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Oil leak on swingarm

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I recentally bought a yz 125 (brand new) and the rubber piece that connects to the silencer and the fatty vibrates back and leaks all over my break line and my swingarm but im not worried about that because i know i can fix it but when i come back from a ride ill look under the swing arm and it will be drenched in oil it will also be on the front of the swingarm bearing and on the other overflow hoses so i know that its coming out of the powervalve overflow hose and theres oil all around that overflow hose, is this normal? And it does leak oil over night which ive heard is normal but i dont know about riding if it should drench the bottom of my swingarm..

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Sounds like your engine is simply jetted too rich for your usage (trail / off-road rather than wide-open MX track riding?)

Or perhaps using a high flash point 'racing' premix in an application that doesn't require it.

 

A few drips at the power valve vent hose is considered normal even for a well jetted engine that's pushed hard,

if it leaks at any other joint (head to pipe o-rings, pipe to silencer slip joint) then you are likely running too rich.

If it's to the point your swing arm is covered, the silencer packing is likely saturated and needs replacing as well.

 

Edited by mlatour

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Ive got the bike jetted perfectly for my weather and i dont trail ride most of the time im ripping through a field at wide open throttle or practicing wheelies on my road but i always clear it out by pullin the clutch in and revving it up or hitting it after ive been going slow for a while

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If you have to 'clear out'  the engine, it's not jetted perfectly !

 

What premix oil and ratio do you run?

Edited by mlatour
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I dont have to clear out the engine i just do it to be safe and on a two stroke your always going to have to clear out the engine if your doing anything thats not wide open throttle.. im running yamalube 32:1

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If your riding at times involves going slow / at part throttle

than it will require leaner settings than recommended for motocross track riding.

 

Yamalube 2S or 2R ?

If the 2R, it may have too high a flash point for your non-racing usage.

Edited by mlatour

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Im not going to lean my bike out when i just need to go slow sometimes and ride wide open throttle other times i run the 2r and my problem is not fouling plugs its the oil leak

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Field riders always have same problem.  I'd take the advice given above if I was you:thumbsup:

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The oil leaks because your combustion temperature is too low to burn off the excess of the higher flash point 2R.

It stays in liquid form and accumulates inside your exhaust system until it finds a place to leak out.

 

Either you switch to a lower flash point premix and/or, lean out the pilot jet a size or two,

it will run crisper at lower rpms, prevent spooging/fouling but have no effect on your wide open throttle moments (that's the main jet)

 

As an example, my MX track ridden YZ125 runs best with 2 sizes leaner pilot, one step leaner needle but has the stock sized main jet.

 Most people tend to 'play safe' and run way richer settings than actually required,

in that case learn to live with major oil leaks and the need to regularly 'clear out' your engine.

 

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Very good advice from mlatour, if you want it to go into your packing and/or out the tail pipe, you can seal the joint under the rubber coupler, get a new coupler that is tighter fitting, but that defetes the problem. 

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Im not worried about the oil coming from the rubber connecter from the silencer to the fatty im worried about the oil some how leaking and getting all over my swing arm linkage and the bottom of my swing arm

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Un-burnt oil makes it's way past around the exhaust valves into the valve mechanism cavity in front of the cylinder.

that cavity is vented, excess oil just leaks out. 

As mentioned, even on a well jetted engine using a low flash point premix it's common for a few drops to leak out once in a while.

 

 

As P84ONE mentioned, you can seal the pipe to silencer joint from leaking there but

that's not fixing the problem but just moving it somewhere else. 

the excess oil will simply accumulate somewhere else, meaning in the silencer & packing.

 

Edited by mlatour
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Exhaust power valves to be more specific.

 

Since you bought this bike brand new, you must have the service manual right.

Have a look at the engine parts diagrams.

Edited by mlatour
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If it is coming out the PV vent hose off the head, you have an excessive amount of "unburnt" 2R and need to change riding style, oil, or jetting. There really are only those three options. 

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No, 

Check the oil chart that a member provided and go with recommended flash point. Make sure to clear out all old fuel/oil mix before adding a new oil. This can gum up valves if not changed out clean. 

 

Edited by P84ONE
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I checked that sight out but it appears the yamalube runs at i think 255 flash point and some of the oils go down to a 160 how do i know which oils right for me because i still want to ride hard and not damage the top end quicker or anything i just hate that oil leak

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I checked that sight out but it appears the yamalube runs at i think 255 flash point and some of the oils go down to a 160 how do i know which oils right for me because i still want to ride hard and not damage the top end quicker or anything i just hate that oil leak

I have the same issue with the 2R, my friends tell me I just need to ride faster.

Sent from my SM-G935V using ThumperTalk mobile app

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