B40 Plug

[pocket]

Hi all.

I have just put a PVL ignition on my BSA B40 trialer care of mr Whitton and reduced the carb down to a 626 as I had got one to hand. It started first time and seemed to run a lot better straight away low down.

It's still missing a bit at the top and that's not if I snap the throttle open. Going to check the tappets next and then put a new plug in. I have got some NGK BP6ES plugs so was going to run it on that. They are the extended nose ones. Thought I'd ask what the thoughts of other people were though.

Cheers Steve.

[old trials fanatic]

I tend to use a BP5ES on closed circuit trials and a BP6ES if there is road work. Saying that dont notice much difference on either plug. One thing though the B40 does tend to eat plugs. Normally get about three events before needing a new one. Then again they dont cost much.

[peterb]

Hi Pocket,

I have used a few different types of plug on my B40. BP6ES are fine. Currently using another extended nose type plug - can't remember the type off hand. Using the old 626 concentric, the plugs would wet quite often, every 1-2 trials. It's a carb problem, lots of wear in many places. I have since fitted a Mikuni 26mm carb straight off a Kawasaki KT250 (all standard size jets) and ended up with a needle from a MkII concentric. It runs very well and almost completely revs out. Great response at the bottom end. Need to make a flange to stub adaptor to fit. Also fitted a total loss Gel Cell battery ign system using the existing points and HT coil with an on/off switch to preserve power when parked up at a section. The plug is lasting well now.

I am still yet to sort out the top end miss, it's not quite 100% certainly not valve bounce. When time permits.

Bye, PeterB.

[pocket]

Thanks for the info folks. Always good to put your mind at rest.

Cheers Steve.