V7 II Cylinder Knock

[matt franklin]

Was it burning/using oil?  You saw deposits on the valves, and attributed that to bad valve oil seals, but didn't mention oil consumption.  Excess oil in the cylinder charge will have the effect of leaning out the charge.  Smart to ditch the K&Ns, you dont need more air.

The extra noise you are hearing, could it just be reflected noise off of the sidecar?  When I had mine, I can remember it sounding "different" from solo form.

[Dirk_S]

Was it burning/using oil?  You saw deposits on the valves, and attributed that to bad valve oil seals, but didn't mention oil consumption.

A minor amount more than usual when solo, but I attribute that to normal sidecar usage. Even the Ural manuals mention to watch oil consumption during long hauls or at speed.

The extra noise you are hearing, could it just be reflected noise off of the sidecar?  When I had mine, I can remember it sounding "different" from solo form.

I considered that once or twice, but the sound is there when solo, as well.

[Dirk_S]

Dropped by my friend’s heated garage yesterday and took apart the left cylinder…again. Let’s be doubly sure, why not.

Before tearing down, I checked the valve clearances— they were both on the mark.

I took pics of the cylinder wall—some scratches, but nothing that I could actually feel. Friendly remember that the whole top end is from one of those limited-edition-self-destructing-crankcase V7 IIs (limited edition is a joke). Piston skirts also shown. The entire top end has under 5,000 miles:

I took a video of the end play of both the big end as well as the piston on the wrist pin. THERE IS NO OBSERVED RADIAL PLAY—NEITHER ON THE CRANKSHAFT NOR THE WRIST PIN:

CONNECTING ROD ENDPLAY VIDEO: https://youtu.be/pgfUKZf8aCg?si=XIQFeBR427hBE2Fc

I noticed that one of the pushrods had a tappet-side head just slightly off-center. I replaced that pushrod with a used spare from the previous top end.

Torqued my stud nuts, set my valve clearances, valve cover back on. Started it up…

…The marble in a tin can rattle STILL REMAINS.

So far I’ve:

• replaced the cylinder head with a spare used one that had no valve guide wear,
  
• lapped the valve seats,
  
• replaced guide seals with new ones,
  
• swapped valves,
  
• checked connecting rod radial play twice,
  
• checked valve clearances,
  
• tightened exhaust nuts and replaced exhaust gasket,

…all without getting rid of that knock.

My next thought is perhaps looking at the rocker assembly.

NOTE: I’m going to keep the focus on the cylinder knock from here out, unless the leanness is directly affecting/causing the issue. I’ll split the leanness issue out into a second thread at some point.[/list]

[John A]

Check the crankshaft end play by prying the flywheel aft and using the clutch lever to move it forward. If it has a timing hole in the bellhousing it’ll be easier but you can pull the alternator cover to visually see the play. if it’s more than a millimeter, it’s time to look at the thrust washers on the crank.

[Dirk_S]

Check the crankshaft end play by prying the flywheel aft and using the clutch lever to move it forward. If it has a timing hole in the bellhousing it’ll be easier but you can pull the alternator cover to visually see the play. if it’s more than a millimeter, it’s time to look at the thrust washers on the crank.

Curious—why would I only get an abnormal sound out of one cylinder due to too much crankshaft endplay? Wouldn’t that cause both cylinders to be abnormal?

[John A]

Don’t know. The cylinders are in different places in relation to the block. You’ve been through the head and cylinder and didn’t find anything wrong. It’s easy to do and could lead to discovering the cause if the crank is moving back and forth too much. Have you taken a screwdriver and put the handle to your ear and the tip at various places on the block?
Edit: another reason is that was a trouble spot on some small blocks that is a major engine disassembly to fix.
Another edit: I re read from the beginning so I see you are familiar with the crankshaft issue. It looks like the rocker is hitting the valve retainer

[Huzo]

Have you checked the timing marks for correctness, then gone ahead and put on timing light on it see if it’s too advanced ?

[Huzo]

Just a thing about gearing…
Remember it is the OVERALL ratio that determines the rpm of the crankshaft to the rear wheel.
If you’re in sixth gear with a 10:1 bevelbox, you are working the engine the same (approx), as fifth gear with a 9:1 bevelbox.
The above is just a numerical example, but the sidecar thing is just BS. If you had a pillion and camping gear loaded, you would not expect to encounter flogging noises in the motor.
Can you get an infrared thermometer onto the header outlets and compare the EGT readings to go searching for leannesss on the left ?
Again also, get a light on it and positively check the ignition timing.
On gearing again.
My point is that if your gearing is too low, all you’ll do is grab the next gear at a lower road speed, or conversely if it’s too tall ? You’ll be selecting the next gear at a higher road speed.
Once the clutch is out, a taller gear gear will just make 1st feel like 2nd, 2nd feel like 3rd….etc.
The crankshaft does not know, if the ratio is applied at the gearbox or bevelbox or rear wheel. The taller gear will widen the steps between gear changes though.

Now a thought about the knocking.
Is it feasible (although messy), to remove the rocker cover and start the motor to get a better indication of the locality of the noise ?

