Revs/speed

[Richard Kuysten]

#3011

I'm sure there's a way to figure out ones engine revs at a given speed but don't know how to do it – can anyone help please? This is for the Sherpa by the way 😉

[Anonymous]

#12335

Hi MalcolmA. RPM / primary ratio / gear ratio / final reduction ratio = Wheel RPMWheel RPM x 60 = Wheel RPH (hour)B. 1000 / wheel circumference (m) = Wheel revs per kmWheel RPM / Wheel RPK = KPHExample:A. 6000rpm / 2.8 (Sherpa primary) / .851 (6th gear) / 3.071 (14/43 tooth sprockets) = 820 Wheel RPM = 49,200 Wheel RPHB. 1000 / 2.07m (based on 660mm diameter 4.10 x 18) = 482 Wheel RPK49200 / 482 = 102 Kph @6000rpmSound close?  There may be differences in the diameter of the tyre, so adjust as necessary.Cheers,DTY

[Richard Kuysten]

#12336

Almost too complex for this old brain Dave – but after a few reads yes it does add up.  I haven't gotten around to checking the Sherpa specs but I figure you've beaten me to it anyway? The reason for my query was because I was wondering what was a reasonable cruising speed on the little machine over an extended ride so as not to overtax the motor.  I have no idea what the red line is on the bike but I guess it's when the limiter cuts in.  Many thanks for you help.Malcolm

[Anonymous]

#12337

Based on this page: http://www.edgeperformance.ca/kawasakioffroad-2007/motorcycle-4.html, max torque occurs at 6000rpm, while max power occurs at 8000rpm.  That's where I got the ratios too.Riding around at peak torque is where your motor should be happiest.  Saying that, I haven't found a torque curve for that bike, so we don't know how flat it is.  I suspect you'd have at least 500rpm either side of that 6000 to play with.Based on the above calculations:5500rpm = 93.5kph6000rpm = 1026500rpm = 110.57000rpm = 119and so on...If you measure the diameter of your rear tyre, we can hit it exactly.DTY

[Dave Ross]

#12338

Malcolm, Paul Edlington has a Sherpa in his garage. It belongs to a friend who uses it for long tours when in new Zealand. The guy is pretty big according to Paul and has full luggage with him. He said that Sherpa has had no problems with the weight and still manages a respectable cruising speed and goes up hill easily.I wouldn't worry about it,  these things are tough as nails. I doubt you'll harm it.

[Richard Kuysten]

#12339

Thanks guys, as you say Dave a couple either way probably doesn't matter and it's very comfortable at 100 – 105 and has shown 110 + in good conditions but I'm not into thrashing it.  Just musing really in case I want to do an extended ride one of these days  😀  I keep getting restless when I see Alex and the others going off on their forays into the wild.  Yes Alex I've talked to Paul abouth his mates bike - although I haven't seen it as it's stored down south now awaiting it's owners return to complete his trip.  I was chatting to Mark Waters a couple of days ago and he took his DZ 250 to Queenstown and back for a couple of weeks over Easter covering most of the well known trails and tracks between here and there and had a ball. 

[Ron McFadzien]

#12340

Thanks guys, as you say Dave a couple either way probably doesn't matter and it's very comfortable at 100 - 105 and has shown 110 + in good conditions but I'm not into thrashing it.  Just musing really in case I want to do an extended ride one of these days   😀  I keep getting restless when I see Alex and the others going off on their forays into the wild.  Yes Alex I've talked to Paul abouth his mates bike - although I haven't seen it as it's stored down south now awaiting it's owners return to complete his trip.  I was chatting to Mark Waters a couple of days ago and he took his DZ 250 to Queenstown and back for a couple of weeks over Easter covering most of the well known trails and tracks between here and there and had a ball. 

Hello Malcolm, we have one of these (SHERPA) in the shed aswell it has done about 1800kms now when we bought it, it had had a 1 tooth larger front sprocket fitted to it. It gets along well with me on it on the open road at 100 kms in 6th gear, the motor sounds just fine at this speed, if you knock it back down a gear and gas it it still has plenty of revs left in it. I will have a look at the owners hand book and see what it recommends for gear change versus KPH for you.Regards boGSer

[Richard Kuysten]

#12341

Howdy G, Thanks for your input.  I do have the owners manual but can't find anything useful regarding engine speed v road speed.  It gives change up and down speeds but doesn't relate these to RPM or say anything about cruising speed/revs.  I'm sure DTY is right and the gear ratios are in the book so could be used to give a pretty good idea.  If I was to ride to Palmy I would be happy to cruise along at the legal limit give or take a few.  My reason for putting the question was not because I was at all worried – just curious and I doubt my riding style will over stress anything.  Hi to CathyTake careMalcolm

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