Exhaust valves - replace early?

[Thorfinn]

One for discussion....I am planniing a BIG Scandinavian tour on the R65 later this year. Yellow Peril has only 45000 miles on the clock, seems genuine but I have no mechanical history.
I noted somewhere on this site that exhaust valves tend to fail around 35000! Is this figure credible, in other words, should I think about replacement and all the expense entailed before setting off?
Bike runs so well at the moment that I'm reluctant to disturb anything...but onthe other hand, it's a long way from anywhere when you're stuck in a forest in Northern Sweden. With the wolves gathering.

[Barry]

I think you will get many responses that say original valves have lasted much longer than 35,000 miles.  Propensity to fail will be dependant on exhaust valve temperature so there is no universal mileage for failure as temperature will vary with how the engine is used, mixture strength and if an air injection system is fitted.  

[Bob_Roller]

What year bike do you have ?

The '81 and '82  model year bikes had problems with valve recession .

I went through this on my '81 R65, had the valves and seats replaced at 45,000 miles, the exhaust valves were worn out .

[msbuck]

I have over 60k on mine and original valves.  Although it is time to think about  having them reworked.  If you take out the spark plug and rotate the engine around to the right spot, you can shine a flashlight down the hole and actually see the edge of the valve.  It should have some lip around the edge.  If it is razor sharp, you need to think about having them replaced.  It's only my right exhaust valve that is showing wear.

You can also keep a check on your valve clearances and if they close up quickly (after 500-1000 miles) on a regular basis, it's time to check them for replacement.

[georgesgiralt]

Do not postpone too much valve replacement.
On these bikes, valve stem is thin and can break without warning.
On mine, I was lucky enough to have a spring break and so the engine making noise and ate a lot of oil.
When the mechanic opened up and removed the valves, one was breaking ! He said to me that it would have broken in less than a hundred kilometre ....
So I was lucky not to destroy the engine....
BTW, the bike had a little more than 100 000 km...

[Air4Life]

@georgesgiralt: what year is your r65?

[georgesgiralt]

Made in April of 1982. Bought new in 1984, early April. She was bought with an RT fairing which was "offered" by the French imported to increase sales of the R65.
They even sold the R65LS with the RT fairing as this model was selling less than the "plain" R65.

[Semper Gumby]

Thorfin,

Your bike will tell you when it is time to replace your valves.  What happens is that the valves start to "recess" into the seats.  The surface of the valve that contacts the seat will wear away making the valve really sharp and thin.  Eventually the valve drops into the head and breaks.  The bits rattle about causing a major amount of damage in about a micro second.

If you are concerned you can look into the spark plug hole and rotate the crank until the exhaust valve comes into view.  There should be a a 1mm contact surface on the edge with darker metal on each side.  If what you see is razor sharp then you are done.  Go no further until you replace the valve.

Also: You should be checking your valve clearance before setting the valves.  If the valve clearance is say .003" instead of the normal .008" then your exhaust valve is receding.  Go no further.  From now until you replace them you should check the valves every 5000 miles  and keep detailed records of what the clearances are, before you set the valves.  If you see recession then as Aïda says check them sooner.  I think I was checking them every 1000 at that time.
 

The Black Diamond valves are a good replacement.

BTW - I replaced my valves at 73,000 miles on my march 1980 R65 after I did an IBA 50 hours coast to coast ride over three weeks putting 7,500 miles on the bike.  I noticed the recession and my mechanic yelled at me to bring the bike to him right then.  When he got it apart he said the exhaust valves were "sharp enough to shave with"  (Nathan at Boxerworks).  This is actually funny as people who know Nathan know that he never shaves - ever!

Good luck.   8-)

[Air4Life]

I replaced my valves at 73,000 miles on my march 1980 R65

S.Grumpy:  I'm curious to know if you had the pulse system installed on this bike the entire time, if not, how long was it off for?

Air4

[Bob_Roller]

The '80 model year bikes did not have the pulse system, it started with the '81 model year .

[Air4Life]

THanks Bob.  I wish I had definitive proof that this system contributes to valve recession.  Though I can't say that I miss having that extra plumbing, one bit.  

Attached is a recent picture, not because you guys don't know what it looks like without the pulse..., more because I'm so proud of how clean the engine is staying now that I figure out the sweet spot for the oil level.