Exhaust Wrap for 2010-2012 YZ450


16 replies to this topic
  • FZ1426

Posted October 19, 2011 - 05:06 PM

#1

Anybody ever seen or done an exhaust wrapping on the header/pipe of the '10-'12 YZ's?

Some of the early speculation on the design was concern over the shock being (over) heated by the exhaust. I can see that happening in certain conditions or long periods without airflow. But it seems like wrapping it might be a good idea in general.

Any thoughts or experience with this?

  • DC_Excitement

Posted October 19, 2011 - 06:41 PM

#2

when i first saw pics of the 10 i loved the fact that i wouldent smash headers any more, (i have bad luck with them). but i was thinking the same thing. im not a pro but im a solid amature rider and i never noticed shock fade. but im out of shape now and i cant do 20+ 2 anymore. i have noticed that when i do some slow trail riding my seat get hot from the exhaust.

i know alot of people claim that the rear suspension is the reason why stewart crashed out alot this year. i know he rides like a nut but i wonder if its true also. i herd he may sign with JGR and there dong different things with the rear shock, possibly even making there own.

  • FZ1426

Posted October 19, 2011 - 07:04 PM

#3

when i first saw pics of the 10 i loved the fact that i wouldent smash headers any more, (i have bad luck with them). but i was thinking the same thing. im not a pro but im a solid amature rider and i never noticed shock fade. but im out of shape now and i cant do 20+ 2 anymore. i have noticed that when i do some slow trail riding my seat get hot from the exhaust.

i know alot of people claim that the rear suspension is the reason why stewart crashed out alot this year. i know he rides like a nut but i wonder if its true also. i herd he may sign with JGR and there dong different things with the rear shock, possibly even making there own.


Nah. Stewart crashes out because he's frickin crazy and rides above his head. That and his forks are so stiff they never even move. That's why he always washes out the front...

  • grayracer513

Posted October 19, 2011 - 07:21 PM

#4

The amount of heat the shock might possibly absorb through convection, even in still air, is not equal to the heat it generates on its own, and the exhaust on the YZ450 will not contribute to shock fade.

  • FZ1426

Posted October 19, 2011 - 08:24 PM

#5

The amount of heat the shock might possibly absorb through convection, even in still air, is not equal to the heat it generates on its own, and the exhaust on the YZ450 will not contribute to shock fade.


I would like to think that's true and feel it probably is. Do you have any data or evidence to back it up?

Even if it's not equal to, it certainly is in addition to.

  • rdrata

Posted October 19, 2011 - 08:54 PM

#6

You know Gray, for shits and giggles on my '06 I wrapped my pipe and added a multi layered anti-heat pad below the shock reservoir and it helped tremendously. I think you commented on this before. I agree that the shock itself will create it's own heat but I must say that my wrap did help cut the heat from the pipe quite a bit. Why do they stick the reservoir right on top of the pipe anyway?:thumbsup:

  • SEOINAGE

Posted October 20, 2011 - 10:25 AM

#7

You know Gray, for shits and giggles on my '06 I wrapped my pipe and added a multi layered anti-heat pad below the shock reservoir and it helped tremendously. I think you commented on this before. I agree that the shock itself will create it's own heat but I must say that my wrap did help cut the heat from the pipe quite a bit. Why do they stick the reservoir right on top of the pipe anyway?:thumbsup:


You measured "helped tremendously" how?

  • grayracer513

Posted October 20, 2011 - 11:32 AM

#8

The principals involved are such that I don't need any test data to be clear on the matter, but if you want, here's what you do: Get a couple of small fans and position them in front of your radiators so that they will prevent your bike from overheating at idle but not move any air around the shock, and then run it for a while with the pipe good and hot. Raise the idle a bit to help with heating the pipe. See how long it takes to raise the temperature of the shock body to 140 ℉ on the side facing away from the pipe.

Then, ride the bike hard for 15 minutes and measure the temperature.

An infrared laser thermometer works well for this.

The pipe is routed under the reservoir on the older models because there's room for it, and the factory testing shows that it doesn't matter to the shock.

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  • HRC

Posted October 20, 2011 - 11:35 AM

#9

i know alot of people claim that the rear suspension is the reason why stewart crashed out alot this year. i know he rides like a nut but i wonder if its true also. i herd he may sign with JGR and there dong different things with the rear shock, possibly even making there own.


