BSA Bantam D3 Engine Rebuild Part 1 - Strip Barrels Piston

Finally getting round to rebuilding my Bantam D3 engine.
Has become very noisy and also has the incorrect (125cc) barrel fitted.

[@retromechanicalengineer]

The usual suspects! There isn't much data in the service sheets. BSA state that the side to side movement on the rod is fine, so as long as there isn't up and down, you might get away with the big end. I'm looking forward to the next installment. It's good to watch someone else working on a Bantam! Best wishes, Dean.

[@InTheShedUK]

Yes lots more to come, all well overdue!

[@a65builder67]

hi ps just an other thought i understand the vid was done a couple of month ago but if you've not filmed that bit would you be kind enough to do a little vid on the subject as there is not a lot on line about it, that's the engine timing that is. kind regards again Adrian.

[@InTheShedUK]

Take a look at Dean's youtube @retromechanicalengineer he's a bit of a Bantam guru!

[@a65builder67]

hi i've just had a look at your bantam vids as you recommended and it looks like my crankshaft has spun in the flywheel, what i've had to do is weld three more lugs on the stator housing case to be able to set my timing not very pretty but it works, i also had a look of you out for a spin on the bantam with that engine noise and i had the very same in fact to the tee, i thought it was the primary chain as they are very lose as standard so i made a chain tensioner but you can buy them, but what i din find out is that the advance curve is to much. it took a while to find this out by test rides and i found is to retard it as it was trying to fire after tdc and more i opened the throttle worse it got with no real throttle response, and also if you look at the intake were the carb mounts and look inside with the engine at tdc you'll see that the piston skirt does'nt clear the intake port properly and if you scribe a line and take some off the skirt of the piston you might be very surprised. anyway thank for your help please take care kind regards Adrian.

[@InTheShedUK]

Thanks Adrian, that's some really useful information. regards Ian

[@a65builder67]

hi i was wondering what the next project was going to be and its right up my street, i have a d1 bantam and it to is fitted with that electrex world kit and i was wondering what are your thoughts on the lighting was because mine is very poor, i have been looking around for a 12 volt coil with the same mounting centers i cant remember off hand but i think the bantam has 57mm/ or 54mm centers, i could put led lights on it but i do like the good old bulbs, also i hope you'll show how you set up the timing to has mine is way out going by the book, i think my engine has seized at some time in its life and shaft has been pulled forward with the flywheel i've put a degree wheel on it and not just right but i've also been told that some of the electrex world flywheels the broaching is sometimes not right, but i have sorted it now with a lot of messing around, anyway take care kind regards Adrian.

[@InTheShedUK]

My lighting is not great either, I am only running a 6v system though, I think it's as much to do with the ancient headlight bulb as anything as the rear light is good. I did quickly cover timing in a previous video, have a look in my BSA Bantam playlist. I tend to tweak the timing by ear/feel once set anyway, not sure it makes much difference though!

[@a65builder67]

hi thank you for your quick reply, i check on your vids out kind regards Adrian.@@InTheShedUK