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.
Help with 2000 yz426Yamaha YZ426F 2000
Posted March 11, 2016 - 11:38 AM
Posted March 11, 2016 - 12:06 PM
Posted March 11, 2016 - 12:39 PM
Posted March 11, 2016 - 01:03 PM
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?
Posted March 11, 2016 - 01:04 PM
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.
Posted March 11, 2016 - 01:44 PM
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.
Posted March 12, 2016 - 03:01 PM
Posted March 12, 2016 - 05:05 PM
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.
Posted March 12, 2016 - 06:29 PM
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?
Posted March 12, 2016 - 06:38 PM
Posted March 12, 2016 - 06:44 PM
avoid holding the same rpms for an extebded length of time.
Really. Why is that?
Posted March 12, 2016 - 07:29 PM
Do you disagree?
Posted March 13, 2016 - 06:52 AM
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.
Posted March 13, 2016 - 11:02 AM