What's the compression on the cylinders.

[BigMac (SoCal)]

Can someone please tell me what the compression should be on each cylinder for our Valks.


Thanks, Dave #4369

[VALKTERY]

171 @400 rpm

[Patrick]

Its like valktery says.. But, each compression gauge is a bit different, the main thing is that all cylinders read fairly close to one another.. Pull all the sparklers when checking this, not one at a time..

[BigMac (SoCal)]

Is that what it would be with just cranking and not running at 400 rpm?

Thanks, Dave

[Udo]

I always measure with closed petcock, WOT, removed sparklers (all). I use the starter. The bike has run before for a few minutes, to get the oil at med. temp.

[FLATSIX]

This is what the shop manual says :

To measure the cylinder compression of each cylinder, remove only 1 plug at a time.
Install the compression gauge into the spark plug hole- shift the transmission in neutral.
Open the throttle all the way and cranck the engine with the starter motor.Cranck the engine until the gauge reading stops rising. The max. reading is usually reached within 4-7 seconds.

COMPRESSION PRESSURE:  1,177 kPa (12 kgf/cm2, 171 psi/400 min (rpm)

So far the bible...

[VALKTERY]

 bring engine up to normal operating temperature, then stop motor, disconect all spark plug wires, so engine does not start when you crank it. follow manuel procedures...

[Patrick]

says to remove just one sparkler at a time.. Maybe that is what Honda wants,,if so,, they are the only one.. There are a number of mistakes in that book,, I'm wondering if thats one of them.. It is as far as I'm concerned.. But,, regardless of what you do,, the value is 170 # while cranking the starter motor.. Take note of the first reading and the final reading after 5-10 revolutions.. They should be within 10# of each other..

[Robert]

The correct way is to let the engine get to temp remove all the plugs and crack the throttle wide open then take the compression on each cylinder. If Honda doesn't recommend this way then I also would have to believe its a misprint. This is the text book way to do it, not to mention I think you would have a hard time achieving the 400 rpm unless you pull all the plugs. Also like stated before its more important that the compression readings are within 5 to 10 lbs of each other.

[Dave Weaver]

I just checked mine last week and got 155# on all 6 cylinders.  1997 Tourer with 37,000 miles.  Engine warm, Mobil1 15w50 oil.