# This is how fast your 2007 WR450 will go...

40 replies to this topic
• # Justang

Posted February 25, 2008 - 09:28 AM

You had calculated in drive train loss for max speed, which isn't needed or correct. That was what I was referring too.

I've tried to get the correct math, but I just can't seem to get it. Using my old formula's for my Mustang and Tundra (I did this to show the cruising and top speeds in all gears with different gear ratio's) it says you'll go 105mph in 1st on the WR. ha ha. I did get one formula to say 34mph in 1st at 11500 red line, but even that seemed to high.

I don't have my bike in the garage this week, so I can't go and test it out.
Are you using the standard rear tire to get these figures? 110/100/18, which is what I believe stock is. It's 26.6" diameter tire.

Can you share the formula? I'm curious.
here's what I did for my Tundra: http://3.8mustang.co...undra gears.xls
I'd like to do that with the WR as well.

• # rbn14

Posted February 25, 2008 - 01:03 PM

I wouldnt say I calculated drive train loss or that I did it incorrect. I just simply compared what I have found to me the max speed with the calculated based on gearing and rpm. 1 - 84/114 = 0.26 or 26%.

For tire diameter I used 27". I pulled this off the Dunlap site for a 110/100 D739 AT since I like this tire. The stock tire (D756) is 27.1" according to the site. This doesnt much of a difference and is highly variable depending on rider weight and tire pressure.

As far as the equations go, it's pretty easy... MPH = (RPM*Tire Diameter)/(Gear Ratio*336)
Where
Gear Ratio = Primary Ratio*Transmission Gear Ratio (1st, 2nd, etc..)*Final Ratio

I can email you the file if you like.

• # rbn14

Posted February 25, 2008 - 01:09 PM

Here is a copy of the file. This one is setup to compare two different gearing setups.
http://www.mediafire.com/?kstw1hho9yt

• # tweav

Posted February 25, 2008 - 02:03 PM

I'm fairly sure that the stock rev limiter is below 11000 . I will check the next time I ride , but I'm still waiting for my rear spocket.like 10500 or 10600

• # Justang

Posted February 25, 2008 - 02:09 PM

Try this for the stock wheel size.

Tire diameter = [(width in mm * aspect ratio)/25.4]*(2)+wheel diameter

[(110*1.0)/25.4]*(2)+18 = 26.6.

Anyway, I did the calculations for the 26.6 and it's negligible. But using those calculations the chart is true. And looking at my cruising speed at 4k in 1st gear it would appear to be true. I just never thought 40mph in 1st was possible. Now I wanna get my bike back and see.

Here's my chart:
http://www.3.8mustan... gear ratio.xls

Each gear has it's own sheet, look at the bottom for the tabs to move through the sheets.

• # Justang

Posted February 25, 2008 - 02:10 PM

I thought the stock rev limiter is 11800ish.

• # rbn14

Posted February 25, 2008 - 02:27 PM

Unfortunately using the tire size doesn’t really work. Pretty much all the manufactures list actual tire sizes on their websites and none of them are what you get if you calculate it, let alone between different brands.
I don’t think you are ever going to see 40 in 1st, it's just not going to happen, just like you wont see 100+ in 5th with stock gearing, jetting, and the free mods. To actually achieve the figures in the chart would require perfect traction, no wind-resistance, no engine, transmission, or drive system friction, and no rider. Not to mention another 100 factors that are being ignored (You seem to understand this Justang). My hopes when starting this thread was to stop some of the BS surrounding this topic.
But, it is a useful way to look at relative changes due to gearing.

• # Justang

Posted February 25, 2008 - 04:55 PM

I think I had my bike up to 80ish in 5th on a long dirt road.
I can't wait to get my bike back to my house so I can check out what I can do in 1st.

• # srfdwg2

Posted February 25, 2008 - 06:20 PM

Kevin where you at?

• # El Monstro negro

Posted February 25, 2008 - 06:27 PM

In the real world KTMs FInish first sell that blue bike and by a KTM:thumbsup:

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
• # rbn14

Posted February 25, 2008 - 06:43 PM

In the real world KTMs FInish first sell that blue bike and by a KTM:thumbsup:

Um, ok.

• # tweav

Posted February 25, 2008 - 07:39 PM

Unfortunately using the tire size doesn’t really work. Pretty much all the manufactures list actual tire sizes on their websites and none of them are what you get if you calculate it, let alone between different brands.
I don’t think you are ever going to see 40 in 1st, it's just not going to happen, just like you wont see 100+ in 5th with stock gearing, jetting, and the free mods. To actually achieve the figures in the chart would require perfect traction, no wind-resistance, no engine, transmission, or drive system friction, and no rider. Not to mention another 100 factors that are being ignored (You seem to understand this Justang). My hopes when starting this thread was to stop some of the BS surrounding this topic.
But, it is a useful way to look at relative changes due to gearing.

I think the highest speed I saw with the stock gearing was like 92 or 93 on the road screaming . and never 40 in first gear maybe 35 but I don't think so more like 32

• # esbotto

Posted February 25, 2008 - 07:41 PM

In the real world KTMs FInish first sell that blue bike and by a KTM:thumbsup:

Imagine that. A 530 is faster than a 450. Go figure.

• # tweav

Posted February 25, 2008 - 07:59 PM

Imagine that. A 530 is faster than a 450. Go figure.

I bet my old beat to death cr500 will still give those 530's a run for their money

• # kevinwr450f

Posted February 26, 2008 - 09:21 AM

Kevin where you at?

Sorry DWG I was in S. Fl.......

• # Speedracer747-400

Posted March 01, 2008 - 04:01 PM

Motorcycle Gearing Worksheet

www.4strokes.com/tech/gearing_calc.xls

• # Justang

Posted March 02, 2008 - 01:39 PM

I think i got just over 30mph in 1st.
and the redline is 10800.

• # Raider50

Posted March 07, 2008 - 09:30 PM

i had my friend drive beside me on the highway and I did 90mph and its a 05' completely stock wr450. I figured that isnt to bad considering i out weigh the bike by about 40 pounds . It got a little hairy tho those there were frost heaves in the road, i saw my life flash before my eyes lol.

• # djrevz

Posted March 08, 2008 - 03:22 AM

what program can i use to open these files?

• # djrevz

Posted March 08, 2008 - 03:26 AM

what i cant believe is i have a kmx 125 and i can get 90mph no wind screaming and know i have a wr426 and that goes the same top speed i upgraded to get more acceleration and expected more top end as well but i guess not what a PLANK lol