Compression Testing
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Compression Testing
I'm borrowing a compression tester from a friend and was wondering what "good" compression would be for a KDX200?
Help on the actual procedure, (besides sticking the gauge in the spark plug hole and kicking over a few times) would be helpful too.
Thanks!
Help on the actual procedure, (besides sticking the gauge in the spark plug hole and kicking over a few times) would be helpful too.
Thanks!
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Ron Black Said:
Accurate Compression Testing
First you need to get a hold of a "GOOD" known compression gauge. I recommend something like a SNAP-ON or MAC TOOLS. Start the bike and run it until it is at full operating temperature. Then do a compression check on your engine. This is performed by installing the compression gauge into the spark plug hole. Then hold the throttle wide open and kick the engine over vigorously several times until the gauge needle no longer moves. Record the gauge reading, do this two to three times. With the spark plug removed, squirt a little WD-40 down the spark plug hole, then kick the engine over several times. This compensates for ring wear. Now re-install the compression gauge and repeat the compression test two to three times and record these numbers.
'89 KDX 198cc '03 Gasgas Ec250 '13 Husaberg Te300
*CANADA* LEADING THE WORLD IN BEING JUST NORTH OF THE UNITED STATES.
*CANADA* LEADING THE WORLD IN BEING JUST NORTH OF THE UNITED STATES.
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I just got 150 psi (average of three readings) on my 2001 220. Have maybe 40 days of riding in the 5 years I've owned it. From the records, I'd say that I'm still on the OEM piston. Looking through the ports on the intake and exhaust side, piston looks like new.
Guess I'm good for a while on the top end.
Kaw manual says: Usable range 655 ~ 1040 kPA (6.7 ~ 10.6 kg/cm2, 95 ~ 151 psi).
Too high : carbon or wrong gasket
Too low: piston clearance, head leakage, rings, ring grooves, or crank seals.
Guess I'm good for a while on the top end.
Kaw manual says: Usable range 655 ~ 1040 kPA (6.7 ~ 10.6 kg/cm2, 95 ~ 151 psi).
Too high : carbon or wrong gasket
Too low: piston clearance, head leakage, rings, ring grooves, or crank seals.
"I hate heli-coils. They are like hospice for motorcycle parts."- BDI
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Re: 'Guess I'm good for a while on the top end.'
No. You're not. Mr. Pro3 is right about that.
If you had read the stories we've heard over the years...you would order a piston for your bike today.
If 10 out of 100 220 pistons blow up..that's not real bad odds for you to gamble on.
If you're one of the 10...your failure rate is 100%
No. You're not. Mr. Pro3 is right about that.
If you had read the stories we've heard over the years...you would order a piston for your bike today.
If 10 out of 100 220 pistons blow up..that's not real bad odds for you to gamble on.
If you're one of the 10...your failure rate is 100%
Consider the source
Using a perceived level of knowledge to boost my self worth.
Non impediti ratione cogitationis
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Re: 'Is there any way to tell?'
The Wiseco/Pro-X pistons don't look the same out of the box.
But...what you can see from the exhaust port? I don't know that, but bet there's something you could see.
How about some 220 riders that've swapped their pistons out and took pics of the both of 'em share!!
Can you ask the PO?
The Wiseco/Pro-X pistons don't look the same out of the box.
But...what you can see from the exhaust port? I don't know that, but bet there's something you could see.
How about some 220 riders that've swapped their pistons out and took pics of the both of 'em share!!
Can you ask the PO?
Consider the source
Using a perceived level of knowledge to boost my self worth.
Non impediti ratione cogitationis
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Yah, your right (as ususal).canyncarvr wrote:Re: 'Guess I'm good for a while on the top end.'
No. You're not. Mr. Pro3 is right about that.
If you had read the stories we've heard over the years...you would order a piston for your bike today.
If 10 out of 100 220 pistons blow up..that's not real bad odds for you to gamble on.
If you're one of the 10...your failure rate is 100%
I've rethought my original opinion ( I must have been impeded by the thought process) and will be getting an order off to FRP soon.
"I hate heli-coils. They are like hospice for motorcycle parts."- BDI
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Re: (back to the original thread )
Sorry 'bout that.
A couple things to keep in mind about compression testing in general:
For one thing...it generally doesn't mean a whole lot. KDXQs quote from Ron notes that having a GOOD guage is the place to start. A lot of guages AREN'T any good..and multiple tests will get you multiply (-ee) different results. How warm the bike is matters. Basically, lots of things matter.
For the purpose of any comparisons, use the same guage and the same method of test.
