BF100 Comp. Test Procedure

[HDCOHEE]

I have the other topic about needing help with BF100 that wont idle. In trying to diagnose it myself, I just performed a compression test. My question is,, The repair manual shows the test spec to be 151 Lbs. at 600 rpms ??, The procedure to perform the test says to crank engine with pull rope ??, I need to know if cranking the engine with the pull rope simulates the 600 rpm test spec. The engine only has 60 psi in each cylinder, which tells me if its suppose to be 151 psi, then I have a burnt valve or two, and my no idle question gets answered. Does anyone know if I have performed the comp. test correctly and if 151 psi is a correct spec. to use for cranking engine with pull rope ?? Please respond A.S.A.P. if you can help me.<br /> Thank You, HDCOHEE

 

[phatmanmike]

Re: BF100 Comp. Test Procedure

im not sure bout your 4 stroke, but my 2 strokes do this...<br /><br />1. remove all spark plugs from block AND leads<br />2. install guage in plug hole<br />3. turn ignition switch for 2-3 seconds each cylinder...<br /><br />on a motor that big, you wont get the same reading with a rope pull, unless your incredible hulk

 

[outboardguy]

Re: BF100 Comp. Test Procedure

Originally posted by phatmanmike:<br /> on a motor that big, you wont get the same reading with a rope pull, unless your incredible hulk

Mike, the Bf 100 is only a 10hp 2 cylinder motor, not 100 hp. <br />dcohee, sounds like you did the test correctly.Did you have the throttle at WOT? That might make a difference.If your compression is still low squirt a little oil into the cylinders and test again. If it goes up it's the rings and not the valves. Generally 60 psi is the minimum compression for most engines, any lower than that and you won't even start up.