Valves and hours?


18 replies to this topic
  • dewking

Posted October 26, 2012 - 01:47 PM

#1

so I finally got 5 hours on my new 2010 checked the valves and they are in spec. my question is do I really need to check the valves every 15 hours of use? I dont race just riding for fun but I do not baby it either..
Regards,
Dewking

  • pre-mixed

Posted October 26, 2012 - 02:43 PM

#2

I just checked the Valves in my 2012 a couple days ago with 60 hours on my bike and the valves have not moved at all. I trail ride, do hair scrambles and enduros in the B class and am pretty easy on the rev limiter but i don't just poke along and clean my air filter pretty much every ride.

  • jcross312

Posted October 26, 2012 - 03:36 PM

#3

From what I can tell, they pretty much let you know when it's time to adjust by not letting the engine start very easily. I don't see how it does any harm to the motor. You will tell when the motor gets easy to kick (low compression), but hard to start.

Edited by jcross312, October 26, 2012 - 03:37 PM.


  • Shawn_Mc

Posted October 26, 2012 - 05:06 PM

#4

Checking them to find out where they are after the first 15 hours is a good practice. That way you know where they basically started. If you wanted to be careful but not anal about it, every 25 hours is plenty. I checked mine like that to about 60 hours...then didnt pull the valve cover till it stopped firing on the first kick. When the carb is right, the bike will fire easy. Assuming nothing has changed, if it suddenly gets difficult to kick start, but will bump start no problem, the intakes have gone to zero. I just shimmed one to day that was hanging open on the base circle. Id adjusted it for the guy about 20 runnign hours before, and he told me it was getting funky to start. So I checked the intakes and sure enough...I had to reshim .008" to get .006"...yup, there was a negative .002" there. Thats why it wouldnt start on the kicker. After the shim, it fired on the first kick.

  • CamP

Posted October 27, 2012 - 06:01 PM

#5

When I had my 04, I'd check them every 25 hours, or so. They never moved and it was pushing 200 hours when I sold it. When I had my 06, I check them every 50 hours. They never moved and it had 150 hours when I sold it. When I got my 08, I figured I would just ride it until it got hard to start. At 125 hours, I haven't even removed the valve cover.

  • gotwings

Posted October 27, 2012 - 06:12 PM

#6

248 hrs. on my '09, valves have never moved. I stopped checking over 100 hours ago. New oil and air filter every 2 rides.
*plus the 5 hours or so I put on before the hour meter!

Edited by gotwings, October 27, 2012 - 06:13 PM.


  • NEKOOHC

Posted October 27, 2012 - 08:19 PM

#7

The valves and springs won't last forever

It's best to replace them as part of preventive maintenance , if the valves fail expect a ruined motor at the least

  • CamP

Posted October 28, 2012 - 05:26 AM

#8

The valves and springs won't last forever

It's best to replace them as part of preventive maintenance , if the valves fail expect a ruined motor at the least


Honda valves typically lose their surface hardening and start to recede into the head long before they are old enough to break. That's actually a good thing because the bike just gets hard to start when the valve is worn, which gives the CRF owner some warning.

Yamaha gets high praise for how long their valves last, but that's a double edge sword because people can run them so long that eventually a valve head breaks off and wipes out the engine.

  • jcross312

Posted October 28, 2012 - 06:26 AM

#9

Honda valves typically lose their surface hardening and start to recede into the head long before they are old enough to break. That's actually a good thing because the bike just gets hard to start when the valve is worn, which gives the CRF owner some warning.

Yamaha gets high praise for how long their valves last, but that's a double edge sword because people can run them so long that eventually a valve head breaks off and wipes out the engine.


In your opinion, at what hour mark would you replace valves as preventative maintenance?

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  • CamP

Posted October 28, 2012 - 07:13 AM

#10

In your opinion, at what hour mark would you replace valves as preventative maintenance?


That depends on how you ride. If you are a pro mx'er, I'd replace them when I replaced the crank, which would be every 50 hours. I you are in the normal 99%, I'd run them until they required the first shim job. If you replace them instead of shimming them, you typically don't need to grind the seats. The exception is when the seat isn't concentric, which shows up when the valves wear out under 50 hours.

  • ljschnel

Posted October 28, 2012 - 07:22 AM

#11

From what I can tell, they pretty much let you know when it's time to adjust by not letting the engine start very easily. I don't see how it does any harm to the motor. You will tell when the motor gets easy to kick (low compression), but hard to start.

