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Discussion Starter #1
I'm going to look at a 1st gen sv650 and would like to do a compression test before I buy (bike not currently running).
Not being familliar with the SV, can someone let me know if there is anything "tricky" with getting a good compression reading? Are the spark plugs easily accessible? What number should I expect on a motor with 3 or 4 k miles on it?
Thanks for the help!
MM
 

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The front plug is a bear to access- you'll have to unbolt the radiator and try to pull it out/away enough to get access, or just remove it altogether.

Don't forget to remove both plugs and hold the throttle at wide open while cranking (but you already knew that).

Not sure what the compression specs are, you can find the manual online (at sv650.org, I think).

HTH

Bill
 

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Discussion Starter #3
Bill,
Thanks. I found the compression spec (215psi, min 156psi).
I'm curious about the spark plug hole. Does anyone know the size? I have an inexpensive compression tester and I'm not sure if I'll need an adapter to fit the plug.
Thanks!
Mike
 

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also remember....the compression numbers should both be within 10% of each other..if not....ya know u have a problem
 

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Discussion Starter #5
Yep.
I looked up the plug at the NGK website and it has a 10mm hole, so I will need an adapter.
I'm assuming that the plugs are deep in the head and I'll need a long adapter, right?
Thanks again
Mike
 

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Also, don't forget that this should be done with the motor warmed up, or the compressions reading don't mean anything. No one else mentioned it, and it seems like it would be with out saying, but I threw it out there anyway. :)
 

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Discussion Starter #8
Re: compression test advice please (getting used bike)

Exactly!

I'm not sure what I'm getting in to, but it seems like a great deal so I'm going to take the chance. The bike has 2400 miles, was dropped (tank dents only, thanks to frame sliders), then put up about 2 years ago. It has been rotting since. Battery is dead (obviously) and I'm sure the carbs are gooey.

I'm going to give the gas a sniff to see if it has turned, drain the carb bowls (probably dry anyway) and see if it will fire with some starter fluid. If it doesn't fire I want to check compression. I know a cold reading won't be accurate, but if one reads 30psi and the other 160psi then I know there is a problem.

I'm sure I'll need to rebuild the carbs, buy a new battery, then repair and paint the tank. Hopefully I'll have a nice 2002 SV to ride around on soon. BTW, it is a black one. Not sure if I love the color until I see it in person, but it will be unusual.

Thanks again. Any advice on things to look at when I go to pick up the bike will be greatly appreciated.
Mikemo
 

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really, a motor with only three or four thousand miles on it should have no compression problems...unless the owner ran dry onoil for some reason or something, in which case the motor could be foo-bared.

Good luck
 

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Why does the bike need to warm in order to compression test? Also why does the throttle have to full on when turning the engine over without the sparkplugs? I also understand why both cyl. need to be within 10% of one another but if one is off what would the problem be, scored cyl. or broken ring?

Thanx,

Grav.
 

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GraVitY said:
Why does the bike need to warm in order to compression test? Also why does the throttle have to full on when turning the engine over without the sparkplugs? I also understand why both cyl. need to be within 10% of one another but if one is off what would the problem be, scored cyl. or broken ring?

Thanx,

Grav.
Rings expand when they are warm, as does all the metal around them. Even though its only thousandths of an inch, it makes a huge diffference when it comes to maintain proper compression.

you can test a cylinder when cold, and it will have a bad reading, but when warm, it will be with in spec.
 
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GraVitY said:
Also why does the throttle have to full on when turning the engine over without the sparkplugs?
Good engine design dictates that they intake air through the carbs/throttle bodies, not the sparkplug holes. Leaving the throttle plates closed severely restricts the amount of incoming air to be compressed.
 
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