Strange Compression loss..

[brettLo]

Ok just ripped the plug out and had a go at that, but still seems to be no compression what so ever... No pressure coming out of the plug hole at all...

 

[my67xr]

can you see the piston moving up and down, put something like a wooden skewer down the bore a little and turn the engine over
it is sounding like the piston is not connected to the conrod now ?

 

[zwebx]

Maybe the primary drive gear has come loose and is jammed on the right side.. (you did fall to the right yeah?)
i had ONE come loose but that just chipped the clutch basket gear but some times felt like it was dropping out of gear..

 

[brettLo]

can you see the piston moving up and down, put something like a wooden skewer down the bore a little and turn the engine over
it is sounding like the piston is not connected to the conrod now ?

Hey yea I popped a skewer down there slightly and had what I beleive to be (the piston) coming up to nudge the skewer.

Was a bit hard to see if it was the actual piston though or just the Conrod ?

Cheers

 

[my67xr]

^^ yeah, it could have broken a kickstart gear ?
but do the rockers move when you kick it over ?

 

[brettLo]

Maybe the primary drive gear has come loose and is jammed on the right side.. (you did fall to the right yeah?)
i had ONE come loose but that just chipped the clutch basket gear but some times felt like it was dropping out of gear..

Hey mate,

Yea I did fall to the right...was that an easy fix for u at all ?

Cheers

 

[brettLo]

^^ yeah, it could have broken a kickstart gear ?
but do the rockers move when you kick it over ?

When I kick it, everything seems to go through the motion, such as valves, Conrod movement aswell as the magneto/ORK (I think that's what it is?) but just no compression what so ever

Cheers

 

[zwebx]

Hey mate,

Yea I did fall to the right...was that an easy fix for u at all ?

Cheers

If your kicking and its pushing your top end then its not what i was thinking.. sorry its prolly time to take your top end off

but yeah it was a easy fix i just locktited it and with only the clutch cover off did it up with a screwdriver.. if i used the correct tool i would have taken the whole side cover off


will be interesting to see whats happend.. keen to see pics when the heads off

 

[brettLo]

If your kicking and its pushing your top end then its not what i was thinking.. sorry its prolly time to take your top end off

but yeah it was a easy fix i just locktited it and with only the clutch cover off did it up with a screwdriver.. if i used the correct tool i would have taken the whole side cover off


will be interesting to see whats happend.. keen to see pics when the heads off

No worries, thanks for the help though..as soon as I get time to get a bit more involved in it I'll be sure to try get some clear pics to post hopefully we can all work it out. The inlet valve was pretty closed I was thinking after resetting that, that it would be right. Not now, it's starting to baffle me a little ....I'll be sure to keep this thread updated though.

Cheers

 

[Cactus Jack]

If it revved its ass off while it was on its side a valve might have floated , got hit by the piston and bent with the end result being no compression . I've also seen a hole melted thru a piston crown causing the same problem .

 

[timeeh]

One that hasn't been mentioned... Check your clutch cable and levers (at both ends) Wifes lifan 125 has a strange thing built in whereas you cant kick it over with the clutch in, it feels just like no compression, then you let out the clutch and it engages the bottom end. Think it's a "safety" thing so it can't be started in gear. Could of just snagged a rock or something under the engines clutch lever, that'd do it.

 

[zwebx]

Hmmn yeah thats true the plonker that im working on is a 125cc cant kick in gear and if you have the clutch in a little it wont turn the motor over and you will spin the clutch.. Feels like your kicking a work out stepper thing

 

[brettLo]

Hey guys,

Sorry for the late replys, still haven't had the time to have a proper look.

But it still feels like no compression still when the bike is in "neutral"

Cheers

 

[timeeh]

Hey guys,

Sorry for the late replys, still haven't had the time to have a proper look.

But it still feels like no compression still when the bike is in "neutral"

Cheers

Even if the bikes in neutral it still doesnt mean that the clutch isn't stuck in the engaged posistion which could cause this problem.

 

[rotn50]

I have worked on a bike that had a similar prob, the bloke had a decent crash and due to the timing chain tensioner rubber that pushes on the tensioner arm being damaged and non existent the timing chain actually jumped some teeth and bent a valve. Obviously you have checked your timing(reason I ask is cause I haven't read the full thread)

 

[rotn50]

Even if the bikes in neutral it still doesnt mean that the clutch isn't stuck in the engaged posistion which could cause this problem.

That's true timeeh, maybe pull on the clutch lever on the bars and is it feeling the same or is there more slack in it than normal.

 

[8r3nd0]

Is this happening on a lifan 140 or a yx 140?

 

[8r3nd0]

You got a pic of the clutch side of this engine?

 

[rotn50]

Has it got a cast or alloy barrel. Need a pic of engine.

If it aint broke, break it.

 

[Cordogs]

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