That said...it's when you're at the margins that all the little things are more likely to add up to what may be an incorrect diagnosis.
150psi should be fine, though.
Consider what you would get with some leaky rings and a fat layer of carbon on your piston/head! Maybe 150!!
Seems to me (not that anyone asked..so sue me) that the value of a compression test is largely in a comparative situation..like with a multiple cylinder engine. If seven of eight cylinders are 240..and one is 150...that's a problem no matter HOW you slice it.
I replace top-ends 'cuz it's time...or when I feel like it. What the compression is or isn't is not something I've even tested.
I've got a good guage. Maybe I'll check it just for fun.
...it'll give me something else to worry about.......
Sorry 'bout that.
A couple things to keep in mind about compression testing in general:
For one thing...it generally doesn't mean a whole lot. KDXQs quote from Ron notes that having a GOOD guage is the place to start. A lot of guages AREN'T any good..and multiple tests will get you multiply (-ee) different results. How warm the bike is matters. Basically, lots of things matter.
For the purpose of any comparisons, use the same guage and the same method of test.
That said...it's when you're at the margins that all the little things are more likely to add up to what may be an incorrect diagnosis.
150psi should be fine, though.
Consider what you would get with some leaky rings and a fat layer of carbon on your piston/head! Maybe 150!!
Seems to me (not that anyone asked..so sue me) that the value of a compression test is largely in a comparative situation..like with a multiple cylinder engine. If seven of eight cylinders are 240..and one is 150...that's a problem no matter HOW you slice it.
I replace top-ends 'cuz it's time...or when I feel like it. What the compression is or isn't is not something I've even tested.
I've got a good guage. Maybe I'll check it just for fun.
...it'll give me something else to worry about.......
Consider the source
Using a perceived level of knowledge to boost my self worth.
Non impediti ratione cogitationis
bike profile: !clicky!
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Yeah, I didn't get into details Other than very rough measurements I consider comp testing on a 2T pretty worthless unless you've tested it since a new top-end, the same way every time, just to measure the loss. Pour a shot of castor in that sucker and watch what happens. Pulling the jug and looking for any blowby/etc is the best way...For the KDX...If it idles well, pulls well off idle, it's got enough compression to not worry about it. This is where you'll see the degredation first.
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'95 KDX 200 Project $600 KDX
'94 WR 250 Always a project
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Re: 'Guess I'm just trying to be proactive with my maintenance.'
Suspension/bearing maintenance, suspension fluid changes are a couple of places 'proactive maintenance' will be a big help.
If you're looking for things to do.........
A BTW...but a bike that idles 'like a champ' with no choke on a cold-iron start needs some carburetor tuning. That's not an example of things being 'right', it's a surefire symptom of something NOT being right.
Suspension/bearing maintenance, suspension fluid changes are a couple of places 'proactive maintenance' will be a big help.
If you're looking for things to do.........
A BTW...but a bike that idles 'like a champ' with no choke on a cold-iron start needs some carburetor tuning. That's not an example of things being 'right', it's a surefire symptom of something NOT being right.
Consider the source
Using a perceived level of knowledge to boost my self worth.
Non impediti ratione cogitationis
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Let me elaborate... I'm in the NE, Connecticut to be exact. My season is May 1, to Nov 1. (for legal riding) The bike has been sitting since Dec. I busted it out the first time this weekend; first start in 4 months. Started on third kick. Warmed it up for 5-10 minutes and rode in my neighborhood. The first 1/5 of the throttle (putting around) felt "chunky", a little hesitant, but from there on out it moves. Then I ran it Sunday for 2 hours and it was great. Just chugging through some tight stuff and in the sand winding through the gears. Suspension felt good... Loved it. I am new to the bike but once it's hot it's awesome; all the way through the throttle, even putting around. I ain't complainin'...
btw, per this forum suggestions, I have replaced/greased the swingarm bearings, and greased the steering.
I am no motorcycle expert by any means! Still learning and you guys are a great help.
btw, per this forum suggestions, I have replaced/greased the swingarm bearings, and greased the steering.
I am no motorcycle expert by any means! Still learning and you guys are a great help.
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Be sure to look at the rear shock rocker arm bearings too. My swingarm pivot bearings looked great, but the rocker bearings were just ok and the small one was pure rust. I don't think it had been greased since the bike was new.
BTW, speaking of proactive maintenance.....where do you guys go to get new nitrogen for the rear shock following dissassembling to replace the oil?
BTW, speaking of proactive maintenance.....where do you guys go to get new nitrogen for the rear shock following dissassembling to replace the oil?