How long should it last?

I bought a 1998 YZ400F in July. I have ridden it raced it since ive had it. The power it has matches my cousins 2000 426 and i see no differences between the two. What i need to know though is how long this 1998 motor should last? because i want to know incase its time is coming to blow up on me and cost me thousands. Should i consider selling it soon and getting a newer YZ thumper?

Thank you for your time and information.

The one thing I would tell you is not to run it until it breaks, its alot more expensive if you run it until it breaks.

I have a 1 year old 01 426 and just finished doing a complete top end including valves, timing chain, rings, piston, and cylinder.

The one thing you must take into account is the time and type of riding your doing, I had 400 hours of MX on mine and it started losing a little compression so being the prevenative maintenance guy I am I tore it down and redid it.

If you are able to push it over TDC without the decomp lever its probably time to rebuild unless its a exhaust valve hanging thats causing the compression loss.

When you lose just a slight bit of compression on a high performance motor you bring on a whole host of problems especially in the jetting area.

If if runs good and everything checks in spec, then keep going, these engines are tough if your good to them.

I was down 11 days, if I would have had my parts I was looking at a 8 hour or less re-build.

Later, Jason

Jason says a lot in a just a few sentences. I would add that different riders are harder on bikes than others. I've noticed that some riders hit the rev limiter consistently while others like myself rarely hit the limiter. An engine that is run into the limiter often will wear more quickly...usually. Conversely, an engine that is lugged too much might have premature lower-end wear. And, of course, a machine that is neglected in its maintenance will wear quickly as well. Have you ever sat on someone's bike and hear the suspension pivots squeak from lack of cleaning and lubrication? The first that comes to my mind when I hear that noise is that I would NEVER buy a machine from that guy.

The bottom line is that it all depends on how much the machine is abused and the level of maintenance that is performed.

I was behind a '01 Camry recently that was smoking through the exhaust. Why?

The Camry probably had too much oil in the crankcase.

MXTuner: The first thing that came to my mind was that the oil/filter had never been changed. Believe or not, some people believe that the oil needs not be changed. . . EVER. They are convinced that this is one huge oil company conspiracy. It doesn't matter that you point out that amber colored oil goes in and pitch black oil comes out, they still insist that the oil is just fine. Typically, these people have several dilapidated cars/pickups/station wagons parked in the weeds behind their trailer home.

[ December 10, 2001: Message edited by: Boit ]

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