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#283124 - 11/09/09 9:35 pm Tuning suggestions for track day A10  
Joined: Aug 2006
Posts: 730
johnnyrvf Offline
BritBike Forum member
johnnyrvf  Offline
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Joined: Aug 2006
Posts: 730
Dordogne, SW France
Hi All, I have client who wants me to prepare his A10 motor for race circuit parading. The bike is a Goldstar chassis with a '56 thick flange A10 motor with stock A10 gearbox. SRM in the U.K repaired the crank for the previous owner who built the bike up with new shells, new oil pump, new valves, 7.5 :1 pistons and a soft cam and on a recent dyno made 34 bhp at the wheel. The bike is in excellent order and has a lot of very nice touches on it and is no way a botched shed. The work was done in the late nineties and then the builder emigrated to France and under the orders of his wife sold the bike on with very little mileage being ridden. The person who bought the bike wanted it so much he sold a Ducati Desmo 350 single to pay for it, he also has a very clean low mileage Mk 111 commando. So my questions are these, I'm familiar with the unit engines but have never really had much experience with the A10 engine, are there any nasty surprises waiting in there? What is the best cam to go for; the spitfire or perhaps an aftermarket such as megacycle? are high compresion pistons still available. I know the risks with high comp pistons in thin flange motors as 33 years ago on the A316 heading into London a mates A10 with 10: 1 pistons blew a big chunk out of the right hand base of the barrel whilst running in , as it was night the flame was very spectacular shooting a good twenty feet across the road! As to the g/box he is happy with the ratios but does'nt like the way the kickstart gets in the way of the rearsets, can the RRT2 kickstart ratchet be fitted directly into the std box or is it a lot of parts and grief? This is NOT a race bike and he does'nt want to spend big money in having the rockers polished or a super porting job but he IS keen for a bit more reliable urge, so any suggestions would be very much appreciated


What d'ya mean it won't rev to 10?
1965 BSA A65D Lightning Rocket
1976 K*w*s*ki Z900.
1978 Triumph Bonn3ville (930 T160 Powered T140)
1988 H*nd* RC30
1990 Moto Guzzi California 3
1993 Y*m*h* TDM 850
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#283860 - 11/13/09 10:15 pm Re: Tuning suggestions for track day A10 [Re: johnnyrvf]  
Joined: Mar 2005
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ca7a Offline
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ca7a  Offline
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Posts: 731
Asheville, North Carolina
Make it to Super Rocket spec. See Bacon's BSA Twin Restoration.

David

#283922 - 11/14/09 6:34 am Re: Tuning suggestions for track day A10 [Re: ca7a]  
Joined: Aug 2006
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johnnyrvf Offline
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johnnyrvf  Offline
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Joined: Aug 2006
Posts: 730
Dordogne, SW France
Hi ca7a, got that book right here, I'll look into it, thanks! Johnny.


What d'ya mean it won't rev to 10?
1965 BSA A65D Lightning Rocket
1976 K*w*s*ki Z900.
1978 Triumph Bonn3ville (930 T160 Powered T140)
1988 H*nd* RC30
1990 Moto Guzzi California 3
1993 Y*m*h* TDM 850
#284110 - 11/15/09 9:55 pm Re: Tuning suggestions for track day A10 [Re: johnnyrvf]  
Joined: Mar 2005
Posts: 731
ca7a Offline
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ca7a  Offline
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Joined: Mar 2005
Posts: 731
Asheville, North Carolina
You're welcome, Johnny and, BTW, a KIckstart Crank Spindle Assy (not the "Ratchet") from a RR.T2 should fit a STD gearbox easily. Alternatively, you could build up the diameter of the Kickstart Quadrant Stop to move the lever forward. Use rubber tubing.

David

#284119 - 11/15/09 11:47 pm Re: Tuning suggestions for track day A10 [Re: ca7a]  
Joined: Feb 2003
Posts: 2,884
Rickman Offline
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Rickman  Offline
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Joined: Feb 2003
Posts: 2,884
Ohio
Umm,
Is it my imagination, or have I seen a BSA A7/10 kick-start quadrant that was assemble on a splined shaft? If so, press the gear off, and move it the 60 degrees rearward???

I could swear I've seen these somewhere....
Brett
P.S. ca7a, I should probably come see you next June, when I'm down that-a-way.... Wonderful riding area...

Last edited by Rickman; 11/15/09 11:50 pm.
#284134 - 11/16/09 1:44 am Re: Tuning suggestions for track day A10 [Re: Rickman]  
Joined: Aug 2001
Posts: 1,852
dave - NV Offline
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dave - NV  Offline
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Posts: 1,852
Elko, Nevada USA
I too dealt with the kicker arm in the way with rear sets on my Goldie. First I cut away the quadrant to allow the kicker arm to travel further forward. This worked except sometimes on a full swing of the kicker, if the engine doesn't start, the quadrant will run off the ratchet gear and lock in the down position until engaging a gear and rocking the bike. A royal pain.

Next I located a splined kicker shaft/quadrant that allows repositioning the quadrant. However I wasn't totally happy with the angle when starting. Worked OK tho.

But the best 'fix' is to fit a folding kicker as used on Triples(?) and various japper bikes which may need modifying. I and some of my friends have fitted folding kickers to our Goldies sold by Sammy Miller in his trials parts catalog which are a direct bolt on, kick and go. The 'hot setup' seems to me.

