Mahindra's New Goldstar 650

[highbury731]

The 62 and 63 West Coast Super Rockets were 9 to 1. That was at Hap Alzina's request.
East Coast and UK cr was lower.
So the RGS at 8.75 would be a slight detune from a late West Coast SR.


Glen

My 1960 Super Rocket, sold new in New Zealand, had stampings on the crank case indicating that it was fitted with 9:1 pistons. It also had the tacho drive from the oil pump introduced that year.
I got it in 1986 with an iron head, 30mm Concentric, a Gold Star 4 gallon petrol tank, seat with white piping round the edge, flat-sided single oil tank and tool box, and a magnetic speedo. The frame and various parts were painted metallic gold. I called it my Rocket Gold Flash.
After melting some spark plugs, I gave it a Super Rocket head and a pair of built Chronometric clocks, the rear Konis off my GS450 Suzuki, and later an RGS exhaust and late '60s 2ls wheel. It became a rather nice roadburner, tho' vibratory.

 

[Monkeypants]

Most A 10 owners won't admit that the bikes vibrate a lot at highway speed.
Instead we use the term "buzzy" as in it gets buzzy above 65 mph ( 55 in reality)!

A10 Power at the rear wheel is around 20 hp @ 4000 rpm, regardless of the model.

A healthy Vincent twin makes nearly twice this amount at 4000, even though the HHC A10 is rated 40hp (early RR-) 46 hp(late SR) and the Rapide is 45.

Glen

 

[highbury731]

My speedo was built by a Chronometric expert, a former Army instrument maker, who made the gears so that it was EXACT. I saw 110mph on it, with ordinary riding gear. I could have got it a bit faster, but discretion..... That speed probably needs a bit more than 20bhp.

 

[Chris Launders]

In the mid 70s I had a Gold Star A10, it was a Goldie chassis fitted with an A10 engine someone had lovingly built with Triumph Conrods a 67-357 cam, oval section pushrods and alloy valve collet holders, it had a Lyta tank, and Eddie Dow alloy top yoke, double damped forks and his Duetto TLS front brake. It would easily leave my mates CB750 on late night motorway races and out brake and out handle it on "ordinary" roads too.

 

[Monkeypants]

My speedo was built by a Chronometric expert, a former Army instrument maker, who made the gears so that it was EXACT. I saw 110mph on it, with ordinary riding gear. I could have got it a bit faster, but discretion..... That speed probably needs a bit more than 20bhp.

Yes, the sporty versions of the A 10 do make more than 20 rwhp at max rpm.
I was quoting power available at 4000 rpm, where you might hold an engine +- if pulling out to pass on a long hill.

Earlier I posted the link to four A 10s that were carefully rebuilt, broken in, then Dyno tuned for max power.
The best of the bunch was a 60 Super Rocket with the hotter 61 on 357 Spitfire cam fitted.
It made 28 rwhp at 6300 rpm. You would not want to hold an A10 there for long, especially if you were needing the headlight bulb to continue working!
The 28 rwhp probably correlates to about 33hp or 34hp at crank.

All of the engines made about 20 rwhp at 4000 rpm, although the lower tuned engines were a bit better here than the higher tuned.

Glen

 

[Magnetoman]

A 10s that were carefully rebuilt, broken in, then Dyno tuned for max power.

All of the engines made about 20 rwhp at 4000 rpm,

In 2006 'Motor Trend' magazine wrote an article on the development of the Dynojet dyno.

The Story Behind the Dynojet Chassis Dyno - The Truth Meter - Hot Rod Magazine

Read about Mark Dobeck and the story behind the Dynojet Chassis Dyno that helped make the aftermarket world more honest about power claims - Hot Rod Magazine

www.motortrend.com

Note the following text from that article:

no matter what they did, the math never added up. Dynojet's final number-fudge was arbitrarily based on a number from the most powerful road-going motorcycle of the time, the '85 1,200cc Yamaha VMax. The VMax had 145 advertised factory horsepower, which was far above the raw 90hp number spit out by the formula. Meanwhile, existing aftermarket torque-cell engine dynamometers delivered numbers that clustered around 120. Always a pragmatist, Dobeck finally ordered his Chief Engineer to doctor the math so that the Dynojet 100 measured 120 hp for a stock VMax. And that was that: For once and forever, the power of everything else in the world would be relative to the '85 Yamaha VMax and a fudged imaginary number.

Aside from anything else, I have to wonder how reliable h.p. readings are when made at only 17% of the calibration/fudge-factor. Also, if the fudge-factor was introduced to reproduce the h.p. measured at the engine on a "real" dyno, that "20 rwhp" actually is 20 engine h.p., making the dyno results even more suspect. The BSA engine dyno curve you posted earlier shows 30 h.p., which is 50% greater than the 20. That's a pretty big discrepancy. And the 20 hp that was displayed assumes the dyno used by the guy in the link you gave isn't out of "calibration."

Anyway, there are several reasons not to accept those dyno results at face value without additional information about the dyno itself.

 

[chankly bore]

All manufacturers do this sort of stuff- speedometers reading 10% optimistic, 70lb. flyweight Japanese testers glued to the petrol tank to get top speed, Phil. Irving's classic "B.H.P. stands for Brochure Horsepower" quote. and it generally gets worse the further manufacturers are estranged from blokes who actually ride bikes.

 

[vibrac]

"Royal Enfield... never disappeared"
Being a nit-picking pedant, I have to disagree.
Royal Enfield did disappear, circa 1971. Royal Enfield's daughter company, Enfield India was set up in 1955, with roughly half the shares owned by Royal Enfield, and half by Indian investors Madras Motors. This company continued after Royal Enfield went bust. Eventually, the owners of Enfield India acquired the name and logos of Royal Enfield, and renamed their company and products as Royal Enfields.

And the real Royal oilfields were built in a cave (at least towards the end )