1952 bsa a10 plunger

[anjimehra]

Hi Guys

Back again with some queries:

1) Have been able to locate locally a 49 tooth rear sprocket for the Flash as opposed to the 42 teeth sprocket that was on the bike ( not useable ). Query being, will this work & what are the cosequences ( lower top speed, better acceleration, vibrations etc ).
What would be the chain size reqd for this ( links ).

2) Gasket thickness for the oil pump & the washer for the 3rd stud.
3) Id asked this before, but didnt get any replies so here goes again. Is their a spacer behind the sprocket side brg & the central long distance piece between the 2 brgs. The illustrated parts list shows but my bike didnt come with on ????

Thanks & ride safe
Anji

[chaterlea25]

Hi Anji,
I can only offer advice on question 2

It is not too important what thickness the oilpump gasket is 0.25mm to 0.5mm should be ok
What IS Important is that the washer on the third bolt is the SAME thickness
I usually make an extended gasket to take in the third bolt (and no washer)
check the mating side of the pump on a flat surface to make sure its not distorted
HTH
Regards
John O R

[anjimehra]

Hi John

Thanks for your help. I actually managed to lay my hands on a gasket set which has the oil pump gasket & the separate washer for the third stud.
How I did the worm to pump setting is by feeding tthe worm in along with the pump till the pump was up against the gasket. I then moved the worm up & down in the backlash zone & in its freest position measured the gap between the timimng pinion & the worm face. Does that sound right to you.
Take care
Anji

[anjimehra]

Hi John
Sorry, I got the wrong end of the stick. What I wrote back was how I set the pump worm drive to pinion gap as my bike didnt have the steel washer between the worm & pinion.. Anji

[Josh Cox]

G'day Anji,

2) I have the same 49 tooth on the back of mine (18 front), it is apparently standard for a side car set up (reference bacon book).

To be honest I have not had the pleasure of riding my bike yet, soon, so can not say if it will be reving too high for normal riding, if it is I will replace with a 42 tooth item from draganfly.

Have had the pleasure of riding a couple of Captain Orabanda's, with 18/42, they were pretty sweet.

Suck it and see I say.

[bsa-bill]

Hi Anji

I altered the gearing on my project but did it on the engine and gearbox sprockets as I was looking for a small change in gearing.
In your case as you've  gone from 42 to 49 teeth rear sprocket the difference of 7 teeth is roughly the difference in chain length, I say roughly because the rear sprocket is now larger and may need 7 rollers +, depends where the spindle is in the swinging arm slot, Ideally you want it near the front.
Best way to test is put the original chain on ( if you have one ) and count the links you need to join it on the sprocket.

I think the answer to question 3 is yes, depends on the year of your Flash maybe, anyway for a late Flash 58 - 61 it's part number 42-6323 distance piece providing were talking about the same thing

All the best - Bill

[Rusty nuts]

cosequences ( lower top speed, better acceleration, vibrations etc ).

In a nutshell, all three, third only if you push it in top gear.
Been a while since I lived in India but can't imagine traffic has changed too much in the interim, so flat out is probably not your aim unless you're suicidal, like the rest 

[anjimehra]

Hi Guys

Thanks for the advice. I have managed to locate a 42 tooth sprocket & will fit this on first & see.
Also managed to fit the pump with a 2 mm washer between the pinion & worm & all seems to be well so far.
Trying to get the bike ready next week but suddenly find that NO tyres available as the factory is on STRIKE, Will post a few photos tomorrow

Thanks once again
Anji

[Josh Cox]

Anji,

To follow up my earlier post, have replaced the 49 tooth with a 42, the bike was great off the mark but reving too high over 55 MPH.

Very happy with the new gearing. 18 / 42.