Valve recession on only one side? (pics included)

[clouseau]

It's been no more than 2000 miles since I have last adjusted the valves.  I've adjusted the valves a handful of times and it's always the right cylinder exhaust that closes up.
 
So I'm thinking maybe the right side is running too lean?
Here's pics of my plugs. I'm holding them in their respective position on the bike.  The left does seem slightly richer, yes? I really can't tell.

[Bob_Roller]

The left looks normal, the right appears to be running a bit richer .

But it also depends on how the bike is operated .

If you don't get up to highway speeds and are mostly in city traffic the plugs will look a bit richer due to combustion deposits not being removed  at higher engine speeds .

[Barry]

Agree with Bob left plug is weaker than right but doesn't look to be a big difference.  I find use of the choke has as much influence as anything else on reading plugs unless you are doing a proper engine chop after a high speed run on new plugs.

With the absence of a normal earth electrode they look like some sort of weird surface discharge plug.

What exactly are they ?

[Rob Valdez 79 R65]

When I experienced valve recession on my '79 (it was a 1980 engine, at the time), it was only my left exhaust valve that was closing up.

Both sides won't necessarily go at the same rate.  Too many variables.  IMO.

[montmil]

Best way to get a proper plug reading would be a WFO run for a couple miles, then whip in the clutch and immediately chop the ignition. Coast to the side and check the plugs. A bit of a hassle but plodding back to the shop would mess up the true plug read.

IMO, those plugs like as good as might be expected. I do miss seeing electrodes.

If you really are concerned about valve and seat deterioration, you'll likely need to pull the head for an inspection. That's not a difficult chore but you will want head gasket/s on hand for refit. And atorque wrench. And some whiskey, should you confirm a valve issue or seat recession. Good luck, Inspector!

Monte

[clouseau]

Thanks for all of the input.

The plugs are BRISK.  I was running iridiums & NGK before with the same recession issue.  

Pulling the head off is not something I want to get into at the moment, but at some point I'm sure I will.
The weather here in southern California so consistently nice, it's hard to bear the down-time.

Cheers.

[Rob Valdez 79 R65]

It is much less expensive to fix them before the valve/seat breaks.

And you have down time, either way.

Less depression if you do it before you need it.

[Barry]

The plugs are BRISK

Never heard of these before. Seems they are designed to spark in 3 places:- between the centre electrode/top band; between top band/lower band and between the lower band/plug body anywhere 360 Deg around the plug according where the mixture is most conducive to ignition.
The last bit may have some merit but as for 3 sparks at once I would need a lot of convincing.

[suecanada]

Leftside exhaust valve only on my bike was closing up. Just keep checking the clearance and if it's closing more than 1 thousandsth in say 5000 miles start getting concerned. Mine was closing up probably immediately after resetting as the valve's collette was thinned to the point that no reset would remain stable. Probably was immediately closing upon the next start-up! Rightside OK but still replaced.
Remember that valve checks are a diagnostic tool; not necessarily a maintenance scheduled chore.

[Ed Miller]

You need another bike to avoid down time.

[nhmaf]

The plugs appear to be within normal expectations, but a slightly richer mixture will run a little cooler.  Also, just check the left side carb and its rubber boots to make sure you don't have a slight air leak, which could lean the mixture between the carb and the head.

I'd keep an eye on things, and if you see the valve clearances closing up by.002" or so within 2500 miles then it is definitely time to plan ahead.  If one runs it to the point of failure you will likely need new piston(s), cylinders, wrist pins, clips, and possibly pushrods, etc. replaced on top of simply replacing and resurfacing new valves seats, and replacing the valves, and their keepers.

[montmil]

You need another bike to avoid down time.

Exactly the reason I have two R65s. Maintenance down time plus the economy of scale when buying bits and pieces.

Monte