ground

Hawk Joined: Jul 21, 2015 Posts: 509 Location: Norway

when measuring compression i'm told i have to ground the sparkplugwires

how do i do that ?

Hawk Joined: Jul 21, 2015 Posts: 509 Location: Norway

so i found out how to ground sparkplugwires.

Link

new question.

is it necessary to ground sparkplugwires when compression testing ?

Posted: Mon Oct 26, 2015 5:17 pm

I think you pull all the plugs and cover up the cylinders not being tested (I stick a shop vac wand over the spark plugs before pulling them to make sure no foreign objects are lurking). You want to be able to turn the engine quickly and easily, no very easy with the plugs all in.

No idea where the grounding the spark plugs come from, only useful if you want to observe you are getting a spark.

Posted: Mon Oct 26, 2015 6:02 pm

Turn the kill switch to "off" then you can spin away without worrying about any stray sparks.

Hawk Joined: Jul 21, 2015 Posts: 509 Location: Norway

the manual that came with the compressiontester i bought says ground the sparkplugwires before testing compression.

so my question is, is not grounding the sparkplugwires like driving without a seatbelt and if so .. at what speed am i driving without a seatbelt ..

Posted: Mon Oct 26, 2015 6:14 pm

If you have your ignition "On" and coils providing spark, you will do damage to coils and/or igniters if the plug is not grounded. Like sfhess says, turn kill switch to off.

Hawk Joined: Jul 21, 2015 Posts: 509 Location: Norway

this thread should probably be in the technical section

Posted: Mon Oct 26, 2015 10:10 pm

When you turn the kill switch to off, you don't need to worry about grounding spark plugs, as the ignition is turned off. In fact don't even put them on the spark plug wires, just pull the wires off the plugs, and leave them off. Remove all the plugs from the motor and run your compression tests with the throttle wide open.

Posted: Mon Oct 26, 2015 10:54 pm

I'm not sure you'd damage anything by not grounding the plug wires, I've never bothered grounding them when I've done compression tests. I think grounding is recommended so that a) you don't get zapped by accidentally touching a high voltage wire while cranking and b) if there happens to be left over fuel mixture in the cylinders it could get blown out of a spark plug hole and ignite from a loose wire spark (but highly unlikely). In any case, the kill switch is the way to go if you're really worried about it.

Hawk Joined: Jul 21, 2015 Posts: 509 Location: Norway

i fail to see how the engine will turn over with the killswitch in the off position

Posted: Tue Oct 27, 2015 9:19 am

super wrote:

i fail to see how the engine will turn over with the killswitch in the off position

By pushing the start button which routes electricity from the battery to the starter motor via the starter relay.
The starter motor will then rotate and in turn cause the crankshaft to rotate.
It will not work if you have a flat battery or fail to press the starter button.

CB1100F Joined: May 13, 2005 Posts: 3217 Location: NE OHIO

thx113 wrote:

super wrote:

i fail to see how the engine will turn over with the killswitch in the off position

By pushing the start button which routes electricity from the battery to the starter motor via the starter relay.
The starter motor will then rotate and in turn cause the crankshaft to rotate.
It will not work if you have a flat battery or fail to press the starter button.

or if the bike is not in neutral or the clutch lever pulled.

Posted: Tue Oct 27, 2015 4:25 pm

super wrote:

i fail to see how the engine will turn over with the killswitch in the off position

Killswitch shuts off the ignition circuit. No power to coils or ignitor boxes. It does not affect the starter circuit. Try it.......

Posted: Tue Oct 27, 2015 4:34 pm

super wrote:

i fail to see how the engine will turn over with the killswitch in the off position

I have actually drained a battery by cranking and cranking and cranking without realizing the kill switch was off... Embarassed

Posted: Tue Oct 27, 2015 10:26 pm

thx113 wrote:

super wrote:

i fail to see how the engine will turn over with the killswitch in the off position

By pushing the start button which routes electricity from the battery to the starter motor via the starter relay.
The starter motor will then rotate and in turn cause the crankshaft to rotate.
It will not work if you have a flat battery or fail to press the starter button.

