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Old 05-20-2012, 06:17 PM   #1
Freeagain OP
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Eek Help - Scary noise from my G/S engine

Hi All,

I had a brilliant 1000km mountain dirt ride over the weekend. 1984 R80 G/S went really well. But.....

At about 650 km's I thought I heard an extra tapping noise. At 800km's it was definately there and gradually getting worse. By the time I got home it was seriously bad.

The bike is still pulling like a train, and smooth.

It is a loud tapping sound, that is related to revs. It seems to quiet down alot with some (3000) revs, but hard to tell.

It seems to be coming from the crankcase/front cover (as opposed to heads).

Can anyone give me thought as to what this might be, what to do diagnosis wise, and any other tips that are relevant?

Thanks in adavance,

Toby
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Old 05-20-2012, 07:24 PM   #2
One Less Harley
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cam lobe or rod bearings would be my 1st guess. Get a stethoscope and see if you can find the exact location.
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Old 05-20-2012, 07:45 PM   #3
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Sounds like my '85 r80.One cam lobe gone bad, along with lifter.It still seemed to run good,albiet noisy.
One cylinder removal will tell the story if that is what it is.
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Old 05-20-2012, 08:25 PM   #4
Freeagain OP
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So Cam Lobe

Thanks Guys,

So, what goes wrong with a cam lobe and why does it make the sound?

What is the "one cylinder off" diagnonsis work? ie what am i going to see/measure with a barrel off?

If this is the problem, what is the fix?

Thanks again,

Toby
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Old 05-20-2012, 08:29 PM   #5
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One less Harley and my bike are twins!

Hey one less,

I just saw your bike, and mine is just like it, blue, beefed up racks etc. And I just bought a 24 litre tank to paint and add!

Except my engine has the "special" noise!

How would I diagnose rod bearings? Do you mean big end?

Thanks,

Toby
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Old 05-20-2012, 08:36 PM   #6
One Less Harley
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some HPN tanks aren't paintable, make sure you have the nylon tank, if not then there is not point to even trying to paint.


The only way I know is to pull the rods to check the (big end) rod bearings, others w/ more know how might chime in. You'll still need to pull the cylinders to check the cam lobes.

Has the bike had good maintenance as in oil changes??? How many miles on the bike??
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Old 05-20-2012, 08:51 PM   #7
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Special engine noise

The bike's service history is unknown. Most of it is very original but weathered. Miles uncertain too. 34,000 k's on the clock when I got it, but no idea if original.

I have changed the oil four times in 4000 km's, and no sign of nasty bits in the oil etc.

would these problems surface so dramatically in just a few hundred k's?
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Old 05-20-2012, 08:59 PM   #8
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You don't need to take a cylinder off to diagnose a worn lifter. Keep track of the valve lash. Your going to have a lot of valve lash on one valve if it's a lifter/cam. It's the lifter that goes bad and then wears the cam lobe. It's pretty rare and I doubt that is your trouble. It could be but it could be a lot of things. Get a stethoscope. The trick using them is to first listen with the contact rod removed to zero in on the noise and then use the contact rod IF it makes the source any clearer. Do that and you tell us where the noise is coming from. No need to be tearing the engine down just yet!
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Old 05-20-2012, 09:06 PM   #9
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Valve Lash and Contact rod

So are you saying that I should reset the vlave clearances to spec and see if a single valve clearance increases over time?

Could also explain what a contact rod is, sorry, not too experienced with diagnosis, but keen to learn!

Thanks,

Toby
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Old 05-20-2012, 09:07 PM   #10
woodgrain
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If you think the rod bearings are gone, drain the oil and pull the oil pan off. If they're toast you'll probably find a nice little pile of copper coloured flakes/dust under the oil p/u screen.Easier than pulling a cylinder.Continue from there.

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Old 05-20-2012, 09:20 PM   #11
Freeagain OP
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SS,

Cancel Contact Rod enquiry. I just googled up the tool and understand.

Still keen to understand about valve lash

Thanks,

Toby
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Old 05-20-2012, 09:39 PM   #12
supershaft
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Check and see what it is. Does one valve have a lot of lash over the others? That would suggest a warn cam lobe.

Rods knock a lot louder under a load. I highly doubt that is the trouble. That problem could be seen in the oil.

I would guess timing chain right now. Get the stethoscope and tell where the noise is coming from. Hot/cold? Load/no load? Etc.

Four times in 4000km? Filter too? Why? Installed correctly? Maybe you have a leaking white O-ring and low oil pressure?
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Old 05-20-2012, 09:51 PM   #13
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I may have jumped the gun on the cam lobe thing.as SS said, check the valve lash as is now.
Could be as simple as adj.screw locknut backing off, increasing rocker/valve clearance.
Tho that sound would be more in the valve cover,it is a quick and easy check.
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Old 05-20-2012, 10:06 PM   #14
Freeagain OP
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The oil changes are primarily because I don't know anything about the engine history, and just want to give it max love from now on. I think it is all installing correctly and never have the oil pressure light come on (apart from start up) so think the pressure is OK.

I will get the stethoscope and have a listen, check the valve clearances/locknut security and pray.
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Old 05-21-2012, 03:00 AM   #15
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update

Hi Guys,

I got the stethoscope, and here what I see(hear):

It sounds very much in the middle of the engine (ie not in a head)

It seems to be closer to he front (louder/clearer on the front cover than the rest of the crankcase etc)

It happens hot and cold pretty equally.

When you blip the throttle, it (momentarily) stops the sound (when you close the thottle/unload the engine).

Thoughts?

Thanks,
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