Help! '05 Ranger 500 carb engine with too much compression? - Page 2
Close
Login to Your Account
PRC Polaris Ranger Club - Powered by vBulletin

Help! '05 Ranger 500 carb engine with too much compression?

This is a discussion on Help! '05 Ranger 500 carb engine with too much compression? within the Ranger Problems & Solutions forums, part of the Polaris Ranger Forums category; Valve lash should be checked on the base circle of the cam lobe in any engine. You may get away with using the one valve ...

Page 2 of 5 FirstFirst 1234 ... LastLast
Results 11 to 20 of 43
Like Tree15Likes

Thread: Help! '05 Ranger 500 carb engine with too much compression?

  1. #11
    (Steve) 1000+ Member pyromedic's Avatar
    Join Date
    Apr 2015
    Location
    W. Of Asheville, NC. and N. FL
    Posts
    2,272
    Member #
    25939
    Liked
    1628 times
    Valve lash should be checked on the base circle of the cam lobe in any engine. You may get away with using the one valve open method while checking the other on some mildly cammed engines like a lawnmower. That doesn't necessarily hold true on all engines. Depending upon cam design base circle can be rather narrow. Some cams have long ramps to take up lash more slowly and ease load on the valve train components. Some cams have long duration so base circle is narrow. Some cams have wide lobe centers which means less overlap on both lift and base circle meaning that just because one valve is fully open doesn't mean that the other valve is actually on base circle but may in fact be on the ramp even though no lift has taken place. I suggest using the manufacturer's recommendation of cam position to check lash.
    2015 Polaris Ranger 570 Full Size XP
    Lock N Ride Polaris Pro Fit Glass Wiper ready Windshield
    Lock N Ride Polaris Pro Fit Glass Rear Window
    Lock N Ride Polaris Pro Fit Poly Roof
    Lock N Ride Polaris Pro Fit Poly Doors with Hinged Windows
    Polaris Windshield Wiper
    Polaris Battery Connection Kit
    Duraclutch
    KFI Front Lower Hitch Receiver
    Pawltector Parking Brake
    Trail Armor Skids
    Odyssey Battery
    SVI Traction Control
    SATV Power Steering
    Badland 3500# Winch
    KFI Winch Mount
    KFI 72" Snow Plow
    Sucool 48w LED back up lights

  2. #12
    Starting Member wrench's Avatar
    Join Date
    Jun 2019
    Posts
    20
    Member #
    77199
    Liked
    2 times
    Quote Originally Posted by pyromedic View Post
    Valve lash should be checked on the base circle of the cam lobe in any engine. You may get away with using the one valve open method while checking the other on some mildly cammed engines like a lawnmower. That doesn't necessarily hold true on all engines. Depending upon cam design base circle can be rather narrow. Some cams have long ramps to take up lash more slowly and ease load on the valve train components. Some cams have long duration so base circle is narrow. Some cams have wide lobe centers which means less overlap on both lift and base circle meaning that just because one valve is fully open doesn't mean that the other valve is actually on base circle but may in fact be on the ramp even though no lift has taken place. I suggest using the manufacturer's recommendation of cam position to check lash.
    I am 90% sure the cam is timed correctly, and the cam is in the correct orientation when checking/setting valve lash. From the original timing, I have move the cam forwards and backward 1 chain pin and checking with a square, those two were significantly off centerline. This leads me to believe my cam timing is correct. Again, this is all with the engine in place, mounted at an angle. But still even with the square it is obvious plus or minus 1 pin is off.

    What I mentioned above about setting valve lash, that I did not follow from the service manual was that you should check/set valve lash for both exhaust valves with the same feeler gage at the same time. I did not do this. Mainly because I do not see the reason, they share the same rocker from the single exhaust lobe. I checked/adjusted one, then checked the other.

  3. #13
    (Steve) 1000+ Member pyromedic's Avatar
    Join Date
    Apr 2015
    Location
    W. Of Asheville, NC. and N. FL
    Posts
    2,272
    Member #
    25939
    Liked
    1628 times
    Quote Originally Posted by wrench View Post
    I am 90% sure the cam is timed correctly, and the cam is in the correct orientation when checking/setting valve lash. From the original timing, I have move the cam forwards and backward 1 chain pin and checking with a square, those two were significantly off centerline. This leads me to believe my cam timing is correct. Again, this is all with the engine in place, mounted at an angle. But still even with the square it is obvious plus or minus 1 pin is off.