[John A]

Thank you to both you and Pete for sharing this information along. I wonder if there’s a way to easily see if the seals have gone bad? Perhaps I’m making my exhaust clearance just a hair too tight, keeping the valve open slightly? (Exhaust is supposed to be 0.20 mm)

Also—I just found this wear mark on my exhaust-side rocker arm during a second look over. Is this a factory wear mark, or is the stem or rocker somehow slipping?





Indeed I will!










That mark looks like the underside of the rocker is hitting the valve retainer. It’s the exhaust valve, there’s another smaller mark on the intake . That would make noise as well as causing the valve to leak until it self clearanced itself.

[Dirk_S]

That mark looks like the underside of the rocker is hitting the valve retainer. It’s the exhaust valve, there’s another smaller mark on the intake . That would make noise as well as causing the valve to leak until it self clearanced itself.

If that’s indeed the case, am i guessing correctly that that would indicate my timing is off?

And yes—I’m very aware of the crankshaft issue on some V7 IIs. A reminder that I rebuilt this particular motor 2 autumns ago due to a spun big end bearing (oil starvation following heavy sidecar use and not checking the oil levels often enough)

Have you checked the timing marks for correctness, then gone ahead and put on timing light on it see if it’s too advanced ?

Can one use a timing light on a modern fuel-injected Guzzi? How? through the starter motor opening?

[Huzo]

Don’t know about your particular bike, but my Norge is FI and the timing mark can be accessed via a rubber bung on the right hand side adjacent to the flywheel.

[Kev m]

IIRC there are no timing marks on the modern smallblocks. When we adjust valves we use a TDC finder of some sort and that's it.

[Dirk_S]

IIRC there are no timing marks on the modern smallblocks. When we adjust valves we use a TDC finder of some sort and that's it.

Ah, thanks for refreshing my memory—I remember back to the rebuild: there were no inscribed marks on the ring gear or flywheel, and neither the manual nor training videos mentioned any such thing when reinstalling or checking. The only thing on the ring gear was some lovely marker that I guess may be the heavy end? No clue:



The rear of the crankshaft did have a scribed slot, and the timing end used dots to line up everything:



For the timing side, the manual/videos just mentioned to line up the dots in the front, throw on the chain, install and tighten the tensioner. After that, a detailed timing check with a timing wheel is used. When I installed everything, I didn’t have a timing wheel, and settled for the two dots being in-line. Maybe in the spring I ought to remove the alternator cover, throw on the timing wheel and check that everything matches up?

Link to the training videos:
https://www.thisoldtractor.com/moto_guzzi_technical_training_videos_eng.html

[SED]

I have read (and some experience confirms) glowing exhaust pipes are either a lean mix or retarded timing at speed.  In both cases the exhaust valve opens when the mixture is still burning so the exhaust pipe heats up excessively.  (lean mixtures burn slowly vs. retarded timing - the mixture burns fast enough, but it is ignited so late that it is still burning when the valve opens)   
These would cause both exhaust pipes to overheat.  (or maybe not if modern bikes have some sort of EGR system that could fail and cause the same symptom)
John A's suggestion about the rocker hitting the valve retainer is worth a good careful look.  If the rocker arm is hitting the retainer, it would open the exhaust valve too early and make an extra rattle.  Missing valve keeper?  failing metallurgy?  tuliping valve?
BTW: my LMIII had a persistent part-throttle lean-out that was only solved by replacing by the valve guides.  The intake guides were very badly worn which was surprising.  They were so loose you could grab the valve retainer and wiggle them back and forth in the head.
Let us know what you find.

[Stingray]

Any updates?
I'm thinking I may have the same issue to resolve but no one knows the cause of the sound.

[Dirk_S]

Any updates?
I'm thinking I may have the same issue to resolve but no one knows the cause of the sound.

Not yet. Had to take a step back due to moving and a good load of freelance on the plate. My next attempt at locating the source will be replacing the rockers. I’ve since purchased a salvage V7 III, and want to try to fix the remedy the issue causing the chatter on the V7 II before I sell it.

[jrt]

Just a wild-ass thought, but could it be a flat lobe on the camshaft?

[Dirk_S]

Just a wild-ass thought, but could it be a flat lobe on the camshaft?

Certainly worth the thought, I suppose. How would I even check that without dissembling the motor completely? Only way I can think is removing one of the cylinders (once again) and sticking a borescope down in and faced upward to view the cam from below?

[jrt]

Unfortunately, I would think that you would need to disassemble the motor as you say.  But- it really is just a thought.  My guess is that any cylinder with a mis-shaped cam lobe would run very poorly.  Hugo's suggestion of temperature would be the first thing I'd do (because it is easiest!).

[tazio]

Just a wild-ass thought, but could it be a flat lobe on the camshaft?

Certainly worth the thought, I suppose. How would I even check that without dissembling the motor completely? Only way I can think is removing one of the cylinders (once again) and sticking a borescope down in and faced upward to view the cam from below?

Couldn't you just pop the valve covers off, and as you rotate crankshaft, indicate the amount of movement of the Rocker arm of the valve in question (say, intake valve), and compare readings to arm movement on opposite cylinder?

[Moparnut72]

Couldn't you just pop the valve covers off, and as you rotate crankshaft, indicate the amount of movement of the Rocker arm of the valve in question (say, intake valve), and compare readings to arm movement on opposite cylinder?

Correct.
kk