125 compression

[noobi]

i had an off on the weekend and cracked the ignition cover, so i took that off and discovered that i could turn the engine over very easily with my hand by turning the ignition
is this normal for a 125?
it feels like it has very little compression, is it supposed to be like that to mellow out the power?
or do i need new rings?

any ideas would be appreciated

its an 07 ec 125 btw

 

[2 strokes 4 life]

i had an off on the weekend and cracked the ignition cover, so i took that off and discovered that i could turn the engine over very easily with my hand by turning the ignition
is this normal for a 125?
it feels like it has very little compression, is it supposed to be like that to mellow out the power?
or do i need new rings?

any ideas would be appreciated

its an 07 ec 125 btw

Hard to say, It takes some effort but I can turn my 250 by hand, so mabe turnning a 125 without much problem is reasonable.

Anyone can conferm this?

 

[GMP]

Turning a 2-stroke over slow by hand allows compression leakage through the rings, thats why you kick it fast for a check with a guage which is what you should do.

 

[iancp5]

Silly thought - as you whacked that side - the crank is turning as well as the flywheel? You haven't broken the key in the impact? As GMP says you can turn it slowly but you should feel considerable resistance until the air leaks past.

 

[widebear]

i had an off on the weekend and cracked the ignition cover, so i took that off and discovered that i could turn the engine over very easily with my hand by turning the ignition
is this normal for a 125?
it feels like it has very little compression, is it supposed to be like that to mellow out the power?
or do i need new rings?

any ideas would be appreciated

its an 07 ec 125 btw

Would you go to your mates for a question regarding a possible serious medical condition?, hook it up to a comp gauge for the correct answer and quit acting like a ?

 

[noobi]

Silly thought - as you whacked that side - the crank is turning as well as the flywheel? You haven't broken the key in the impact? As GMP says you can turn it slowly but you should feel considerable resistance until the air leaks past.

dont think thats the case, cuz i rode it away form the accident, and it ran fine, although it was in first cuz the gear lever was bent 180 degreed into the peg
so yes the flywheel is still connected to the crank, unless it broke on the way home while sitting on the trailer

 

[noobi]

Would you go to your mates for a question regarding a possible serious medical condition?, hook it up to a comp gauge for the correct answer and quit acting like a ?

ok did the comp. test, measured 130-135psi
is that ok?

 

[iancp5]

ok did the comp. test, measured 130-135psi
is that ok?

I don't know for a 125, you'd expect more for a 250 /300 but it sounds enough to start it to me.

 

[widebear]

ok did the comp. test, measured 130-135psi
is that ok?

That may be a little low for sea level or it may just be the gauge, they can and will vary quite a bit I cant tell you spec because I dont know exactly what a healthy tiddler should be at, somebody will chime in I'm sure, If it starts ok your prob fine. Keep in mind that a worn piston can still give you good comp numbers. I did a leak down test on my mc and it showed zero leakage but the piston to bore clearance way, way out of spec.

 

[noobi]

i have been reading around and it seems that your supposed to hold the throttle at WOT and kick the sh*t out of it to get a correct comp. reading, is this right?
i did nothing with the throttle, and i was only kicking it like i would to start it, not like trying to start a hot xr 600 or anything

 

[skid jackson]

Yes ... throttle wide open and kick a few times ... on a cold motor.

I did a comp test on a husky 125 I bought this past fall. It blew 155 which I thought might be low. A post on a few husky sites lead me to believe it should be more towards 180. I pulled the jug and there was definite evidence of a cold seize. had the jug honed and am waiting for a piston to come in. Don't know if I'm out of the woods yet. Might need to re-nik.

 

[GMP]

Kick the bike with the throttle wide open and kill button depressed until the pressure reading stops climbing, thats the number. 130 sounds low. I honestly don't remember for sure but I beleive my nephew's GG 125 was well over that with a fresh top end. I'm sure Google will turn something up.

 

[skid jackson]

Why do you need the kill button depressed??

 

[coolum74]

Why do you need the kill button depressed??

I'm sure that question is tongue in cheek

 

[Disco_STu]

Procedure for doing a compression tests is to remove spark plug and screw in comp guage. Put spark plug back in plug cap and earth on motor somewhere to protect CDI ignition. Have the guage face where you can see it or have a friend watch it. With the fuel tap off wind the throttle to full open. Kick over the motor brisquely until the until the needle stops moving on the guage.

Depending on the guage, how fast you turn the motor over and how the motor is set up compression wise you may see readings from 135 to 185 psi.

Hope this helps, Stu

 

[noobi]

Procedure for doing a compression tests is to remove spark plug and screw in comp guage. Put spark plug back in plug cap and earth on motor somewhere to protect CDI ignition. Have the guage face where you can see it or have a friend watch it. With the fuel tap off wind the throttle to full open. Kick over the motor brisquely until the until the needle stops moving on the guage.

Depending on the guage, how fast you turn the motor over and how the motor is set up compression wise you may see readings from 135 to 185 psi.

Hope this helps, Stu

yea cleared it up a bit, thanks
did that except left the throttle alone, does that make a huge difference?
we've been relectant on the rebuild front because parts are so hard to get for my bike, its the rare of the rare here in NZ

 

[widebear]

Noob. If it starts and runs, just ride and enjoy it. Givin your circumstances with parts availability and NZ parts prices and questionable financial means, this assumtion of course based on your age. any more discussion on this point would just be academic.

 

[noobi]

Noob. If it starts and runs, just ride and enjoy it. Givin your circumstances with parts availability and NZ parts prices and questionable financial means, this assumtion of course based on your age. any more discussion on this point would just be academic.

yea, i will , ill have a rethink about this during the off season
thanks for all the input everyone