Wide open in 5th


18 replies to this topic
  • TWILES

Posted May 26, 2006 - 10:11 AM

#1

I am not hitting the rev limiter in 5th wide open going down the road. I still have the stock muffler with the baffle out. I'm running a 170 main jet. I know I've got plenty of gas going to the motor. Does the muffler have anything to do with it or am I just too heavy at 250lbs?

  • whiteboy29

Posted May 26, 2006 - 10:14 AM

#2

how long are you wide open for???
is the bike still pulling?????

  • bg10459

Posted May 26, 2006 - 10:16 AM

#3

You aren't hitting the rev limiter, no matter how hard you try? I'd guess you're a bit rich on the main. Try the 168, then the 165 and see how it reacts to each.

  • MountainMax

Posted May 26, 2006 - 10:37 AM

#4

Dam, mine (stock gearing with free mods) hit 126km/h and was still revving and pulling hard (not like the stock restricted throttle screw) but i was afraid to keep going, i didn't know if i could trust my limiter.

  • TWILES

Posted May 26, 2006 - 11:06 AM

#5

You aren't hitting the rev limiter, no matter how hard you try? I'd guess you're a bit rich on the main. Try the 168, then the 165 and see how it reacts to each.

It will hit the limiter in the other gears. Its just 5th where it won't rev all the way out to the limiter. I've never encountered this problem before. I've also put on nearly 30lbs since the last MX race one my Banshee going on 4 years ago. Thats why I said that I might just be too heavy and it just won't pull me to the rev limiter in 5th. I don't know how fast I'm going. It was 85 - 90 degree's with high humidity the last time I rode it. I don't have a 168 and can't get one without ordering it. I do still have the stock 165.

  • bg10459

Posted May 26, 2006 - 11:09 AM

#6

At those temps, you should be OK with the 165. Try it and see. That's what I run in the summer with the JD red needle and a YZ exhaust.

  • MountainMax

Posted May 26, 2006 - 11:16 AM

#7

I have never hit the limiter on mine, Im use to high revving 2 smokes but these thumpers don't sound right to me at high rpm, im a bit scared to get them up that high expecially without tachometer to see where the motor is at.

  • TWILES

Posted May 26, 2006 - 02:33 PM

#8

They didn't to me either but they are built to run that way. To me the best power is 5/8 - 3/4 throttle. After 3/4 it plains out like a powervalved 2-stroke. Its just hard to run in that range here in Kentucky. When I bought mine all I heard was " throttle control ". I ran a gear too high because I thought thats the way to ride a 450 4-stroke. I learned that its a whole lot easier to control the bike and get the best out of it at or right at max HP, just like a 2-stroke. Trying to lug it is not the way to go. They have so much grunt that its to easy to get out of control when the power really starts to come on.

  • Bamster

Posted May 26, 2006 - 03:41 PM

#9

I have never hit the limiter on mine, Im use to high revving 2 smokes but these thumpers don't sound right to me at high rpm, im a bit scared to get them up that high expecially without tachometer to see where the motor is at.


Don't worry about it, you will be amazed how much power they make at a high RPM. Remember lugging too much can be worse than revving.

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  • TWILES

Posted May 26, 2006 - 04:49 PM

#10

Don't worry about it, you will be amazed how much power they make at a high RPM. Remember lugging too much can be worse than revving.

Thats what I said. My question still stands: why can't I hit the rev limiter in 5th gear? I'm 250 on the bike and running a 170 main and stock needle and stock muffler with the baffle out.

  • MountainMax

Posted May 26, 2006 - 05:55 PM

#11

What speed are you hitting when she wont' pull any more? did you try it on pavement also? what gearing do you have?

I read somewhere the max Hp on these bikes is at 8000 rpm and they redline at 11000, i wondered why they rev so high if they start to lose power and torque after 8000 rpm, i was told so they can be in max power after you shift them up a gear. but i wish i had a tach..........

  • OneToGo

Posted May 26, 2006 - 06:41 PM

#12

The standard CDI rev limit is 10800. The WR without cam and head mods will make its peak torque around 8-9000, close that anyway. The torque curve is fairly smooth so the peak power is around the same RPM, maybe a tad higher.
Now, these thumper engines rev cleaner when the mixture is right on, but will rev higer if slightly lean. The power produced will be less though (less fuel consumed). Everyone here is giving good advice. At the temps you are riding in I'd also recommend a 168 or 165 Main jet.
Standard gearing is good for just under 100mph, around 150km/h. I have not got anywhere close to this...I doubt whether this speed would equate to the rev limit though, but rather, where the power produced is just enough to maintain the speed. ie just as the power trails off.
Now, if you are heavier than the norm and bigger, so offering more wind resistance (the main absorber of power at higher speeds) then the bike may not get past max power...but should get there if the gearing and jetting are OK. I reckon you will see 140km/h (90mph) before the bike stops pulling - if it is correctly jetted.
My .02c worth
:ride:

  • sabrecat700

Posted May 26, 2006 - 08:48 PM

#13

You should never hit the limiter in 5th gear. It is to protect the motor from way over reving incase you miss a gear or when it is in a lower gear and is not shifted and held WFO. If it does hit it in 5th you would be way under geared and way over reved.

