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Author Topic: R.P.M @ 60 (55)  (Read 3101 times)

cyrusb

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R.P.M @ 60 (55)
« on: March 10, 2008, 07:12:26 PM »
Has anyone tached out their classic at 60 mph (indicated) ? Looking for a ballpark figure, stock (17t) sprocket. Thanks.

fredgold52

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Re: R.P.M @ 60 (55)
« Reply #1 on: March 11, 2008, 08:08:46 PM »
I wanted to bump this back up - I'm interested in knowing what RPM's we are turning at various speeds too.  I know this is sort of a lazy engine and that's one of the reasons I like it so well.  But still, RPM's would be nice to know.
2006 '65' and a 200cc Stella, Indian all the way

cyrusb

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Re: R.P.M @ 60 (55)
« Reply #2 on: March 11, 2008, 08:28:35 PM »
I cant believe no ones done it yet! I guess I'll have to dig up an old dwell meter or the like. Haven't seen any of those old tuneup tools in 20 years. I'm going to take a guess at 3800 and hope I'm wrong.

Foggy_Auggie

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Re: R.P.M @ 60 (55)
« Reply #3 on: March 12, 2008, 12:37:41 AM »
Transmission ratio in 5th gear.

Sprocket ratio = rear sprocket / front sprocket

Engine rotation / km = trans ratio * sprocket ratio * wheel rotation / km

Engine rpm = engine rotation / km * bike speed / 60

One mile = 1.609 km

Wheel rotation travel found by using a string to measure the distance traveled in one rear tire rotation.  Can be performed on the center stand with a helper.  Measure in inches - convert to millimeters - convert to three decimal points of meters.
(example only:  wheel travels 65.25 inches in one rotation - this equals 1658 mm = 1.658 meters).
Diagonally parked in a parallel universe.

Fortiter Et Fideliter

baird4444

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Re: R.P.M @ 60 (55)
« Reply #4 on: March 12, 2008, 01:36:17 AM »
                                       FOUND IT!
Below is a post from "DWM" Dave was the builder of Hanuman in the members
rides. What he didn't know he figured out and shared.   - Mike
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I wanted to know my RPMs at different speeds, so got this little tach;
http://www.tinytach.com/tinytach/gasoline.php
Not bad for $37 US, being digital, it's useless for shifting. but, if you need
a
tach to shift a
RE, you're stone deaf, and yer butt has gone to sleep. Also has a 2 second lag.

Anyway, here are speeds/RPMs, with a 19T countershaft sprocket on the five
speed.
(XT- extrapolated.interpolated)

50MPH-2870 RPM
55MPH XT - 3146 RPM
60 MPH - 3450 RPM
65 MPH XT- -3737 RPM
70 MPH - 4025 RPM
75MPH XT - 4312 RPM
80MPH - 4600 RPM
85MPH XT- 4887 RPM
Theoretical;
90 MPH XT - 5175 RPM
MAX RPM-5500 - 95MPH

The speeds above are from a GPS corrected speedo, and I think they're pretty
tight
numbers.
I don't think the bike would do 95 MPH if you pushed it off the Sinny Arbor
Bridge, but it
touches 85 with my 220 lb on board, so I think a lighter rider would see 90.
(535cc, 8.5:1. 34mm Mikuni, short Brit exhaust, K&N)
More importantly, it means my "75 MPH all day, 80 to pass only," are usable
limits. I just
can't see that motor objecting to 4300 RPM. It sure sounds relaxed.
Below are extrapolated numbers for 19 and 18 tooth sprockets;
18T (19/18ths of above RPM)
50MPH-3029 RPM
60MPH-3642 RPM
70MPH-4249 RPM
80MPH-4855 RPM

17T (stock, 19/17ths of 19T readings)
50MPH-3207 RPM
60MPH-3855 RPM
70MPH-4498 RPM
80MPH-5141 RPM

BTW, I installed the black bar-end mirrors from CMW on "Lady Triumphantes", the
$15
ones, and they have been fine. Of course, the Trumpet vibrates a bit less.
Best,
DWM
"You can't drink all day if you don't start in the morning!! "
        -Cody Baird
'My dear you are ugly,
 but tomorrow I shall be sober and you will still be ugly'
 - Winston Churchill

jdrouin

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Re: R.P.M @ 60 (55)
« Reply #5 on: March 12, 2008, 01:50:01 AM »
Wow! Cyrusb's guess of 3800 rpm on a 17T countershaft sprocket is pretty much dead on, balls accurate.

Jeff
« Last Edit: March 12, 2008, 01:51:32 AM by jdrouin »

cyrusb

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Re: R.P.M @ 60 (55)
« Reply #6 on: March 12, 2008, 04:52:36 PM »
Thanks baird444, I printed that out. I had a feeling the revs were in the high 3000's but didn't think my guess was that close!

Bankerdanny

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Re: R.P.M @ 60 (55)
« Reply #7 on: March 12, 2008, 06:53:07 PM »
dead on, balls accurate?
Endeavor To Persevere

luoma

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Re: R.P.M @ 60 (55)
« Reply #8 on: March 12, 2008, 11:10:04 PM »
Appreciate the info. My bike has a 19-tooth also. It feels pretty tight at 75, but I guess it's not.

jdrouin

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Re: R.P.M @ 60 (55)
« Reply #9 on: March 12, 2008, 11:43:40 PM »
dead on, balls accurate?

That's Marisa Tomei's line in My Cousin Vinny. She's the daughter of a mechanic who clinches the mystery of an armed robbery at the end of a lost-cause trial.

http://www.youtube.com/watch?v=DhL5exi_avE

Jeff

LotusSevenMan

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Re: R.P.M @ 60 (55)
« Reply #10 on: March 13, 2008, 12:33:03 AM »
I have never seen that film Jeff but I liked the clip!!!!  ;D
If it ain't broke-------------------------- fix it 'till it is!

Royal Enfield Miltary 500cc  (2003)
Honda VTR FireStorm (SuperHawk) 996cc 'V' twin
Kawasaki KR1 250cc twin 'stroker
Ducati 916 'L' twin

jdrouin

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Re: R.P.M @ 60 (55)
« Reply #11 on: March 13, 2008, 02:10:36 AM »
Actually, I sent the wrong one. It's in this clip, from about 1:15 to 2:15. For some reason I thought the line was repeated later as a clincher in the trial, but it wasn't. The technical humor is good in this one too, as well as certain other... ahem... aspects.

http://www.youtube.com/watch?v=M-ZyxRNCTuc

Jeff

LotusSevenMan

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Re: R.P.M @ 60 (55)
« Reply #12 on: March 14, 2008, 09:47:45 PM »
The  new clip is "Dead on, balls accurate" !!!!  ;D
If it ain't broke-------------------------- fix it 'till it is!

Royal Enfield Miltary 500cc  (2003)
Honda VTR FireStorm (SuperHawk) 996cc 'V' twin
Kawasaki KR1 250cc twin 'stroker
Ducati 916 'L' twin

cyrusb

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Re: R.P.M @ 60 (55)
« Reply #13 on: March 14, 2008, 10:05:12 PM »
Its an industry term!

LotusSevenMan

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Re: R.P.M @ 60 (55)
« Reply #14 on: March 15, 2008, 04:46:26 PM »
Maybe I'd better not ask which 'industry' if it turns out to be the worlds oldest profession  ???  :o
If it ain't broke-------------------------- fix it 'till it is!

Royal Enfield Miltary 500cc  (2003)
Honda VTR FireStorm (SuperHawk) 996cc 'V' twin
Kawasaki KR1 250cc twin 'stroker
Ducati 916 'L' twin