pre600 compression test

[FMFGSX]

Well I just did a compression test on the 600.
90 - 150 - 120 - 165
WTF!

[arsenic]

not good dude, we've talked about this in the SB, but I'll post it here
Compression:
142-213 PSI (minimum 114 PSI)
variation - 28 PSI
need at least one set of piston rings, or the gaps are just wrong. I'd hone the cylinders and use a ridge reamer, but that's just me, you don't HAVE to do that.

[md86]

Or it could be losing compression at the head gasket , or a valve . Next step is a leakdown test to see WHERE it's leaking from ....

[arsenic]

yes, could be that too, I doubt it's losing compression that fast, that's why you need a leak down test.

[steves]

Actually, I'd do a leak down test any way. I was getting wonky compression readings on the kat... because the gauge wasn't sealing correctly.... but the leak down read 96% or better on all pistons.

[md86]

that's why you need a leak down test.

I'm sayin . Will tell you for SURE where it's leaking from and what to do next .

[FMFGSX]

Don't think a HG would be that low and next be in good shape.

[Newbie2it]

Hey FMFGSX,

Just a question for ya. When you did the compression test, Did you hold the throttle WFO? If not, you will get low compression results.

[arsenic]

good call, you need to do that, I know it make's no logical sense, but a lot of things with engines make no logical sense

[bluekat04]

it seems, wide open or not you get the same readings i have not seen a diff between wide open throttle or closed, if you have one hole that is week its going to be week either way

[Newbie2it]

On a motor like a Kat where the CV carbs are in use, you do need to hold the throttle WFO so proper air levels are able to enter the cylinder, Unlike a car.

Leaving the throttle closed would be simular to putting your hand over the end of a vaccum pump with a straw between your fingers and then wondering why its so hard to draw the handle up.

[elkat]

I would think with the vacuum operated slides it wouldn't matter either way. Kinda like you can't hold the throttle open to clear out the bike if it is possibly flooded. Either way it looks like you have a bad cylinder.

[Newbie2it]

Correct on not being able to clear the bike if its flooded, However the vacuum created to lift the slides is created on the backside of the throttle plate. Holding the throttle open opens the metal plate open to allow unrestricted air flow.

[arsenic]

Haynes manual 88-96 Katana 600 REF*41, Checking engine compression
4. On motorcycles with electric start only switch (engine stop switch) to OFF and turn the ignition switch ON; open the throttle fully

see, we can argue all day about weather this makes sense or not, really don't care if it makes sense, you're supposed to do it, it DOES matter.

[redrider]

just ordered the shop manul last week for my 750/2006 lots of good reading for the up coming months ahead ,Gets me high! Yes arsenic1016 those Suzuki Dudes have it down to a science. Although some of you are master mechanics the shop manul is the bikes bible LOL!