sh*t is fast i had my trail tech hooked up and it is accurate i checked riden by another car and i was only in 5th
blaster did 58mph
- Thread starter 06blasterboy06
- Start date
My friend's old Blaster with the OEM tires had a 14 tooth front sprocket and Toomey B1 and he could top out about 1mph less than a 400ex...it was close, so he was probably around 65ish.
its pretty easy to debunk top spped myths
Use the formula
MPH= TIRE RADIUS / 168 X ENGINE RPM / GEAR RATIO.
If I could get you guys to do this then I could stop cause I HATE MATH
Anywho
The formula is simple you just gotta do some work to get the numbers.
We know the stock engine will pull 8500 rpm. So let’s just say for $hits and giggles that with all the added power of a pipe, reeds etc the engine will pull 9000rpm
We first have to figure out what the engine drive/output shaft rpm is, not the crank rpm.
So we know by looking in a manual that the primary reduction is 71/22 that = 3.227
9000/ 3.227 = 2789
The gear ratios are the following
1st 34/11 = 3.091
2nd 31/14 = 2.214
3rd 25/15 = 1.667
4th 20/16 = 1.250
5th 19/18 = 1.056
6th 19/21 = 0.905
We know the 6th gear ratio is .905
2789 / .905 = 3082
3082 is the counter shaft rpm (or engine output rpm at 900rpm in 6th gear)
If the final gear ratio is 38/14
38/14 = 2.71
If the tire size we are dealing with is 18" so the radius is 9"
Now we can figure out a top speed. It should look like this
MPH= TIRE RADIUS / 168 X ENGINE RPM / GEAR RATIO.
MPH= 9 / 168 x 3082 / 2.71 = 60.9 mph
But remember this is what you bike is capable of on paper this does not take into account for rider weight, wind resistance, drag etc.
If I were to take a guess the average top speed of a bike that shows 61 mph on paper would be around 56-58 mph.
if larger tires were used to speed would be about 2 mph faster for 20 and another for 22
Use the formula
MPH= TIRE RADIUS / 168 X ENGINE RPM / GEAR RATIO.
If I could get you guys to do this then I could stop cause I HATE MATH
Anywho
The formula is simple you just gotta do some work to get the numbers.
We know the stock engine will pull 8500 rpm. So let’s just say for $hits and giggles that with all the added power of a pipe, reeds etc the engine will pull 9000rpm
We first have to figure out what the engine drive/output shaft rpm is, not the crank rpm.
So we know by looking in a manual that the primary reduction is 71/22 that = 3.227
9000/ 3.227 = 2789
The gear ratios are the following
1st 34/11 = 3.091
2nd 31/14 = 2.214
3rd 25/15 = 1.667
4th 20/16 = 1.250
5th 19/18 = 1.056
6th 19/21 = 0.905
We know the 6th gear ratio is .905
2789 / .905 = 3082
3082 is the counter shaft rpm (or engine output rpm at 900rpm in 6th gear)
If the final gear ratio is 38/14
38/14 = 2.71
If the tire size we are dealing with is 18" so the radius is 9"
Now we can figure out a top speed. It should look like this
MPH= TIRE RADIUS / 168 X ENGINE RPM / GEAR RATIO.
MPH= 9 / 168 x 3082 / 2.71 = 60.9 mph
But remember this is what you bike is capable of on paper this does not take into account for rider weight, wind resistance, drag etc.
If I were to take a guess the average top speed of a bike that shows 61 mph on paper would be around 56-58 mph.
if larger tires were used to speed would be about 2 mph faster for 20 and another for 22
its pretty easy to debunk top spped myths
Use the formula
MPH= TIRE RADIUS / 168 X ENGINE RPM / GEAR RATIO.
If I could get you guys to do this then I could stop cause I HATE MATH
Anywho
The formula is simple you just gotta do some work to get the numbers.
We know the stock engine will pull 8500 rpm. So let’s just say for $hits and giggles that with all the added power of a pipe, reeds etc the engine will pull 9000rpm
We first have to figure out what the engine drive/output shaft rpm is, not the crank rpm.
So we know by looking in a manual that the primary reduction is 71/22 that = 3.227
9000/ 3.227 = 2789
The gear ratios are the following
1st 34/11 = 3.091
2nd 31/14 = 2.214
3rd 25/15 = 1.667
4th 20/16 = 1.250
5th 19/18 = 1.056
6th 19/21 = 0.905
We know the 6th gear ratio is .905
2789 / .905 = 3082
3082 is the counter shaft rpm (or engine output rpm at 900rpm in 6th gear)
If the final gear ratio is 38/14
38/14 = 2.71
If the tire size we are dealing with is 18" so the radius is 9"
Now we can figure out a top speed. It should look like this
MPH= TIRE RADIUS / 168 X ENGINE RPM / GEAR RATIO.
MPH= 9 / 168 x 3082 / 2.71 = 60.9 mph
But remember this is what you bike is capable of on paper this does not take into account for rider weight, wind resistance, drag etc.
If I were to take a guess the average top speed of a bike that shows 61 mph on paper would be around 56-58 mph.
if larger tires were used to speed would be about 2 mph faster for 20 and another for 22
We ran into one of the biggest bullshitters of all time down at Wayne. He had a 250R Honda and was telling this group of kids his 250R could hit 200mph.....and no he wasn't leading them on and yes he was serious. 8-| I really wanted to go over there and call this guy out on his bullshit but you could tell he was just one of "those guys" so I didn't even waste my time. I went over after he left and let the kids know that he was a total assclown and it wasn't possible(common sense). What's sad is 1 dumbass kid even had the audacity to say "I don't know man....those 250R's are pretty fast...he might be for real".
