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Old September 25th, 2010, 08:55 AM   #279
ScOoTeR
hoo dat. wat.
 
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Join Date: 11-09-05
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Quote:
Originally Posted by cglenn View Post
I might be looking into a dirtbike soon. Guess it would be good to learn on or whatever. The guy at the local dirtbike shop suggested a 250 4-stroke, and I'm thinking Yamaha. I didn't know a 4-stroke would be better suited for me but oh well.
I'll be hitting up the desert so nothing but wide open space to screw around on. I'm not sure if there are classes that are meant to be taken for dirtbikes or not. I just don't want to look like a total douche out there since I've never ridden.
Quote:
Originally Posted by BlooMule View Post
I'd consider a Honda over a Yamaha. Every Honda I've owned has been dead solid reliable, even the ones that sat abandoned for 10 years fire up with minimal hassle.

Yamahas, well, most of the ones I've had get carb or electrical problems if not kept scrupulously clean.
And a 4 stroke is a more forgiving bike to learn on. Plus they live longer. Everybody on a 2 stroke will pass you like you hit the brakes, but they will be rebuilding their engine twice before your first oil change (OK, that's an exaggeration all you 2 stroke guys)


Usually, I would happily defer to Bloomule's extensive motorcycle, but I'd like to share my experience with Honda vs. Yamaha 4 stroke 250s:

Bought my wife a brand-new 2006 CRF250X; at the time we were shopping for a good trail bike with an e-start. A close friend has a 2005 WR250 - basically the same bike, but from Yamaha. They would trade bikes once in awhile (either her KX107 or CRF175) for a few miles - once she got on the Yammy, she would frickinn haul the goddamed mail. That sealed the deal on getting a big-wheeled bike - but I was a dumbass (in hindsight) and insisted she buy the Honda so her and our friend wouldn't be twinkies.

So, 13 hours on the engine, both intake valves start to lose clearance. This is the classic CRF250 valve problem - honda makes so many of these damn engines that they allow shitty components to be used so they can keep up with demand. Basically, they use Ti intake valves - which need a hardened coating applied so the area it contacts with the valve seat will be durable. Problem is - they can't meet demand AND guarantee all valves meet spec.
In 2006, they went to a softer seat material that was supposed to solve the problem, but they still had it in spades. So, the coating isn't uniform and starts to wear away at the thin spots. From there, it will completely erode/wear off the valve / seat interface; when that happens, the Ti valve starts to cup around the seating surface. The net result is now the valve sits deeper in the seat and you loose your valve lash.

So, pull it apart (after buying a $70 shim kit) and re-adjust your lash to spec - by installing a smaller / thinner shim. Well, now that the coating is gone, it will take about an hour of running to eat up the lash clearance. Pretty soon, you will run out of adjustment - your thinnest shim will be too thick to set proper valve lash.

When this happened, I said "Fuck It" and ordered a 2007R head, SS intake valves and a big cam. I did all the work myself and spent about $600 (IIRC) to fix honda's fukc up.
I swapped in a new piston @ 185 hours and my valve lash hadn't moved at all from when I set it up. That's how it is SUPPOSED to be with Hondas. Not how it is with the 250 four strokes these days. If you look on the internet, you will find out that you have a good one or a bad one - riding style doesn't seem to be a factor either.

ON THE OTHER HAND...
Our friend's WR250.
He bought it used in 2006 - nothing had ever been done to the bike except the addition of a bling Ti exhaust before he got it.

That goddamed bike is indestructible. Period.
He's been riding it four years now and has not touched the engine. Here is the list of shit it has been through:
  1. Torn intake boot for a whole, dusty Michigan summer;
  2. Ran it without coolant for about 30 minutes before he noticed funny operation and a shitty idle;
  3. Submerged the thing and we had to evacuate the water through the exhaust (didn't have the right sparkplug socket) and he had to ride it 15 miles out of the woods after that.

I found and fixed the intake boot - did compression/leakdown/lash check - all withing specs. After the water incident, I did the same checks - no problems. When he overheated it, we found the leak (caused from an earlier crash), replaced the hose and rode for the rest of the weekend.

And this is that stupid 5-titanium valved motor.
He can't fricking kill it - and IMHO, he's tried pretty fawking hard to.

Just my experience with two of the bikes you mentioned.
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