Valve adjustment

Discussion in 'Mechanic and Repair' started by weeze, Jan 17, 2012.

  1. weeze

    weeze LawnSite Fanatic
    Messages: 11,565

    i'm not adjusting them yet...i probably will not adjust them until after the 2012 season depending on how many hrs i mow this year. i just like to be prepared ahead of time. i will not adjust them until 300hrs. at that time my mower will no longer be under warranty i dont' think. it's not really about that it's just i don't trust people. i mean when i bought the mower i had them adjust the air intake hose connected to the carb so it wouldn't vibrate against the metal piece on the back of the mower possibly causing a hole in the hose over time. i watched them adjust it before i bought the mower. they did fine but they forgot to tighten one of the bolts on the metal piece back down. (they had removed it to get at the bolt for the hose better) it's just little mistakes like that. who knows what little mistake they could make while working on the engine? :laugh:

    the reason i asked about where to get a feeler guage is because i've never bought one before. i've never used one either. i don't think we've ever had the valves adjusted on any engine we've ever owned and we've never had any problems. so who knows? anyways i'm remembering seeing a feeler guage before in my dad's garage. if i can find it i'll just use it. i may practice on my pushmower first since the valves on it have never been adjusted. most feeler guages go as small as .0015 like ridin' said. i figure i'll use .003 since it's right in the middle of the recommendations. i hope it doesn't have some sort of star bit or special type of bit to adjust them. i hate that kind of junk. they try to make everything where you can't work on it yourself nowdays or you have to buy some special tool. i hope it's like the honda engine in the video and i'm able to use two wrenches to do it. has anyone done theirs and know what you use on the kawi fx engines?
    Last edited: Jan 19, 2012
  2. jdunk

    jdunk LawnSite Member
    Messages: 20

    if it ant broke dont fix it. i would not ajust anything unless you are having a problem
    just keep the oil changed and the motor clean and let it go
  3. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,004

    That's the ticket!
    More than anything, pull the fan/cyl. shroud on a regular basis and clean around the heads especially around the valve guide casting/opening.

    I would/do run straight 30wt oil also, as long as the temps don't get too low. I see yer in Alabama so low temps shouldnt be an issue.
    Also, valve adj aren't covered under warranty. So if ya let the dealer do it yer gonna pay.
    Last edited: Jan 23, 2012
  4. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,004

  5. weeze

    weeze LawnSite Fanatic
    Messages: 11,565

    i worked on my pushmower valves today. the intake valve was perfect and didn't need any adjustment. the exhaust valve was a little loose so i set it right. when i tightened the nut back down i guess i tightened it too much and it stripped out the adjustment screw. :laugh: ordered a new one. they cost about $2.00. those things are so fragile and weak it's pathetic. i'm sure the ones on the kawi mower engines are beefier. the adjusting part is simple it's just on that pushmower those screws are like toothpicks almost. :laugh:

    here's a page of valve clearances for honda engines:

    the engine on my pushmower is the gcv 160

    there's something i'm wondering. why do they make valves adjustable in the first place? why can't they just make something that keeps them in spec that way they never get loose? instead of an adjustable screw why not just make a metal rod the right length that's part of the rocker arm? that way they would never get out of spec and never need adjusting. i'm no engine expert or anything but just wondering why they make them adjustable when they are supposed to remain at one setting?
    Last edited: Jan 29, 2012
  6. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    Tolerances in manufacturing is one reason. And parts wear.
  7. grasscutter96

    grasscutter96 LawnSite Member
    Messages: 2

    Old subject, but see that OP question was not answered.

    Most engines have a 'compression release' lever built into the cam. When this wears out, you will get MAJOR kickback that will just about rip the pull handle out of your hand!

    You have 3 options:
    1-make sure you pull start it on the compression stroke.
    2-make sure valves are set perfectly. (must be done with engine cold. This means sitting overnight.)
    3-Replace the cam. (some manufacturers have a replaceable comp release lever. Others need to have whole cam replaced. Either way, the engine is coming apart.)
  8. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,327

    Grasscutter96....a sheared flywheel key or a cylinder full of gas from a leaking carb...will lengthen your arm also...I had a Honda 5.5hp on my logsplitter that would always kickback if you just yanked the rope...however..if you pulled up on the rope nice and easy..till you started to feel compression..and then yanked never kicked back and always started on the first pull...sometimes its cheaper and less painful to just get along with your eqipment..

    Jason...they do have engines that don't need valve adjustments..Kohler Commands...they have hydralic lifters...
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  9. grasscutter96

    grasscutter96 LawnSite Member
    Messages: 2

    piston slapper: True that! I did base my answer on the assumption that the engine was in good working order, besides having hard kickback. & yes, the other 2 options you mentioned can cause it as well.

    POWDER SL UT LawnSite Member
    Messages: 14

    Almost all of the quality small engine manufactures recommend the valve adjustment at 300-350 hours, but it's really more of a valve inspection. In my experience, usually the valves are still within tolerance at this hour of use range.

    I also believe the majority of folks don't even adjust or inspect at the recommended 300-350 hours.

    Most likely, you'll just take the cover off and discover with the feeler gauge that it's within tolerance and put the cover back on. If it needs to be adjusted, then you can DIY or pay the dealer, but it cost nothing or any adjusting to close a valve and check with a gauge first.

    Note: My experience is if in fact at the actual recommended hours and NOT just at anytime during the life of a small engine.

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