BSA Owners' Club Forum

General => The Star and Garter => Topic started by: chrisgoodwin on 13 August, 2017, 23:57:09

Title: B31 Valve seats - lead free
Post by: chrisgoodwin on 13 August, 2017, 23:57:09
Sorry Folks, I can imagine the rolling of the eyes and the cries of "Not this one again!"

The rebuild (Rigid B31) is going really well, can't take much more apart before I will have to start bolting things back together for a change.

Head and barrel off, today the Gods smiled and the dreaded push rod gland and shock absorber retaining nut 'gave' without drama. All hail to E-bay, C spanner worked a treat.

Finally to the question! What is the feeling regarding hardened valve seats, I have read so much, I have decided to give up reading.

There seems to be three schools of thought,

1. Do nothing and fill up as and when required.
2. Fit hardened valve seats
3. Use an additive

I estimate my annual mileage to be fairly low at 4 - 5K PA, weekend tootle of say 50 miles and weather permitting the occasional summer run to the office and back -60 miles and with the seventeen horses on tap, maybe a speed of 50-60  MPH?

In my defence, I left the UK to work abroad ages ago and did not follow the no doubt legion of advice on this subject at that time.

As always, your comments / advice are really welcome.

Title: Re: B31 Valve seats - lead free
Post by: STAR TWIN on 14 August, 2017, 07:02:54
I run a B31, an A7 and various old iron-head Land Rovers. They all do just fine. I invariably use super unleaded petrol, but that's just to minimise the effect of ethanol.
When all this started, the SVVF (I think) commissioned tests on valve seat recession. None occurred below 3,500 rpm. Do you cruise your B31 well above this?
I would suggest putting any paranoia in a quiet corner and not disturbing it.
Title: Re: B31 Valve seats - lead free
Post by: Greybeard on 14 August, 2017, 10:23:18
Im with Star Twin on this one, Chris. I converted my Rover P4 to unleaded years ago by simply filling up at the pump with a green nozzle and she's fine ;)
I occasionally treat the bikes to a dose of the Super Unleaded if Im feeling particularly flush but that's as far as it goes. Whether it's psychological or not the modern Bonnie does seem to run better on it and I could definitely tell the difference when I had my over-bored Harley Road King The oldies just carry on regardless.
A lot of firms made big money on head conversions when this all kicked off by playing on the hype. My view was to run it as it is, and mend it if it ever breaks - its saved a fortune so far!
If it puts your mind at rest then something like Millers VSP would do the trick, but I think its main benefit is as a fuel stabilizer if you dont burn the petrol quickly enough.
Check your valve clearances dont tighten up now and again which might reveal some valve seat recession, but sleep easy and ride - not at the same time of course  ;D