1965 R50/2 - run-in advice wanted

[niall4473]

The standard flat sump plate is steel, the aftermarket deep ones are usually, but not always, aluminium.

[skyler.robbins]

Curious.. what size tire is on the front?

[808Airhead]

Going through a break in at the moment on my 58’ R69, and I am doing similar to “Dave79X” & “schraeder’s” advice….. keep revs low but not lugging, and VR -1 Valvoline is a excellent oil for these old ladies. Have fun! Keep it under 10k rpm’s!

[Slash2rider]

I've broken in two of these after total rebuilds. An R50 and an R69. I had to be very careful with the R50 as my machinist bored 1st over to only 2 1/2 thou clearance.
Just curious,as far as I know both bikes require 0.05 or 2 thou clearance with modern KS pistons so unless you are using nos Nurals you are about half way to piston slap already.I have both bikes,ridden hard from start,no problems I think piston manufacturers knows better than 50's manual what clearance is required.

[Daves79x]

viewtopic.php?p=80906#p80906. This was Vech's take on piston/cylinder clearance. And he did a bunch of them.

Dave

[Slash2rider]

Not surę what is he writing about,on the top of the KS pistons for the r 69,r50r69s three is 0.05 number stamped so 0.002inch Is close enough.0.003 or more depend on applications is right for the Nural pistons in r69 or69s,why make it to loose when no longer needed?

[Seek]

In my R25 I used a KS piston with 0.05 mm clearance. I got a piston seizure at 600 km. Of course, the singles are more vulnerable, cooling is not as good and you tend to run them at full throttle more often. Now it has 0.07 mm clearance and no problem so far.

[Slash2rider]

My r25 runs really hot too it did run to lean on factory main jet size,no problems with piston so far.Very quiet engines.