how difficult is it to install new valves??????


46 replies to this topic
  • grayracer513

Posted August 20, 2009 - 08:22 PM

#21

grayracer, do I recall correctly that Ti valves should never be lapped? I remember reading that lapping a Ti valve would remove the hard coating or something to that effect one time...

Yep. I mentioned that in post 10 here.

  • bakeyz426f

Posted August 21, 2009 - 06:15 AM

#22

i think all repace all of the valve parts. you said i can use the 2000 model parts so since they are a $100 cheaper ill get them. how will i know what lash pads i need when i get the valves in? do i measure the space?

  • grayracer513

Posted August 21, 2009 - 09:40 AM

#23

Use the thinnest of your current shims as a trial fit and measure the clearance you get. If you can verify that the button on the underside of the lifter contacts the valve stem before any part of the lifter touches the spring retainer, you can assemble the lifter onto the valve without a pad, and test fit pads between the cam and lifter, but you have to be sure.

  • bakeyz426f

Posted August 21, 2009 - 12:46 PM

#24

i think i lost some shims when it blew up where can i get them.

  • USED YZ426F

Posted August 21, 2009 - 09:16 PM

#25

I am not completely certain, but I think that Honda CRF 450 shims are the same size as the Yamaha YZ 426 shims.

I only mention this, because my local Yamaha dealer doesn't carry shims in stock, but can have them in a few days (he doesn't carry much in the way of spare parts at all). If your dealer is the same, and the Honda dealer has them it can save you some time.

Do a search in this forum, I seem to recall there being a posting discussing using Honda shims in a Yamaha engine.

  • grayracer513

Posted August 21, 2009 - 10:12 PM

#26

You are correct. There are basically two different sets of shims used in nearly all current (last 10 years) models of bikes from the 4 Japanese makers: the smaller 7.48 mm diameter shims used in the YZ250F and others, and the 9.48 mm shims found in the big YZF's, CRF's and the other 450's.

  • bakeyz426f

Posted August 22, 2009 - 06:08 AM

#27

if im installing a new head and valves why cant i buy the pad adjustment for the valves it numbers on the oem parts list. i think there size is 1.20

  • grayracer513

Posted August 22, 2009 - 07:54 AM

#28

if im installing a new head and valves why cant i buy the pad adjustment for the valves it numbers on the oem parts list. i think there size is 1.20

Look again. There are 25 different pad sizes listed for the '01 model, ranging from 1.20 to 2.40.

The assembled head must be measured to detrmine which shims to use, as I said.

  • bakeyz426f

Posted August 23, 2009 - 04:47 PM

#29

is having you crank rebuilt just as good as getting a new one?

  • thatraptorguy

Posted August 23, 2009 - 04:50 PM

#30

is having you crank rebuilt just as good as getting a new one?


better off just getting a new one man.q

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  • bakeyz426f

Posted August 23, 2009 - 06:32 PM

#31

i figured, i guess its only about $150 difference

  • mxmaddman

Posted August 23, 2009 - 06:34 PM

#32

better off just getting a new one man.q


Not 100% true. Some hot rods have larger oiling passages that help increase lubrication. Its all about who installs it. If its trued on a v block it will be great. I always have my big bore cranks welded *180 then balanced.

  • grayracer513

Posted August 23, 2009 - 08:31 PM

#33

Not 100% true. Some hot rods have larger oiling passages that help increase lubrication. Its all about who installs it. If its trued on a v block it will be great. I always have my big bore cranks welded *180 then balanced.

Larger oil passages in the crank do not increase lubrication of anything. The main restriction to feed oil being pumped to the crank is in the oil filter cover, and it's there by design so that oil pressure to the top end will be maintained.

One big question with rebuilt vs. new is the condition of the cam chain sprocket on the left axle. If that's bad, the new crank would be cheaper.

  • mxmaddman

Posted August 24, 2009 - 01:13 PM

#34

I wasn't talking about the crank, I said hot rod. The wrist pin lubrication holes are larger on some aftermarket rods resulting in better lubrication. Which does in fact help it.

  • grayracer513

Posted August 24, 2009 - 02:06 PM

#35

I wasn't talking about the crank, I said hot rod. The wrist pin lubrication holes are larger on some aftermarket rods resulting in better lubrication. Which does in fact help it.

I apologize. For whatever reason, I did not associate the term "passage" with a simple hole in the rod eye. I'm also having some trouble recalling that any OEM Yamaha rod for a YZ4** has any such hole in it. :ride:

  • bakeyz426f

Posted August 24, 2009 - 07:27 PM

#36

what grease, sealants, and lubricants do i need when i rebuild my 426? i ordered the head, valve componets, valve/ spings, cam assemby, cam chain, cam tensinor, and gaskets. i still need to order the crank assembly/ bearings, piston/rings, and the water pump seals as you guys recommended. also do i need a chain breaker tool to install or remove the cam chain?

  • bakeyz426f

Posted August 25, 2009 - 12:22 PM

#37

what grease, sealants, and lubricants do i need when i rebuild my 426?
also do i need a chain breaker tool to install or remove the cam chain?

  • USED YZ426F

Posted August 25, 2009 - 12:37 PM

#38

what grease, sealants, and lubricants do i need when i rebuild my 426?
also do i need a chain breaker tool to install or remove the cam chain?


Check the service manual for lubricants and sealers. It will list what is needed and either your Yamaha dealer or local auto parts store will have them.

No, you do not need a chain breaker tool for the cam chain. It comes as a single piece and needs to remain a single piece.

  • bakeyz426f

Posted August 25, 2009 - 04:05 PM

#39

ill have to remove the motor totally from the frame to split the cases wont i????????

  • moto2000

Posted August 25, 2009 - 05:11 PM

#40

Yup, remove the engine....


Have a flywheel puller?

Yamaha service manual?

Yamabond or threebond to seal the center cases....

Air impact will help to loosen clutch hub nut...





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