SF3 vs earlier versions

S

smlav

Senior member
Location
Shropshire UK
I’ve only ever owned a GTL which I’m busy restoring. It’s taking ages unfortunately. My memory is that the drum brakes were adequate, provided they were set up okay. But it’s >30 years since I rode the bike, so memory could be wearing rose tinted. I’ve a chance to buy an SF3, which I’ve never ridden and have never considered. I prefer the look and aesthetics of the drummers, but hey, it’s a Breganze twin. When assessing the SF3, is there anything about the cast wheels or Brembo callipers I should be paying close attention to? Thanks.
SM
 
I really like the SF3, but thin web wheels are not very strong. They crack and bend on occasion but can be repaired. Check for cracks around the transition between spoke and rim. The casting quality is pretty crap, loads of bubbles etc to be expected. But they seem to weld ok.
 
For Brembos make sure there,s no leaking fluid from the hose connections, and that the brake pads slightly retract after they,re engaged by the lever. Look for excessive wear marks on the brake rotors and with no brake engaged, the front wheel should rotate with very little brake drag. Check the pads for glazing and wear and proper thickness- easy to remove and inspect. Install new pad pins and springs if worn and rusty. There are pads and rebuild kits available. Flush and bleed the system w/ proper dot 4 if it,s not a clear honey color. Some prefer the look of drums but disks are lighter. Modern disk brakes outperform drums and no longer used for racing because of this.
 
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SF3 is another of the fantastic twins, go for it if it is in ok condition. The brakes at that age should be stripped and inspected and the chrome steel pistons (if still fitted) replaced with the later light weight ones. This is a job any competent home mechanic can do. At the same time swap out the hoses for modern steel spun type. Lots of SF3 are still on their original wheels but as said give them a good checkover and be very careful at tyre changes.
 
"Or revert/convert to disc brake spokers, like my SF1"
SF1's had drum brake up front , with drum rear
SF2's had one (very rare) disc or two discs brakes up front, with drum rear
SF3 had cast wheels and three disc brakes.
CLEM
 
CLEMTOG said:
"Or revert/convert to disc brake spokers, like my SF1"
SF1's had drum brake up front , with drum rear
SF2's had one (very rare) disc or two discs brakes up front, with drum rear
SF3 had cast wheels and three disc brakes.
CLEM
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Was being flippant, Clem :cool: 'Reversion' from drum to disc is nothing but a forward step IMHO.
 
Why are you Guy's forgetting the 70/71 Breganzie 750 SFO. It came right after the 69 Breganzie 750S and was basically a street version of a detuned SFC with a street cam, ball bearings on the crank rather then needles - Same head, valves and compression ratio as the SFC ?

Had wonderful open mouth Dellorto VBH 32's rather then them awful 36 trickle Amils (Sorry but ran them Amils on a 69 Bonney and they SUCK ;o(

Only good for a long duration cam at Hi-RPM's on the track.

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The Street cam of the SF0 could easily reach 120 mph down any straight at say 7400 rpm+ approaching 8000rpm but be aware them heavy cast Iron valves are pounding your valve seats to death - Go Light Valve and change your valve springs out every year if you intend to Race her.

Can't say there's any better Piston then the Cast Aluminum Mondel as the rev's never go much above 7600 rpm.

Been there.

If inclined spend money for after market light weight forged pistons for a few rev's more - Just might hit 8000rpm with them enriched open mouth 32 Dellorto VHB's. If NOT go Mickuni 34's or 36's ;o)

Guaranteed you will not be able to keep tires on her and will test you to extreme limits of your physical limits.

Not the fastest Motorcycle I've saddled but have to say one of the most interesting and satisfying 2 wheeler s I've encountered and capable of winning a race.

If you are going to run her hard change oil twice a season ( Simple 15w40 Trucker's Dino Oil - Delvac, AC Delco, Mobile, Shell whatever works but I preferred DURON if you can find it.)

Warning DON'T run your carbs lean or you will melt a piston under load keep the jets slightly rich ;o)
 
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I saddled that Breganzie 750 SFO for some 45 years and believe me you don't want to face your Wife after calling her to led me through a thunder storm with her Volvo some 20 miles from home on a Sunday outing - Your LATE and she doesn't understand the concept of Hydroplaning ;o(

Breganzies are notorious for Hydroplaning were as a Harley will tank right trough it !

PS:
What really gets me just how much power them 2 small pistons get out of the Breganzie 750 SF for such a heavy high weighted bike. I could cream a Ducati 750S even an 1100 Kawasaki on a road course.

Gotta say I did love that Ducati 750S for handling - But wasn't fast enough and she was down more time for adjusting the Mechanical Desmo Valve system ;o)

Really had a fondness for the Norton 750 Commando and 850 Interstate - Rattle as they might but Predictable and Enjoyable.
 
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I raced a lot of Japanese bikes back in the early 70's and eventually ran them down with my Breganzie 750 SF0 ;o)

I did like the Japanese Enduro 2 strokes Vs my Triumph 250 Trophy in the Bush. But that Trophy was a wonder on back roads and deliver a Keg of Beer ;o)

7870642186_1a3e5da09f_o.jpg


And do 80 Mph on Asphalt.

Really wish I had a PIC of my 2 Stroke 500 Suzuki Titan Cafe - She was Beautiful, Stinky and FAST!
 
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Only thing I would say is keep an eye on the wheels for cracks where the spokes meet the rim , and fit lightweight teflon coated caliper pistons ( if you can still get them ) in place of the heavy chromed steel ones .......... Having said that , seeing it`s a 48 year old bike you`re considering buying , then rims and brakes could well be the last of the things you will need to worry about ........ but I guess you know that already ........ Personally , electrics would come top of my list of things to check , apart from all the obvious used bike stuff ......... and even if things like wheels do appear to be in good order , then regular visual checks are the way forward .......

But my real reason for replying is ........ Ron ! .......... I never realised you had a T25SS ........... great little bike , although mine got stuck in top gear twice ....... oil in frame , quick swap electrical pack , much more a works replica than any GSX-R ........... ( Better leave it at that .... this is supposed to be about SF3 wheels and brakes ....... :) ..... ) .........
 
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