XS1100 Compression Check

[alice]

Test was done in the shop dry with a relatively hot motor. 1 test only....

Yeah...I thought compression was a bit high (don't know motor history..odometer 85k when purchased) as the motor is running rich and blows puffs of smoke when changing up or down gears...smoke looks a bit blueish but at times dark..

[Miti]

...#2,,,if you did it was the motor hot or cold?,, if cold did you #1,,,do 2 tests,,, 1 dry,,, #2 wet,, use a bit of oil down the pot

Only needs to be a squirt of oil... First cold check should be dry and remember to hold the throttle wide open.  Anywhere near 140 cold & dry is good.

Expect to see a +10psi change after adding the oil... If the change is higher, you have worn rings/bores... The greater the change, the greater the wear.

If testing hot, DON'T do a wet test... There's a tiny risk of the oil "compression-igniting" and blowing the tester to kingdom come (or into your mush...!!)

And a final note... If you don't KNOW that your valve clearances are correct, then don't bother wih a compression test... A tight valve will leak precious psi away and ruin the results..

HTH

Miti

[steptoe]

 #1,,,did you check them yourself or were they done in a shop,,if so you'd hope they did it right, and what did they say

#2,,,if you did it was the motor hot or cold?,, if cold did you #1,,,do 2 tests,,, 1 dry,,, #2 wet,, use a bit of oil down the pot

7 pnd isn't that huge a difference,, but they do seem a bit high,,,,,,,,

you could always do the test again and see if they come up with same numbers

[pgnz]

yeah,  even readings are more important

[melbxs]

Those guages are rarely accurate. It is more important IMO that the compression is relatively equal across all 4 pots and that it is at a decent looking level.

[B.Walker]

160 is bloody outstanding!!!, considering stock pressure was 142. Is your engine stock?

[pgnz]

around the 160 mark is bloody good

[alice]

Hi All,

I have just had the compressin checked on my 1100G.
Range is from 155psi to 168psi.

What is the nominal for the model and/or others...?

Thanks....Justin