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Enduro Engine - 2 stroke Cylinder, Piston, Tranny, Bearings, Clutch, Pipes & Silencers, etc.


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Old 08-29-2009, 03:50 PM
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Default Crank seal gone on rebuild?

Have just finished putting the top end together but had a few niggling doubts about everything was well..

When running - idling - there still seemed to be a lot of mechanical noise at a guess could the big end be worn even though I checked it? Again - how obvious is it when the big end it worn?

After about 4 to 5 starts and restarts with the choke on the pipe has about 1/4 of a cup of fuel/oil in it. It certainly contained a reasonable amount of oil as it was quite a bit thicker than fuel.

After 1 start and coming quickly off the choke there was about say 5mm worth of oil in the pipe.

I changed the oil and pulled out 650ml though the engine was warm and not 'hot' I put 900ml in, level looked approx OK in the window.

I pulled the crankcase drain and there was about 1/8 to 1/4 cup of oil in there - it looked like clean oil (maybe the stuff I had just put in)..

Looking in the exhaust port I found 2 pieces of brown rubber approx 3mm x 2mm, also later I found one piece near the neck of the pipe again about the same size.

There were also some small flecks of aluminium on top of the piston which I fould by running my finger over the top and it stuck to my finger.

It also felt as if at one point the engine was running tighter or perhaps partially seized though not sure if this is my imagination.

There was some evidence of white emulsion in the RH PV assembly where the rod goes on the inside of the case and a bit near the cylinder stud/nut there.

My guess is the bits of rubber are a crank seal or similar hence only pulling out 650ml oil plus oil in the bottom of the crankcase and the pipe... I can't think why it still sounded loud mechanically though?

My guess also is any damage has only occurred after the rebuild, the reason being if I was loosing that much oil the last time(s) I used the bike surely it would have used all the gearbox oil?

I'm wondering if maybe when I lifted the PV actuating rod to reinstall it some of the ball weights dropped out (is that possible) and have been rattling around the crankcase and damaged the seal?

Is there any possibility I don't have to pull the bottom end apart?

Also I was going to try and check the PV rod moved correctly when revved, how do you do this with the cover removed doesn't the exhaust gas just come out there?



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Old 09-01-2009, 11:47 AM
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I think I'll be stripping the bottom end unless anyone thinks different.

ho hum
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Old 09-01-2009, 07:13 PM
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Are you ever going to have any trust or faith in the bike if you don't split the cases?

Top ends I do myself, bottoms I pay to have done.
just my $.02
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Old 09-02-2009, 02:26 PM
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Quote:
Originally Posted by stay_upright View Post
Also I was going to try and check the PV rod moved correctly when revved, how do you do this with the cover removed doesn't the exhaust gas just come out there?
No. Take off the pipe, remove the cover, put the pipe back on. Start the bike up and rev'er.
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Old 09-08-2009, 09:46 AM
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So no smoke should come out of there?
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Old 09-08-2009, 02:19 PM
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yes you might get some but that isn't the point. In fact that is why the cover is there. You are watching for the power valve movement. Also, if you caused the balls to unseat for the PV actuator I don't think that they actually fall out of the actuator, they just dislodge from their "seats" and cause the PV to stay open or closed (not sure).
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Old 09-08-2009, 02:21 PM
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Some exhaust will vent through the PV bearing.

You can't loose a PV governer ball into the cases by pulling on the rod, but you can dislodge them from the ramp(s) and jam the governer partially open.

It sounds like you damaged the seal on install as a minimum. If you have a milky looking emulsion that means coolant in the oil as well. Perhaps you have more than one problem from your rebuild.

When you say its loud. what kind of noise? A knock/rattle or a roaring noise?
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Old 09-08-2009, 05:23 PM
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I would say a knocking noise - I originally thought it may be the little end - hence doing the top end
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Old 09-09-2009, 07:57 AM
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I think you need to back up, and tear the top end down, as well as remove the side cover and primary components to inspect the crank seal. The fact that you found traces of rubber in the exhaust, and the bike may have partially seized, also indicates a possible pinched head o-ring. Coolant can wash down the cylinder and cause this. Did the rad cap valve blow off from the system being pressurized? Coolant low/dirty?

Could you nave been chasing a power valve rattle from the start? I have never seen a small end/wrist pin get bad enough to knock by itself.

Take some photos. Take your time, and if your not absolutely sure what you are seeing or doing, ask and we will help.
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Old 09-09-2009, 10:13 AM
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The rubber I found was brown - the head orings I installed were black.

I inspected the PV when I did the top end - all good.
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