Done, showing just under 8 bar on both cylinders. HAYNES says 9.2 for the 900. Do I need new rings? :Blackeye:
It is just as/more important that they are even, the lower reading could be caused by many innocuous reasons, low engine temp, dry bores etc.
As mentioned above, compression testers vary considerably due to many different reasons so if they are both very similar then it is more likely to just be the tester reading low.
What's your problem with the bike? You could redo the test hot, but if your readings were that close cold, and even, I wouldn't bother.
Rear plug is fouling, sooty with small trace of oil. Front is light brown sooty round egde. A small trace of burnt oil out back on initial start up. Test results on cold engine Rear cylinder Dry 107 psi Wet 111 Front cylinder Dry 110 Wet 120 What you think?
That's reasonably close, but for piece of mind you could redo hot, but this is a test for compression rings, if it's oil burning it would be caused by worn oil rings, worn valve guides and/or seals, glazed bores or something like this.
Definitely...............No good testing a cold engine........ Your results.......When you say 'dry' and 'wet' what do you mean? Even if you test when cold, the engine should still be 'wet' from residual oil........
If compression is suspected of being low, you retest with a small squirt of oil to help seal the rings to isolate if the compression is being lost by the rings or valves. If the compression is still low after oil it is probably valve related.
Dry, no oil Wet, squirt of oil, in both cylinders compression wet up. Will try hot too. Think I will change seals anyway if its just taking valve covers off
It will if you keep squirting it into the cylincers to do the compression tests............. And, it will be giving false readings as well.............cold oil will create more of a seal.......if it actually gets all round the rings, which it won't on the front cylinder, 'cos it it will run down.
"It will if you keep squirting it into the cylincers to do the compression tests............." That's before the test I'll take your advice and post results
If it is burning oil, you will almost certainly see it from the zorsts...... ....but if there is blow-by and the crankcase is breathing hard, you might find oil in the air-box, in which case it will smell, but not necessarily burn it. I assume you have switched your spark plugs around to see if the oiling gets transferred to the other cylinder?
