Help with 2000 yz426

Until the cams are installed, there is no compression stroke, exhaust stroke, or any other kind.  The cams are what makes one upstroke compression and not the other.  Since the engine fires every time around, it makes no difference "which TDC" you use.  They're all the same. 

I have the tensioner out now. Should both cams spin freely? When I torque down the intake cam it does not want to spin freely with the free play in the chain.

Yes they should spin freely. Pull the cam caps off and make sure the little circlip is seated properly and the cam is seated properly.

Yeah, the cam wasn't all the way pushed back. Got it back together, starts easy with the choke (sounds a little off). But it Will not run correctly at all when I push the choke in. I Can keep it alive for awhile but it sounds awful. I've never done the valve chims or even checked them, but it seamed like the .15 was pretty tight to get under my intake side but it did go under. How often do you usually have to re chim your valve?

Yeah, the cam wasn't all the way pushed back. Got it back together, starts easy with the choke (sounds a little off). But it Will not run correctly at all when I push the choke in. I Can keep it alive for awhile but it sounds awful. I've never done the valve chims or even checked them, but it seamed like the .15 was pretty tight to get under my intake side but it did go under. How often do you usually have to re chim your valve?

You should check them fairly frequently. As for shimming them, that's tough to say. Some may need the be shimmed more often than others. If the start to wear pretty quick, it's time to replace the valves.

If it still won't run without choke, you really need to get into the carb again. Clean it really well. Make sure the hot start plunger isn't sticking, make sure the pilot jet is clean so you can see light through it clearly. Once you do that, you'll need to get the pilot screw and idle set properly. It sounds like your pilot screw is probably too far in. How many turns out is it?

first off its shim*. and they should be checked fairly often. Re shimmed whenever necessary. Ive seen guys go 100+ hrs within factory spec, ive seen people with less be way off from factory spec. I would replace your cam chain & tensioner and adjust your valves and go from there. 

If you have tried cleaning the pilot jet by the methods I described in the link I posted, you should probably next try replacing it with a new one.  It's either that, or a partially blocked pilot passage in the carb, or a problem with the slide plate or slide plate seal.  Possibly a major air leak.  Be sure the hot start does not leak air when closed.

That yz450fx is sounding pretty good right about now.

I've had the carb off twice today and no luck. I have a carb from an 04 yz450f laying around. I know I need the hot start assembly and throttle tubes. But should I switch it? Posts on tt say 05 450 carbs work best. But should I use my 04 carb anyway?

It would definitely be an improvement.  Open it up and check the jets first.  Your throttle assembly will work, but you need the 450 cables.  

Seams to be running with the 450 carb, it's storming here so I can't run it anywhere but the garage. Thanks for the help. I was planning on putting that carb on eventually anyway..

The clymer manual is kind of brief on the break in time. How long should I be easy on it? I don't really have a good place to break it in. Is it not ok to ride it in sand right away?

Ride as normal, just avoid holding the same rpms for an extebded length of time.

 avoid holding the same rpms for an extebded length of time.

 

Really.  Why is that?

Matter of opinion mainly...and numerous manufacturer service manuals that provide break-in guidelines. Also happens to be what was taught to me many years ago when I was received my yamaha and harley davidson service tech certification. But there are as many opinions on this subject as those of "what oil do I use?"

Do you disagree?

Yup. No reason whatsoever to avoid holding a steady RPM under a normal load.  Except for two-strokes.

 

Break in is overblown any more, anyway.  It should be over with in under 20 minutes as far as the rings go.  Essentially, just run the bike in a normal manner up to 85-90% of its capacity and avoid extremes of lugging it down or revving it out.  And don't "baby" it.

What the heck!!!! I went out started the bike with the choke on, started first kick. I let it run, went to open the garage and it slowed down and died. Can't get it started back up. The spark plug (that is brand new) seams wet, and looked like it had a piece of dirt on it. Put it back in and still no start. What is going on!

ImageUploadedByThumper Talk1457935136.748638.jpg

She lives

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