Posted: Wed Oct 28, 2015 12:06 am

DOHCRob wrote:

super wrote:

i fail to see how the engine will turn over with the killswitch in the off position

I have actually drained a battery by cranking and cranking and cranking without realizing the kill switch was off... Embarassed

That's so funny.
I've never been dumb enough to do something like that.
Oh, well, except a couple of weeks ago when I spent a good 5 minutes increasingly angrily and violently trying to kick start one of my CT110 postie bikes. Then discovered the kill switch in the off position. Sadly there was a witness. My groin and hip were sore for a few days after that little effort.

Posted: Wed Oct 28, 2015 11:58 am

I rarely use the kill switch, so it should not have been a problem, but....the 4-year old kid next door had come over to visit while I was working on a bike. He was "helping" me by picking up and moving around tools and twisting the throttle. He obviously also moved the kill switch - without me noticing. That's when it happened. I had a good laugh after that...

Posted: Wed Oct 28, 2015 12:59 pm

DOHCRob wrote:

super wrote:

i fail to see how the engine will turn over with the killswitch in the off position

I have actually drained a battery by cranking and cranking and cranking without realizing the kill switch was off... Embarassed

+1 ... and called roadside assistance, and then spotted it ...!

Regards,

Max

Posted: Thu Oct 29, 2015 4:20 am

The idea is that grounding the plug wires removes load off the spark units, some brands and cars say can pop the electronic boxes if the spark is trying to jump through infinity. I've had a crap rider mower do it before when not paying attention.

Old first gen Mopar electronic ignition of the mid '70s could do it if you did the leads just right.

Not wise on any electronic ignition, use the kill switch.

Hawk Joined: Jul 21, 2015 Posts: 509 Location: Norway

you've convinced me on the killswitch.

unfortunately the compression tool i bougt did not fit.

so is there a compression tool with 4 gauges that measures compression without removing sparkplugs or is this another tool ? like the tool one would use to synchronize carburetors ?

CB1100F Joined: May 13, 2005 Posts: 3217 Location: NE OHIO

super wrote:

you've convinced me on the killswitch.

unfortunately the compression tool i bougt did not fit.

so is there a compression tool with 4 gauges that measures compression without removing sparkplugs or is this another tool ? like the tool one would use to synchronize carburetors ?

You have to remove the spark plugs to do a compression check , whether it be all at once or one at a time , all removed is the best . A lot less drain on the battery when all are removed . I have never seen a 4 gauge compression tester . Why would you need it ? Do you need a 8 gauge tester to do a V8 engine ?

Posted: Thu Oct 29, 2015 8:05 pm

DOHCRob wrote:

I rarely use the kill switch, so it should not have been a problem, but....the 4-year old kid next door had come over to visit while I was working on a bike. He was "helping" me by picking up and moving around tools and twisting the throttle. He obviously also moved the kill switch - without me noticing. That's when it happened. I had a good laugh after that...

I accidentally bumped mine to the off position while waiting to make a left turn on a busy street one time. What the......

Hawk Joined: Jul 21, 2015 Posts: 509 Location: Norway

Luckysox wrote:

super wrote:

you've convinced me on the killswitch.

unfortunately the compression tool i bougt did not fit.

so is there a compression tool with 4 gauges that measures compression without removing sparkplugs or is this another tool ? like the tool one would use to synchronize carburetors ?

You have to remove the spark plugs to do a compression check , whether it be all at once or one at a time , all removed is the best . A lot less drain on the battery when all are removed . I have never seen a 4 gauge compression tester . Why would you need it ? Do you need a 8 gauge tester to do a V8 engine ?

i was going for the killing two birds with one stone type of thing
is the tool used in this video also usefull for measuring compression ?

Link

CB1100F Joined: May 13, 2005 Posts: 3217 Location: NE OHIO

Hawk Joined: Jul 21, 2015 Posts: 509 Location: Norway

ok then

Posted: Thu Oct 29, 2015 9:12 pm

You only want to do one at a time. You don't want compression in all the cylinders slowing the spin the starter can muster. Just pull all the plugs, leave the kill switch in the off position and measure one cylinder at a time with the throttles wide open. You obviously need a compression tester or adapter for 12mm plug hole.