Stupid Question of the Day

[Jim Bronson]

When checking compression on my 2013 Dyna, do I need to disable the fuel pump? The SM doesn't mention it.

[fbn ent]

I have a button set up that I jump battery power to where the green wire attaches to the starter solenoid. I crank it with that while holding the throttle plate (?) wide open.

[rigidthumper]

No. Pull both plugs, install compression tester in first cylinder to be tested, hold throttle open 100%, then key on. Crank at least 3-5 revolutions, stop when reading has peaked/stabilized.

[Jim Bronson]

Thanks guys. I'm on it.

[Jim Bronson]

130 front and rear.

[kd]

Are the ACR's disabled?

[Hossamania]

Are the ACR's disabled?

And battery fully charged?

[Coyote]

Did you physically hold the butterfly open?

[Jim Bronson]

I did hold the butterfly open. Battery was fully charged on the tender. ACRs were NOT disabled  . How much difference would that make? Plugs are still out, so it would be easy to repeat the test.

[rigidthumper]

Easy to disconnect/test reconnect.
Big difference

[kouack]

What FBN ENT suggested, just use a jump wire from + battery to the starter solenoid, easy to do and no need to unplug ACR or worry about anything else, no need to turn the master switch on, just make sure bike is in neutral.

[Jim Bronson]

OK got it. I think I'll make a jumper with a switch to make it more convenient. It will have to wait until tomorrow. Stand by please.

[kd]

I did hold the butterfly open. Battery was fully charged on the tender. ACRs were NOT disabled  . How much difference would that make? Plugs are still out, so it would be easy to repeat the test.

There should be a difference if the ACR's are not disabled now.  As mentioned you can make up a jumper as fbn described to crank the engine with no power to them.  I do it that way and end up with a new tool.    You can also do what Rigid says and just disconnect the m by pulling the connector off them.  Another method I have used when not in my shop (with no access to my jumper switch) is to simply remove the system relay from the fuse panel and proceed with the key on and start button while holding the throttle valve wide open. 

What is most important is both cylinders are even or close to it.  If you want to check the cranking compression to compare it to the expected healthy compression for your engine, cam etc, the test without ACR's activated is what you will need to know and do.

Added Later

I eventually bought a solenoid button for my RGU that permanently fastens to the starter solenoid cap.   It's chrome, looks good and if anything fails in the starter button.  It's there to use and works well for all of the above or if you break down on the road.  Here's one of many choices out there.   California Phil from our Vendor Support list can help you with that.

https://www.amazon.ca/Bikers-Choice-Solenoid-Starter-Button/dp/B001KO2EB8

[Ohio HD]

I have one of these from Lisle. Good quality and not expensive.


Lisle 20750 Remote Starter Switch

[Jim Bronson]

It also seems like I could use the tender connector to power the solenoid. Test lead should work for just the solenoid. Starter motor would still be powered by the battery.

[fbn ent]

You might poof the fuse...

[Hossamania]

You might poof the fuse...

My thought too

[kd]

It also seems like I could use the tender connector to power the solenoid. Test lead should work for just the solenoid. Starter motor would still be powered by the battery.

A battery tender won't have enough power to activate the pull in winding.

[Hossamania]

It also seems like I could use the tender connector to power the solenoid. Test lead should work for just the solenoid. Starter motor would still be powered by the battery.

A battery tender won't have enough power to activate the pull in winding.

I think Jim is talking about using the pigtail off the battery to send power to the green solenoid wire. Like mentioned, not sure the inline fuse will tolerate the load.

[kd]

It also seems like I could use the tender connector to power the solenoid. Test lead should work for just the solenoid. Starter motor would still be powered by the battery.

A battery tender won't have enough power to activate the pull in winding.

I think Jim is talking about using the pigtail off the battery to send power to the green solenoid wire. Like mentioned, not sure the inline fuse will tolerate the load.

 

[Jim Bronson]

Sorry I wasn't clear. I would disconnect the tender, so using the pigtail would be the same as connecting a lead to the battery except more convenient. I don't recall whether the tender harness between the connector and the battery has a fuse. I should check it before I try my method, as I might not have a spare fuse if it smokes. Of course I'll need to remove the battery cover to make sure so I might as well just connect to the battery. BTW my solenoid wire is red/black (2013). Yes, I did verify it on the schematic.

I'll get started tomorrow as soon as the garage warms up.

[Hossamania]

Your pigtail should have an inline fuse, it's how they are manufactured. It is most likely a 5 amp if it wasn't changed. I run a 15 for my heated jacket.

[kd]

Sorry I wasn't clear. I would disconnect the tender, so using the pigtail would be the same as connecting a lead to the battery except more convenient. I don't recall whether the tender harness between the connector and the battery has a fuse. I should check it before I try my method, as I might not have a spare fuse if it smokes. Of course I'll need to remove the battery cover to make sure so I might as well just connect to the battery. BTW my solenoid wire is red/black (2013). Yes, I did verify it on the schematic.

I'll get started tomorrow as soon as the garage warms up.

If you have a dual lead starter button (like Ohio described) with alligator clips for the hook-up you can put the red (positive) clip on the battery post stud under the rubber cap on the solenoid and the black lead to the small wire that activates the pull in winding (red/black).  You'll be hooking in to that wire anyway so you can do them both down there. That kinda follows the KISS method and no modifications are required.

[Jim Bronson]

Front = 195
Rear = 200

I wonder why the difference. I'll repeat the front in a little while. Maybe I didn't have a good seal at the gauge. The tender lead does have a fuse near the battery positive terminal (but you knew that already)

[Ohio HD]

You're within 2.6%, all is good.

[rigidthumper]

Front = 195
Rear = 200

I wonder why the difference. I'll repeat the front in a little while. Maybe I didn't have a good seal at the gauge. The tender lead does have a fuse near the battery positive terminal (but you knew that already)

Small differences in combustion chamber size, deck height, carbon build up, cam chain slack, and cam grinding can show up to ~3%.  Like Ohio said "all good".

[Jim Bronson]

Repeated test on the front. It reads 200 now, so I'm calling it good. Many thanks to everyone who helped.