WRF4?? on the MX track ?


71 replies to this topic
  • flatnacker

Posted July 18, 2005 - 11:57 PM

#61

Oh, I getya now, I thought you were talking just in general. Yep couldnt agree more with you, choose the right tool for the job.

Just out of interest though, where besides the starter, lights and battery do they save on weight? Whats the total difference (Im to lazy to check for myself)

  • RADRick

Posted July 19, 2005 - 08:45 AM

#62

Yeah thats what Im getting at-why would you want to change the ignition timing unless you change the cams? Shouldnt it already be timed correctly for the cam thats in it? My understanding was that this mod advances the ignition timing, I thought you would only want to change timing if you change the compression or cams...ahhhh this is all getting to confusing for my meager brain!! Beside I'll admit in this department I have no idea what Im talking about really.....

Let me explain. Like most newer cars, the WR and YZ have an electronic ignition module. Using input from the coil (RPM) and the Throttle Position Sensor, the timing module determines the slope of the ignition timing relative to engine demand and adjusts it for optimum performance using preprogrammed maps that are stored in the module. Basically retarding and advancing the timing as needed. Unfortunately, so the WR can meet EPA noise requirements, the maps accessible by the module are rev limited when the gray wire is connected. Disconnecting it allows the module to use the same maps as the YZ and lets the WR rev higher. Cam timing is a mechanical process and does not change while the engine is running. You would have to physically open the engine, undo the cam chain, rotate the cam gears and reinstall the chain to change cam timing. It is possible to do this on a WR to match YZ cam timing, but you lose autodecompression release if you don't use actual YZ cams. Bottom line: cam timing and ignition timing are completely separate things.

  • flatnacker

Posted July 19, 2005 - 03:45 PM

#63

So what your saying is that in the stock form the map only caters to a certain amount of revs, so if you take the throttle stop out and make it rev harder the map cant cater for these additional revs. However the YZ map which would cater for these revs can be accesed by removing the grey wire. O.K so far so good, BUT the problem Im having is with the different cams-the cams do alter the timing of the valves opening/closing. So you are effectively using an ignition map designed for a different cam to what you are actually using. Is there anywhere I can read more about this? Thanks

  • RADRick

Posted July 19, 2005 - 05:27 PM

#64

BUT the problem Im having is with the different cams-the cams do alter the timing of the valves opening/closing. So you are effectively using an ignition map designed for a different cam to what you are actually using. Is there anywhere I can read more about this? Thanks

Which is why you need to swap to YZ cams to get the full benefit. Beware: swapping to YZ cams in a WR will change the characteristics of the engine very much. Some riders prefer the "softer" hit of the WR and are unsatisfied with the more 2-stroke-like hit that these mods result in. Regardless, shortening the throttle stop and disconnecting the gray wire will overcome the EPA-mandated shortcomings the factory built in. These mods can really wake up the sluggish WR, more so with a change of exhaust and some airbox mods. Cam timing and lobe design are far too complex to cover in a forum like this. Eric Gorr's web site is a good place to start.

  • CRF_173

Posted July 19, 2005 - 05:34 PM

#65

How much does the stock wr weigh? just wondering

  • Matty05

Posted July 19, 2005 - 08:17 PM

#66

How much does the stock wr weigh? just wondering

Around the 115kg (255lbs) mark I do believe maybe dry, can't remember.

I could be wrong but it is definately a porker compared to the YZ's.
A WR250 is about 10kg heavier than a YZ450. You can feel that kind of difference.

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  • Matty05

Posted July 19, 2005 - 08:25 PM

#67

Oh, I getya now, I thought you were talking just in general. Yep couldnt agree more with you, choose the right tool for the job.

Just out of interest though, where besides the starter, lights and battery do they save on weight? Whats the total difference (Im to lazy to check for myself)

The YZ's run a 19" rear wheel compared to our 18". I haven't felt the weight difference compared to my mates YZ's but I think that thara would have to be a kg or two to save just in rubber alone.

I know that the WR mufflers are definately heavier for sure, maybe by more than 2kg.

The tanks are obviously different so there would be a small weight saving there.

It is all the small things that add up quickly. Oh yeah, I almost forgot, TITANIUM footpegs!

  • Math

Posted July 20, 2005 - 05:35 AM

#68

How much does the stock wr weigh? just wondering


Dan Lorenze weighted his Trick dual sported 450 at 262 ready to go / no fuel. This was with a canadian pipe so you could probably figure his bike would be more like 259 with a FMF or a YZ pipe...

Here is the link:
http://www.thumperta...1&highlight=262

  • deadcarnahans

Posted July 20, 2005 - 12:05 PM

#69

[quote name='mjskier']Hi all,

I'm toying with the idea of trading in my YZ250 for a WRF4?? ]


What exactly is a WRF4??
???

  • bg10459

Posted July 20, 2005 - 02:15 PM

#70

WRF4?? is any of the WR series bikes, either WR400, WR426 or WR450. 450's are '03 and newer, 426, I believe was '99 to '02 and 400 was pre '99. I could very well be wrong. If so, someone will correct me shortly.

  • mjskier

Posted July 20, 2005 - 02:19 PM

#71

What exactly is a WRF4??

It is a computer geek notation to mean 400, 426, 450, and anything else
that has 2 digits after the 4.
Considering that you are the only one to have asked this in 7 page of answers, me think there are a lot of geeks on this board. That's probably why I feel right at home :-)

bruno.

  • Math

Posted July 21, 2005 - 07:24 AM

#72

WRF4?? is any of the WR series bikes, either WR400, WR426 or WR450. 450's are '03 and newer, 426, I believe was '99 to '02 and 400 was pre '99. I could very well be wrong. If so, someone will correct me shortly.


Usually we use the x like WR4xxf, not the "?"

For the YZ4xxf they were 400cc in 1998 and 1999. The bore was raised to achieve 426cc for year 2000 and then the 450 came out in 03.

For the WR4xxf, they were 400cc in 1998, 1999 and 2000. The only years the WR was a 426 were 2001 and 2002. Then it followed the YZf in 2003 and became a 450.

People get confused because the 2000YZf were 426s whereas the 2000WRf was still a 400cc.




 
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