:ride: :banana: :busted: :smirk:

  • TWILES

Posted May 27, 2006 - 10:48 AM

#14

The standard CDI rev limit is 10800. The WR without cam and head mods will make its peak torque around 8-9000, close that anyway. The torque curve is fairly smooth so the peak power is around the same RPM, maybe a tad higher.
Now, these thumper engines rev cleaner when the mixture is right on, but will rev higer if slightly lean. The power produced will be less though (less fuel consumed). Everyone here is giving good advice. At the temps you are riding in I'd also recommend a 168 or 165 Main jet.
Standard gearing is good for just under 100mph, around 150km/h. I have not got anywhere close to this...I doubt whether this speed would equate to the rev limit though, but rather, where the power produced is just enough to maintain the speed. ie just as the power trails off.
Now, if you are heavier than the norm and bigger, so offering more wind resistance (the main absorber of power at higher speeds) then the bike may not get past max power...but should get there if the gearing and jetting are OK. I reckon you will see 140km/h (90mph) before the bike stops pulling - if it is correctly jetted.
My .02c worth
:ride:

Thanks. Thats more what I was looking for. It doesn't feel like it could go any faster. I think I'm probably doing 90 when pinned. Come to think about it, it won't hit the rev limiter in the field in 5th either. It spins bad in the grass when I get about 3/4 throttle. The power does plain out right at max speed so it is pulling me on past max hp. I'll probably just leave the jetting alone. Its close enough for me. Again, thanks for the explaination. I was affraid there was a problem. T Wiles

  • JSanfilippo

Posted May 27, 2006 - 12:28 PM

#15

Thanks. Thats more what I was looking for. It doesn't feel like it could go any faster. I think I'm probably doing 90 when pinned.


Yeah, thats about what they'll do

  • OneToGo

Posted May 27, 2006 - 06:13 PM

#16

Just for info..
The laws of Newtonian Physics apply -
Eg: If on a particular day for you, on your bike, with a paticular setup etc. the back wheel power required to maintain a speed of, for example, 45mph is 12hp or around 9Kw. (an example, not actual figures but you will see why I chose these..read on..)
Under the same conditions, if you double the speed (x2) and now run the bike at 90mph the back wheel power required increases by the Square ie. (x2) squared = (x4). So, the power required to double the speed from 45 to 90mph is now 12hp x 4 = 48hp.
Now, to step it up a notch...but slightly off the topic- Why is 200mph a tough ask for road bikes? (yeah theya re electronically limited to 186/300kmh).
Well, it rougly takes around 50hp to a achieve 100mph - we are talking rough figures here. So, to increase the speed to 200mph requires (200/100) squared x 50hp = 200HP. MotoGP anyone? :prof: To go 300mph = 450hp, now we are talking :applause: power and Bonneville Salt Flats.. :D
Sorry to bore those not interested, my kids needed a physics lesson...

  • evilinsano

Posted June 03, 2006 - 11:02 PM

#17

Has anyone ever had and issue with the bike dieing when riding at extended full throttle? It seems as thought the bowl went empty and I ran out of gas and it never recovers until I am completly stopped. Then it starts right back up and off I go. Is it a jetting issue? What the heck? I know I need taller gears but wouldn't think it would do that when pegged.

  • johnnyjeep

Posted June 03, 2006 - 11:25 PM

#18

Has anyone ever had and issue with the bike dieing when riding at extended full throttle? It seems as thought the bowl went empty and I ran out of gas and it never recovers until I am completly stopped. Then it starts right back up and off I go. Is it a jetting issue? What the heck? I know I need taller gears but wouldn't think it would do that when pegged.


Yeah but i forgot to turn the fuel on.

John in Vegas

  • Matty05

Posted June 04, 2006 - 12:20 AM

#19

I am not hitting the rev limiter in 5th wide open going down the road. I still have the stock muffler with the baffle out. I'm running a 170 main jet. I know I've got plenty of gas going to the motor. Does the muffler have anything to do with it or am I just too heavy at 250lbs?


If you can only hit 90 pinned, dont worry about it. I can only go ~90mph with 14/50 gearing.

I can't really hit the rev limiter in 5th either - that is because of my exhaust system. Oh yeah, I have a vortex ignition too, with a 11,600 rev limit.
I have a procircuit Ti GP lowboy exhaust, it is ment for huge torque, it works best in the low / mid range.

So, 90 is all you will get out of 14/50 gearing, if you want to go faster, change your sprockets. Your bike has enough power to pull it, but get a 168 main. You look too rich for that temp and humidity (same as me!).




 
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