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oil question...

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everytime i race my rm-z 450 i have to refill with 50-150 ml. oil is that normal and whats the limit before replacing piston...?

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In between rides,I top off the oil check screw by the manual procedure. 2 hrs of riding I have been topping off 60cc or 60ml. Since new this amount has not changed. Some say you need rings,but I beg to differ,so I say it is normal to a certain degree. A new top end can vary,different riding levels,different types of riding. I will tell you, I am a upper B rider MX,I also will do trails if given the chance, with a 130hrs on original top end,it feels and sounds as strong as ever. I will be doing a leak down test to see if anything shows up,but for right now I am on my 250f. I have to say though,we know 4 stroke machines of today need very good maintenance habits. I see a lot of owners doing top ends at the 50 hr mark on 450's,I believe that is a overkill on the RMZ and I am a maintenance hound,TRUST ME. :thumbsup: I am all for keeping up on top end rebuilds and valve train components,the RMZ 450 motor is a very durable machine.We all heard in the beginning how often a top end should be rebuild on today's 4 stoke MX MOTORS.I am saying they can go much longer than what was expected, the RMZ 450 anyway.Each time you change your oil and air filter plus changing the oil prolongs life. To give a exact number of hrs for a top end,I will not give. Just too many variables.

It strikes me funny how the manual is over zealous with top end changes,but they are way off with the oil filter and oil changes. Leaving the same oil in the motor for 8hrs is just TOO LONG,with these motors. I am not sure what the manual stated for a oil change,my manual is down in the basement. I do know whatever it was, is just asking for trouble.

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Oil threads are always hot topics! I have two bikes we use both of them for harescrambles, Enduros, trailriding and occasional MX track riding. Enduros are 50 - 70 miles each for about 4.5 hours of riding pretty much steady. Harescrambles are 1.5 hours and about 20 - 30 miles. We put on a lot of miles a year, not as high RPM as MX racing but a lot of hard hot work for the engine, including hill climbings.

I had to rebuild the our 04 RMZ250 this year because I did the classic over torque of the cam this summer. It was burning a about 4 - 6 oz of oil per day, I could smell it burning oil if I got behind him in a race. When we tore it down to replace the head, there were still hone marks on the cylinder wall, no ring groove, the piston looked great, so did the cams and the valve buckets, just the one intake valve was starting wear the seat down.

I expect to get 2 season out of an engine and change the oil only two or three times a year. I've been using Mobil 1 15w-50 for 4 years in the dirt bikes and a lot longer in my street bikes. DirtRider mag ran a CRF450 for 200 hours then did a total tear-down and said everything looked great.

Your experience my vary :thumbsup:, lots of high RPMs equals more maintenance on a two or 4 strokes. Generally speaking I would believe that a 4 stroke should last 2x that of a two stroke per rebuild for a given situation. And why replace the valves if they are staying in spec, maybe every other time if by inspection they look good? Besides that I really love the torque of a 4 stroke.

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