Author Topic: Fin repair - dual carb head  (Read 1803 times)

Offline Rocket Racer

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  • A kiwi with a racing A10 rig and too many projects
    • NZ Classic Sidecar Racing
Re: Fin repair - dual carb head
« Reply #15 on: 26.04. 2012 00:27 »
If we're talking about holding a motor flat out on the race track, then a big carb, the right cam & gas flow/turbulence into a big inlet valve will give slightly higher top speed.
But on the street we're probably losing bottom end and mid range to an engine with stock carb, and valves during roll on riding.

The big valve motors were developed for the competition mad american market *respect*
Mods do provide some bragging rights *beer* in the bar or carpark for road riders however.
For a quick road motor I would leave carb & valves stock, go for compression of around 8-8.5:1 and fit a 356 or 357 cam and some nice rods that could live with keeping the throttle open.  Buts thats just my humble opinion.
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Offline Fast 58 BSA

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Re: Fin repair - dual carb head
« Reply #16 on: 26.04. 2012 06:11 »
Perhaps it is a case of bigger isn't always better....As seats aren't cut yet and no mods have been made to the head I can still opt for stock 1.41 or slightly larger 1.455 valves as opposed to 1.5. Based on feedback from this excellent forum it sounds as though I might be happier with smaller intake valves. There are hardly any roads in Norway where you can go flat out in 4th anyway....but I would lose some bragging rights going stock *smile* *smile*
Telemark, Norway

'58 Golden Flash project bike - reborn as angry dual carb cafe racer/rgs rep

Offline Stephen Foster

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Re: Fin repair - dual carb head
« Reply #17 on: 26.04. 2012 06:59 »
Better get the welding repair done first before working on the valves , may be a good idea to check mating surfaces remain flat ?

Best Wishes ,
Steve ..
I own a 1955/56 B.S.A Swinging Arm "Golden Flash" , had it since 1976 .