    What I mentioned above about setting valve lash, that I did not follow from the service manual was that you should check/set valve lash for both exhaust valves with the same feeler gage at the same time. I did not do this. Mainly because I do not see the reason, they share the same rocker from the single exhaust lobe. I checked/adjusted one, then checked the other.
    I was not questioning cam timing, simply pointing out the importance of checking lash while the lifter is on the base circle of the cam and making the point that on some cams the location of the base circle can be small.

    I don't know whether it will be helpful or not, but starting at about 7 minutes in this video by my favorite YouTube small engine mechanics, Taryl, you can see the effect of valve lash that is too loose causing high compression. Granted this isn't a Polaris engine but the principle is the same.


    Taryl gets away with "his method" of adjusting valve lash on your typical small engine but higher performance engines like those in Polaris may not respond to shortcut techniques as well as your typical mower engine.

    Bottom line, if you are CERTAIN that valve lash is adjusted properly it is probably not the cause of your high compression issue. No one else had mentioned it so I thought I would toss it out there.

    One last thought, simple mistakes are easy to make, we all make them. It would be easy to make the mistake of setting valve lash accidentally using the metric numbers on a feeler gauge labeled with both metric and Imperial sizes. For example, .008 mm would only be .0003 inches, much smaller than .008 inches. Once again, trying to cover all the bases to help you find the problem.
    2015 Polaris Ranger 570 Full Size XP
    Lock N Ride Polaris Pro Fit Glass Wiper ready Windshield
    Lock N Ride Polaris Pro Fit Glass Rear Window
    Lock N Ride Polaris Pro Fit Poly Roof
    Lock N Ride Polaris Pro Fit Poly Doors with Hinged Windows
    Polaris Windshield Wiper
    Polaris Battery Connection Kit
    Duraclutch
    KFI Front Lower Hitch Receiver
    Pawltector Parking Brake
    Trail Armor Skids
    Odyssey Battery
    SVI Traction Control
    SATV Power Steering
    Badland 3500# Winch
    KFI Winch Mount
    KFI 72" Snow Plow
    Sucool 48w LED back up lights

  4. Remove Advertisements
    PRCForum.com
    Advertisements
     

  5. #14
    Starting Member wrench's Avatar
    Join Date
    Jun 2019
    Posts
    20
    Member #
    77199
    Liked
    2 times
    Thank you sir.
    pyromedic likes this.

  6. #15
    Starting Member wrench's Avatar
    Join Date
    Jun 2019
    Posts
    20
    Member #
    77199
    Liked
    2 times
    Does anybody know if there is a sensor that would cause the engine to govern? Maybe a seat sensor, or temp sensor?

  7. #16
    RJ
    RJ is offline
    (Rod) Elite Member RJ's Avatar
    Join Date
    Nov 2012
    Location
    SE Michigan
    Posts
    876
    Member #
    18732
    Liked
    316 times
    I dont think on an 05. Been following...something doesn't add up. Is it possible you received the wrong piston or got it in backwards? Is it clearing the intake and exhaust ports like it should be? Almost sounds pinched off. Back in my sledding days a lot of guys squeaked there machines running wisecos. Didn't have their tolerances right and that forged piston would swell up and down they'd go. Might be worth a look in the ports either way. Just brain storming.
    Last edited by RJ; 06-11-2019 at 08:18 AM.
    2018 1000 XP Titanium Matte Metallic
    Lock n ride glass windshield and roof
    MMA lift
    27-11-14 Tusk Trilobites
    G5 tune

    Past rides
    2004 Ranger. 2x4 with trusty 425
    Built like a tank and still running strong.

    2012 800 XP LE
    Wire chaffing fuel pump eater but never left me stranded!

    2016 900 XP Titanium Matte Metallic

  8. #17
    Starting Member wrench's Avatar
    Join Date
    Jun 2019
    Posts
    20
    Member #
    77199
    Liked
    2 times
    Arrow on the piston pointing towards the exhaust. Ring gap was within spec. Rotating the engine with the spark plug out, there is no interference felt.

