Nice Goldy

[Motu]

If I was still playing around with BSA singles,this is what I would of ended up putting together.1954 was the best frame - QD rear wheel and 8in front brake.Updated engine with electronic ignition and 12 volt electrics.Getting a Triumph clutch centre with a BSA keyway and taper was the Holy Grail of pre unit BSA owners.What are ''touring cams''? Give us the numbers man! Standard B31 cams would be classed as touring cams...a Goldstar has something a bit more than ''touring!''.

The only naughty thing I'd do to make it a bit more of a sleeper - would be to paint the barrel and head black,leaving the pushrod tube alloy.Then it would take a bit more than a casual glance to cotton on to what it was.

http://www.trademe.co.nz/Trade-Me-Mo...-193712786.htm

[xwhatsit]

That's very nice.

Touring cams -- well they sold the Goldie in a number of different specs, didn't they? Clubman, trials, and -- of course -- touring. Could it be they're simply cams from the touring-spec version? I read it had different gearbox ratios, could it not have slightly less aggressive cams too?

[Motu]

The Goldstar was always a performance bike,so always had cams to suit.Even standard B31/33 cams would be considered pretty lumpy by todays standard - 25/65...65/25.The DB Goldstar race cams at 120 degrees overlap were about the most radical around - when I ran those you could see a fog of fuel at the carb mouth when ''off cam''.

[xwhatsit]

Why so lumpy if the engine is spinning so slowly? I know it's a big hole to fill up, but you've got all day to get the mix in there before the piston heads back up again compared to a Jap twin spinning 11,000rpm?

[Motu]

Inertia - it takes time to get that slug of air/fuel moving,and you don't shut the door until the last minute.Same on the exhaust side - it's going out the door....tie a string to it and let it drag the new stuff through the in door.It only works in a small range,and then it all goes to hell with stuff going in and out the wrong doors.

From memory...and I burned these in deep - 65/85....80/55 is the timing of the DB cams.So the inlet opens 65 degrees BTDC,and the exhaust closes 55 degrees ATDC - 120 degrees when both valves are open.The exhaust valve opens 80 degrees before BDC,just over half way down,and the inlet valve closes 85 degrees after BDC....the inlet valve only shuts when the piston is nearly half way up on the compression stroke.Goldstar caqm timing is just so extreme....

[rudolph]

Very nice , I love those old BSA singles, wanted a goldstar once but settled for the B31 with the hot up bits in the end.

[koba]

One day (if I won the lotto) I'd like one
My mate has a DBD34, I followed him up the takas once, the sound was amazing and it went like fuck.

[pete376403]

Inertia - it takes time to get that slug of air/fuel moving,and you don't shut the door until the last minute.Same on the exhaust side - it's going out the door....tie a string to it and let it drag the new stuff through the in door.It only works in a small range,and then it all goes to hell with stuff going in and out the wrong doors.

From memory...and I burned these in deep - 65/85....80/55 is the timing of the DB cams.So the inlet opens 65 degrees BTDC,and the exhaust closes 55 degrees ATDC - 120 degrees when both valves are open.The exhaust valve opens 80 degrees before BDC,just over half way down,and the inlet valve closes 85 degrees after BDC....the inlet valve only shuts when the piston is nearly half way up on the compression stroke.Goldstar caqm timing is just so extreme....

that is pretty radical timing. Standard Jawa Speedway two valve was 60-80-80-50. I wonder if running meth allowed Jawa to be a bit more conservative with timing yet still get good power over a pretty wide rev range.
When I first started speedway there was a guy at Te Marua running a B31 (350) which would stay with the JAP 500s but he had to rev the tits off it to do so.

[pete376403]

Why so lumpy if the engine is spinning so slowly? I know it's a big hole to fill up, but you've got all day to get the mix in there before the piston heads back up again compared to a Jap twin spinning 11,000rpm?

What makes you think the old singles revved slowly? DBD34 was rated about 43HP at 7000, which might well be a fast idle for a 250/4, but not too shabby for a big iron lung.
http://www.motorcyclemojo.com/articl...us-gold-stars/