Blaner
Your Friendly South African Ambassador
hahaha, some dudes.. but good info yfs101, you should put that stuff into a seperate thread and add to it with some more figures and get it stickyd for us who like to crunch numbers
Ive owned a banshee and a 250R trike.
The 250r was the faster of the two, modified I was able to amp up the gearing to get 100mph out of it. The banshee could be done but it costs 2X as much to build them up and thats the only reason Im not a big fan of the shee anymore.
The blaster is still my favorite. Small and very basic, cheap to maintain, build up and ride.
The formula work for ANYTHING.
MPH= TIRE RADIUS / 168 X ENGINE RPM / GEAR RATIO
The only difference will be your final gear ratio and tire size. A stock blaster or even lightly modified will run 8500. I piped with head work and portwork will run 9000. however most fall off the powerband and have a hard time pulling the extra 500 rpm.
The 250r was the faster of the two, modified I was able to amp up the gearing to get 100mph out of it. The banshee could be done but it costs 2X as much to build them up and thats the only reason Im not a big fan of the shee anymore.
The blaster is still my favorite. Small and very basic, cheap to maintain, build up and ride.
The formula work for ANYTHING.
MPH= TIRE RADIUS / 168 X ENGINE RPM / GEAR RATIO
The only difference will be your final gear ratio and tire size. A stock blaster or even lightly modified will run 8500. I piped with head work and portwork will run 9000. however most fall off the powerband and have a hard time pulling the extra 500 rpm.
The problem with going fast on quads, trikes, bikes, etc. is that they are aerodynamically inferior and on off road vehicles, the tires can not handle that kind of velocity before they go boom at 100+mph and you say bye bye to your life.
You got it. trikes are a lot smoother at high speeds due to the lack of touchy steering control. not sure I would want to try it on a quad with stock suspension dimentions... shakey ride
I could get about 15 miles out of my tank with the 250r.
here is a formula you can use on any engine and vehicle.
RPM / Primary Ratio / Gear ratio / Second Ratio (final ratio or sprocket ratio)
like yfs101 said, this is the rpm the tire is turning
then take that number
RPM of tire * pi * (diameter of tire)
this is now how fast you are moving in in/min
you need to convert this to mph so
in/min of tire * 60 / 12 / 5280
this is now the mph of the vehicle.
so using 9000rpm on a blaster with 21" stock tires and stock gearing (13/40) the speed will be 62.5 mph in sixth gear.
if you was in fifth at 9Krpm, you would only be going 53.6mph.
if you change that to 10Krpm, in 5th you would be going 59.6 and in 6th 69.5mph
RPM / Primary Ratio / Gear ratio / Second Ratio (final ratio or sprocket ratio)
like yfs101 said, this is the rpm the tire is turning
then take that number
RPM of tire * pi * (diameter of tire)
this is now how fast you are moving in in/min
you need to convert this to mph so
in/min of tire * 60 / 12 / 5280
this is now the mph of the vehicle.
so using 9000rpm on a blaster with 21" stock tires and stock gearing (13/40) the speed will be 62.5 mph in sixth gear.
if you was in fifth at 9Krpm, you would only be going 53.6mph.
if you change that to 10Krpm, in 5th you would be going 59.6 and in 6th 69.5mph
The most power ful Blaster I built was based on the Mac Dizzy build, but slightly different specs, lightened flywheel, lightened counter balancer, 1/2" reed spacer, Cr cage, toomey pipe. etc. aprox 9000rpm was the highest this lil engine would pull.
tuned using digitron EGT/CHT.
if you had a full out drag engine MAYBE you would get 10k out of it but I doubt it
tuned using digitron EGT/CHT.
if you had a full out drag engine MAYBE you would get 10k out of it but I doubt it
58 mph thats good what gearing do u have? my blaster (totaly stock just got wheel spacers) hit 54.6 mph yesterday and i could not push it any harder without blowing the engine
yep thats about right.
some clain to get a bit more out of it with race fenders etc but really what is the point of 1-2 mph...
in was in 5th gear i have 14/40 gearing jeteed and bored 80 over i dont know what size tier i got im new at atv but man this thing could move i bought this used i do not know what else in the engine it was in high rpm's man no bs i no people come on here and bs but there is no need to and that guy with that 250r is bs i just blow 1 a way unless he has a jap motor cycle motor in there like gsxr then yea
You won't blow the engine. You can peg it in 6th and it will be fine. It will be limited by gearing, drag, weight, etc by that point in most scenarios. Either that or you will just be past the powerband and won't be going any faster.
baaaaaahahahaa god i love when these blaster top speed threads come up . at least this time it seems about reasonable lol I:I
. at least this time it seems about reasonable lol I:I
just going by what i estimate mine can that calculator seems more accurate than the gearing calculator that is here someplace
now im going to change my back sprockets to a 38 and i got the jetting and pipe and its bored our 80 over i had me when that power band kicked right in wow my goggles got stuck to my face i have some pics where i was riden all sand like for a couple of miles o man it was great until my back tier all most feel off i put my new rims on and didnt screw them in tight
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