So what problems do valves cause? Are they a pita to check and adjust? From doing some reading online last night, I read that 4 strokes should have their valves adjusted around 25-30 hours and a rebuild with new piston around 75-100 hours.
They don't cause problems. If you can use a feeler gauge and operate a wrench, valve clearance adjustments are extremely simple. All two valve and older RFVC Honda XR's use stud and jam nut adjusters which involve removing an inspection cover to check and adjust. It can be done in a matter of minutes.
Others, like my KLX, require the cam cover to be removed and the clearance checked with a feeler gauge. If adjustment is needed the cams have to be removed to change the shims. All in all, it takes a couple of hours to do.
Honda XR's aren't built like modern high output fourstrokes. A 200 or RFVC 250, 400, or 600 will go far beyond the 100 hour mark on a top end. Valve adjustments need to be made, but the process is simple on these machines so it is really a no brainer.
Also what about lowering bikes down like 1 in?
Lowering the front can (not always though) be as simple as sliding the forks up in the triple clamps. Lowering the rear can (again, but not always) be as simple as changing the shock linkages. I have never lowered an XR before, but I have lowered an older KLX250R. I made my own linkages out of plate aluminum to lower the rear and combined lighter spring rate fork springs with sliding the forks up a quarter of an inch to lower the front. It worked out well, but the change in shock geometry made the rear a little harsh which took some tweeking to correct.
And now that you guys have me interested in 2 strokes, what is usually the case of rebuilding a motor? How much will it cost if you do it yourself vs a reputable shop. With a good manual I would probably feel confident in doing it myself.
In the case of a two stroke, if the bottom end is sound all that needs to be done is a piston and ring job. For most common two strokes it can be done for around 50 bucks if you do the work yourself.
A KX100, for example, costs less than 100 bucks in parts and can be done in two to three hours depending on if the power valve needs cleaning or not.
My old KX500 routinely went far over 100 hours on a top end and I never suffered a piston failure. Parts for the job cost me just over 150 bucks and it took me around three hours to do the job (lots of time wasted swilling beer and bullshitting in that time too).
Keys to two stroke longevity are using high quality oils, premium fuel, good maintenance and common sense.
I am open to other bikes in the 200-300 range if its a 4 stroke. It I were to get a 2 stroke, it would be around a 125. I really only plan on doing trail riding no motorcross what so ever so winding a motor out wont be a huge deal for me on a constant basis which is why I wanted the torque of the 4 stroke.
Aside from Honda XR's, Kawasaki makes the KLX line. Older KLX250R's and KLX300R's can be found for a good price and are as bulletproof as they come. They are more of an "old school" thumper, which means they don't have a lot of top end, but the mid-range and lower end output is excellent. My KLX300R has more usable torque than my old 500 two stroke did down low. The 500 would kill the thing in a hillclimb, drag race, you name it, but it was a very unpredictable machine that ate rear tires like donuts. My 300 four stroke wasn't a perfect machine when I bought it, but I have it almost where I want it now. I was going to upgrade to the KLX450R this year, but until it gets fuel injection my 300 will do. I actiually plan on racing it this year too.
Both the KLX250 and 300 are basically the same outside of some fork changes and engine displacement increses over the years. Both can be lowered and both have very tame and predictable engine output. The really nice thing is that they also have good aftermarket support, so if you get bored you can always make it faster!
Anyways, I could write a novel on this stuff. There are tons of options out there that are inexpensive to boot. Honda, Kawasaki and Yamaha all make excellent machines. Suzuki does as well, but their trail machine line is pretty minimal outside of the DR-Z (125, 250 and 400) models which carry a big price tag due to the fact they haven't been around for very long. Older XR's and KLX's are pretty abundant for cheap.
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