signs of when to adjust the valves


17 replies to this topic
  • dkwok

Posted April 13, 2004 - 12:31 PM

#1

hi,
besides following the no: of hours or mileage used,when do we need to adjust the valves,
what are the signs that we need to adjust them, say we forgot how many hrs or mileage we have used the wr4,
are there any signs? noise perhaps, hardstarting??????
will the motor be damage if we did not adjust it as per the regd period?
:)

  • tctrailrider

Posted April 13, 2004 - 12:40 PM

#2

Hardstarting.

  • Indy_WR450

Posted April 13, 2004 - 12:50 PM

#3

Once a year for the average rider not racing. Racers may have to do them twice a year. Yamaha four strokes hold their valve clearances longer then the adjustable designs by others. :)

  • Hamish

Posted April 13, 2004 - 04:45 PM

#4

on top of whats been said, if u can kick it thru the compression stroke without the decompressor, it's time to check the shims. It's a pretty easy job to do, and if they are in spec it's only gonna cost you a few hours of your time. If you have a friendly dealer close by you may even be able to exchange the shims for free.

Hamish

  • EricZ

Posted April 14, 2004 - 06:24 AM

#5

Don't wait for symptoms to show up. By then your valves may already be hanging open due to insufficient clearance. You are risking a burned valve. I agree with the above, once a year for average, more for racing.

  • Rudy

Posted April 14, 2004 - 02:36 PM

#6

I thought the valves generally tighten up--not hang open. I had thick oil in my bike all winter and could not start it. Then I had no compression and could kick away without using the decomp lever. I finally tore it down, and all 5 valves were off spec and the middle intake was 2,000ths too tight! I reshimmed all 5 to max spec for $10.00 plus gas money swapping shims between 2 dealers (got a list of what one dealer had and what they needed, and same for the other and went back and forth--only had to buy one shim!) Then I put a mix of 0w40 and 10w40 Amsoil and an 03' cam and WOW--what a difference--shifts and clutches like never before and starts first kick cold with choke, and usually never more than 4 kicks hot without using hot start button, and that's only because I am tired when the bike is hot and sometimes don't get a good kick on it. I just put over 200 miles of ST riding on it last week and am going to tear it down and check the clearance again and see if anything changed. It sure doesn't sound or feel like, but I want to be sure. I went over a 1000 miles of trail riding on it before checking them.

  • RobRantzow

Posted April 14, 2004 - 05:34 PM

#7

Hey I didn't go to the dealer for shims. As the other post says the valves lose clearance so you need to reduce shim thickness so I measured clearance wrote down the amount for each valve used a micrometer and removed material from the shim with 600 wet and dry paper after using a honing stone to get down to what was close to what I needed to make clearance and polished the surface up. No the amount you need to take off won't go through the hardness of the shim as it has to be hardend either all the way through or if it was case hardened it would be hammered to death at 10,000 RPM. No need for the dealer shims. And my bike has 1300 miles since modification to shims.

  • dkwok

Posted April 16, 2004 - 04:30 AM

#8

hi,
my son's wr4 dont have hardstarting?
only a bit noisy,
will the engine be damaged in any way if we didnt do the valves as per
schedule,
thank for all the advise,
:)

  • x2smoker

Posted April 16, 2004 - 07:29 AM

#9

Hey I didn't go to the dealer for shims. As the other post says the valves lose clearance so you need to reduce shim thickness so I measured clearance wrote down the amount for each valve used a micrometer and removed material from the shim with 600 wet and dry paper after using a honing stone to get down to what was close to what I needed to make clearance and polished the surface up


This is a great method, but caution must be used. If you have a "Machineing" buddy, have him polish the shims. With sandpaper, you cannot control it well enough to ensure that the surfaces remain precise and parallel.

