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1969 BSA A65 CARB question #728284
03/11/18 2:03 pm
03/11/18 2:03 pm
Joined: May 2012
Posts: 60
New York, USA
N
Nick Zag Offline OP
BritBike Forum member
Nick Zag  Offline OP
BritBike Forum member
N

Joined: May 2012
Posts: 60
New York, USA
Hi - please can someone confirm correct jets and slide for 1969 BSA A65? Reason for asking and not going by the book I think someone told me that there may be a better setup than original factory. Thank you in advance!


1968 Triumph Bonneville
1969 Triumph Tiger
1972 Triumph Tiger
1969 BSA Lightning

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Re: 1969 BSA A65 CARB question [Re: Nick Zag] #728285
03/11/18 2:13 pm
03/11/18 2:13 pm
Joined: Aug 2001
Posts: 7,550
scotland
triton thrasher Online content
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triton thrasher  Online Content
BritBike Forum member

Joined: Aug 2001
Posts: 7,550
scotland
Is it your twin-carburettor Lightning?


Amateur Loctite enthusiast.
Re: 1969 BSA A65 CARB question [Re: Nick Zag] #728294
03/11/18 4:29 pm
03/11/18 4:29 pm
Joined: Feb 2014
Posts: 1,162
Lancaster, California
C.B.S Offline

Parts Dealer
C.B.S  Offline

Parts Dealer

Joined: Feb 2014
Posts: 1,162
Lancaster, California
Look in a 1969 A65 parts book and install the jets accordingly. At least you have a "place to start". Once running you can then start the tuning process.

Re: 1969 BSA A65 CARB question [Re: triton thrasher] #728298
03/11/18 4:54 pm
03/11/18 4:54 pm
Joined: May 2012
Posts: 60
New York, USA
N
Nick Zag Offline OP
BritBike Forum member
Nick Zag  Offline OP
BritBike Forum member
N

Joined: May 2012
Posts: 60
New York, USA
Yes twin carb model


1968 Triumph Bonneville
1969 Triumph Tiger
1972 Triumph Tiger
1969 BSA Lightning

Re: 1969 BSA A65 CARB question [Re: Nick Zag] #728330
03/11/18 9:31 pm
03/11/18 9:31 pm
Joined: Aug 2001
Posts: 4,081
argyll. scotland, uk
gavin eisler Offline
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gavin eisler  Offline
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Joined: Aug 2001
Posts: 4,081
argyll. scotland, uk
69 A65L , 930/21, 930/22 , 190 MJ , slide 2 1/2 ,,, needle position 2, NJ . 106 , no exhaust balance pipe.

70 A65L , 930/34, 930/35 , 180 MJ, slide 3 , needle position 1 NJ .106, has exhaust balance pipe.

71 on have the same size carbs but very different airbox/ filters , silencers. Filters sit in a ~2.5 litre plenum , use 220 MJs otherwise same as 1970.

Apart from the exhaust balance, silencers and air filters, these models are essentially in the same tune. same compression ratio and cam.

All share the same .106 NJs, which should be renewed as a matter of course if starting with old carbs.

Sup to you which slides you try first , if it bogs and blubbers on the 2.5s try the threes, if it spits back on 3s try the 2.5s.
Two point fives can become threes if you are competent with a file and confident they are too rich, make sure to leave marked as 2.5s to create future confusion.
You can get this almost correct without riding the bike, just twist the throttle ( once warm ) , if it spits back coming off idle then the cutaway is too lean. Once riding If it blubbers at a steady throttle just above idle , but pulls like a train when opened further , then its too rich, needs more cutaway.

Same applies to needle height but throttle needs to be opened about 1/2 way before this has any real effect.
.
I would try three pairs of MJs , 180s, 190, 200s.

A lot will depend on your silencers, particularly MJ final size, some pattern items are very restrictive , some are not. Each bike is different.

There is no easy magic first time setting, mark your throttle twist grip so you know what stage the carb is at , ride, observe and fiddle. You can try plug chops , but modern fuel makes this a lot more difficult, when MJ tuning beware of holing a piston, if the throttle is WFO and as you roll it closed the motor picks up revs before slowing , thats a sign of weakness not to be ignored , means go up at least one jet size. Luckily conc MJs can be swapped through the drain plug, throttle slides not so easy.


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: 1969 BSA A65 CARB question [Re: gavin eisler] #728467
03/13/18 9:08 am
03/13/18 9:08 am
Joined: May 2013
Posts: 4,956
Rotherham - S. Yorkshire
Allan Gill Offline

BritBike Forum member
Allan Gill  Offline

BritBike Forum member

Joined: May 2013
Posts: 4,956
Rotherham - S. Yorkshire
Originally Posted by gavin eisler
69 A65L , 930/21, 930/22 , 190 MJ , slide 2 1/2 ,,, needle position 2, NJ . 106 , no exhaust balance pipe.




That jetting should have changed for 69, it is infact the 2 stroke jetting as fitted to the 68 models, although if it came from the parts manual and not the AMAL guide then it would explain the 69 year.

The 180 main jet, 106 needle jet, with needle in upper most position and No.3 slide is the best setup for a bike running stock airfilters and exhaust pipes. even for 68 wink although between 180 and 190 and 200 you wouldnt notice the difference until your at the last 5mph in its range.


beerchug

Moderated by  Allan Gill, Jon W. Whitley 


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