Author Topic: 1951 A 7 plunger  (Read 1053 times)

Offline anjimehra

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1951 A 7 plunger
« on: 23.10. 2013 12:07 »
Hi

A very basic question. What is the difference between the std A & plunger & its relative the Star Twin ?

Thanks
Anji

Offline anjimehra

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Re: 1951 A 7 plunger
« Reply #1 on: 23.10. 2013 12:12 »
Sorry missed out the 7. It should read A 7

Online muskrat

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Re: 1951 A 7 plunger
« Reply #2 on: 23.10. 2013 20:29 »
G'day Anji.
Higher compression (7.25:1), 356 cam and manual advance.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline anjimehra

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Re: 1951 A 7 plunger
« Reply #3 on: 29.10. 2013 03:23 »
G'day Anji.
Higher compression (7.25:1), 356 cam and manual advance.
Cheers

Hi Muskrat
Thanks
Long time "no speak". How are you doing down under? Any new bikes in the collection/ ,. Just finished doing a 1976 Honda 550 F & a 1961 BMW R50S for a friend & now eyes down for this basket case. Wish me LUCK !
Another 2 questions ( many more to follow ): Does the crank bush on the timing side have a collar on the inside, & how does one set the end float. The currently installed bush is a plain one without collar.
What is the correct end float on the camshaft ?
Thanks & take care
Anji

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Re: 1951 A 7 plunger
« Reply #4 on: 29.10. 2013 08:59 »
G'day Anji, good thanks mate. Only the A65 that I blew up a month ago. Found half a little end and bush in the sump (see pic). Haven't worked up the courage to look further yet.
The "collar" (thrust face) of the timing side bush is needed to be able to set the crank end float. Without it the crank would flop around like a c@ck in a sock  *eek*. Shims are used behind the inner of the drive side bearing, (between the crank web and the inner when pushed on the shaft). Cam end float would be nil once the cork on the pinion is squashed a little by the breather valve in the inner timing cover.
Cheers
ps Use the search to find lots of info about crank end float.
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

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Re: 1951 A 7 plunger
« Reply #5 on: 29.10. 2013 20:49 »
Another A65 bites the dust!  *dunno*
Any idea why, Musky? They seem to be vulnerable to blowing up.
Trev.

Offline Brian

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Re: 1951 A 7 plunger
« Reply #6 on: 29.10. 2013 22:57 »
Thats a bugger Musky, looks like it could be expensive.

Unfortunately A65's are hand grenades and the factory supplied them without the pin !

Everybody has a theory about them and mine is vibration. Poor bottom end design coupled with bore and stroke dimensions that dont work. Shame really as they had some really good design features and could have been so much better.

To think at the end of the sixties you could walk into a motorcycle shop and choose between a A65 or a Honda 4, doesnt really take much working out.

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Re: 1951 A 7 plunger
« Reply #7 on: 30.10. 2013 07:09 »
I should heed my own advise. I picked her up for a song and just got her going with a tune up. I always tear'em down to check. Did about 1000 miles and she was a bit rattly. 60 miles into a 150 mile ride at 80mph the rattle worsened and went bang. Such is life. She already had the roller conversion and Boyer. Got it cheap as the PO had it wired up as neg earth and it wouldn't start. *whistle*
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline anjimehra

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Re: 1951 A 7 plunger
« Reply #8 on: 07.11. 2013 05:46 »
G'day Anji, good thanks mate. Only the A65 that I blew up a month ago. Found half a little end and bush in the sump (see pic). Haven't worked up the courage to look further yet.
The "collar" (thrust face) of the timing side bush is needed to be able to set the crank end float. Without it the crank would flop around like a c@ck in a sock  *eek*. Shims are used behind the inner of the drive side bearing, (between the crank web and the inner when pushed on the shaft). Cam end float would be nil once the cork on the pinion is squashed a little by the breather valve in the inner timing cover.
Cheers
ps Use the search to find lots of info about crank end float.

Thanks muskrat.sorry to hear about the A 65. It's a bugger to get these old gals sorted nowadays, especially in India. No genuine parts. Have to make most of them. At least that's still possible in small specialized shops.
Riding down to Goa next week on the Golden Flash. It's a round trip of approx 1500 kms. Will post some photos. Take care
Anji