More importantly, you will either need to put a chamfer on the edge that you just polished OR make sure that the freshly polished surface is facing up when installed. If the edges are real square (no chamfer), the shims are likely to stick in the keepers and become almost impossible to remove without some damage. I learned this from experience!

x2

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  • Hamish

Posted April 16, 2004 - 12:46 PM

#10

my son's wr4 dont have hardstarting?
only a bit noisy,
will the engine be damaged in any way if we didnt do the valves as per
schedule,




Probably not, but it's an easy and cheap job to do so why take the risk??
If they are way loose you may experience premiture camshaft wear. You need to remember that the WR/YZ family is a race engine, and should be maintained accordingly. The similarity with XR's and the like ends with the term 'dirt bike'

Hamish

  • dkwok

Posted April 17, 2004 - 11:07 AM

#11

thanks for all the replies,
i have been comtemplating doing it for a few months now,
no confidence is the word,
i figured if i touch it & buggerred it, it would be worst than if
i leave it alone for a while,
i will get to it asap when i have found plenty of time to do it,
thanks again,
:)

  • Hamish

Posted April 17, 2004 - 11:43 AM

#12

don't be scared by it.. it's not rocket science.
In my opinion it's a good idea for you to look at the top end when you have the lid off and visualise how everything works (which way the cams rotate, when the valves open etc etc) When you understand how it works, you are much more likely to be sucessful.
This page will help you understand. Our enginns only differ from this illustration in that they have 2 camshafts and no rockers. If you wish to read the whole artice start reading here

Hamish

  • RobRantzow

Posted April 19, 2004 - 01:45 PM

#13

Yes I did take the edge and chamfer it. Maybe its not for the average back yard do it yourselfer. But it saved me a trip to Yamaha! Also the paper used was wet & dry with cutting lube on a flat surface. I figured that a few thousands couldn't hurt too bad so?

  • dkwok

Posted December 25, 2006 - 10:29 PM

#14

hello again guys,
i did my son's wr4 valve a year ago & it was in spec,
i check it agian now & its in the lowest spec, meaning0.15mm for the intake(spec 0.15-0.20mm) & 0.25mm for the exhaust(spec 0.25-0.30mm)
question is shld i do the valves now or ride it for a few more months,
thanks again,
u guys are great:applause:
:thumbsup:

  • tigerowner_ut

Posted December 26, 2006 - 01:30 PM

#15

hello again guys,
i did my son's wr4 valve a year ago & it was in spec,
i check it agian now & its in the lowest spec, meaning0.15mm for the intake(spec 0.15-0.20mm) & 0.25mm for the exhaust(spec 0.25-0.30mm)
question is shld i do the valves now or ride it for a few more months,
thanks again,
u guys are great:applause:
:thumbsup:


Adjust them NOW! You should always adjust if at min spec. After all it is halfway tore apart anyway. Buying a shim kit (~$75 from hotcams) can pay for itself compared to what the dealer charges for individual shims. It is also recommended that you record the tolerances of all valves and record the shim size for each valve. Factory shims are not the standard 0.05mm increments so you may be able to swap shims around to get some of the valves close to max spec and purchase only a couple. Also if you record the sizes in the bike you will know what sizes you will need the next time.

  • MN_Paul

Posted December 27, 2006 - 08:09 PM

#16

If you are talking about trying to make a shim thinner with sandpaper or such, you are asking for trouble. One guy who tried it ended up with shim that did a lot of spinning due to the slight uneveness of the shim.

Paul

  • dkwok

Posted December 29, 2006 - 03:03 AM

#17

yes, shims are cheap, but they have their reasons, too far away from shops is one of the reasons,
:lol:

  • dkwok

Posted December 30, 2006 - 01:44 AM

#18

well i went to do my valves,
after putting in new shims, 2 old ones from the exhaust & 2 new ones,
i started to put everything back as per the online instructions here, then i had to drop the rubber washers from the rocker cover, one into the spark plug hole which i could fish out but the other disappeared somewhere into the cavity next to the spark hole, i could see some parts of it parts of it along wif some parts of the valve spring,
i am now stuck, dont noe wat to do,
tilt the bike upside down & hope tat it would fall out,
pls help,
:lol:




 
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