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Arjan van Druten

Max engine running hours before piston rings / rod - lower pin - replacement

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Hi all,

 

I need to know how sensitive the piston rings / rod lower pin or other parts are for wear / fatigue failure under medium load conditions.

(I ride in flat woods  (Enduro), not on cross-tracks)

 

Yamaha Manuals require every 5th race or 1000 km (?) or .... ? before preventive replacement.

 

I doubt if this is a reasonable margin. It does not differentiate between loading conditions. What do you think, What should it be under medium conditions.

Is 10.000 km Feasible?

Anyone experience with WR400F running much more hours without failure? 

 

Thanks for your info!

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No way to know exactly without pulling the motor apart and checking the service limits in you service manual.

You can check the top end with micrometers and feeler guages, and just 'wiggle' test the bottom end.

 

I tend to follow these guidelines for a WR motor:

20 hours max for oil and filter change (offroad):

10 hours max for air filter changes (off road)

300 hours max for piston/rings/wristpin

1000 hours max for bottom end bearings and rod

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No way to know exactly without pulling the motor apart and checking the service limits in you service manual.

You can check the top end with micrometers and feeler guages, and just 'wiggle' test the bottom end.

 

I tend to follow these guidelines for a WR motor:

20 hours max for oil and filter change (offroad):

10 hours max for air filter changes (off road)

300 hours max for piston/rings/wristpin

1000 hours max for bottom end bearings and rod

Do you actually run 20 hours on a oil and filter change? I don't see how that would be possible on one of these engines unless the bike is idling the whole time.

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Do you actually run 20 hours on a oil and filter change? I don't see how that would be possible on one of these engines unless the bike is idling the whole time.

What does idling have to do with it....

Either the oil breaks down, or it doesn't.

Either the oil gets dirt in it, or it doesn't.

I usually go three rides on oil, which is about 18-22 hours of riding.

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What does idling have to do with it....

Either the oil breaks down, or it doesn't.

Either the oil gets dirt in it, or it doesn't.

I usually go three rides on oil, which is about 18-22 hours of riding.

Oil breakdown increases a lot at higher load and rpm, thats why I mentioned idling which would get you max run time from an oil change. I am not trying to start an oil debate or derail this thread but what oil do you run and what type of riding? I just read through a bunch of your posts and don't see it mentioned anywhere.

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No way to know exactly without pulling the motor apart and checking the service limits in you service manual.

You can check the top end with micrometers and feeler guages, and just 'wiggle' test the bottom end.

 

I tend to follow these guidelines for a WR motor:

20 hours max for oil and filter change (offroad):

10 hours max for air filter changes (off road)

300 hours max for piston/rings/wristpin

1000 hours max for bottom end bearings and rod

Opened up my top end last winter after about 125 hours on it, I came from 2t bikes and wasn't sure if I should risk not changing  it, after the fact I can see that the 300 hr number is totally reasonable, other than a bit of carbon on the piston crown things were really clean...now I know and the next top end will be after 300 hours for sure. Oil wise I'm in the 20-25 hour range usually, unless my shifting feel notchy then my interval is less. These really are great engines jusk keep fresh oil and clean filters on it and it will serve you well.

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Thanks for your information!

 

Guess I have to open the engine in that case, once in a year or so... 

Or just risk a jammed engine... :(

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Yamaha wr 450 f , 2008

I've only odometer / km / Replace piston and timing chain  every other season. Mileage ca. 2500 km. I'm from Poland , we have winter :(

Oil change every 400-500 km -  motul 300V 10/40 . Drive enduro and cross-track.  I never opened case because didn't need to. Dont see enybody have problem with cranckshaft in wr 450f

 

 

ps : sorry for my english :)

Edited by adamek

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