Speedfight street sleeper

Hi all... I thought id show you my Speedfight winter project for you to have a smile at...Its a Bsa Bantam frame with an Aprilia rs250 rear wheel, Rg400 bottom end with as you can see s/fight cylinders....Haha...eat my shorts suckers....

 

Here is another look at her

 

Dunno quite what to make of this one.
Why the air cooled heads and not water cooled, like the gamma engines had originally.

 

Sure beat's my twin!

 

im sorry, just don't like this.
you've ruined a BSA which could be restored and ran as they should be and then your running air cooled bores instead of watercooled on a bottom end which will only fuck up the bores by putting so much power through them. speedfight bores aren't supposed to have that much power being put through them.
I appreciate the work and engineering etc and I shall watch BUT I just don't like it.

 

View attachment 9702
Hi Steve...Engine transplants are too easy...If i fitted an Rg 500/400 engine in a different frame all i would have, would be an engine in a frame....Not very exciting to me at all. Here is one i did earlier its a 1968 Bsa Bantam (old school) wirh a Rg500 bottom end and aircooled 1960 Ariel Arrow cylinders with a bucket of sillyness poured over her....

 

Hmmm, quirky most definately. Wouldn't want to roast my leg on that upper pipe though.

 

i like it, but not sure why you would put those cylinders on there, why not something with a bit more grunt? what would be cool would to be to put an rgv motor in a square 4 frame....

 

are they 70cc bores? i NEED to know more about this project!

 

and the forks, are they suzuki? or are they BSA? and would you be willing to sell it to me when its done? (i live in norway though!)

 

Hi again...The, or my history behind this sillyness started wirh me putting an RG500 engine in a Aprilia RS250, so now its an RS500. Next came a Bsa Bantam with a 250 Ariel arrow engine (1960 2 stroke twin)...Then i did the Bsa 500 4 cylinder aircooled as in the ealier pic (same cylinders and heads)...I wanted to do another 4 cylinder and i spotted the 100cc Speedfight cylinders. These should work out ok as the Speedfight is crankcase read and the Rg is disc valve induction (no carb on the cylinder) The 100cc Speedfight cylinders will be shortened by 11.5mm and i will use 19mm adaptor plates and this should be good for, well enough horse power to hoon about on without drinking fuel and eating rear tires as my RS500 does...Yes, shortened gn125 forks...Here is a pic of my 250. I did tune her some time ago and i fitted a 2 stroke exhaust that i had made for her...Haha, she chimed in at 8000rpm and screamed to 10500rpm..... She now wears her winter exhaust in stainless steel...enjoy..

 

how does it run with those pipes? haha i like the subtle arrow on the side panel, i bet that gets some funny questions at bike shows.. i was speaking with a guy in the summer with a BitSA, made to look like a golden star.... i told him the exhaust was wrong and he told me to shut up!

 

I'm glad the "Arrow" gave you a smile, some people think it's "this way forward" haha. It's the look i was after when i built the bike, sort of a "Rockers bike from the 1960's in the uk". It goes ok with this exhaust but it does top out at 75mph. But then again the deck height to the exhaust port is a huge 35mm with the grunt cylinders on so its never going to be a ball of fire. With the quick cylinders the deck to ex port is 26mm but the gearbox ratio's are not made close enough to stay in the power band...I have now modded the engine to be twin carb crankcase reed with electronic ignition.... It will be interesting doing the "hot Scooter/Bantam" and see her evolve before us.

 

Aint she sweet..

 

you got the heads on the wrong way round? i think? or are the different heads? do you think it will be cool enough at the back cylinders? oh man, i love projects like this one. im fixing up a friends old BSA next month actually, never worked on a BSA before so should be intresting, will my AF spanners fit or will i NEED to use whitworth? (im betting half of the guy here no nothing about either!)

 

Hi. Whitworth spanners for old British bikes. Yes the front heads are reversed because i want the spark plugs pointing all the same way as well as missing the fuel tank on the rears...I did try all combinations of spinning them around, but the way they look now is best. Yes, the rears will be ok and wont give any problems, well my other 500 with 2 thou clearance between the piston and bore never gives trouble. Next job to do is the rear subframe and then were onto the exhaust..
Later
Roy

 

heheee love it, cant wait to see the progress of this

 

any more progress?
ive got the parts for my freinds BSA now, going to start that next week, got a nice billet oil pump from SRM.... very shiney....

 

Hi. Yes, she is coming on ok... She is ready to start her up, well ten minutes putting some fuel hoses on her and wire up the coils....I'm tinkering with my RS250 Aprilia getting her ready for the road. Here is a pic or two, note the new Speedfight exhaust my mate is using so we can start to design the four pipes for my bike.