Author Topic: Longstroke Twin Carbs  (Read 2306 times)

Offline LJ.

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Longstroke Twin Carbs
« on: 04.06. 2011 19:40 »
So who's snapped up that Longstroke cylinder head complete with its twin carbs & rocker boxes etc?

I thought the buy-it-now price of £250 was pretty reasonable considering how rare the manifold is, and the carbs are likely to be a matched pair too. I've been watching these with interest to see just how much they would go. I'd probably have had a bid on them too.

Come on own up!

http://cgi.ebay.co.uk/BSA-A7-EARLY-STAR-TWIN-CARB-HEAD-ROCKERS-48-52-/330570608076?pt=UK_Motorcycle_Parts&hash=item4cf78b2dcc
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline 900triple

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Re: Longstroke Twin Carbs
« Reply #1 on: 05.06. 2011 00:35 »
Was'nt me but I do have a good condition long stroke head complete with valves and springs for sale if anyone is intersted. PM me

Cheers

Alan

Offline terryk

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Re: Longstroke Twin Carbs
« Reply #2 on: 05.06. 2011 08:26 »
I dont think they are the correct carbs it says 276 but Star Twin longstrokes had 275 carbs.
1950-53 A10 rigid/plungers, 1958-61 A10 super rockets, 1947-50 A7 longstrokes, 1949 Star twin,
1951-54 A7 plungers, 1940s M21, WDM20s,
1948-50s B33s rigid/plunger/swingarm, 1948-50s b31s rigid/plunger/swingarm

Offline LJ.

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Re: Longstroke Twin Carbs
« Reply #3 on: 05.06. 2011 19:40 »
Your quite right about that Terry as my manifold had a sort of recess that made fitting of 276s difficult, I got round it by using some tufnel spacers. Looking at the carb & head set up that was just sold there appears to be no spacers... Maybe this might be a late manifold made for the 276s?? I'm wondering now how long the twin port longstroke heads were made for.
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Online trevinoz

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Re: Longstroke Twin Carbs
« Reply #4 on: 05.06. 2011 23:08 »
LJ,
           All of the long stroke heads were two port.
The ST head had the ports machined to accept the projections on the manifold as were the carbys.

 Trev.

Offline Brian

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Re: Longstroke Twin Carbs
« Reply #5 on: 06.06. 2011 03:25 »
Heres a pic showing what Trev means about projections.

You will be able to see the two spigots or tubes in the inlet manifold. These tubes protrude in to the head and into the carby's. Both carby's and the head have recesses in them to accept these projections.

Only the Star Twin has these, the carby and the head on a normal longstroke A7 are the normal flush fit.

Offline rum558m

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Re: Longstroke Twin Carbs
« Reply #6 on: 11.06. 2011 19:25 »
apologies, twas me  that bought them, had to at that price.they are a matched pair of 275's with original fuel connections and pipes. my 49 star twin has a single monoblock on at the mo which spoils it.

Offline muskrat

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Re: Longstroke Twin Carbs
« Reply #7 on: 11.06. 2011 22:48 »
G'day rum558m, welcome to the forum.
                                                    Good score, your ST will love you for it.
Now tell us about you and your ST.
Cheers
'51 A7 plunger, '57 A7SS racer now a A10CR, '78 XT500, '83 CB1100F, 88 HD FXST, 2000 CBR929RR ex Honda Australia Superbike .
Australia
Muskys Plunger A7

Offline rum558m

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Re: Longstroke Twin Carbs
« Reply #8 on: 12.06. 2011 00:59 »
Hi im in heckmondwike,west yorkshire. i bought the bike 2 years ago as a rough old thing missing various parts(including carbs). i fitted a new monoblock and a pair of silences along with other bits and pieces and have run it since unrestored and covered about 2000 miles! with very little gone wrong.i will upload a picture when i get chance.

Offline LJ.

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Re: Longstroke Twin Carbs
« Reply #9 on: 12.06. 2011 10:07 »
Congratulations Rum! Indeed that was a good price, You will enjoy the twin carb set up although dont expect any increase in performance, the set up is really only cosmetic and an interesting talking point. With some time and patience the setting up is not difficult. I find on tickling my carbs (both the same time) start up is often a bit lumpy untill they even out. We look forward to hearing more about the bike soon along with some photographs!

Cheers
LJ.
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline rum558m

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Re: Longstroke Twin Carbs
« Reply #10 on: 12.06. 2011 16:17 »
daft question but why did they fit the twin carbs?i read they dont improve performance,was it for economy?or maybe just because they could perhaps? regards, Joe