Building up a bantam engine

Timbantamracer wrote:

No, it was a red one. I have no photos of it unfortunately but I managed to find one in my BSA Bantam Bible so I'll scan it in and put it on.

Tim

Ah! The D10/D14 sport! Pretty little things, but sadly BSA didn't give them any extra go to live up to the name (though the D10 sport was the first with 4 speeds!)

Yes, that was it! It was a D10 Sport with modded parts etc. Since I am an utter failure at hosting images on the Forum, I am having to give you the link to my Photobucket album:

https://s968.photobucket.com/albums/ae168/timbantamracer/

They're all in there. Have a look. It's the first 3 that are the cafe racer.

In response to the oil ratio, 25:1 is the recommended volume.

Tim

Timbantamracer wrote:

Yes, that was it! It was a D10 Sport with modded parts etc. Since I am an utter failure at hosting images on the Forum, I am having to give you the link to my Photobucket album:

https://s968.photobucket.com/albums/ae168/timbantamracer/

They're all in there. Have a look. It's the first 3 that are the cafe racer.

In response to the oil ratio, 25:1 is the recommended volume.

Tim

Lovely! Though I think that seat i the first pic is stuffed with a dead animal. Love the ace bars on the 2nd&3rd pics.

Regarding the oil, I will be running the engine in, so will need it richer. I've a feeling BSA said 16:1 for running in.

Yeh! It does look like that! I think BSA stated you should try 1:18 if your running the engine in.

Tim

Good news!

http://www.flickr.com/photos/35741071@N03/4281076209/

Bad news. guess which pillock put the crank seals in backwards?

Put the piston in this morning, and put loads of 2t oil on the conrod bearings with a syringe. Put the barrel on (more oil in the bore), then did the timing with a DTI. It isn't set accurately, just good enough to get going. Did a quick check with a paintbrush full of petrol, made a few bangs and even ran for a second or two! Popped the carb on, put some petrol in and she starts first or second kick. Of course, it was only after all this I realised I'd cocked up the seals. Oh well.

Haha oh well. Seems that double checking really does help! Love the exhaust sound though! Should put a megaphone on!

Tim

I know, tempting. It really is LOUD. My camera microphone doesn't do it justice.
Not all bad news though. I will run it a bit more in the yard to start bedding things in, which will probably mean I have to re-do the end play. I should be able to sort the seals without stripping the gearbox and clutch, and it gives me chance to check everything is OK.

Will seem a good idea really. Performance will be low but that won't matter because you have SOUND! Just seen this on a website:

http://www.denandtheartof.co.uk/media/uploads/1950%20Bantam%20Engine%20%20JPG.jpg

Pretty good conversion to a megaphone. Looks really good. Wonder what the sound might be like!?

Tim

YES! Finally my Bantam engine arrived! starting to take it apart now. Clean everything etc. Also got a whole envelope (large) of Bantam tuning manuals and the sellers photos of himself. The seller was Dave Brasier.

Now what to do now....

Tim

Timbantamracer wrote:

YES! Finally my Bantam engine arrived! starting to take it apart now. Clean everything etc. Also got a whole envelope (large) of Bantam tuning manuals and the sellers photos of himself. The seller was Dave Brasier.

Now what to do now....

Tim

How does this grab you?



Been working on the r/h side this weekend-gear lever and linkage, kickstart and exhaust. The kickstart is at a funny angle to clear the gear lever, and I had to cut and weld the downpipe so the silencer tucks under the gear linkage. It all works quite nicely now

I would say it is lush. Ha Lovely bike in itself. Should try pin striping it.
High-rise exhaust would suit me but it's judged on personal opinion. I practically love your project.

Here are some of the pictures of the engine I bought. I just recently bought a frame, a D14/4 one, in order to build the bike up from. Will upload pictures when it comes:





Tim

Timbantamracer wrote:

I would say it is lush. Ha Lovely bike in itself. Should try pin striping it.
High-rise exhaust would suit me but it's judged on personal opinion. I practically love your project.

Here are some of the pictures of the engine I bought. I just recently bought a frame, a D14/4 one, in order to build the bike up from. Will upload pictures when it comes:







Tim

Looks good. How will you fit that reed valve? I'd like to try them on mine, but I don't want to hack about the barrel.
The exhaust is just to get it on the road and ran in, I nicked the silencer off my D14. I want a proper expansion chamber, eventually. A mate had a nice stubby silencer too, looks a bit like a goldie pipe

After a long disagreement with my money, I have decided to use the D1 ported barrel Dave gave to me since I am having to restrict myself on parts, barrels, con rods etc I am going to have to buy. I will fit a reed valve (danger zone) to it soon enough and see what I can do with the bore. Probably a 50x56 would be best. I have recommendations from other racers but all apart from the con rod. Any ideas for which one to use? I'm either thinking of using KTM, CR125, KX125, RM125 etc most 125 MX's.

Cheers,

Tim

That is a truely beautiful machine.

That is a truely beautiful machine.

The bike is very close to roadworthy, so I thought I'd better sort out the backwards crankcase seals.
First, the left hand seal had been rubbing against the crank and had put a few bits of rubber in the case. Should be OK when they are the right way round!
My main concern is the big end bearing. It feels OK and has no play up and down, but when rotated I can here it clicking. Is that normal? I'm not sure if it is the rollers tapping together or something worse. Sorry, no pictures, I forgot.

Do you use standard BSA bearings or crowded rollers ones?

Timbantamracer wrote:

Do you use standard BSA bearings or crowded rollers ones?

Rollers. It is the T&G rod kit, though I think BSA used crowded rollers on these.