Return of my 2003 YZ450

Haven't been on here in awhile, but i recently got my bike, 2003 YZ450F, back after a WORLD of trouble. The original problem was that the bike had pretty much stopped running, I figured it was a clogged-carb or a valve adjustment issue. Tried to clean the carb myself, seemed to make it worse. Took it to a small shop, got the bike back, wouldn't start at all unless it was warm outside, and even then it was a pain to start. When I'd get it running, it had no power, and stalled when I'd stop. The shop said the carb was cleaned and valves adjusted, and that "it's just a COLD-NATURED bike...." BULL! I took it to a different, more experienced guy, a racer....turns out the "shop" left the half-moon shaped cir-clip off of the exhaust cam, allowing the cam to move back and forth laterally, causing the bike to jump out of time (I think). Anyways, got it back and it is ROCKIN, to say the least. Running better than ever, starts within 2 kicks, idles low and smooth, has monsterous power and literally "thumps" when it runs. I was really lucky that it didn't cause any significant damage to the internals. Point of the story is if you're unable to do the work yourself, find someone who has had DIRECT experience with your type of engine. From what I've heard, this cir-clip is a really easy piece to lose, as I'm sure a lot of small pieces are.

Haven't been on here in awhile, but i recently got my bike, 2003 YZ450F, back after a WORLD of trouble. The original problem was that the bike had pretty much stopped running, I figured it was a clogged-carb or a valve adjustment issue. Tried to clean the carb myself, seemed to make it worse. Took it to a small shop, got the bike back, wouldn't start at all unless it was warm outside, and even then it was a pain to start. When I'd get it running, it had no power, and stalled when I'd stop. The shop said the carb was cleaned and valves adjusted, and that "it's just a COLD-NATURED bike...." BULL! I took it to a different, more experienced guy, a racer....turns out the "shop" left the half-moon shaped cir-clip off of the exhaust cam, allowing the cam to move back and forth laterally, causing the bike to jump out of time (I think). Anyways, got it back and it is ROCKIN, to say the least. Running better than ever, starts within 2 kicks, idles low and smooth, has monsterous power and literally "thumps" when it runs. I was really lucky that it didn't cause any significant damage to the internals. Point of the story is if you're unable to do the work yourself, find someone who has had DIRECT experience with your type of engine. From what I've heard, this cir-clip is a really easy piece to lose, as I'm sure a lot of small pieces are.

wow that sucks, good to hear its running. I hear you though. i am so meticulous about how my bike is worked on. I do everything by the book and don't "rigg" anything. Everything on my bike is torqued with snap on wrenches and everything that needs to be lock tighted or anti seized is. If something seems sketchy, I wont do it. And for sure I would not take my bike to a shop no matter what happens.

As experienced as I am, I really don't like to take on much of anything I haven't worked on before unless I have a manual handy. Yes, I can figure out just about anything, but there's always some little critical detail that can be overlooked unless the book is handy, like why I have 4 O-rings and 3 places to put them? Just saves time and avoids errors. Shops or techs who think they don't need the reference materials are kidding themselves very seriously at times.

I hate taking anything in to get worked on too. I didn't have time to winterize my boat last season so I took it to a local shop... last weekend I put the boat in the water for the first time this year and kind of held my breath hoping it would start... it fired right up and ran fine all weekend, but I still have a hard time trusting others to do the job right.

I could have been something as simple as you putting the black plate on the side of the slide upsidedown after cleaning the carb. and the 2nd guy you took it to spotted it right away

The valves on the Yamaha's really don't need adjusting They will go for a long long time before they tighten up NOT like a hOnDa:bonk: they take a dump in a year :banghead:

For the clip that centers the cam bearing if it was missing it won't make the chain jump a tooth If it did

the chain came off

If that happend the valves would hit the head Not cheap fiX

That's my 2 cents worth :banghead:

I'm glad you say that the absence of the c-clip most likely wouldn't cause the chain to jump off the cam, because it keeps me awake at night thinking of the amount of damage my bike could've sustained had it actually jumped-time. I'm still curious as to why the bike would be running so weak, and be almost impossible to start, unless the timing was off. When I say running weak, my YZ450 felt like a scooter on valium... I've recently seen a motor off of a YZF450 Quad torn down (the top ends are apparently the same) and it actually wasn't as complicated as I thought it'd be.

I'm glad you say that the absence of the c-clip most likely wouldn't cause the chain to jump off the cam, because it keeps me awake at night thinking of the amount of damage my bike could've sustained had it actually jumped-time. I'm still curious as to why the bike would be running so weak, and be almost impossible to start, unless the timing was off. When I say running weak, my YZ450 felt like a scooter on valium... I've recently seen a motor off of a YZF450 Quad torn down (the top ends are apparently the same) and it actually wasn't as complicated as I thought it'd be.

why dont u just ask the guys that fixed your bike what they did??

I'm definitely gonna stop by and talk to them about it, and I'll ask them exactly what they did. I know they have a copy of the work order, but it's been 5 months since they had the bike in there. Nice guys, but maybe not a lot of experience with race bikes..

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