Major engine work?

I've owned my '06 YZ450 for about 6 weeks and have about 20 hours on it of fairly hard track use. My suspension has made it clear that it needs to be serviced soon and it made me start wondering about other more major service. Since I live in Mexico now it would be best if I can plan it out and have the work done on one of my trips back to the States as opposed to waiting until something major happens and I'm forced to make an unexpected trip or be without a bike.

At approximately what hour intervals does major engine work come into play and what all does that entail? I hear bottom end and top end but what does that mean in terms of service? I hear guys talk about how expensive 4 strokes are to maintain but I have no idea what that means.....$500, $1000, $2,000 per year?

I ride mostly SX with some fast trail riding thrown in on occasions. I don't want to jump the guy on major maintenance but I don't want to push it either so I'd like to know what's the longest I can safely go? Or do I ride hard all year and then get a new bike when I come back each summer? A year old '06 goes for as much down here as what I can buy a new '07 for so one option is to bring a new bike down each year.


Oh, and I change the oil about every 7 hours and put in a new air filter every 1-4 rides depending upon whether or not I'm the only one on the track or if there is someone else kicking up dust.

Check your valves on a regular basis. After they have tightend and you have had to shim them a couple times, it will be time for new valves, springs, retainers, etc. When you do the valves it would be a good idea to put a new piston in. If you haven't even shimmed your valves yet, don't bother doing any major engine work.

While it doesn't hurt to check your valves occasionally, it is a Yamaha and if its only got 20 hours on it they will be fine. (You can always tell when a Honda rider is in here giving responses.) Provided you keep the oil changed and the filter cleaned, you should be able to get 100 hours or more before needing major work.

I'm not a honda guy. I did have a couple hondas in the mid 90s, but I've been yamaha ever since. I'm just saying, even though it is a yamaha, check your valves every 10-15 hours. They do wear out over time. The first couple times you check them you will not need to shim them, but incase you do need to, you have caught the problem early. Things do wear out and not every bike is exactly the same. Better safe than sorry.

You are right and thats why I said it never hurts to check them. However, I am now on my 5th Yz 426/450 and I have never yet had to adjust a valve. Two of the bikes went to approximately 100 hours before I sold them and my current bike, a 2006 YZ 450 has 47 hours on the hour meter and the valves are in spec.

KJ 790, after looking at your garage, I realize the Honda comment was a low blow, sorry, no one who owns 3 yamahas should be treated with such disrespect!:applause:

Haha, thanks man, I just added a new one to the house a little while ago, I got an '07 YZ250F, and I have my old YZ250F for sale. I'll get some pics of the new one when I get it all set up. Now I have 5 yamis sitting at my house.

What does it take to check/adjust valves and how hard is it to screw up? I'm sure the checking part isn't too tough but what do you need to do it?

Lets say that I'm getting close to 100 hours.....are there signs to look out for that will let me know that I should do some engine work so that I can plan a trip back to the States or will the engine just blow without warning? For sure I'll put on more then 100 hours per year.

When the bike starts getting hard to start, then it is time to break it open and adjusting valves....until then just ride the crap out of it.....I have checked every on of the yamahas I have owned after breakin (8 of them)....not any of them needed any adjustment. Occasionally a tighter exhaust valve I see but it is very rare. Even then starting becomes very difficult....These ain't Hondas, Suzukis or Kawis.....the Yamis have a bullet proof valvetrain from the factory:thumbsup:

That's great to here and is the main reason I went with Yamahas since I knew I'd be a long drive away from a qualified shop. The hard to start that something that will come on over a period of months, weeks, days? Hopefully I'm given enough notice that I can plan a trip back to the States accordingly.

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