compression

[r savard]

What should to compression be?
Thanks,

[friend]

According to the Honda shop manual it is 156 + or - 7. at 400 rpm.
Normally this is taken on a warm engine, both spark plugs removed.
Bill

> -----Original Message-----
> From:
> anzhonda600owners@yahoogroups.com
> [mailto:anzhonda600owners@yahoogroups.com]
> On Behalf Of
> r
> savard
> Sent:
> Tuesday, April 03, 2012 11:20 AM
> To:
> anzhonda600owners@yahoogroups.com
> Subject:
> [anzhonda600owners]
> compression
> What should to compression be?
> Thanks,

[r savard]

Thanks, Bill!

> From:
> "billmyong@..."
> To:
> anzhonda600owners@yahoogroups.com
> Sent:
> Wednesday, April 4, 2012 5:49 AM
> Subject:
> RE: [anzhonda600owners] compression
> According to the Honda shop manual it is 156 + or - 7. at 400 rpm.
> Normally this is taken on a warm engine, both spark plugs removed.
> Bill
> > -----Original Message-----
> > From:
> > anzhonda600owners@yahoogroups.com
> > [mailto:anzhonda600owners@yahoogroups.com]
> > On Behalf Of
> > r
> > savard
> > Sent:
> > Tuesday, April 03, 2012 11:20 AM
> > To:
> > anzhonda600owners@yahoogroups.com
> > Subject:
> > [anzhonda600owners]
> > compression
> > What should to compression be?
> > Thanks,

[blake neilson]

Need to hold the throttle wide open when checking compression.  That will help to ensure the cylinder walls are not washed down with fuel which will affect the reading.  I know this sounds counter-intuitive  but with the carb at WOT and the engine turning at cranking speed there is not enough airflow (or vacuum) to pull fuel from the float bowl.  With the throttle closed you will have enough vacuum to pull fuel through the idle circuit.

[r savard]

Thanks to all, but I just turned it over with the starter and got a reading of 105 psi. I wanted an idea if that was about right before I installed the motor.

> From:
> blake neilson
> To:
> "anzhonda600owners@yahoogroups.com"
> Sent:
> Thursday,
> April 5, 2012 6:58 PM
> Subject:
> Re: [anzhonda600owners] compression
> Need to hold the throttle wide open when checking compression.  That will help to ensure the cylinder walls are not washed down with fuel which will affect the reading.  I know this sounds > counter-intuitive >  but with the carb at WOT and the engine turning at cranking speed there is not enough airflow (or vacuum) to pull fuel from the float bowl.  With the throttle closed you will have enough vacuum to pull fuel through the idle circuit.
> From:
> "billmyong@..."
> To:
> anzhonda600owners@yahoogroups.com
> Sent:
> Wednesday, April 4, 2012 5:49 AM
> Subject:
> RE: [anzhonda600owners] compression
> According to the Honda shop manual it is 156 + or - 7. at 400 rpm.
> Normally this is taken on a warm engine, both spark plugs removed.
> Bill
> > -----Original Message-----
> > From:
> > anzhonda600owners@yahoogroups.com
> > [mailto:anzhonda600owners@yahoogroups.com]
> > On Behalf Of
> > r
> > savard
> > Sent:
> > Tuesday, April 03, 2012 11:20 AM
> > To:
> > anzhonda600owners@yahoogroups.com
> > Subject:
> > [anzhonda600owners]
> > compression
> > What should to compression be?
> > Thanks,

[blake neilson]

Doesn't sound too good.
You could squirt some oil into the cylinders and see if that affects the reading.  If the pressure rises significantly you have worn/broken rings and a complete teardown is in order.  If the reading doesn't change then you have a leaking valve/valves and might get by with a valve job only.
From:
r savard
To:
"anzhonda600owners@yahoogroups.com"
Sent:
Thursday, April 5, 2012 7:11 PM
Subject:
Re: [anzhonda600owners] compression
Thanks to all, but I just turned it over with the starter and got a reading of 105 psi. I wanted an idea if that was about right before I installed the motor.

