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If it is the rider that scrubs everything but then has a last lap time 10 seconds off the previous lap my bet is one muffler is better than two.
Had another guy tell me the secret was throttle body size to muffler core diameter ratio.
The reality of sound testing circa 2015 is the mechanical noise and induction noise sources are conflicting with getting accurate sound measurements. I learned of the extent of this problem at the MXoN in 2014 and provided an isolation blanket the AMA tested at the MEC in 2014 and 2015.
It just isn't the teams that get to try new stuff at the MEC.
The Shop
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Luxon 4-Post Bar Mounts
$189.95 - $239.95
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I'm jus' sayin'...
Ya it might lose some HP, weight a little more, and cost more to replace in a crash but "the future of the sport" makes me think duals just are not that big of a deal.
Example of counter intuitive technique
The Fosbury Flop
This allows the center of gravity to be lowered even before knee flexion, giving a longer time period for the take-off thrust[citation needed]. Additionally, on take-off the sudden move from inward lean outwards produces a rotation of the jumper's body along the axis of the bar, aiding clearance.
Combined with the rotation around the jumper's vertical axis produced by the drive leg (think of an ice skater spinning round on the spot) the resulting body position on bar clearance is laid out supine with the body at ninety degrees to the bar with the head and shoulders crossing the bar before the trunk and legs. This gives the Flop its characteristic "backwards over the bar" appearance, with the athlete landing on the mat on their shoulders and back.
While in flight the athlete can progressively arch shoulders, back and legs in a rolling motion, keeping as much of the body as possible below the bar. It is possible for the athlete to clear the bar while his or her body's center of mass remains as much as 20 cm below it.
There are two categories of techniques where control comes from. One is your body movements, always moving in order to maintain the center of balance.
" When you want more traction in a corner, it's better to have a crouched back. This lowers your bike and body's center of gravity for more traction and control in the corner."
At the same time, it is necessary to keep on pressing the outer stand in order to sustain low center of gravity, especially while cornering without using trail braking.
Athlete uses the front seat to reduce the overall center of gravity of the system "racer - motorcycle" regarding the track surface, loading the front wheel and increase of the coefficient of road adherence.
MX - COG is KEY ! To controlling motorcyle - The faster your go the more it factors.
Body Position
-grab grips up high with a lot of overgrab, this will help you keep elbows up high and to the side
-move upper body side to side, dont twist
-ride with low center of gravity
-attack position, arch your back slightly
-elbows up and out, lean forward, be able to read the number on the number plate
-weight on foot pegs first, on seat secondly not on handle bars
-keep low center of gravity
-make movements from center point
-keep upper body relaxed
-let the bike do all the work for you, dont fight it, flow with it
Remember that adding weight off center in a corner or turn or jump works like a pendulum adding momentum to the pendulum - That is why KEY to control is to remain in front of COG gives you control of the motorcycle - Acceleration moves the COG to the front of the motorcycle.
So when designing sport equipment tennis racquet bicycle MX bike - Its good to know what proper technique is required to do the sport properly or better - Golf club are huge example.
When one considers all these diverse elements, it becomes clear as to why the BMWs are so well suited to this sort of racing. Their very low center of gravity makes the huge petrol tank at least manageable, if not comfortable, and the flat topped crankcase of the boxer engine even provides a large area on which the copious, and essential spares kit can be carried.
More info
https://www.moto101.co.za/bike-of-the-week/33137-1981-bmw-dakar-racer.h…
Mass Centralization #20
Moto3 KTM - 250 cc 4 T
Pit Row
Without a doubt a repack is the cheapest "performance bolt on" going. Nine years ago MXA tested and found a gain of 1.9 hp between 7 and 8K RPM and a foot pound of torque across entire power and just by a fresh repack on a 250F.
Just realized it's your garage door windows. Duh.
I appreciate the opportunity to point out that you (depending if you skill level and type of riding) spent probably 60 to 70 hours on the underperforming machine. Well my 450 has more than enough power you could say. True but this is peak HP. If we were drag racers or road racers it would be a different discussion.
In our sport repacks (as demonstrated in and MXA article in October 2007) restore horsepower between 7k and 8k RPMs and add torque across the power band. On a the KX250F MXA dyno'd the gains were 1.9 horsepower and a foot pound of torque in the ranges I referenced.
You don't have to do a lot of things repacking included. Ask Bryan Friday how much better his CR450F ran after I repacked his stock can.
He can tell is how many hours he had but like you it was a ton.
My advice to people with stock cans is to not repack them but instead go with an aftermarket muffler since they have available spark arrester and or a sound insert. It also helps bike resale to have a bike that can have a spark arrestor. Lot more people ride than race for sure.
Still cannot believe people spend two hundred bucks and labor to bolt a spark arrestor to a stock can when they can spend a little more for an aftermarket muffler AND have a spare muffler.
Like the FMF mega bomb but using more of them like lots of ring donuts that where exact match to the wave form emitted from the exhaust - Well tuned to specifically reduce the waveform as it get emitted. For example a straight pipe would have the exhaust gas wave form bounce up and down along the tube till the end and then return to the exhaust valve where it would cause destructive interference and loss of power ( Reverse of 2 stroke expansion chamber charging the cylinder ) But in effect a expansion chamber for a 4 stroke would not be a straight pipe but a number of increasing concentric donuts if you will such the the cross section would match the waveform of the bouncing exhaust gases offset s fraction so to interfere with and slow the pattern so that the return waveform was reduced significantly.
This same guy have this system patented and the concept used to increases military vehicles performance and fuel economy by 20% - Drive faster use less fuel compared to a standard exhaust system. So he did have some real world cred on his concept.
Did you see the exhaust with the complete circle in its header ?
maximize horsepower gains throughout a broad powerband, while maintaining reasonable sound levels for street use.
Not really per cylinder but seems top performance vehicle go for max outlet v inlet
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