WR and and auto de-compression. Year?


12 replies to this topic
  • Krannie McKranface

Posted June 23, 2007 - 08:24 PM

#1

I've been looking at a few used WR450's and my friend mentioned that some years do not have auto decompression to aid in starting. Is this possible? I thought all modern kick-start 4-strokes had this. You mean one would have to do the TDC search-then-kick method?

  • pilsner

Posted June 23, 2007 - 08:44 PM

#2

yep, you betchya. 03 and newer wr's have got the decom.

  • Krannie McKranface

Posted June 23, 2007 - 09:09 PM

#3

yep, you betchya. 03 and newer wr's have got the decom.


........and when was e-start first offered, '05?

  • JSanfilippo

Posted June 23, 2007 - 11:13 PM

#4

........and when was e-start first offered, '05?


03...

However the 03 and 04 bikes are red stickered. 05 and newer are green:thumbsup:

  • JSanfilippo

Posted June 23, 2007 - 11:18 PM

#5

You mean one would have to do the TDC search-then-kick method?


Its more like
1. Kick through till you hit TDC
2. Bring kicker to the top of the stroke
3. Pull de-comp lever and nudge the piston past TDC (about 2" of kickstarter travel)
4. Release decomp lever, kick, and start.

It becomes second nature after a while...just sucks on the side of a hill or tight singletrack.

  • brolo747

Posted June 23, 2007 - 11:31 PM

#6

Just a thought but you should kick every bike 4t, 2t, decomp, or not from tdc... Unless you like putting wear on your kickstart for no good reason.:thumbsup:

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  • woodsk

Posted June 24, 2007 - 03:52 AM

#7

All 450's are auto decom the 426 and 400s were manual decom

  • Krannie McKranface

Posted June 24, 2007 - 09:27 AM

#8

Thanks guys. What about an auto-decompression aftermarket cam. Is there such a thing?

  • JSanfilippo

Posted June 24, 2007 - 11:41 AM

#9

Thanks guys. What about an auto-decompression aftermarket cam. Is there such a thing?


Hotcams and Yamaha both have you covered. If you want to stay OEM, just pick up a 03+ YZ cam.

You'll need the decompression plugs from the TT storehttp://shop.thumpert...p/qmr-03dpb.htm

  • Krannie McKranface

Posted June 24, 2007 - 12:34 PM

#10

Hotcams and Yamaha both have you covered. If you want to stay OEM, just pick up a 03+ YZ cam.

You'll need the decompression plugs from the TT storehttp://shop.thumpert...p/qmr-03dpb.htm


Cool! Thanks!:thumbsup:

  • ultravista

Posted July 05, 2007 - 07:51 PM

#11

How long does the process take to install the cam and plug? Is it a simple procedure?

  • Alternative

Posted July 14, 2007 - 08:32 PM

#12

How long does the process take to install the cam and plug? Is it a simple procedure?


If you've ever had to check/adjust the valve clearances (which you should have) you'll know it's not very hard.
1. Pull off the top engine cover and cam chain tensioner
2. Take the camshaft cover off, remove the old camshaft
3. Replace with new camshaft, torque the cover down
4. Check valve clearances, and adjust if necessary (change shims, requires removing the camshaft again)
5. Get the timing right
6. Double check the timing
7. Replace cam chain tensioner (might need an extra hand to do this)
8. Triple check the timing
9. Put engine cover back on
Shouldn't take more than 2 hours if you know what you're doing and have the correct shims to get the clearances right.

  • Chaindrive

Posted July 15, 2007 - 02:21 AM

#13

My '99 WR400 has the auto-decomp cam conversion with a YZ250F cam gear on it (matches the WR's timing chain pitch better). Three or four kicks with the choke on when cold (as easy as kicking a 2 stroke) and one decent kick when warm. I love it!

The old 4-stroke ritual wasn't hard; but getting my stiff old leg high enough was when combined with the ritual, much less the dreaded side hill. I modified my kickstarter to be much shorter until I could finally afford a prettier Protech billet (still shorter than stock) kickstarter. They were very pricey back then. The bonus is the shorter kicker spins the motor over faster, too.

Did it all with info and contacts here on TT. Yamaha swore up and down it wasn't possible to do such a conversion back then of course. TT'ers proved differently. Now you can buy the cam conversion ready-made. You should find TONS of detailed info in the archives...




 
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