> From:
> blake neilson
> To:
> "anzhonda600owners@yahoogroups.com"
> Sent:
> Thursday,
> April 5, 2012 6:58 PM
> Subject:
> Re: [anzhonda600owners] compression
> Need to hold the throttle wide open when checking compression.  That will help to ensure the cylinder walls are not washed down with fuel which will affect the reading.  I know this sounds > counter-intuitive >  but with the carb at WOT and the engine turning at cranking speed there is not enough airflow (or vacuum) to pull fuel from the float bowl.  With the throttle closed you will have enough vacuum to pull fuel through the idle circuit.
> From:
> "billmyong@..."
> To:
> anzhonda600owners@yahoogroups.com
> Sent:
> Wednesday, April 4, 2012 5:49 AM
> Subject:
> RE: [anzhonda600owners] compression
> According to the Honda shop manual it is 156 + or - 7. at 400 rpm.
> Normally this is taken on a warm engine, both spark plugs removed.
> Bill
> > -----Original Message-----
> > From:
> > anzhonda600owners@yahoogroups.com
> > [mailto:anzhonda600owners@yahoogroups.com]
> > On Behalf Of
> > r
> > savard
> > Sent:
> > Tuesday, April 03, 2012 11:20 AM
> > To:
> > anzhonda600owners@yahoogroups.com
> > Subject:
> > [anzhonda600owners]
> > compression
> > What should to compression be?
> > Thanks,

[mygto_1999]

I would also make sure the valve adjustment is good also, tight valves can cause bad readings too.
Mike

[friend]

�
You are correct, remove all the plugs and the then hold the carb wide open to allow the single cylinder to expel pressure while the compression gauge maintains an accurate reading of the pressure.  Then if you're watching the pressure gauge you will notice that it moves higher with the first two or three rotations but should be given at least 6 power strokes to get a good reading.  Record it and do the same with the other cylinder.
There shouldn't be more than 15 Psi difference between the two cylinders, and make sure the engine is free spinning during the test (I have left my engine in gear with the wheels off the ground putting an extra load on the starter) which makes it hard to achieve the necessary 400 RPM's.  Now put in a Tea spoon of 10W30 into the spark plug hole the test is taken to the next step and perform the same test.  If the pressure shows a decided increase, there is a compression loss past the piston and rings.  If there is no change in the compression then this is an indication of not only good rings but that the valves are seating properly.
Thanks for your input
Bill

> -----Original Message-----
> From:
> anzhonda600owners@yahoogroups.com
> [mailto:anzhonda600owners@yahoogroups.com]
> On Behalf Of
> blake
> neilson
> Sent:
> Thursday, April 05, 2012 4:59 PM
> To:
> anzhonda600owners@yahoogroups.com
> Subject:
> Re: [anzhonda600owners]
> compression
> Need to hold the throttle wide open when checking
> compression.  That will help to ensure the cylinder walls are not washed > down with fuel which will affect the reading.  I know this > sounds > counter-intuitive >  but with the carb at > WOT and the engine turning at cranking speed there is not enough airflow (or > vacuum) to pull fuel from the float bowl.  With the throttle closed you > will have enough vacuum to pull fuel through the idle > circuit.
> From:
> "billmyong@..."
>
> To:
> anzhonda600owners@yahoogroups.com
> Sent:
> Wednesday, April 4,
> 2012 5:49 AM
> Subject:
> RE:
> [anzhonda600owners] compression
> According to the Honda shop manual it is 156 + or - 7. at 400 rpm.
> Normally this is taken on a warm engine, both spark plugs removed.
> Bill
> > -----Original Message-----
> > From:
> > anzhonda600owners@yahoogroups.com
> > [mailto:anzhonda600owners@yahoogroups.com]
> > On Behalf Of
> > r
> > savard
> > Sent:
> > Tuesday, April 03, 2012 11:20 AM
> > To:
> > anzhonda600owners@yahoogroups.com
> > Subject:
> > [anzhonda600owners]
> > compression
> > What should to compression be?
> > Thanks,