Hi Sav,
I'm not too experienced with the FS bikes and how the asphalt affects things differently than the dirt. I imagine that you rack up the klicks quite a bit faster on your rides than us dirt guys though. But, the hours will be about the same.
I've got 192 hours on my 04 550, and about 3700 miles. 99.9% of which is off road, and has been a mix of faster desert stuff, and slow technical riding.
Again, I would imagine that you have a lot less clutch usage on your FS than my FE, so not only would the clutch last longer, but, the oil shouldn't be getting as abused as it does on my bike. However, I would assume that you would have more sustained rev's than I would, and higher speeds so engine temps should stay lower as well.
The reason why I'm making these comparisons is because 500 klicks sounds like a lot to me on an oil change. That's 310 miles, and I usually do about 70-80 miles on an oil change. 70-80 miles for me takes the better part of 3 to 4 hours. The farthest I've gone on an oil change has been 150 miles. I personally don't like my oil to come out black, I dont' want to see it any darker than a dark amber. These bikes don't hold much oil in the first place so keeping the oil clean and fresh is a must.
Keeping the valves adjusted is the other main maintenance item on your bike. The harder you rev it the more the valve lash is going to change. With the newer motors like yours 30 hours is a good figure for checking the valve lash. And you may find that at 30 hours the lash is still okay, this is another reason to check your valve lash with feeler gauges even if you do the turn out method, so you can keep track of the changes. I have gone as long as 45 hours without having to adjust my valves. But, that was a lot of slow single track stuff where I wasn't using the upper revs very much. You're coming up on 25 hours since the last adjustment, you might have a go and check the valve lash just to see where it is at the moment. It won't take you more than an hour max to check them, and once you get proficient you can do a check/ adjustment inside of 30 mins. I've done mine in 15 minutes before when I was "motivated".
The general consensus on the cam followers is about 150 hours. If you notice that your valve lash is getting looser instead of tighter, then it's time to pull the rocker box and check things out. I just replaced both of mine, and the exhaust was on it's way out, and I'd say that it was about 186 hours when I noticed it starting to go south. This is why it would be a good idea to check the valves more frequently, especially on an engine with 100+ hours on it. I also replace my cam bearings, and cam chain while I was at it. The cam chain definitely needed replacing, only two clicks left on the adjuster. But the cam bearings, while not as tight as new, were still in good shape, but, prudence dictated that I change them while I had the cam out. I'm planning on a full tear down at 250-260 hours. And other than a water pump seal that's all I've done.
One thing you might check now that's pretty easy to do, is your cam chain tensioner. Have a look at how much the adjuster is sticking out. Once the chain has stretched enough that the auto tensioner can no longer keep tension and the chain continues to stretch, it will start to rub on some aluminum parts of the motor and that's when you see the aluminum in your oil. Be sure and take the 10mm bolt out first and release the spring tension.
And to answer your question, yes it is expensive to rebuild these motors, and it's cheaper to do before they break. Most of the time you are going to get warning signs, like excessive amounts of metal on the drain plug magnet. You'll always get some material on the magnet, but, when a bearing starts to go bad you'll start to see an unusual amount of debris there. Or, if you start to see lots of aluminum in the oil, or perhaps it starts consuming oil.
I believe it was member Coffin that recently had something go awry in the lower end of his 550 after a full day of ice riding, and some extended full throttle speed runs. When he rolled up to the truck he could hear something knocking down low, and when he drained the oil there was a lot of stuff that shouldn't have been there. So, he shipped it off to nsman for rebuild. I don't know how many hours he had on that motor.
Member Baja racer recently had the big end bearing of his 05 or 06 FE650 start knocking at 140 hours, but, as he told me, he really rides his bikes hard.
And then there's member Cheeseberger and his 04 FE550. 9000 miles, and I would guess 300+ hours now, and I think all he has done is replace the cam chain.
I don't know much about the stock pistons other than they are forged. Others on the site may want to comment here TAffy would be a good one to tap for this info as he has been in and out of his motor quite a bit with all of the upgrade work he has done.
I would say that as far as performance mods go, the first thing I would suggest here is getting the bike jetted right. There is no shortage of threads on this subject in the fuel section. You may find there is a great deal of performance to be had just by swapping some brass. I know I have found a great deal more low and mid range power by getting the jetting right.
That's about all I can think of right now, best of luck.
Oh, and be sure to check the Owners Doc! for idea's as well.