  9. #18
    Starting Member wrench's Avatar
    Join Date
    Jun 2019
    Posts
    20
    Member #
    77199
    Liked
    2 times
    I went back and readjusted the valve lash per the manual, exhaust adjusted with the same feeler gauge at the same time. Still no difference. When you turn the key, the start pauses, then turns the engine over and starts right up. Idles smooth, it will accelerate to 15-20mph fine then just fall on it's face and not go any faster and just sounds like it is cutting out and missing. The exhaust lobe doesn't have any signs of wear. The owner said other than smoking badly before I rebuilt it, it ran good around 45 mph.

    He brought it back to me yesterday and I have taken the valve cover and cam gear cover off. I think I will try adjusting the timing 1 pin advanced and seeing how it runs.

  10. #19
    (Steve) 1000+ Member pyromedic's Avatar
    Join Date
    Apr 2015
    Location
    W. Of Asheville, NC. and N. FL
    Posts
    2,272
    Member #
    25939
    Liked
    1628 times
    I didn't go back to your original post, or any other posts to see, but if you haven't done so, you might check the starter. You may not have a high compression problem at all but rather a bad starter. Starters have brushed motors and brushes do wear out; bearings can get rusted and be resistant to rotation and winding can be burned out.

    It may have been mentioned already but if not the cam on some engines has a compression release that works while starting and stops with the higher RPM of the engine running. Since the engine is running smooth at idle and doesn't act up until higher speeds compression may be fine but the compression release isn't working properly. If compression was truly that much too high you would probably be experiencing pinging or detonation when under load, especially on regular gas and once the engine was fully warmed.

    Your higher RPM problems could be caused by weak valve springs which allow the valves to float at high RPM rather than seat. Valve float will cause missing.

    Have you replaced the spark plugs? Spark plugs can develop a glaze on them, especially if they had carbon build up from burning oil and hard acceleration was attempted. The high heat of hard acceleration turns the carbon into a conductive glaze on the porcelain of the plugs which shorts them at higher RPM. The reason is that as RPM increases so does cylinder pressure and spark has more difficulty jumping the gap under high pressure than it does at the lower pressure of low RPM. The spark, like all electricity, takes the path of least resistance so if resistance is higher across the spark plug gap at high cylinder pressure than it is across the glazed porcelain the spark goes down the porcelain to ground.

    Inadequate fuel supply will cause missing and cutting out. Check fuel pressure under those conditions. Clogged filter, tank vent, lines pinched, bad pump or low voltage to the pump can all be causes of low fuel supply.

    Up to this point we have assumed that everything electrical is in good condition, however, if spark is weak and plugs are good, it may be due to a low voltage condition at the ignition coils or somewhere in the electrical system. Polaris states that 80% of electrical problems are caused by bad connections. If you haven't done so you might check all your connectors for corrosion and dirt.

    Use caution changing cam timing. I don't know how many degrees 1 pin affects it, but I suspect its a lot, and may cause valve/piston interference. I wouldn't go outside the manual's directions for timing the cam.
    Rangerwhit likes this.
    2015 Polaris Ranger 570 Full Size XP
    Lock N Ride Polaris Pro Fit Glass Wiper ready Windshield
    Lock N Ride Polaris Pro Fit Glass Rear Window
    Lock N Ride Polaris Pro Fit Poly Roof
    Lock N Ride Polaris Pro Fit Poly Doors with Hinged Windows
    Polaris Windshield Wiper
    Polaris Battery Connection Kit
    Duraclutch
    KFI Front Lower Hitch Receiver
    Pawltector Parking Brake
    Trail Armor Skids
    Odyssey Battery
    SVI Traction Control
    SATV Power Steering
    Badland 3500# Winch
    KFI Winch Mount
    KFI 72" Snow Plow
    Sucool 48w LED back up lights

  11. #20
    1000+ Member Rangerwhit's Avatar
    Join Date
    Feb 2017
    Posts
    1,643
    Member #
    49442
    Liked
    439 times
    Have you taken flywheel cover off and made sure tdc compression. I slipped a tooth when I did my top end. Cleaned the carb checked diaphram, vent line and slide? You can rig a gas can with line straight to carb (gravity fed) to eleminate fuel problems. Exhaust restriction? I'm thinking you are chasing a couple of problems. Throwing ideas out here.
    2007 Ranger 500 (Carb)

Page 2 of 5 FirstFirst 1234 ... LastLast

Sponsored Links

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •