WR450F2012 which YZ cams perserve WR E-start ability


11 replies to this topic
  • WRF-Rowdy

Posted June 03, 2015 - 05:42 AM

#1

My input so far: Putting in an '06 YZ exhaust cam (5TA-12180-10, has decomp)

will

- lower the idle drastically, you'll need to max out the idle adjuster

- be able to kickstart easily

- allow the starter impressive rpms but won't fire up

 

A failure so far, so what is a drop in replacement for an EFI WR (2012 onwards)  that has YZ timing AND functions well with the E-start?

 

This is the stock WR450f cam in position

WR450F-2012-ex-cam-installed.jpg

 

This is the YZ405F 2006 cam installed in my 2012 WR450F, notice the differen angle the decomp mechanism is sitting:

YZ450F-2006-ex-cam-installed.jpg

 

At least this explains the various 13 pin vs. 14 pin counts between the 12 'o clock positions:

'06 YZ cam has the 12 'o clock punch at a different position than the '12 WR cam, hence the count towards intake cam is different.

 

 

But how can that be, that the decomp mechanism is "rotated", if we keep the 9 'o clock alignment punch flush as it should be?

 

Does a non e-start YZ450F '06 (ist that correct '06 YZ were kick start only?) 

need the decomp activaed at another position in the compression stroke, than a WR450F'12 needs it to be able to e-start?

 

I'm am puzzle to see the differently positioned decomp. I assume the activation direction of the pin relative to the decomp mechanism is always the same.


Edited by WRF-Rowdy, June 03, 2015 - 07:02 AM.


  • chu

Posted June 03, 2015 - 06:25 AM

#2

There's GYTR cams but they're expensive.



  • WRF-Rowdy

Posted June 03, 2015 - 06:56 AM

#3

There's GYTR cams but they're expensive.

Shouldn't there be a model year YZ450 whose decomp exhaust cam will work nicely in an E-start WR?



  • grayracer513

Posted June 03, 2015 - 08:46 AM

#4

How many threads are you going to start on this subject? 



  • Krannie McKranface

Posted June 03, 2015 - 11:58 AM

#5

Shouldn't there be a model year YZ450 whose decomp exhaust cam will work nicely in an E-start WR?

 

Only hotcams

 

This has be covered adnaseum



  • stevethe

Posted June 03, 2015 - 01:27 PM

#6

Yea the factory YZ cams need to have the decompression pin ground down to electric start on the aluminuim frame WR's. It is about 1mm to 1.1mm as I have heard.
The heads may be similar however the WR is an electric start bike and the YZ kick only.
Maybe Bill can post up the exact amount as he is doing it.

Edited by stevethe, June 03, 2015 - 01:28 PM.


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  • patrick2wd

Posted June 03, 2015 - 11:32 PM

#7

How many threads are you going to start on this subject? 

hahahahahaaa...

 

as long as people are tooo lazy to read..

 

 

anyway,

cam should work fine,

you could use stock cam too (exhaust) and advance it a tooth, but would be crap to start.. (deco)

 

I'll be waithing for the 2016 WR450!!



  • WRF-Rowdy

Posted June 04, 2015 - 03:29 AM

#8

you could use stock cam too (exhaust) and advance it a tooth, but would be crap to start.. (deco)

 

Careful with your wording (newbies might take you literally):

Yamaha has advanced the WR exhaust cam one tooth, we should retard it (make it act later) one tooth.

 

 

I'll be waithing for the 2016 WR450!!

Why is that? finally a WR (less compression earlier rev. limiter, more flywhell weight, fine so far, has always been)  but with YZ timing?  

THAT would be a great bike for sure!

 

If yamaha'd ask me i'd like a YZ450F but with

- WR-like reduced compression (thicker cylinder base gasket),

- increased flywheel weight

- coolant catch tank

 

but with WideRatio grearbox and EXC-quality e-start, nothing else. 

So it should weight YZ450F+battery+starter, yipeee!

 

In fact I got to ride a week in Idaho once, on a buddy's YZ400F, with flywheel weight and lowered final gearing, and it was a hoot in the mountains!



  • chu

Posted June 04, 2015 - 04:49 AM

#9

I think you actually move the cam a tooth counterclockwise which would be advancing it.  I could be wrong, never done it before.



  • grayracer513

Posted June 04, 2015 - 06:32 AM

#10

Yes, that would be advancing it (looking from the sprocket side).  But we've established that's not something you should do.



  • Krannie McKranface

Posted June 04, 2015 - 06:57 AM

#11

Yes, that would be advancing it (looking from the sprocket side).  But we've established that's not something you should do.

 

...but is it getting through ?  I'm not so sure..



  • patrick2wd

Posted June 04, 2015 - 10:28 AM

#12

Im sorry,

retarding is the way to go, more flow..

etc..

 

in mea culpa :(






 
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