BSA Bantam D7- 1960 Engine Rebuild 

The following article covers off my restoration of one of three of my D7 BSA Bantam Engines. This is my second, and spare engine. Bought via a post on the owners club FB page. I'll start by saying I'm no expert in either electrics or mechanics. 

If you spot me making a mistake, or can help me do it a better way then please contact me via the contact form on this website. I have purchased only two specialist tools. A clutch removal tool ( photo below ) and a clutch holding tool ( photo below ) 

engine stand mod 11

Evening 7th March 2016

Well I'd spotted that the piston had no rings, but that was only the start. Last night I started to take a closer look at the engine, and realised that whilst it appeared complete it was nothing more than a loose build. Having said that As I started to remove the

clutch basket the thread on the end of the crank was good, meaning the woodruff key ( on order - missing ) will hold and the ignition timing will hold. The central bronze bush on the stator will need replacing, and I'll employ a local St. Ives Engineering company to do this for me. As described by the seller, not one gasket appears to have been used on this engine. One bonus is that the wrong sealeant has been used and has turned brittle making its removal easy. 

Evening 8th March 2016

Continued to diss-assemble the engine no major shocks encountered. Although I did have to use the clutch puller with a socket attached to pull the splined clutch shaft from the main shaft. Further inspection will be required to understand why it's so tight. 

I noticed the brass hat bush was a bit of a bodge job, so I'll replace it. All the bearings seem to be in resonable condition. So far it's all good news. General condition seems to be good. Threads are all good. Noticed the use of a ball race washer - usually found on the D14 not the D7 - I have a spare of the correct type so this will be used. 

11th March 2016

Friday 11th March 2016 

Almost white out. Woodruff keys have arrived from Rex, along with the carb studs for the head on the second bantam engine. The replacement front number plate has arrived. Could not have been pacakged any better, but the thing is again of poor finish. It's made very well but the internal number plate is miss-aligned. TBH I dont know what to do about it. Grrrrr. picking up the courage to go to the shed. .. 10am - an hour in the shed. All parts came off easily enough. Only slight concern was that the piston had now clips and theirs only a brass bush no needle bearing. Will order one up. Piston is being posted to Rex this afternoon.

16th April 2016 - It's been a while. 

Update, I have rebuilt the engine using sealant and gaskets, Some parts still need assembling, but Rex has posted the rings, and my piston back. The cases, and head and barrel have been taken to Jason for blasting. I have also had a new brass bush inserted into the Stator. It's all slowly coming together. I cannot recommend highly enough the Facbook forums for assisting with the rebuilds. 

May 3rd - Painted the cylinder barrel. Slow progress due to accident on my running D7 and health problems.