Hi,

I've just acquired a B40 that isn't a trials bike but has been modified a bit for green laning. I'm intending to have a go at a few trials even though I know the geometry, frame, footrests etc. won't be ideal but it's just for fun right.

Anyway it really needs a rebore but is already on plus .060. The head is also not very good so I am looking for a complete top end if anyone knows of one that may be for sale. Ideally one that I could just put on and go but beggers can't be choosers so anything considered if it wasn't going to cost the earth to put right. It is a late B40G engine.

Thanks, Keith.

Edited September 2, 20187 yr by victor

Blimey, a lot of people would say you are lucky to own a B40. The cylinder barrel could be resleeved back to standard and a piston with rings obtained from TJ Wassell ltd in Lincoln (web site but they only supply trade so you will need to locate a dealer) or other specialists. What’s bad with the head? The price of these bikes is quite high if they achieve thier market prices, either way you have a bike that deserves to be ridden and enjoyed. ?Here are a few contacts for you to consider, but I have to say if you should be lucky enough to find a good head and barrel you will be paying ?for it. These contacts should be able to give some costs that you can compare with s/h stuff. If it were me in your position, the bike would be in the process of returning it to its former original spec or sorted into a good trials iron, you have a win win situation....enjoy, you may even double or treble your investment. Care to swap for a sorted Bultaco?? l seem to remember that if you intend to lift the cylinder head and barrel with the engine still in the frame there may be some interface with the frame top tube... depending upon what frame mods have been carried out already, if any. You may have to release one or two studs to enable the head to be wriggled out, or it could be that the barrel can’t be removed without a stud or studs being removed at the same time, sorry I can’t be more precise. Yes I can, you need to remove the outer edge of the top rear fin...about 2-3mm not a lot but it gives you the extra wriggle room to get the barrel off. 

Westwood Cylinder Liners 01905 796414 www.westwoodcylinderliners.co.uk

T&L Engineering 01234 352428 www.tandlengineering.co.uk

SEAGER Engineering 01473 232908 www.seager-engineering.com

Fekked will also supply most of your needs.

Edited September 3, 20187 yr by section swept
Added material information