Different values for L/R cylinder compression

[Zigo]

Checked the cylinder compression today. left pot read 170 psi, but right pot read only 130 psi. Is this normal or should I start worrying a lot?
Somebody with any experience on this out there?

regards Terje

 

[st247]

Compession test results for individual cylinders should usually be within 10% of each other, so your results aren't good.

I'd try running the test again and make sure that everything (equipment wise) is seated properly, and that your battery is fully charged.

If you still get a low result you could try a wet test for the low side to try and narrow down what could be wrong.

Some more reading here.

The standard test results from reprom for a 1200 (pre 2010) are-

Good 10 bar
Normal 8.5 - 10 bar
Poor less than 8.5 bar

 

[thornley]

Compession test results for individual cylinders should usually be within 10% of each other, so your results aren't good.

I'd try running the test again and make sure that everything (equipment wise) is seated properly, and that your battery is fully charged.

If you still get a low result you could try a wet test for the low side to try and narrow down what could be wrong.

Some more reading here.

The standard test results from reprom for a 1200 (pre 2010) are-

Good 10 bar
Normal 8.5 - 10 bar
Poor less than 8.5 bar

Bar is 14.5037 psi so 130psi = 8.96 bar
170 = 11.7 bar

The 170 reading seems high rather than the 130 reading which is in the normal range. I would retest and verify these results.

 

[Rob Farmer]

If the bike has a compression ratio of 12:1 then 170 will be about right (170/14.7)

Zigo's right pot is only 8.8:1.

 

[thornley]

If the bike has a compression ratio of 12:1 then 170 will be about right (170/14.7)

Zigo's right pot is only 8.8:1.

You're right Rob. I took st247's numbers. 170 psi is nigh on perfect at 12.1

130 is low but I would still do a best of three readings ensuring the seal is good

 

[littleredrooster]

Throttle wide open?

 

[Zigo]

Scare over

Thanks a lot guys for the speedy response! I checked the link from st247 and realized my mistake, stone cold engine, not used for many months and throttle not wide open . New readings showed 170psi/11,7bar for left pot and 185psi/12,7bar for right pot .

A bit wiser
Terje

 

[thornley]

Thanks a lot guys for the speedy response! I checked the link from st247 and realized my mistake, stone cold engine, not used for many months and throttle not wide open . New readings showed 170psi/11,7bar for left pot and 185psi/12,7bar for right pot .

A bit wiser
Terje

Superb result. Your compression is v good

 

[st247]

Result