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Thread: cr 500 compression release

  1. #1
    Join Date
    Nov 2002
    Location
    hinesville ga.
    --
    200

    cr 500 compression release

    i've been trying to solve my compression problem. i've added 3 head gasket and it's still hard to crank.after reading the thread about the compression release valve ACCU_Productors offer for $200.00 i had no choice but to try it out. i spoke with my machanic and another guy about this 200 big ones for the valve and they both mentioned about the compression release valve they use for the harley's...so i bought the valve they use and had it installed in my cylinder head since i had an xtra cylinder head...here's what it looks like.[photo's] i closed the valve and could not spin the motor over by hand...now when i opened the valve it was alot easier buy hand to spin over...now sometime this week i will put the motor on the frame and see what really happens...

  2. #2
    Join Date
    Nov 2002
    Location
    hinesville ga.
    --
    200
    Quote Originally Posted by gasmask
    i've been trying to solve my compression problem. i've added 3 head gasket and it's still hard to crank.after reading the thread about the compression release valve ACCU_Productors offer for $200.00 i had no choice but to try it out. i spoke with my machanic and another guy about this 200 big ones for the valve and they both mentioned about the compression release valve they use for the harley's...so i bought the valve they use and had it installed in my cylinder head since i had an xtra cylinder head...here's what it looks like.[photo's] i closed the valve and could not spin the motor over by hand...now when i opened the valve it was alot easier buy hand to spin over...now sometime this week i will put the motor on the frame and see what really happens...
    also as kasey mentioned the 85 cr 500 motor is a 1 year bike. if you remember i was trying to figure out if the transmission and clutch gear from a 91 will work in a 85? no not at all...however if you swap the sprocket case bearing out along with installing seals...you would need the complete transmission gear set with shaft and the entire clutch assemble it would work...you can not use the 85 clutch cover. it's not deep enough to accept the clutch basket etc...

  3. #3
    Join Date
    Mar 2004
    Location
    North Central Ohio!!
    --
    2,712
    That seems like a super. simple design. Sure am excited to see how it works! I plan on having my engine out next week to do the accu-start mod. Maybe i'll go your route if it works well for you.
    2007 YAMAHA YTZ450 went to a great home RIP Sam


  4. #4
    Join Date
    Mar 2003
    Location
    Kansas
    --
    1,507
    yes, definatly let us know how it works.. Im in need of something like this also for my motor.

  5. #5
    Join Date
    May 2003
    Location
    Houston, Texas
    --
    2,409
    I may need that as well. I have KTM 550 two stroke that will make starting all those 'small bore' 500's like starting a 125...ha ha

    Hey Gas Mask....that cylinder looks kinda small...are you sure its not a 250....

    compared to my 550cc....ha ha!!



    Good luck!!
    Last edited by Darius1502; 07-29-2005 at 03:07 PM.

    SEND ME PM HERE - CLICK HERE

    1986 ATC 250r, 1986 Tri Z, 1990 LT 500R "Quadzilla"


    Dirtbikes:

    1994 KTM 550 MXC (yes its a two stroke...66 hp stock!)
    1988 Yamaha DT

  6. #6
    Join Date
    Nov 2002
    Location
    hinesville ga.
    --
    200
    Quote Originally Posted by Darius1502
    I may need that as well. I have KTM 550 two stroke that will make starting all those 'small bore' 500's like starting a 125...ha ha

    Hey Gas Mask....that cylinder looks kinda small...are you sure its not a 250....

    compared to my 550cc....ha ha!!



    Good luck!!
    forsure cr 500

  7. #7
    Join Date
    May 2003
    Location
    Houston, Texas
    --
    2,409
    Just messing with you. I know they are all monsters!!

    really interested in how it turns out. I guess you will have a handlebar mounted lever, right?

    SEND ME PM HERE - CLICK HERE

    1986 ATC 250r, 1986 Tri Z, 1990 LT 500R "Quadzilla"


    Dirtbikes:

    1994 KTM 550 MXC (yes its a two stroke...66 hp stock!)
    1988 Yamaha DT

  8. #8
    Join Date
    Nov 2002
    Location
    hinesville ga.
    --
    200
    honestly ebay have complete compression release valve for under $40.00 shipped...hand lever,cable,valve and adjustment tools........look up compression release..................

  9. #9
    Join Date
    May 2003
    Location
    Houston, Texas
    --
    2,409
    I am wondering if that mounting postion (i.e., on the head) may affect combustion.


    The other company had it on the cylinder wall. Which is fine but if you screw it up its a new cylinder. I would rather put it on the head....

    I am really curious to see how it runs.

    These things are beast to start huh, gasmask? TDC does not help that much!!

    SEND ME PM HERE - CLICK HERE

    1986 ATC 250r, 1986 Tri Z, 1990 LT 500R "Quadzilla"


    Dirtbikes:

    1994 KTM 550 MXC (yes its a two stroke...66 hp stock!)
    1988 Yamaha DT

  10. #10
    Join Date
    Nov 2002
    Location
    hinesville ga.
    --
    200
    HAVE ACCU-PRODUCTS DO THE PROCESS....the first kick the valve closes...

  11. #11
    Join Date
    May 2003
    Location
    Houston, Texas
    --
    2,409
    Any results yet???

    Very interested in how it turns out!

    SEND ME PM HERE - CLICK HERE

    1986 ATC 250r, 1986 Tri Z, 1990 LT 500R "Quadzilla"


    Dirtbikes:

    1994 KTM 550 MXC (yes its a two stroke...66 hp stock!)
    1988 Yamaha DT

  12. #12
    Join Date
    Nov 2002
    Location
    hinesville ga.
    --
    200
    the results were disappointing...the valve was not strong enough to with stand the cr 500 compression...after a half-a-kick the valve closed...then water was leaking thur the insert into the piston...lucky i had an extra cylinder head...however i spoke with allen from ct racing and he said that they drill 2 holes on the exhaust side of the cylinder which releases some compression while kicking it...once the bike cranks it's compression is back to what is was...have anybody heard of this?

  13. #13
    Join Date
    Mar 2004
    Location
    North Central Ohio!!
    --
    2,712
    That really sucks that it didn't work. But, thank you for sharing your experience with us. I will be sure to post about the Accu-Start kit, once it's installed.

    My project is taking longer than I hoped, working 70+ hours a week and no time to work on it.
    2007 YAMAHA YTZ450 went to a great home RIP Sam


  14. #14
    Join Date
    Nov 2002
    Location
    hinesville ga.
    --
    200

    New Update....

    in my previous post i did not have any luck with that compression release valve installed in my cr 500 cylinder head... however i took it back to the shop and they reweld the insert to stop the leaks. so today i reinstalled that cylinder head on my bike and tryed kicking over. still the same problem. the valve closing to early...so i found something that would hold that valve open while i kicked it over...to my surprise it crunk up...so i let it run for a few minutes shut it off and tryed cranking it again and after finding something to keep that dogon valve open it crunk again...so i believe i solved my compression problem.....i also solved that removing the kicker after cranking the bike problem

  15. #15
    Join Date
    May 2003
    Location
    Houston, Texas
    --
    2,409
    good for you man! Keep at it the solution is just around the corner!!

    Glad you are back up and about!!

    SEND ME PM HERE - CLICK HERE

    1986 ATC 250r, 1986 Tri Z, 1990 LT 500R "Quadzilla"


    Dirtbikes:

    1994 KTM 550 MXC (yes its a two stroke...66 hp stock!)
    1988 Yamaha DT

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