Ground the plugs...

[Kevin Werner]

I see countless times that when checking your cam chain tension ( I haven't yet on my new to me bike, but I want to) to remove the plugs and check the plunger motion while cranking the engine with plugs out and grounded. Is there a reason one could not instead just disconnect the coil? I have spade connectors on my coil but grouding the plugs involve 4 alligator clips, anyone of which could easily be dislodged.

 

[DogBunny]

I have never used the e-start when checking cam chain tension. I turn the crank by hand, counter-clockwise, at the charging rotor. You remove the plugs so that it is easier to turn. If the ignition is off, which it should be, there is no reason to ground the plugs.

 

[5twins]

I think the easiest way is just to run the bike and observe the plunger movement at idle. If it's too loose and ticking because of it, you'll also be able to hear the noise go away as you tighten the adjuster.

 

[Kevin Werner]

I think the easiest way is just to run the bike and observe the plunger movement at idle. If it's too loose and ticking because of it, you'll also be able to hear the noise go away as you tighten the adjuster.

I had wondered about observing while running.. I didn't see it mentioned previously and wondered if it was an oily mess. The downfall of louder pipes is the music drowns out engine noises.

 

[5twins]

Oil won't squirt out or anything like that, but you may get a couple of drips during the process. I just fold up a paper towel and place it under the adjuster to catch any. I adopted this "adjust while running" technique from Yamaha's procedure for doing their 500 singles. An excerpt from the 500 shop manual .....

The first part about setting the motor on the "T" mark won't apply to a 650 because there is no spot in a 650 engine's revolution where no valves are exerting pressure on the cam and cam chain. It's the "note" at the bottom that I based my technique on.

 

[Kevin Werner]

Thanks 5Twins. I used that procedure today. The rod remains recessed in the adjuster housing but seem to move in and out a finger tip calibrated 1 mm.

 

[Jim]

If I'm checking chain tension, I'm also checking valve clearances at the same time. So.....

Plugs out.....17mm wrench on the (alternator) rotor nut and rotate ccw until TDC mark lines up.
One cyl will be on compression the other will be at valve overlap.
Let go of the rotor nut and crank will jump forward slightly so both valve are open and there's spring tension holding the cam in place.
Take your 17mm and rock the rotor back and forth. That alternates slack and tension on the cam chain. Watch the tensioner rod and you'll see it move in and out with the slack.
Adjust 'till you get the 1-2mm in and out movement and set the valves on the cyl not on valve overlap.
Rotate the crank 360° 'till it pops into the "overlap" on the other cyl and adjust the other 2 valves.
Done.

I've looked at the tensioner rod while it's running after I adjust it this way and the in/out is identical to what I adjusted it too.

 

[5twins]

If you look at the maintenance schedule in the manual, you'll find a cam chain tension check/adjust called for every about 4K miles I think. Several years back, a guy posted on here that his long time Yamaha dealer told him that wasn't frequent enough. He told him to check it every 1000 miles or so. Since I try to change my oil every 1000 to 1500 miles, I've made a cam chain tension check part of that routine. I also like to do the check on a warm motor and this routine plays right into that since I have the motor all warmed up for the oil change. I used to set/check it on a cold motor but when I finally got around to checking it hot, I found the adjustment a bit tight, most likely due to all the parts expanding from heat.

 

[gggGary]

No alligator clips needed.

just have the bare copper touching motor or frame somewhere if you have two coils.
I keep a set like this in the work bench. Handy for several tests.
Prefer not dealing with heat from a running motor while fiddling with the adjuster.
Jim's method should be OK too.
Book sez check cold using static method and sez flush not 1mm of movement.
Opinions vary. RG first posted the 1mm method? Anyways it's my goto.
I'm usually checking plugs, valves, and compression when doing an oil change so plugs are out anyways, since Madness has a "real" filter that's at about 3K mile intervals.