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From The Stix 2 Da Brix
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Discussion Starter · #1 ·
Over-rev reffer's to the rpm of a motor after it's peak torque is produced. Such as if a torque curve ends at 12 but the bike redlines at 15, anything above 12 is considered over-rev. When a engine is in over-rev there is usually a drop in torque sometimes quite a significant drop. However it helps in alot of way's when used correctly for mx riding. It realy helps when your coming into down hill sections becouse it greatly reduces engine breaking in lower gears and alows you to set up for your next corner. It alows you to stay in a specific gear a little longer instead of just falling on its face and alows you to shift into the power band of an mx bike, if your bike is tuned right youhave two options. iether over rev and shift into the power cuvrve of the next gear on shift when you hit the power of a specified gear and drop in below the full power of your next gear.
Its a give and take scenary and both are used for diferant situations and riding styles. You can tell if your in over rev becouse you will feel the power smooth out and the torqe will fall off a little bit.
In my experience the DMC,Barker(duals) or the Sparks(single) racing series pipes alow for alot more over rev becouse the are a bigger expancion chamber and alow for more exaughst preasure there for more H.P.
I am by far no expert so i hope it helps, there is alot of guys who know more and might have a differant opinion.
 

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#327 "After Hours"
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1,130 Posts
If my bike quits making power at 12k rpms or whatever I want the limiter to be at 12.5. Going to that many RPMS over peak power is worthless. Not only are you floating the hell out of valves, but your loosing critical time in wasted RPMs from where you could of already shifted and started going through the powerband again. When the bike runs out of steam, shift. I honestly can't think of one time during a race I've engine braked. I've always come in the curve at a comfortable speed, clutch in if necessary, and use the actual brakes where I could, if needed. And you're only going to build power as the bikes gearing allows you. So by over reving and thinking your going to jump in halfway up the next gears power band is probably not going to happen. There's a lot of times during races that I've cut gears short and never even come close to the limiter, just because I knew that the next gears power will be more than enough to gain good ground and still have enough power to keep you in control. All it really comes down to is knowing your bike.
 

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I am unique
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22,621 Posts
Torque peak doesn't mean you are at the horsepower peak.................

For instance, a 7.3 power stroke has its max torque at 1400 rpm and its horsepower peak at 3000 rpm...........but this is a diesel but still shows you what I mean...............:D
 

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From The Stix 2 Da Brix
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11,616 Posts
Discussion Starter · #4 ·
So is my definition correct Willy? I was going off 2 stroke DB experience when I used mx. I shoulda used a drag scenario instead of mx.
 

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I am unique
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Spider-Lōc;996818 said:
So is my definition correct Willy? I was going off 2 stroke DB experience when I used mx. I shoulda used a drag scenario instead of mx.
On two strokes, I see most of the time that the torque peak and the horsepower peak are close, usually 0 to 200 rpm difference, with the HP peak higher then the torque, BUT 4 strokes, depending on the engine can be 1800 to 2000 rpm difference, so it is important to see the dyno specs per engine and either clutch or shift to those specs, so if you have the HP peak at a certain rpm, that is where you shift at, or in close proxility to that peak.
I remember one of my drag sleds from 25 years ago, it's HP peak was at 10,000 rpm, any higher and the HP fell off like jumping off a cliff, there was no over rev on this engine............
 

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From The Stix 2 Da Brix
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Discussion Starter · #6 ·
Gotcha yeah mine doesn't fall off much past peak. So I rev it out a bit so I'm at just below peak when I shift again
 

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From The Stix 2 Da Brix
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11,616 Posts
Discussion Starter · #7 ·
Peak tq is at 5500 and is flat to 7500 which is where they both fall by about 10 points to redline. I got 60 tq for over 2k RPM's hp peak and tq peak are 2k apart. So my over rev I'm talking bout is past the peak tq drop off near the hp peak. Did I just loose ya cause I think I'm lost.
 

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I am unique
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Spider-Lōc;996828 said:
Peak tq is at 5500 and is flat to 7500 which is where they both fall by about 10 points to redline. I got 60 tq for over 2k RPM's hp peak and tq peak are 2k apart. So my over rev I'm talking bout is past the peak tq drop off near the hp peak. Did I just loose ya cause I think I'm lost.
Shift at the HP peak.............other then that you lost me............:wow:
 

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From The Stix 2 Da Brix
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Discussion Starter · #9 ·
Thanks Willy
 

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Cola Crew
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Some of this is in the trans (gearing) Like 1st to 2nd maybe very close but 3rd and 4th not so much... I may shortshift 1st to 2nd but not 3rd to 4th..
 
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