Compression check

[Neville Lush]

Ok, so finally I have the chance today to get back to working on my bike. When doing the compression test I have one plug out of each cylinder and one plug wire grounded from each coil. When cranking over I have the throttle wide open but the secondaries stay closed. Also it won't turn over at at regular cranking speed. If I hold the starting button in the engine will turn over one stroke at a time with a pause between each cylinder like I'm letting the button off but I'm not. What am I doing wrong?
Ridefree

The engine will not turn over more than one turn with no compression. Put all your plugs back in except the one with the comp gauge in it. Take off all the primary coil wires, the power one (common colour to all three coils),cannot remember which colour sorry, this will stop sparks/running engine. Then do your comp test at wide open throttle. Repeat for each cylinder.

 

[kmrmike]

I had a similar starting problem yesterday when trying to start my bike...backed out of the garage and tried to start and seemed to crank one cyl then stop...turned key off then on...same thing, crank one turn then stop... got out my portable lithium battery and jump started....cranked right up. I'm thinking the battery voltage was so low the ECU couldn't tell the starter to work properly(just guessing)...my resting battery voltage is 12.3 volts...maybe time for a new battery?

 

[Ridefree]

I had a similar starting problem yesterday when trying to start my bike...backed out of the garage and tried to start and seemed to crank one cyl then stop...turned key off then on...same thing, crank one turn then stop... got out my portable lithium battery and jump started....cranked right up. I'm thinking the battery voltage was so low the ECU couldn't tell the starter to work properly(just guessing)...my resting battery voltage is 12.3 volts...maybe time for a new battery?

Battery was getting weak so I put in a new battery as part of this operation

 

[Ridefree]

The engine will not turn over more than one turn with no compression. Put all your plugs back in except the one with the comp gauge in it. Take off all the primary coil wires, the power one (common colour to all three coils),cannot remember which colour sorry, this will stop sparks/running engine. Then do your comp test at wide open throttle. Repeat for each cylinder.

Thanks Neville, that did the trick. Came up with 211~ 214 psi between all three cylinders so I know the engine is solid. Sprayed carb cleaner on all vacuum connections and throttle body boots. Found one vacuum hose to the map sensor was a little loose so I changed it no vacuum leaks anywhere else. Runs better now but still going to check tps settings, crank sensor cleaning, etc to make sure everything it right
Thanks to all for your replies,
Ridefree

 

[Neville Lush]

I would say it's brand new in the comp department. This goes to show how many people have actually done a comp test....... Good work .