Acceleration

Derek,

I have worked out a way for you to stay the same weight but get the acceleration you need, 12 tooth front 60 tooth rear, of course it will be even better if you use a 21,26 output pair. Not sure you will have enough top speed but if you can get it rev on to say 20,000 should be ok

Good reaseach James .... Derek - You must have the big back sprocket? Didn't you use a 74t at three sisters once? Nearly the same dia as an 18" rim!! lol

Mike

james "pack it in" -

but great maths on the formula now "if im running 22/25 top with a 21 26 middle pair / and doing 10,700 with a 16 x 54 what is my top speed ? the only person Iknow who has the formula for this is John senddle in NZ.

Seriouse point on revs, many many moons ago we did see over 15,000 on the rev counter we were karting in the BM class 1 100cc at the time, and modified ports and pipe accordingly, wednesdat test mallory - it did/would not pull the lid off rise pudding, it did wear everything out and very quickly, and touched the head even with a squish of 1.6mm and burnt out two clutches the same morning - usable power is what we need, I believe in Alan I think we all need more talk" TORQUE"!

Hi Mike -blimy what a memory ? sorry you are guessing 76 ? 80 I think, but will check it still have it,

But Mike is correct- it's as big as the rim, and yes its at three sisters too - never did any good though.

Derek

That would be 99.34 mph

regards Mark

Ah Mark, but was is it in bottom and second with the rare output gears and second gear sliders??

Hope your bike is up and running and ready to go..... any pictures?

Mike

Hi Mike,

Calculations were made with the rare output gears and second gear sliders, but top speed would be no different as 3rd gear is direct drive through the mainshaft to output!

The bike is coming along must get some pictures on the forum, still plenty to do but the engine is ready to go thanks to Brian.

Mark

Mark there arn't any gearbox calulations for top gear. Only primary 17/38(engine sprocket/Clutch) and
secondary gearing 16/54. Gearbox in to is 1:1 regardless of any gears(teeth).

Taken from a 'Speed Chart for Dunlop K18 Tyre(TT100)' written by Mick Scutt BRC mag 216 circa 1981:-

16x54 has a value of 9.03 times by 10.7 (for the revs 10'700) = 96.62 and round up '97mph'

Now with std c/r box 96.62 x 0.84 = second gear = 81mph

Bottom gear 96.62 x 0.77 = 74mph

Don't know what second and bottom gear ratio are with Snell output pair and D1/3 trails competition sliding gears ... James where your 'Maths'

Regards Mike

My Maths say


For l = 1 To count
first = (d / c) * g * (rw / gs)
first = (srev / first) * b
first = first / a
second = (d / c) * f * (rw / gs)
second = (srev / second) * b
second = second / a
third = (d / c) * e * (rw / gs)
third = (srev / third) * b
third = third / a
'output value, Front sprocket size, rear sprocket size, result
r = tbl.NewRow()
r("RPM") = srev
r("First (MPH)") = first
r("Second (MPH)") = second
r("Third (MPH)") = third
tbl.Rows.Add(r)
srev = srev + revgap


does that help

No! but it looks impressive!

Actually on std CR box - Mike is spot on, I was timed with a radar gun at the end of 100meter board at back straight at Snetterton back in the day, 1989 the following top speeds were recorded.
the sheets read.

TOP SPEEDS.
Derek Betts 96.9mph
Brian White 95.4mph
Mike Powell 91.6mph
John Sawyer 92.0mph
Peter Tibbetts 90mph
Mark Carkeek 88mph

Amazing :- This surprised a few people in the paddock, as timed sheets do not lie ? there was talk of the top three doing well over 105 OR 107MPH ?? Like TrevorAmos says when the flag drops the bullshit stops. JAMES THERE IS A BIG DIFFERENCE BETWEEN CALCULATED AND ACTUAL, THE SAME CAN BE ALIED FOR BHP

Mark-k did have a lot of DNF that year, but there was nothing between him Mike and Peter, I usually followed these three in with brian or john, when Mark's bike lasted the distance he usually won, but towards the end of the season Mark became un-catchable, his times at Pembrey were simple astonishing, speed for a bantam !. I know the Fox has since beat these times, but they are not down on this site, ? The Fox" knows this, what I believe is an attempt to hide his true speed. !!

anyway moving on, In the above timed speed race, I actually had a race long battle with Brian W and John S, it was one of the most fun rides, similar to the Pembrey one with the FOX, simply nothing comes close to having a race long battle where your constantly changing, but win or lose does not matter, slip-streaming is a great fun, my bike was taking longer to get there, but had a similar top speed, only at the very last 100meters before the board 100m board, truly memories I will cherish.

I still have the print outs, there are several with slightly varying speeds but the above prints were the fastest of all, and done by a police officer who donated a day for the club after Jane & chris some how twist his arm to do it for the club, she always was the king, when came to getting things like this done and organised.

For me great development years in my life, and truly great memories, others must have similar calls.

James great maths again could you do a similar thing for the exhaust gas temp and variation in sonic wave speed seems we have a genius in our group, we need to use this as a resource could create an interesting topic,



When we get Trevors, bit i have asked for, maybe we can put this information on a std page for all to view so never lost to view from time to time.


kind regards Derek