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Leakdown testing pressure & a couple other questions ???

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    Leakdown testing pressure & a couple other questions ???

    Hey everybody...I'm about to do a leakdown test on my bike (81 GS1100E) & I'm not sure what pressure I should be putting into the motor. I know most automotive motors usually take about 100 psi. (in-feed pressure) but I'm thinking that may be too much for a bike motor. Is there any standard psi setting for these bikes? Or do i just put enough pressure in to be able to hear any leaks? I was also wondering if it matters if I have the valve cover off while doing this test. Reason being, is I'm trying to find out why I have positive pressure on the intake of cyl.#4 , it's making so much pressure on the intake side that it's literally blowing my carb sync hose off the nipple on the intake. And it's constantly popping out the exhaust while running. I just had the carbs professionally cleaned & I adjusted the valves myself while my carbs were being done, so I'm trying to narrow this problem down. Everyone is telling me it has to be a intake valve, but both of the intake valves on that cyl. are set at .005 (they were at .003 before adjusting them) (actually all the valves are set to .005 now) I have re-checked all my valve clearance setting at least 6 times now so i know they are spot on. I just can't understand why its doing this now & it didn't before. I'm hoping the leakdown test will tell me more. I've already done a compression test & the results of that test tell me that cyl.#4 is my best cyl. (#1-120, #2-115, #3-115, & #4-125lbs.) So this thing is really throwing me for a loop. / I would appreciate any help you guys can offer me on this problem.
    1981 GS1100E Stock motor except for Kerker Exhaust w/K&N pods

    #2
    My leakdown says 90 PSI feed in the instructions. Bring the cylinder being tested to TDC on the compression stroke and verify with the timing mark in the ignition plate. Take off the oil cap and slide the airbox back off the carbs so you can listen to the face of the carbs. If its air noise from the oil cap its rings. if the carbs its an intake valve. if neither its an exhaust valve. Just a process of elimination by listening to the carbs and oil fill hole.
    Last edited by chuck hahn; 11-12-2017, 11:15 PM.
    MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
    1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

    NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


    I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

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      #3
      Thanks for the info, Chuck, appreciate it. Hopefully I'll know more after this test. Thanks again...
      1981 GS1100E Stock motor except for Kerker Exhaust w/K&N pods

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