JGR actually have made an exhaust-shield between the rearshock and the exhaust. Look closely in this pic and you will see it. I had a better pic but can´t find it right now :thumbsup:

Posted Image

  • FZ1426

Posted October 20, 2011 - 01:13 PM

#10

JGR actually have made an exhaust-shield between the rearshock and the exhaust. Look closely in this pic and you will see it. I had a better pic but can´t find it right now :ride:

Posted Image


Looks like they've got a supplementary shied under the tank as well. The thing I don't like about going that route is it looks like it would actually reduce the airflow that's helping to carry the heat away to the rear. That's why it seems wrapping the exhaust itself would make sense. But maybe all that extra heat in the exhaust would have a detrimental effect elswhere, like cooking the silencer too much?:thumbsup:

They have a custom shock on there also. Looks like cooling fins on the body. Problem is those fins pick up more heat from the pipe just as they dissipate it from the shock...

  • grayracer513

Posted October 20, 2011 - 01:49 PM

#11

...maybe all that extra heat in the exhaust would have a detrimental effect elswhere, like cooking the silencer too much?:thumbsup:

They have a custom shock on there also. Looks like cooling fins on the body. Problem is those fins pick up more heat from the pipe just as they dissipate it from the shock...

The extra heat at the silencer will be far more a potential problem than the heat on the shock.

You're looking at the bike as a static system. Remember it moves. Heat gets from the pipe to the shock almost entirely by convection. Air carries it from the heat source to anything colder along the way. But as the motorcycle moves, air moves over it in predictable ways. The air that reaches the shock will have some engine heat in it, but if the fins on the reservoir are hotter, the air will carry of a part of that heat. The heat from the pipe will move rearward, not forward even if the air moves only at 1 or 2 MPH.

The slower one goes, the more effective things like heat shielding become. There's a lot of money in Pro SX, and you have top level competition looking for every edge they can find. Plus, the unnatural terrain of SX puts continuous loads on suspensions to an extreme you don't see many other places. Shock fluid temps over 200 ℉ are possible, and at that level, it starts to become a concern. These things combine to make the idea of cooling a shock on a PRO MX'er a worthwhile pursuit. For the rest of us who operate at a lower level than that, it's nothing that needs any real attention or resources spent on it.

  • OUTERLIMITS

Posted October 20, 2011 - 05:56 PM

#12

JGR actually have made an exhaust-shield between the rearshock and the exhaust. Look closely in this pic and you will see it. I had a better pic but can´t find it right now :thumbsup:

Posted Image


I don't think exhaust wrap would be such a bad idea, but look at how much room there is around the reservoir for airflow as it is and the fact that the heat from most of the exhaust is rearward. Now go back and look at the '09 and you'll find there is literally less than a half an inch between the pipe and reservoir. No one complained much about heat fade on that bike and it likely had more of a heat effect on the shock than the new model does.

  • FZ1426

Posted October 20, 2011 - 07:24 PM

#13

I don't think exhaust wrap would be such a bad idea, but look at how much room there is around the reservoir for airflow as it is and the fact that the heat from most of the exhaust is rearward. Now go back and look at the '09 and you'll find there is literally less than a half an inch between the pipe and reservoir. No one complained much about heat fade on that bike and it likely had more of a heat effect on the shock than the new model does.


No doubt all the 450's pipes run real close to the shock. I'm not so concerned about the reservoir itself as it's just a bladder that pressurizes the oil. If it gets hot the effect would be an increase in pressure which would essentially help keep the oils vapor pressure/viscosity intact.

The odd thing about the '10-'12 design is the attenuator in front of the shock and the spiral behind it really surrounds the shock body more so than conventional layouts, potentially depriving the shock of the cooling it may need in extreme conditions.

Not to obsess on it. It will never be a problem for me. I don't ride hard enough for it to be a problem. Just want to discuss the technical merits of the design.

Like I said, I don't think the JGR approach is best as it seems it would limit the amount of airflow which otherwise would help carry the heat away.

It seems to me if exhaust wrapping is not the answer then simply applying some heat reflective tape on the shock body and reservoir would be better than their approach. The more airflow taking heat away from the area the better.

  • honda907

Posted October 22, 2011 - 07:52 AM

#14

Some people really worry about the smallest things. For my 10-15 minute race, I agree with grayracer. If you could go 35 minutes plus one warm up lap at Southwick like JS7, possible be a problem. But he isn't a normal mortal on a bike.

His crashes that he gets up from prove he is no mortal!

  • tech24

Posted October 23, 2011 - 05:51 AM

#15

anyone know what the canister device behind the radiator is? Sorry to change subject but the curiosity is killin me.

  • honda907

Posted October 23, 2011 - 03:40 PM

#16

anyone know what the canister device behind the radiator is? Sorry to change subject but the curiosity is killin me.


If the radiator starts to boil over, it will catch the antifreeze so it won't puke it all out. Like if they have an extended 2 minutes on the line and the bike would get hot. Catch tank

  • tech24

Posted October 24, 2011 - 03:51 AM

#17

If the radiator starts to boil over, it will catch the antifreeze so it won't puke it all out. Like if they have an extended 2 minutes on the line and the bike would get hot. Catch tank


thought thats what it may be





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