MORE DUMB QUESTIONS FROM NEWBIE 1960 B31

[rustyboots]

1.  what would be the ideal fuel to use,

2.  what engine oil to use,

TIA

Mark

[idie]

Ideally fuel wise E5. I have always used E10 with no problems in my M33 and my B33. Oil I use a straight 40 and if I remember I use a 50 grade in the summer same grade in gearbox. 20 in chaincase.

[Barnsey]

Does anyone bother with a lead replacement these days, or is that an issue which has passed us by? 

[idie]

I think that if you were to do many thousands of miles every year for years, then the lack of lead may start to lead to valve seat recession. I gave up using lead replacement years ago as I wasn't doing enough miles

[DAVE BRADY]

Hi,

Never worried about lead free petrol and covered many tens of thousands of miles with no problems. Big ends wore out before the valve seats. Ditto E5 and E10.

Dave.

[V500]

Yep, like Y2K and AIDS, more puff than reality.
Strange to see Mike Brewer still advertising those useless lead balls though.

[Roy]

Regarding lead free conversion,if using cast iron cyl head the seat area will,work,harden and quite likely have no or very little valve recession ,however if valve seats have just been refaced hard skin will be gone and then it's quite likely to have valve recession, so either fuel,additives or hard seat inserts fitted ,

[DAVE BRADY]

Hi,

Recut valve seats will loose their work hardened layer but it should reform over time so perhaps initially a bit of recession.  I would think that the engineer doing the work would advise on this otherwise go for new seats.

Dave.
 

[Roy]

TAPPET clearance would be approx 0.003 so it wouldn't  take long before loss of compression with valve being partially held open ,due to valve recession,,
Should the head be off at moment I would suggest to have harden lead free seat in now ,only exhaust side needed , jobs done properly,

[rustyboots]

TAPPET clearance would be approx 0.003 so it wouldn't  take long before loss of compression with valve being partially held open ,due to valve recession,,
Should the head be off at moment I would suggest to have harden lead free seat in now ,only exhaust side needed , jobs done properly,

Bike only delivered this morning, definately not looking to pull it apart just yet

[neil1964]

My own suggestion would be to use it and enjoy it as it is (keeping an eye on tappets not tightening up.
I would buy a replacement head of correct era (early small fin or later large fin). I would rebuild it with replacement exhaust seat, new guides (ie recut seats) and valves/springs.
That way I would have a suitably rebuilt head sitting on the shelf ready to go.  These iron heads seem pretty cheap now so probably a good time to do this.

[V500]

On the other hand, any B31 head is going to be a nicely seasoned and work-hardened lump of cast iron with diamond-hard valve seats, and will likely outlast everyone on this forum by decades.
I would suggest a suck it and see approach before spending money.