Good info to understand , 500 vs 450 bore and HP, numbers are exaggerated for illustration purposes
- Thread starter byeatts
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If you take the same gearbox and put on a 450 and a 500 and ride in the same gear at 5000 rpm they will both have identical track speed , However at full throttle the 450 will have significantly more track speed 5-7 mph in most cases due to the much higher RPM.For my style riding i prefer the 450,s RPM and over rev, For a grunt motor the 500 may be preferred for some.
Nice. What was the spike sticking off the bottom of the crank on the demo video? The over Rev does help a bunch.
Believe thats for oil distribution.
I assume you mean "at max rpm..." rather than "at full throttle..." since a bike can be "at full throttle" (aka wide open throttle) at any rpm. But I agree with the notion of what you are saying regarding the higher rev ceiling of a 450 adding some flexibility by virtue of any given gear spanning a wider rpm range. The caveat there being a 450 will already be up close to its max rpm/rev limiter to make max hp just like the 500 is when it's making max hp. Track speed at any given rpm will simply be a mathematical product of engine rpm, the gear ratio of any given transmission gear at a given time and the gear ratio of any given snowbike kit (stock or re-geared). Put another way, if, instead of your example of two identically geared 450 and 500 bikes starting at the exact same rpm (which would have the 450 making quite a bit less hp at that low rpm), I contend one should start that comparison with the two bikes running at whatever rpm where each makes max hp since a 450 and 500 make about the same hp but at very different rpm. Then, gear each bike and snowbike kit so the track speed is identical between the two at that starting point. From that point, they both are making about the same hp, have the same track speed, and both have about the same amount of headroom before they hit the rev limiter and require shifting. The 450 revs to a higher rpm but that is where is makes its max hp and so will spend it's time at a higher rpm range than the 500 in order to make the same hp but both will be operating within an rpm range that is about the same distance from each bikes rev limiter.
Drifting off topic, but somewhat related, where I found the wider rpm range of a 450 valuable was when switching from a wide ratio 500 to a close ratio 450. I used to prefer a 500 wide ratio snowbike but after a couple of those, now prefer a close ratio 450. I thought the close ratio 450 would be busier to ride and that it would require more shifting, but with the higher rpm ceiling of the 450, I've found the close ratio 450 has a wide enough spread of track speed to make up for the wide ratio gearing and more torque of the wide ratio 500. Particularly in casual riding, I found that I don't have to shift any more often than my previous two wide ratio 500 snowbikes so it doesn't feel any busier. The added benefit of the close ratio has been when on a long, steep, uphill run, and I do have to downshift, the next lower gear is the perfect spacing compared to the huge jump encountered with the wide ratio bikes which inevitably lead to being immediately at the rev limiter and would actually slow down track speed and ground speed because of it. The only con to the close ratio has been lack of high speed/low rpm gearing for the trail ride in and out. If money and time were no object, I'd crack open the case and swap my top gear for a really tall enduro gear from a wide ratio transmission which would allow for faster speed and lower rpm trail riding without impacting powder gearing since I use gears 1 - 4 (and most often 2 and 3) in the deep stuff.
I'm pretty sure the Boondocker tune on my KTM 500 raised the rev limiter substaintailly and there haven't been any issues
You can raise the limiter to the moon however the physics of the long stroke will never run at the same rpm as a 450. The longer stroke takes more time on every stroke, These are physics and the dynamics of the stroke length. The 350 will run 13000 rpm and a 450 will never spin at that rate.
Interesting and informative video...I have watched it several times over the last couple of years.
So having said that...both the 450ktm and the 500 ktm have bores much larger than their respective strokes.
The 450 has a 95mm bore and a 63.4mm stroke
The 500 has a 95mm bore and a 72mm stroke or about .33 of an inch longer stroke than the 450.
A 450 is really 449cc's
A 500 is really 510cc's
Given this information...I will tell you that on a dyno...doing the exact same mods to each of the motors...14:1 compression piston, cam, exhaust, intake, throttle body, ported head, etc...the 500 makes both more torque and horsepower than the 450 motor does...within 500 rpm difference on the top end...with the torque curve and horsepower curve being quite a bit broader on the 500.
Heck...if you add a 490 kit to the 450 with all of the mods listed above...it still doesn't produce the horsepower and torque of the stock bore 500 with the same mods....with both motors now turning the exact same peak hp rpm.
These 2020+ ktm 500's like to rev!
My big bore 500 (now 550cc's, 98.5mm bore) has its peak hp at 9450, and easily revs to 11k rpm. (You have seen the dyno sheets)
This bike now has its track on it so no more dyno time until summer time.
If you don't believe me...contact Lloyds Performance or Built Motors or AirForce Intakes or Web Cams or DC cams to name a few...they have all built higher hp 500 based engines than their previous 450 based ventures.
Building high hp dirt bike motors is all about getting the best bore to stroke combo to match the other intake and exhaust flows. For 2020+ the 500's finally got a 450sx based head so that it could breath. We all like revvy motors so having a bigger bore than stroke is a must. Both the current ktm/husky 450/500's have much larger bores than strokes. The current generation of 500's are making more hp and torque when modified than the 450's. Plus...there is no replacement for displacement.
If you would like me to post up dyno sheets AGAIN...I will. I seem to be one of the few to do this instead of just posting my opinion...hmm
Have fun out there on your snow bikes...and be careful...the snow is deep and fluffy right now.
Chris
So having said that...both the 450ktm and the 500 ktm have bores much larger than their respective strokes.
