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Cold compresion testing? 650z
Posted: Tue Nov 11, 2014 7:51 pm
by craven wine
I can only assume compression test figures of 90-90-60-90 psi on the four pots is not good news and points to a problem on pot four. What would the normal 'cold' figures be. Apologies if this is fixtures on another thread!
Re: Cold compresion testing? 650z
Posted: Tue Nov 11, 2014 8:28 pm
by callyboy
Not very high

You mean 3 not 4 right ?
Were the carbs on? I only recently found out that your supposed to have the throttle open
Pete
Re: Cold compresion testing? 650z
Posted: Wed Nov 12, 2014 8:27 am
by craven wine
callyboy wrote:Not very high

You mean 3 not 4 right ?
Were the carbs on? I only recently found out that your supposed to have the throttle open
Pete
good point! the silver lining being any residual petrol is sucked out of the carbs..and yes it was pot 3 that was deflating.. I don't expect any great difference with an open throttle other than the joys of my first proper rebuild!

Re: Cold compresion testing? 650z
Posted: Wed Nov 12, 2014 1:31 pm
by sparki
And plugs out...
Re: Cold compresion testing? 650z
Posted: Wed Nov 12, 2014 6:34 pm
by bobster
Then try it again with a squirt of engine oil and see what the difference is between dry and wet....
Have you checked the valve clearance on all the cylinders. How many miles has the oild girl done? You need to have the throttle fully open to do a comp test as Pete says!
Re: Cold compresion testing? 650z
Posted: Thu Nov 13, 2014 3:39 pm
by johnr
have you first checked the valve clearances to make sure they arent being held open.
Re: Cold compresion testing? 650z
Posted: Thu Nov 13, 2014 4:55 pm
by bobster
I guess you never read my post then John..................

Re: Cold compresion testing? 650z
Posted: Thu Nov 13, 2014 7:09 pm
by stockcar
regardless of exact throttle opening used you need to ensure you repeat the method used for each cylinder for comparable results
Re: Cold compresion testing? 650z
Posted: Thu Nov 13, 2014 11:40 pm
by johnr
tiny screen on the phone i was reading it on. i didnnt see that bobster.
Re: Cold compresion testing? 650z
Posted: Fri Nov 14, 2014 12:37 am
by Pedda
bobster wrote:I guess you never read my post then John..................

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