WR450F '12 hints for toying with cams

Just some hints I collected over the past 3 hours installing an '06 YZ cam into my 2012 WRF:




- you have to get the park plug out, make sure you have a socket for it


- after removing the whole tank loosen the two screws that hold the electricity panel in place.

these screws are on the underside of the left and right side studs of the frame.

You then have a chance of relocating that dreaded electricity rack a little bit fore, aft and up(!)


- while you are at it do make sure the cables above the cylinder head cover are CLEAN, or you will drop debris into your engine


- you need a lot of light from the left side, just saying, for those guys with dark garages


- tuck the spark plug connector and the engine ventilation tube (1/2" tube coming out of the cylinder head cover) out of the way


- make sure the rubber gasket stays with the cylinder head cover. it's easier to reinstall that way.

tilt the cover to the left to loosen the right side. when trying to lift up the cover "help" the big rubber sections on the left side by pushing them upward, too


- you only have  to reomve the exhaust cam cover, intake can stay installed

do NOT try to grab these four bolts singlehandedly, they are oily and might vanish into the engine


- be very careful when removing the cam cover the first time. 

it might be very well seated, but it contains three items that very easily might fall into the engine:

two hollow dowel pins and the 180° circlip positioning the cam bearing.

DO NOT remove the cover by passing it over the cam chain cavity


- don't forget to remove the cam chain tensioner, we need all chain slack we can get


- grab some wire and fix the cam chain to the intake cam sprocket tightly. it is possible to remove the exhaust cam with the intake cam seated and still wearing the chain


- the 3 'o clock and 9 'o clock punches WILL align perfectly with the cylinder head top IF you tension the chain by pressing your finger into the chain tensioner openeing while checking their positions.

Did I mention you do need lots of illumination from the left side?


- do not rely on the number of pins between the 12 'o clock punches on the sprocket:

my WR'12 had 14 pins stock, with the '06 YZ exhaust cam there were only 13 pins between the 12 'o clock pins with the cams perfectly aligned to the cylinder head




- never turn the crank 360° w/o the chain tensioner in place and active. the cam chain WILL skip one tooth per revolution on each cam, even with the cam cover tightened, BTDT.

  If that happens you have to realign both cams!


- should you have to realign the intake cam be very careful not the drop the chain into the engine

route a thicker isolated wire across the cylinder head through the chain.

It IS possible to get the chain back over the intake cams sprocket w/o removing the cam or even its cover.

You might not believe it but the is enough clearance between sprocket and cylinder for the chain so it can be moved "in front" of the sprocket.

But you won't need to do that beacuse you payed attention and 1) fixed the chain to the intake cam sprocket  and 2) did not turn the crank w/o chain tensioner installed, right?


- don't try to reinstall the cam cover with the 180° circlip installed.

Put the circlip onto the bearing (make sure the bearing sits snug in its boss) and hover the cover over it. it's hard enough to prevent them dovel pins from falling out

Edited by WRF-Rowdy

Pictures tell a thousand words.



How did you go getting the decomp to work with the 06 cam? Estart still work?

Edited by xy500

Maybe i've gotten it all wrong but I do hope that by


- not retiming an '03 -'06 WR cam - would result in too much decompression due to the enlongated decomp pin of '03 - '06 WR cams


- not retiming an '07 - '14 WR cam - would result in too late decompression due to normal but too late for YZ timing decomp pin


-  but instead  using an YZ cam at YZ timing I'd have the same kind of decomp-quality e.g. (E-)startability  as all stock YZs have.


decomp mess background:

On the '03 - '07 WRs one could retime the cam to YZ timing BUT one would have to grind down ~1mm off the pin to mimick the stock YZ cams pin duration.

These WRs had gotten the exactly same exhaust cam (with regard to relative pin - lobe position) as their respective YZ sisters, timed one tooth early and hence with a longer, square decomp pin.


On the WRs with true WR timing exhaust cam ('07 onwards)  where Yahama decided the WRs would get their own cams, with stadard pin length but different angle between pin and lobe, one has to replace the cam with a true YZ cam.


We'll see what has survived.

Pictures tell a thousand words.




Yeah right, that's how my WR400F would have looked like.

An aluminum frame WR would have the right half of the intake cam covered by the frame.

And viewed from above you won't be albe to see the cylinder head cover due to thick layer of cabling, see pic.

And these cables in the picture are all neatly pinned dwon onto a bracket that goes from frame rail to frame rail

and thanks to no clearance towards the coolant pipe of the radiator cannot be moved out of the way for more than half an inch laterally.

I almost bite off more than I wanted to chew when diving down to the cams


Edited by WRF-Rowdy

The wiring on the WR is a mess.

Well, a first E-start try in my appartment didn't work out. Even kicking it required two kicks. Then I maxxed out the idle stting on the choke knob, as the idle seems to be very low. I'veto take her outside to check what I've got me here.

Apparently my theory is flawed: Kickstarting the YZ-timed (punch mark aligend) YZ'06 cam works, idle is rather low, but estarting fails.

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