Last edited by dave - NV; 11/16/09 4:23 am.

dave - NV
#284165 - 11/16/09 7:15 am Re: Tuning suggestions for track day A10 [Re: dave - NV]  
Joined: Aug 2006
Posts: 730
johnnyrvf Offline
BritBike Forum member
johnnyrvf  Offline
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Joined: Aug 2006
Posts: 730
Dordogne, SW France
Hi All, thanks very much for the tips, I'm off later this week to sort out the forks ( someone has fitted a 1968 rear cable entry ) TLS front wheel and brake and the owner is'nt sure if the forks are A10 or later ; they are really soggy so I guess A10 but I'll dismantle them just to make sure. I've got a fix for the forks whatever type they are. Alex the Jap kicker sounds great, as the owner isn't in any way an originality nut ; not that there are many rivet counters in France, well I have'nt come across any! Johnny.


What d'ya mean it won't rev to 10?
1965 BSA A65D Lightning Rocket
1976 K*w*s*ki Z900.
1978 Triumph Bonn3ville (930 T160 Powered T140)
1988 H*nd* RC30
1990 Moto Guzzi California 3
1993 Y*m*h* TDM 850
#284188 - 11/16/09 4:30 pm Re: Tuning suggestions for track day A10 [Re: johnnyrvf]  
Joined: Mar 2005
Posts: 731
ca7a Offline
BritBike Forum member
ca7a  Offline
BritBike Forum member

Joined: Mar 2005
Posts: 731
Asheville, North Carolina
The comments re moving the quadrant on its splines are good.
Rickman, you're always welcome to come here and ride the Blue Ridge with me.

#284275 - 11/17/09 12:22 am Re: Tuning suggestions for track day A10 [Re: ca7a]  
Joined: Aug 2001
Posts: 1,852
dave - NV Offline
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dave - NV  Offline
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Joined: Aug 2001
Posts: 1,852
Elko, Nevada USA
Wanna go fast .. safe?
Early A65 fork legs with double dampening rods from a bike with SS front brake will fit/work nice on all pre unit BSAs.

Or a pre unit fork fix for usable dampening vs the 'imaginary' OEM rebound dampening is to install repop Eddie Dow dampening rods with one way valves suspendend from the fork caps.

I strongly suggest replacing the worn out and notchy 'push bike' type free ball steering head bearings with nice snug tapered roller units.

Replace the worn out Girling shocks with longer 13.5" modern shocks. Better dampening Plus the increased length will give much better 'turn in'.

Brakes?

And then ...

Last edited by dave - NV; 11/17/09 7:49 pm.

dave - NV
#284320 - 11/17/09 9:18 am Re: Tuning suggestions for track day A10 [Re: dave - NV]  
Joined: Aug 2001
Posts: 3,405
gavin eisler Offline
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gavin eisler  Offline
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Joined: Aug 2001
Posts: 3,405
argyll. scotland, uk
The quickest A10 Ive ridden had a twin carb alloy head (oversize inlet v/v s) from an A7 fitted, with flat top pistons it was 9.5:1 comp. A 357 "spitfire" cam , stock pipes with goldie pattern gutless megas and 32mm Mikunis. This did not run like an A10 , more like a CB 250, in that it really wanted to rev. The crank broke at the drive side big end!
The stock super rocket tune is not too much for the motor.If you want a bit more pep in your motor the 357 cam would perk up the top end a bit . It will run smooth with the 7.5 to ones and have a little perk up about 3,500 - 4,000 rpms.
Theres no nasty surprises in an A10. You need a pushrod comb to help fit the heads/ rocker boxes but nothing too tricky.
They do wet sump a bit and chuck oil out of the breather after a long stand .As long as you have a good crank and oil pump ,they are mostly the same as the unit motor but less stressed all round.The K2F Lucas mag is a good bit of kit.
The seperate gearbox makes life a lot easier when building.
Id say the 6 spring clutch was / is the worst single element, it can be made to work, but is more fiddly than the later 4 and 3 spring unit clutches.
Dave NV is bang on with his fork upgrades.
If the owner can stand it a seperate set of wheels with 18" alloy rims , modern rubber and the later 8" twin leading shoe front brake would add a lot to his parading fun.
Cheers
pod


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
#284382 - 11/17/09 8:16 pm Re: Tuning suggestions for track day A10 [Re: gavin eisler]  
Joined: Aug 2006
Posts: 730
johnnyrvf Offline
BritBike Forum member
johnnyrvf  Offline
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Joined: Aug 2006
Posts: 730
Dordogne, SW France
Hi Pod, Hi Dave O.K. He has the later twin leading shoe fitted so no probs there and an 18" rear with modern rubber on both wheels , as to the forks I have a '65 Lightning with the A10 fork with Paul Goffs fork conversion and longer shocks (50mm longer than stock ) and it turns very nicely on 19" rims with the longer fork tubes in the "dropped " yokes and I'm over to his later in the week to let him see how they feel, I've opened up the bottom damper holes to soften them a bit and they do work well, in an old fashioned way. As to the engine it has had a LOT of money spent on it and only needs a pepping up rather than a complete rebuild although the timing side conversion is probably a good idea as it will be ridden hard.( but not hard enough to break the crank ) Johnny.


What d'ya mean it won't rev to 10?
1965 BSA A65D Lightning Rocket
1976 K*w*s*ki Z900.
1978 Triumph Bonn3ville (930 T160 Powered T140)
1988 H*nd* RC30
1990 Moto Guzzi California 3
1993 Y*m*h* TDM 850

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