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Motorcycle mechs enter

This is a discussion on Motorcycle mechs enter within the Domestics and Foreigns forums, part of the Vehicle Specific category; I was curious as to why motorcycle engines seem to need valve adjustments every 5-10k miles? What adjustments are made, ...

  1. #1

    Motorcycle mechs enter

    I was curious as to why motorcycle engines seem to need valve adjustments every 5-10k miles? What adjustments are made, and why are they necessary on a motorcycle motor rather then any run of the mil car motor which can go sever times longer without needing adjusting (some being never with care)?

    Get technical

  2. #2
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    red
    2001 formula

    My guess would be becasue a lot of motorcycles have solid lifters and are constantly runing at such high RPM's. I have a 2003 honda 1100CC cruiser and it has hydraulic lifters and I have 39K miles on the bike and the owners manual tells me the lifters never need adjusting.

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    Member silverz28camaro's Avatar
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    sebring silver
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    most motorcycles do not have hydraulic lifters, they have a valve, then a shim then the bucket, then the cam lobe.

    when the valve hits the head over and over and over it starts to sink into the head and now you cam lobe to bucket clearance becomes tighter. If the clearance is 0 (usually spec is .004-.007in.) the valve will not close all the way and will leak causing poor performance. Also if you have a k@n filter you will probably need to do valve adjustments sooner because the little bit of dust that gets sucked through the filter starts wearing the intake valve seat. when the seat starts to become recessed the stem then protrudes further int the head causing again, a tight clearance

    a k@n isn't that bad on a street bike , but if you have a yzf450 or other similar fourwheeler do not put a k@n into it, fourwheelers see allot more dirty areas and a k@n just simply cannot stop all that dirt or sand. a foam filter with oil is the best choice for clean air entering the motor

    if you ever have a shop adjust you valve clearance, have them put it on the loose side of spec. This will prolong the term until you need another valve adj.

    on a 2006 yz250f dirt bike i will actually run the valve clearance .002 out of spec. on the loose side. this actually makes the bike run better. the little motors are equivalent to a 350 sb having 650hp, when you put the clearance on the loose side it make the combustion chamber slightly cooler resulting in more performance out of the bike, now don't do this to your bike, it has only been proven to work for the yz250f.

    hopefully i explained it well enough.

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    Member 1bad99ss's Avatar
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    im not too sure about that but ive never heard of people having to do that on any newer sport bikes...i have a 2002 hayabusa and never had any problems

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    old timer blue02Z's Avatar
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    Quote Originally Posted by silverz28camaro View Post
    most motorcycles do not have hydraulic lifters, they have a valve, then a shim then the bucket, then the cam lobe.

    when the valve hits the head over and over and over it starts to sink into the head and now you cam lobe to bucket clearance becomes tighter. If the clearance is 0 (usually spec is .004-.007in.) the valve will not close all the way and will leak causing poor performance. Also if you have a k@n filter you will probably need to do valve adjustments sooner because the little bit of dust that gets sucked through the filter starts wearing the intake valve seat. when the seat starts to become recessed the stem then protrudes further int the head causing again, a tight clearance

    a k@n isn't that bad on a street bike , but if you have a yzf450 or other similar fourwheeler do not put a k@n into it, fourwheelers see allot more dirty areas and a k@n just simply cannot stop all that dirt or sand. a foam filter with oil is the best choice for clean air entering the motor

    if you ever have a shop adjust you valve clearance, have them put it on the loose side of spec. This will prolong the term until you need another valve adj.

    on a 2006 yz250f dirt bike i will actually run the valve clearance .002 out of spec. on the loose side. this actually makes the bike run better. the little motors are equivalent to a 350 sb having 650hp, when you put the clearance on the loose side it make the combustion chamber slightly cooler resulting in more performance out of the bike, now don't do this to your bike, it has only been proven to work for the yz250f.

    hopefully i explained it well enough.

    pretty much hit the nail on the head there. good job but a yzf450 is a bike not a quad. a yfz450 is tho. ha ha i'm just nit pickin. on my crf450 and my little brothers, 02sunsetorangeZ, crf250 we check em every other ride or so. we dont have to do much adjusting tho. both have hotcams

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    megs 02sunsetorangeZ's Avatar
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    sunset orange
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    thanx for remindin me blue02Z i prolly need to check mine, i did some hard ridin last week.

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    Its a 4 door vette bitch! JOHN_DEERE_LS6's Avatar
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    i get mine adjusted on my gsxr 1000 when it starts to start harder and harder... you shodul be able to barely cycle the starter and it will fire instantly... when it starts having to roll over longer and longer its time for a valve adjustment.... plus youll hear a slight tick tick tick...

    hey will .02 loose on my 03 yz250f work liek runnin it loose on your 06??

    p.s. anyone wanna buy a 03 yz250F?? 2000$

  8. #8
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    2002 Z06

    What type of motorcycle. INLINE or TWIN. Most inlines don't get it tell 15,000miles. Look in the back of your owners manual.

  9. #9
    Member silverz28camaro's Avatar
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    sebring silver
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    Quote Originally Posted by John_Deere_LS1 View Post
    i get mine adjusted on my gsxr 1000 when it starts to start harder and harder... you shodul be able to barely cycle the starter and it will fire instantly... when it starts having to roll over longer and longer its time for a valve adjustment.... plus youll hear a slight tick tick tick...

    hey will .02 loose on my 03 yz250f work liek runnin it loose on your 06??

    p.s. anyone wanna buy a 03 yz250F?? 2000$
    not on the 03, the 06 is just a much more radicle motor that it is equivelant to a 350 chevy having about 680 hp, so when you run the valve alittle loose it removes lift and dur., so it somewhat helps keep the engine cooler, some say about 20 degrees, everytime i do this to a cust. bike, they say that it does run better, as far as the 03, don't do it. They only have 4 valve compared to the 5 valve on the 06

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    old timer blue02Z's Avatar
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    hey silverz, what kind of mods do have done to that little yamaha

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