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How to know when to adjust valves?

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Is there a way other then hrs to know when to get valves adjusted. I have a 2008 CRF450r and was told I have steel valves that last a long time. Ive also been told if your bike starts Ok your valves are Ok. Any thoughts??

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Hard to start is the most common symptom of the valve lash closing. Were you told the head had steel aftermarket valves installed? The stock OEM intakes valves are coated titanium and are prone to wear quicker then most stainless steel valves. The stock OEM exhaust valves are steel.

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MRMOTO35, no I was told in passing one day never researched but thanks for the info. The bike starts right up but starts to pop after warmed up for a while not at first I haven't rode since last year (had surgery) so I'm hoping the popping will pass after I burn up gas, I guess Ill change plug but my guess is its time for a valve adjustment.

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the pop is from lean condition tweak the carb screw out just a little if you do not have a aftermarket adjustable mixture screw then you need to order one they are about 12 dollars, also from sitting up the pilot jet might be partially clogged.

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How do you know when to adjust valves? By checking them on a regular basis. When the clearances are no longer in spec, it's time to adjust them.

 

It really is that simple.

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How do you know when to adjust valves? By checking them on a regular basis. When the clearances are no longer in spec, it's time to adjust them.

It really is that simple.

This^. You need a SERVICE manual. You can buy one on eBay or maybe cheaper on amazon and it'll tell you everything you need to know. Also there's a FAQ thread at the top that has about everything imaginable in it.

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checking is wicked easy.. adjusting if out of spec will require more mechanical know how, but still not to difficult. I don't split cases, but even i learned to adjust valves on this motor. But really, checking clearance is super super easy. tank off, valve cover off, push the kickstarter till the cam lobe is pointing backward level with the head, slide in the appropriate feeler gauge under the intake cam lobe. That's it.

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I say if you are running stock valves you should check your valves every other oil change. Its not that hard to do. Though like a few people have said if the bike becomes hard to start get to checking. The stock valves can move on you fast as well and you may not even catch it if you checked them every oil change. Once the coating is warn off the titanium valve its done.

 

Good quality stainless steel valves valves can take a wile before they start to show signs that they are moving. Check them equally as often and you can catch it before it leaves you kicking and kicking on a trail.

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Chasing the valve lash does nothing for you. If you check them at the intakes are at .004" and they started at .006", You can reshim them, but its only a matter of time.

 

Ive seen my buddies leave the truck after reshimming the intakes back to .006, go out on a full day trail ride only to have the intakes closed up to zero by the time we get back to truck. The lash going to zero isnt going to cause a valve to "drop" like some people will say. As a matter of fact, as the lash closes up, the valve gets set into the pocket easier and easier. When the bike suddenly takes 4-5 kicks or more to fire..thats when I check them. They'll usually be at .002".

 

The stainless valves are a little better if you just throw them in. If you lap them in, a little better yet. But if you have the seats cut and do the stainless, its much better.

 

The best solution is to install copper berylium seats and a good Ferrea steel intake (proflo version is lighter than the Ti believe it or not) and you wont have to mess with it again until the bike is obsolete.

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I didn't know Ferrea makes hollow-stem stainless intake valves for CRF250 and 450 that are lighter than the stock Ti valves!!! Sweeeeet. What year bikes?

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I didn't know Ferrea makes hollow-stem stainless intake valves for CRF250 and 450 that are lighter than the stock Ti valves!!! Sweeeeet. What year bikes?

 

Thats just it, they arent even stainless, or hollow stemed. They're black nitrided steel with a "manley proflow" design where the exposed stem to the head is reduced in size. The offer springs too, pretty reasonable pricing.

 

http://www.ferrea.com/Honda-Engine-Valves/p34269?right_select_year=2006&right_select_make=28&right_select_model=2825&right_select_motor=6496&right_select_submodel1=4841

 

F0248 HONDA CRF (2002 - 2006) 450 INTAKE COMPETITION MOTORCYCLE VALVES

Off-road Motorcycle Applications

Intake

Head Diameter: 36 mm

Stem Diameter: 5.49 mm

Overall Length: 84.6 mm

Tip Length: 1.15 mm

Reference: 20" Flo Dish Head. Stock size. Black Nitride

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I couldn't find the weight of the valves listed, but with Ti having such a low density compared to stainless steel I don't know how the stainless valve could weigh less without being hollow-stemmed and cutback for flow. Even then I don't think it's enough to be lighter than a Ti alloy. I don't know what the stock valves weigh.