I've got 208 hrs on my '07 and it just recently became difficult to start when cold (like more than 4 kicks). Checked the valves (for the first time) and the left side intake was out. I've got a new shim on order and I won't check them again unless I have trouble starting. I think usage should dictate how often you check them though. I ride in the woods and am rarely ragging the motor off the rev limiter. If you are wringing every last bit out of it some proactive maintenance would be in order....and that goes beyond the top end. The crank does not give benign indications that it is failing like the valves do...

  • CamP

Posted October 28, 2012 - 04:28 PM

#12

I've got 208 hrs on my '07 and it just recently became difficult to start when cold (like more than 4 kicks). Checked the valves (for the first time) and the left side intake was out. I've got a new shim on order and I won't check them again unless I have trouble starting. I think usage should dictate how often you check them though. I ride in the woods and am rarely ragging the motor off the rev limiter. If you are wringing every last bit out of it some proactive maintenance would be in order....and that goes beyond the top end. The crank does not give benign indications that it is failing like the valves do...


Do yourself a favor and replace the valves/springs before you ride the bike again. Right now, the seats are probably still good, but if you continue to ride with worn out valves, the seats will be ruined too. Shim jobs only last a few hours on Ti valves and they wreck the valve seats in the process.

Replacing the valves/springs now will save you $150 in seat grinding later.

Edited by CamP, October 28, 2012 - 04:34 PM.


  • jcross312

Posted October 28, 2012 - 05:48 PM

#13

Do yourself a favor and replace the valves/springs before you ride the bike again. Right now, the seats are probably still good, but if you continue to ride with worn out valves, the seats will be ruined too. Shim jobs only last a few hours on Ti valves and they wreck the valve seats in the process.

Replacing the valves/springs now will save you $150 in seat grinding later.


I will have to agree, I just put new steel intakes in my bike after shimming the ti's one time and I am very pleased with the outcome.

  • ljschnel

Posted October 28, 2012 - 09:06 PM

#14

Do yourself a favor and replace the valves/springs before you ride the bike again. Right now, the seats are probably still good, but if you continue to ride with worn out valves, the seats will be ruined too. Shim jobs only last a few hours on Ti valves and they wreck the valve seats in the process.

Replacing the valves/springs now will save you $150 in seat grinding later.

I will have to agree, I just put new steel intakes in my bike after shimming the ti's one time and I am very pleased with the outcome.

Good advice. That sounds consistent with my experience with my crf250r... Should I replace the gaskets at the top and bottom of the cylinder? Probably piston, pin, and ball hone it too???

  • CamP

Posted October 29, 2012 - 06:26 AM

#15

Good advice. That sounds consistent with my experience with my crf250r... Should I replace the gaskets at the top and bottom of the cylinder? Probably piston, pin, and ball hone it too???


Yes, at 208 hours, it's time to replace the piston/ring/wristpin. A ball hone will take off the cylinder glaze, but you can use scotchbrite to do the same thing.

  • 02sedona

Posted October 29, 2012 - 06:36 PM

#16

I ride mostly woods with a bit of desert mixed in I the winter. I'm not wringing my bike out too often. Other than a hill climb for 10-20 seconds. Did a fresh top end last winter and am at 130 hours with out any movement in a fresh 2008 head, oem exhaust, and pro x intake valves. I feel once the oem valves move, then you should replace with new steel valves and then call it good for a while. hopefully I can go through a few pistons instead of valves from now on.

  • Dirtclods

Posted October 30, 2012 - 09:41 AM

#17

04 CRF 450 R I've ridden the piss out of this bike two top ends so yes check those valves. Don't wait till it's hard to start then it's too.... LATE!!

Edited by Dirtclods, October 30, 2012 - 10:46 AM.


  • meeh350

Posted October 30, 2012 - 02:48 PM

#18

2002...original valves....150hrs in the last 2 years


Mine stretched when I baked the bike.

The only issues I have had are difficultly starting...adjust the valves and its happy again. Im on my 3rd and final adjustment...its time for new valves.

Edited by meeh350, October 30, 2012 - 08:26 PM.


  • FOUR STOKED

Posted October 30, 2012 - 06:42 PM

#19

I replaced my '05 head with an '07 head and new valves earlier this year. As soon as my intakes started to move I disassembled the top end to get some new valves and springs. What I found was although the intakes had only moved a few thousanths, the exhaust valve guides were worn out- as in the exhaust valves wobbled back and forth a lot. The bike probably has over 300 hours on it now, and I put a crank in it shortly after the new head when one of the bearings started rattlling. You can do what you want, but I found that the exhaust guides needed replacing by the time my intakes started moving. I assume the accelerated guide wear on the exhaust guides in comparison to the intake guides is the side load of the rocker arm.





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