FJFOOL Posted June 8, 2014 Posted June 8, 2014 My 2000 V11 Sport's numbers just don't seem right. 6th gear, 4,000 rpm shows 55 mph. Sure seems like I'm going faster than that. What do yours read at that rpm ? Thanks!
jwh20 Posted June 8, 2014 Posted June 8, 2014 According to the workshop manual for the V11 Sport the "Total ratio (engine-wheel)" is 1:4.1737 in 6th gear. In other words for every 4.1737 turns of the engine you get 1 turn of the rear wheel. The biggest uncertainty is the circumference of your rear tire but a 170/60-ZR17 should be about 78.64" according to a tire size calculator. At 4000 rpm (engine) you would have 4000/4.1737 = 958.38 rpm of the rear wheel. At 78.64" around, that gives you 958.38 * 78.64" = 75367.18 inches/min. Now just convert to miles/hour... 75367.18 inches/minute * 60 minutes/hour = 4522030.81 inches/hour / 12 inches/foot / 5280 ft/mile = 71.37 miles/hour So unless your rear tire is WAY smaller than it should be, either your tach or your speedo (or both) is way off. Speedo is easy to check with a GPS.
FJFOOL Posted June 9, 2014 Author Posted June 9, 2014 Thanks, I, ll have to check that, might pull off the alternator cover and check the rpm with my photo tach.
AndyH Posted June 9, 2014 Posted June 9, 2014 My tacho is all over the place so is no use in these equations, but my engine is definitely lugging in 6th anywhere below 80mph on the level and I know I can trust the speedo within about 5mph. It'll take me up to an indicated 130+ (good day, following wind, off a cliff etc). I have a 160 section tyre so it'll be spinning more rather than less for the same number of revs than a 170 so 70-ish sounds a bit on the low side to me at 4000 rpm.
FJFOOL Posted June 10, 2014 Author Posted June 10, 2014 Andy, Sounds to me like I need to modify my riding technique on this bike, I may be lugging it too much. Usually shift around 3500 rpm.
dangerous Posted June 10, 2014 Posted June 10, 2014 She just really wakes up at 5,000! hell yeah... 6 even beter LOL At 4000 rpm Mine shows 120 kph which = 74.5 mph same if not a bit faster According to the workshop manual for the V11 Sport the "Total ratio (engine-wheel)" is 1:4.1737 in 6th gear. In other words for every 4.1737 turns of the engine you get 1 turn of the rear wheel. The biggest uncertainty is the circumference of your rear tire but a 170/60-ZR17 should be about 78.64" according to a tire size calculator. At 4000 rpm (engine) you would have 4000/4.1737 = 958.38 rpm of the rear wheel. At 78.64" around, that gives you 958.38 * 78.64" = 75367.18 inches/min. Now just convert to miles/hour... 75367.18 inches/minute * 60 minutes/hour = 4522030.81 inches/hour / 12 inches/foot / 5280 ft/mile = 71.37 miles/hour So unless your rear tire is WAY smaller than it should be, either your tach or your speedo (or both) is way off. Speedo is easy to check with a GPS. HUH? fark happened just then ;-)
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