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Old 10-01-2013, 02:46 AM
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Default 2000 cr 125 blow by

     

My 2000 cr 125 has a lot of oil coming from the expansion chamber where it meets the cylinder, I think its jetting but bike seems to run just fine when its warmed up. Any suggestions?

---------- Post added at 12:46 AM ---------- Previous post was at 12:36 AM ----------

if it helps at all, I just did a top end rebuild. Before thr rebuild it did this but not nearly as bad.

Last edited by crchris; 10-01-2013 at 05:18 AM.
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Old 10-01-2013, 06:41 AM
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Default ???????

What does your spark plug look like?
What fuel mix are you using?
Have the crank seals been changed?
Have you checked your float height?

Paw Paw
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Old 10-01-2013, 09:50 AM
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WHAT ABOUT REPACKING silencer. also check the premix it should be about 32/1.
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Old 10-01-2013, 10:09 AM
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If you are sure its blow by pull the piston and get a new one. Those pistons shatter, specially when running too loose in their cylinder.
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Old 10-01-2013, 10:42 AM
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Double check the mating area where the pipe meet the port. O-ring may have torn or rolled.
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Old 10-01-2013, 11:09 AM
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Quote:
Originally Posted by PawPaw View Post
What does your spark plug look like?
What fuel mix are you using?
Have the crank seals been changed?
Have you checked your float height?

Paw Paw
My spark plug is pretty black, im going to change it tonight and I run 32:1 maxima pre mix. And no ive never changed the crank seals.

---------- Post added at 09:09 AM ---------- Previous post was at 09:06 AM ----------

The o ring is torn in half.. thats probably why it comes out of the expansion chamber but why would so much come out?
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Old 10-01-2013, 11:59 AM
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Default OK

Ok if plug is black then you are running rich.
If the crank seals have not been changed on a 14 year old bike, then do so ASAP.
Also set the float level and make sure the needle is shutting off fuel flow.
If you are attempting to run a fuel mix using less oil, like a 40 : 1 or a 50:1 then that will make you run rich.

Pick up a service manual for your bike.

Paw Paw
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Old 10-01-2013, 10:12 PM
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I have a service manual but it doesnt tell me much about problems like this, the bike was preowned so I couldn't tell when the last rebuild on anything was but ill tare it down soon and change the seals. Thanks guys.
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Old 10-02-2013, 10:58 AM
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Quote:
Originally Posted by PawPaw View Post
If the crank seals have not been changed on a 14 year old bike, then do so ASAP.

Paw Paw
+1. It's actually very easy to do and can save your motor.
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Old 08-30-2018, 10:32 PM
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2000 cr125 with alot if money in and less than 10 hours on a top end less than 5 on a new transmission. running 40:1 with motors cross power full synthetic but I still have alot of after birth from my silencer especially when it's cold it's Smokey af it gets better as it warms up but jetting ? maybe ? runs great and has lots of jam .it bogs a bit

---------- Post added at 10:32 PM ---------- Previous post was at 08:41 PM ----------

2000 cr125 with alot if money in and less than 10 hours on a top end less than 5 on a new transmission. running 40:1 with motors cross power full synthetic but I still have alot of after birth from my silencer especially when it's cold it's Smokey af it gets better as it warms up but jetting ? maybe ? runs great and has lots of jam .it bogs a bit
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Old 08-31-2018, 03:38 PM
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Plug check will tell you how the jetting is. I dont know what you have ridden before or any history of you and the bike, but 125s arent know for their bottom end.....so if you dont already think this way, here's my two cents. Consider the throttle your clutch and your clutch your throttle.
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