The 450 has a 95mm bore and a 63.4mm stroke
The 500 has a 95mm bore and a 72mm stroke or about .33 of an inch longer stroke than the 450.
A 450 is really 449cc's
A 500 is really 510cc's
Given this information...I will tell you that on a dyno...doing the exact same mods to each of the motors...14:1 compression piston, cam, exhaust, intake, throttle body, ported head, etc...the 500 makes both more torque and horsepower than the 450 motor does...within 500 rpm difference on the top end...with the torque curve and horsepower curve being quite a bit broader on the 500.
Heck...if you add a 490 kit to the 450 with all of the mods listed above...it still doesn't produce the horsepower and torque of the stock bore 500 with the same mods....with both motors now turning the exact same peak hp rpm.
These 2020+ ktm 500's like to rev!
My big bore 500 (now 550cc's, 98.5mm bore) has its peak hp at 9450, and easily revs to 11k rpm. (You have seen the dyno sheets)
This bike now has its track on it so no more dyno time until summer time.
If you don't believe me...contact Lloyds Performance or Built Motors or AirForce Intakes or Web Cams or DC cams to name a few...they have all built higher hp 500 based engines than their previous 450 based ventures.
Building high hp dirt bike motors is all about getting the best bore to stroke combo to match the other intake and exhaust flows. For 2020+ the 500's finally got a 450sx based head so that it could breath. We all like revvy motors so having a bigger bore than stroke is a must. Both the current ktm/husky 450/500's have much larger bores than strokes. The current generation of 500's are making more hp and torque when modified than the 450's. Plus...there is no replacement for displacement.
If you would like me to post up dyno sheets AGAIN...I will. I seem to be one of the few to do this instead of just posting my opinion...hmm
Have fun out there on your snow bikes...and be careful...the snow is deep and fluffy right now.
Chris
I have totally uncorked 500 in my trailer full exhaust ,ecu ect. It makes power lower in the RPM and that does not equate to track speed. The 450 has much higher track speeds. The 500 does not Rev near as high do to physics. Its a lower grunt power delivery . to each his own but side by side the properly setup 450 kills it . HP alone does not make a great snowbike its RPM and the over Rev that builds track speeds, The 500 is a better choice for those using in it the dirt for summer.
To each his/her own...whatever makes you feel good about your particular riding experience.
If you feel that a lower horsepower and lower torque motor spinning 11k rpm is better than a higher horsepower and higher and broader torque motor also spinning 11k rpm is better....then have at it.
In thinking about it a great deal...specifically on the 2020+ 450's and 500's...and talking with both Brock Buttars and David Lloyd about this topic...I think what you are mostly feeling is the difference in flywheel weight...which controls how quickly the motor spools up. The 450 flywheels are quite a bit lighter than the 500 flywheel...with the 450sx flywheel being the lightest, and therefore spooling up the quickest. Brock (who is a pro-level rider) likes the feeling of the lighter 450sx flywheel on any of his his setups...including his 550... the lighter flywheel explodes through the rpm range and revs noticeably quicker than the heavier 500 flywheel...thus causing more track acceleration. I on the other-hand, prefer the heavier stock 500 flywheel because it makes the bike more controllable for my 60 year old, out of shape, self.
It makes sense to me that if you have less hp and torque you would want to spool the motor as quickly as possible in order to get it into its happy place...because it has a narrower powerband, you want to keep it there.
It also makes sense that since kits and rider weights vary so much...what works for one person or kit, might not be ideal for another.
Chris
Bottom Line Racing
If you feel that a lower horsepower and lower torque motor spinning 11k rpm is better than a higher horsepower and higher and broader torque motor also spinning 11k rpm is better....then have at it.
In thinking about it a great deal...specifically on the 2020+ 450's and 500's...and talking with both Brock Buttars and David Lloyd about this topic...I think what you are mostly feeling is the difference in flywheel weight...which controls how quickly the motor spools up. The 450 flywheels are quite a bit lighter than the 500 flywheel...with the 450sx flywheel being the lightest, and therefore spooling up the quickest. Brock (who is a pro-level rider) likes the feeling of the lighter 450sx flywheel on any of his his setups...including his 550... the lighter flywheel explodes through the rpm range and revs noticeably quicker than the heavier 500 flywheel...thus causing more track acceleration. I on the other-hand, prefer the heavier stock 500 flywheel because it makes the bike more controllable for my 60 year old, out of shape, self.
It makes sense to me that if you have less hp and torque you would want to spool the motor as quickly as possible in order to get it into its happy place...because it has a narrower powerband, you want to keep it there.
It also makes sense that since kits and rider weights vary so much...what works for one person or kit, might not be ideal for another.
Chris
Bottom Line Racing
My 450 also made over 72 on Llyods dyno. and Karsons personal 450 reads 74 on it. Same as your 500 CB BLR . I can tell you that the extra rpm I get when LLoyd's has my rpm at 12k is significant for snowbiking. You can make power with both and I agree the 500 on average modded is more power number wise.
There is no right answer, as they both excel at different things. the 500 will not lug down as quick, it may hold higher track speed up a steady slope given it is in the powerband.
The 450 will rev out faster not only because the flywheel but because the shorter stroke. It will accelerate faster on medium load, feel more nimble. It will pull wheelies alot better with more lift quicker and longer, you have better gearing and power band due to more available power across entire RPM. In some cases the 450 will be faster because it will be making more power to the ground at certain track speeds.
So yes if you only care about speed up long steady slopes the 500 will downright win. Funfactor and everything else 450.
P
portgrinder
Well-known member
My dad can beat up your dad.
