a video while riding down the road hopefully this will turn out. if it does i'll post a link to the video probably on you tube. that way people can hear the noise to get a better understanding of what its sounding like. havent really gotten into any carb work been concentrating on valve area. like i said earlier maybe do a carb/top end overhaul this winter if i dont locate source of the noise before then.

[Dave_17954]

engine noise

finally tore down my 1981 gs650gl in search of my mysterious engine noise and quite possibly have it located. tore down the top end today and this is what i found in the #4 cylinder. the area from which the noise was coming from. no broken rings but looks like they were stuck at one time. the other 3 cylinders showed the usual normal wear and tear. gonna measure it and hoping to just hone them out and put in a new set of rings in all 4. and the usual maintenence while i'm in this deep. gaskets looked good but will replace of course. will take the cylinder head and block down to my local machine shop and let them work it over in the meantime time to round up gaskets and get my seat redone and clean up wiring harness connectors. lots of things to do to my suzi girl lol.

[Steve]

WOW, good find.

That would definitely be making the noise.

Now I wonder ... why didn't I see these posts while it was happening? I live not too far from TCK, but was out of town at the time, so could not have stopped by to lend an ear, but this is the first time I have seen anything about your problem.

Good luck with the rebuild, hope just a honing and re-ring job will take care of it.

.

[Dave_17954]

The number #4 conrod seems to have excessive side to side play compaired to the other 3. Is this normal given its next to clutch? push/pull on the conrod and its snug. Can see no signs of any abnormal wear and tear on the crank just the side to side play. Measured the piston,valves, springs and all well within spec according to suzuki service manual. Should I split the case and change the bearing in #4 (actually I'd change them all if i split the case)? There was no noise coming from the lower end when I had it together and running. Had numerous people listening to it as well as a very qualified motorcycle service mechanic and even he said didnt sound like lower end noise. I will pick up head tomorrow from machine shop and he said it could be honed out with just a bottle brush and it would clean up fine. Don't really want to split case if i dont need to. Thoughts?? And is the porosity between the #3&4 and right above the #1 valve area normal? I'm a machinist by trade and if I ran something like that I'd question it. The gaskets were good when i tok them off.

[Dave_17954]

Piston pic and valves. all clean and in spec.

[chef1366]

Do the marks on the #4 cylinder have ridges? Does your nail catch on it?
I'd measure the back and forth play and ask a techy.

[Dave_17954]

yes. thats what there honeing out. they're not deep but you can feel them. machinist there said a bottle brush hone job should clean them up.

[Dave_17954]

heres my # 4 crapped up bearing. number 3 looks very similar while numbers 1 & 2 shows wear but not nearly this bad. will replace all 4 sets. should i replace the crankshaft bearings as well? none of them look really to bad. I have pix and also whats the best / easiest way to remove and reinstall valve guide seals. the guides themselves are in excellent shape. what kind of tool could i use..........

[duaneage]

Check the crank journals. Get some plasti-gauge and use it to establish what the bearing torque should be. You may need a crank in the end. Look out for journals that are not square any longer. A crank can be turned, sometimes oversized bearings can be found.

Also torque the rod up and measure the diameter in several directions on the big end and make sure it is round within specs.

In this situation you need to measure everything and pay attention to the details. I would also check the rods to make sure they are not twisted or bent. These things do happen.

As a final suggestion I would examine that #4 piston for ring to groove clearance and check the piston wrist pin as well. The violence that took out the bearing plays hell with the piston and wrist pin.

There is around 15 tons of force on the rod at highway speeds. It is a fast tug but still a lot. Things have to lubricated and at the proper clearances for it all to work right.

[duaneage]

I have pix and also whats the best / easiest way to remove and reinstall valve guide seals. the guides themselves are in excellent shape. what kind of tool could i use..........

Use a needle nose to get the old ones off and your finger to put new ones on. It's that simple