Author Topic: 9:1 pistons  (Read 553 times)

Offline Erico

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9:1 pistons
« on: 20.06. 2014 10:11 »
Hello....has anyone fitted 9:1 pistons to an A10 with auto advance and retard. I've heard that you need to junk the auto unit and fit a manual advance and retard set up to deal with the compression fuel etc. I don't want it pinking and knocking. Thanks Erico
ERICO.
1961 BSA Super Rocket. 1991 Yamaha V-Max.
1991 Suzuki 1400 Intruder. 2006 Yamaha Royal Star Venture TF.

Online bsa-bill

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Re: 9:1 pistons
« Reply #1 on: 20.06. 2014 10:33 »
Quote
I don't want it pinking and knocking.

Shouldn't of fitted 9:1 piston then  *smile*

Yes a manual advance would be help in that respect on hills or acceleration , although the A/R unit I think only retards at very low revs so I bet someone has left it on and just timed the bike accordingly
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online muskrat

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Re: 9:1 pistons
« Reply #2 on: 20.06. 2014 11:14 »
Yes I found the AR unit advanced a bit too quick for high comp. Retarding it enough to stop the pinging meant it wouldn't pull the skin off a banana!! I was in the process of removing weight off the bob weights to slow it down when I ditched the magie and went electronic. A little better but not perfect. My solution is if it pings throw it back a gear and rev it.
A manual advance magie would be better for normal road work. (Normal isn't one of my riding styles  *evil*)
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline wilko

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Re: 9:1 pistons
« Reply #3 on: 21.06. 2014 00:41 »
Stronger springs in the advance unit should slow the advance characteristics.

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Re: 9:1 pistons
« Reply #4 on: 22.06. 2014 03:54 »
That's right wilko, but it's hard enough finding good std ones down here, let alone ones a few oz heavier.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline wilko

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Re: 9:1 pistons
« Reply #5 on: 22.06. 2014 23:35 »
Got any old car dizzies you could compare with lying around? Springs I mean.