357 Cam - 1961 Swinging Arm

[worntorn]

PatM20, I have 2 A10s, 1 with the 356, my GF, and 1 with a 357, my SR. My SR motor is built to RGS specs, bigger inlet valve,  standard2 gearbox, SRM bearing mod, as 9:1 pistons and 110 octane leaded petrol etc. and goes like hell and sound great but I notice that when I get into hilly/ mountain areas, if the RPM drops below 3k, it's performance is not so good. I'm constantly shifting to 3rd and pushing it up to almost 4k so I can then get into top gear and over 3k. once it's over 3k then it pulls really hard, but let it go below 3k and try to open it up on a hill and it just bogs and with 2 up it's obviously worse. I don't have that issue with the GF, although the motor build is a lot softer, 7:1 pistons. I have decided that next time I have to split the cases on my super rocket, I'll change the cam out to a 356 as at my age I rarely take the motor over 4500 RPM. So my advice is if you want the bike to "fly" and keep the revs up, it's the 357, but for tractability go with the 356.

I often see the reference " built to RGS spec". Pretty sure the RGS just used a dead stock late SR engine. I have a 1963 West Coast SR all stock, 9 to 1 , 357 cam. Isn't this engine identical to a factory RGS?



Glen

[chaterlea25]

Hi Glen,

Isn't this engine identical to a factory RGS?

Yes, the RGS engines were taken from the Super Rocket production line
There is often confusion when you see a 1571 head for sale advertised as "RGS"
The 71 is over stamped onto the last two figures of the 1549 cast on number
There are more 1571 heads floating around than there were RGS's built 

John