Author Topic: Speed/RPM?  (Read 926 times)

Offline Johnny J

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Speed/RPM?
« on: 01.04. 2015 16:31 »
Since I bought my bike in November I have been out riding a few times (and lots today) and I love it!
One thing that I'm not used to yet is (besides footbrake left and gearshift right) how high you can rev it.

What is the max recommended RPM and can any of you with RPM counter give me an example, like "at 20mph in first gear you are at 3500RPM" (with std. gearing).

Of course riding is not a problem now, would just be interesting to know the limits.
   Gothenburg, Sweden

Online bsa-bill

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Re: Speed/RPM?
« Reply #1 on: 01.04. 2015 16:48 »
Quote
What is the max recommended RPM

Do you have a rev meter on the bike Johnny,  I know I've read 6000 rpm  is about max power but maybe that requires a well fettled engine, some of our faster moving members will surely comment.
My self (with no rev meter) I back off when I start to see three of everything  *smile*
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 Greybeard

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Re: Speed/RPM?
« Reply #2 on: 01.04. 2015 17:30 »
I am a careful rider, these days: I want my A10 engine to last as long as possible and I don't want to have an accident so I do not push the 'ole girl much past 65mph.

Offline Johnny J

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Re: Speed/RPM?
« Reply #3 on: 01.04. 2015 21:34 »
No I don't have a rev meter, just wanted a sample of "the tone, frequency" as a reference, say at 5000RPM so I don't go over this.
But I have noticed that the cowling, meters and other parts starts to vibrate when you go up a bit, right now I use this as the limit.
   Gothenburg, Sweden

Online muskrat

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Re: Speed/RPM?
« Reply #4 on: 04.04. 2015 20:18 »
G'day Johnny. 5000 RPM would be close enough to 70 MPH if all the gearing is standard.
There was a chart for revs-gear-speed, I'll keep looking.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, .
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Offline East_Coast_BSA

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Re: Speed/RPM?
« Reply #5 on: 05.04. 2015 02:11 »
3500 RPM gives me about 65 MPH and I'm pretty sure my gearing is stock (I know the gearbox is anyway).

Online orabanda

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Re: Speed/RPM?
« Reply #6 on: 05.04. 2015 02:18 »
Note the flat torque "curve", and that the engine is almost at peak power at 3,500 rpm.

This is from a Golden Flash, with 356 cam.

Richard

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Re: Speed/RPM?
« Reply #7 on: 05.04. 2015 10:02 »
Glad you chimed in Richard. Was it you that did the RPM/speed chart?
Both mine have 357's in them. They get a good hurry up at about 4500
The cafe has the equivalent to a 23 engine sprocket but std gearing g/box & final. 3800 at 60.
Cheers
Edit: I forgot to say it has an 18" rear wheel
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, .
Australia
Muskys Plunger A7

Online orabanda

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Re: Speed/RPM?
« Reply #8 on: 05.04. 2015 12:50 »
Hi Musky,
No, I didn't do the chart.

I have attached the results from a SR engine, with 357 cam.

Got to go; thoroughly enjoying a couple of DVD's of last year's TT races, sent to me by one of nature's gentlemen!

Richard

Offline MG

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Offline Johnny J

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Re: Speed/RPM?
« Reply #10 on: 05.04. 2015 13:45 »
Very good! So at 100km/h I have around 5000RPM in 3rd gear, good reference point!
   Gothenburg, Sweden

Online chaterlea25

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Re: Speed/RPM?
« Reply #11 on: 05.04. 2015 15:54 »
Hi Johnny,
If the bike feels "revvy" then very likely its under geared,
The bike/ engine will last longer and feel a lot better when geared up and feel relaxed at cruising speed
Rear tyre size has a pronounced effect as well
I am running a 23 tooth engine sprocket on my Super Rocket and 100/90 rear tyre
3300rmp at 60 mph and 4000 at 70 means it is happy staying with modern traffic when it has to

HTH
John
1961 Super Rocket
1963 RGS (ongoing)