BSA Owners' Club Workshop Discussions

The BSA Workshop => Singles => Topic started by: Steve C15 on 31 May, 2021, 10:01

Title: C15 Unleaded Petrol Cylinder head mod
Post by: Steve C15 on 31 May, 2021, 10:01

Hi does anyone have any info about how to best convert a C15 cylinder head to run on unleaded petrol please ?

Or know a company that does the required work to the head ?

Steve
Title: Re: C15 Unleaded Petrol Cylinder head mod
Post by: Mike Farmer on 31 May, 2021, 21:22
 :) :) :)

Run it with REDEX in the fuel

Mike 8) 8) 8)
Title: Re: C15 Unleaded Petrol Cylinder head mod
Post by: DAVE BRADY on 31 May, 2021, 21:35
Hi Steve,

If the seats are in reasonable order then have the seats ground rather than cut and they should be good for many thousands of miles.  The seat inserts used by BSA where of good quality unlike those of the motor industry of the same period.
I have run an A65 for many thousands of miles on the original seats with no excessive seat recession.  Unleaded from the pump with no additives.

Dave.
Title: Re: C15 Unleaded Petrol Cylinder head mod
Post by: Colin SS90 on 01 Jun, 2021, 15:06
I was also worried that my SS90 hadn't been modified to run unleaded, but after reading various articles about the high mileages that need to be covered to damage valves and seats I decided to just run it on straight unleaded, although I now add some Castrol R to the petrol (about 100/1 mix) just for a bit of peace of mind and a classic exhaust smell. I also worry about the oil settling in the bottom of the tank, so I give the bike a good shake before turning on the fuel.
As another added precaution I check the valve clearances quite often, they don't change so that's another good indication that unleaded fuel is not detrimental to the engine.
Title: Re: C15 Unleaded Petrol Cylinder head mod
Post by: Steve C15 on 01 Jun, 2021, 20:58
Thanks for the info lads.

I like the R40 trick.

I will give it a try.