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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: cycle thread on September 08, 2015, 01:40:34 PM

Title: K75 compression test
Post by: cycle thread on September 08, 2015, 01:40:34 PM

Hello all,

I would like to do a cylinder compression test on my 1989 K75, and not wanting to risk damage to the ignition system, or have petrol going everywhere, is there a way to isolate the ignition and fuel pump, but still be able to turn the engine over on the starter motor?.

The last engine I did, an older car, it was just a mater of disconnecting the power feed to the coil, and spinning it over on the starter!.

Thanks,

John

Title: Re: K75 compression test
Post by: The Mighty Gryphon on September 08, 2015, 11:52:08 PM

Just did a compression test on my K75.  Unplugged spark plug wires, removed the plugs and ran the test.  Only took 3-4 revolutions to get a reading on each cylinder.

Put everything back together and the bike runs just fine.

Title: Re: K75 compression test
Post by: rbm on September 09, 2015, 08:06:53 AM

To stop the fuel pump, pull the 4-pin connector going to the fuel tank.  To disconnect the ignition and injectors, pull the 4-pin connector for the secondary harness located on the rear left side under the tank.  As Gryphon says, it's probably not needed for the test you are performing.  BTW you'll need a 14mm adapter for your compression tester; just saying because this size is usually not included in the kits you can buy and must be obtained separately.

Title: Re: K75 compression test
Post by: cycle thread on November 26, 2015, 01:53:47 PM

Hello, sorry for my ridiculously late reply.....

Thanks for you're good advice, MG and RBM, have only just got back to working on the K75 after a lay off, advice very much appreciated,

John

Title: Re: K75 compression test
Post by: Gio on November 26, 2015, 05:59:25 PM

More importantly John - did you obtain ridiculously satisfactory compression numbers on all cylinders?

Title: Re: K75 compression test
Post by: cycle thread on November 28, 2015, 06:11:54 PM

Hello Gio,

Ashamed to say I have not performed the compression test yet!!, shall post the results here when I do, hopefully they will be very satisfactory...... :)

John