compression??

[oct6454]

i know that perfect compression is 150psi. My ski the 99xpl is at 140 and 135 is this good? What does this say about the life of the motor?

 

[Nate Surveyor]

It says that the motor is broken in, and probably in good shape, for several more seasons, if it is not allowed to run lean, hot, or without oil.

Compression is mostly a look at the condition of the rings, cylinder walls, and their fit together. These items are important.

N

 

[Dans97challenger]

That is definitely very good. Mine in my Challenger are at 110 and 112 each. That is ok but it will need a new top end next winter. I will get by next season with it like that with no problem. Then I will have new pistons and rings done next winter.

 

[seadoosnipe]

spread?

The compression isn't so much about what your readings are but about the amount of compression between the two cylinders. With a 5 pound spread, your almost at the edge of the limit. If you get between 7 and 10 or 9 to 11, your really pushing it and will be close to throwing a rod through your motor.:cheers:

 

[oct6454]

Thanks!! thats what i thought. but i wanted to be sure. I will check the spread again the the first reading was at 140 the second may have been closer to 136. but thanks for the info i'll keep an eye on that.

 

[Nate Surveyor]

Mr Sniper is right. :agree:

If you can imagine a team of mules, and one of them is a race horse. The race horse is going to be out of step with the others, and wear himself out, at the others slow pace.

So, if one has more compression than the others, then the overall balance of the motor is going to be off. Most of my experience is with single cylinder motors.

This is one reason the gray fuel lines are so bad. On 2 carb models, one carb and cylinder can run lean, and upset the balance of the motor, and overheat one cylinder, and wear, and upset the compression of ONE cylinder, without the other. Now, we have a "loping effect".
So, I think gray hoses are bad, but particularly in dual carb models.

PWC Blessing:
So, may your fuel be clean, your carb filters be clean, and your compression even, and you wife have the house clean when you get home!

(Wink)

Nate

 

[oct6454]

Makes sense. . .

OK that makes sense. all of the fuel lines have been replaced and i'm rebuilding the carb this winter. "Wish me luck!!!!!" but on question do i need to remove the pipe to remove the carb. It looks that way to me but i'm new so i could be wrong.

 

[Dennis]

Carbs

You have 2 carbs and they can be removed WITHOUT removing the exhaust.
They will both come off together( not 1 at a time )
Good Luck, DAWG