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I like this site, every once In awhile

You can really learn some shit..

Now you have me thinking tho. When I checked "the kids" valves about a week ago one of his intake valves was about zero'd and one of the exhaust was zero'd. Not this is on a 250r but I can't help but wonder if the shop he had tear his motor apart a few months prior just threw the motor back together and didn't keep track of the shims or match them up... I would like to lap in some new SS intake valves and reshim the exhaust and think that'd be fine... Or should I just have him spend the money and have one of these big names do all the work? Thoughts?

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Put in stainless, Diggla! Likely swapped the shims on you as exhaust don't close up often.

If I can find stainless Intake valves that are lighter than the stock Ti Intake valves I will buy some right now. Where are they? 2014 CRF250R and CRF450R. I had no idea they existed.

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Put in stainless, Diggla! Likely swapped the shims on you as exhaust don't close up often.

If I can find stainless Intake valves that are lighter than the stock Ti Intake valves I will buy some right now. Where are they? 2014 CRF250R and CRF450R. I had no idea they existed.

I think I might try it man. I'm gonna order a spring clamp and check out the guides and if they're good then I think I'm gonna give it a go.. First I should prob do the gas test on the exhaust valves tho huh? That should tell me somethin right?

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I like this site, every once In awhile

You can really learn some shit..

Now you have me thinking tho. When I checked "the kids" valves about a week ago one of his intake valves was about zero'd and one of the exhaust was zero'd. Not this is on a 250r but I can't help but wonder if the shop he had tear his motor apart a few months prior just threw the motor back together and didn't keep track of the shims or match them up... I would like to lap in some new SS intake valves and reshim the exhaust and think that'd be fine... Or should I just have him spend the money and have one of these big names do all the work? Thoughts?

 

I think I might try it man. I'm gonna order a spring clamp and check out the guides and if they're good then I think I'm gonna give it a go.. First I should prob do the gas test on the exhaust valves tho huh? That should tell me somethin right?

 

Pull the head, clean the combustion chamber with carb cleaner spray (does an amazing job) and then check the combustion chamber with alcohol. You can lap in stainless valves and be pretty good to go.

 

The Ferrea steel (Not stainless) have a reduced stem from the guide to the head and the head has less profile to it, thats how it ends up a gram or two lighter. Its not a lot, but its enough to be able to use and OEM spring and not float the valves. I wouldnt lap the black nitrided valves, it'll grind off the nitride and reduce the valve life.

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Pull the head, clean the combustion chamber with carb cleaner spray (does an amazing job) and then check the combustion chamber with alcohol. You can lap in stainless valves and be pretty good to go.

The Ferrea steel (Not stainless) have a reduced stem from the guide to the head and the head has less profile to it, thats how it ends up a gram or two lighter. Its not a lot, but its enough to be able to use and OEM spring and not float the valves. I wouldnt lap the black nitrided valves, it'll grind off the nitride and reduce the valve life.

Heads already off. Cool deal man I'll try this later. Appreciate it

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The Ferrea steel (Not stainless) have a reduced stem from the guide to the head and the head has less profile to it, thats how it ends up a gram or two lighter. Its not a lot, but its enough to be able to use and OEM spring and not float the valves. I wouldnt lap the black nitrided valves, it'll grind off the nitride and reduce the valve life.

Lighter is lighter! I don't see any listings for the newer bikes though, and I don't see any weights listed...

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CRF 250R (2004/2007) - Motocross

• CRF 250R (2008-2009) - Motocross

• CRF 250R (2010) - Motocross

• CRF 450 (2002-2006) - Motocross

• CRF 450 (2007-2008) - Motocross

CRF 450 (2010) - Motocross

 09-2012 all the same intakes.

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