Is it worth it

[pastfast125]

Is it worth it for me to adjust my valves on my z400? I've had it since a lil before I joined the site and never adjusted them, but I don't have any ticking or any weird noises, should I just let sleeping dogs lay? I just figure while I already have my plastics and gas tank off it would be a good time to do it, but if I'm just gonna end up making it worse then I'd rather leave em alone.

[Iliketogofast]

If you have an idea of what ou would be doing (and know the clearances, of course) I would suggest that you go ahead and do it.

If you are afraid that you will screw it up, I would fiund somebody who knows how to do it or not do it at all.

[pastfast125]

I've never done it before, but that's what this site is for:D If theres not really any improvement or anything in it though, I'd rather just not do it.

Oh and PS: I don't take my stuff for anybody else to work on em;)

[wilkin250r]

Originally posted by pastfast125
I've never done it before,

Oh and PS: I don't take my stuff for anybody else to work on em;)

These two statements are entirely contradictory.

You don't let anybody else work on your stuff, yet you're not willing to do something so simple as a valve adjustment?

Valve adjustments are really easy. You take the covers off, check the clearance on the valves. If they need to be adjusted, you loosen one locknut, twist the adjustment, and tighten the locknut again.

If you're afraid of screwing it up, then maybe you SHOULD let somebody else work on it.

[400exrider707]

Originally posted by wilkin250r
These two statements are entirely contradictory.

You don't let anybody else work on your stuff, yet you're not willing to do something so simple as a valve adjustment?

Valve adjustments are really easy. You take the covers off, check the clearance on the valves. If they need to be adjusted, you loosen one locknut, twist the adjustment, and tighten the locknut again.

If you're afraid of screwing it up, then maybe you SHOULD let somebody else work on it.

that isn't correct on the z400, its a shim and bucket style.

Check the valves and if they're off then you need to get some shims, I prefer the Hotcam shim kit.

[wilkin250r]

Oh, right. Missed the Z400 part, DOHC.

Regardless, the premis still stands.

Adjusting your valves isn't about "improvement". You're not going to see any power increase. What it does is allow your valves to last longer, as well as your cam, and all components associated with your valvetrain.

Just because it "seems okay" doesn't mean it is. By the time you actually hear a noise, it's probably too late. As the saying goes, an ounce of prevention is worth a pound of cure.


Dead space can create a "hammer" effect. If your valves are in constant contact with your cam, you cam pushes and your valves open. If you have improper clearance in there, it probably isn't too small, it will be too large. That means there is dead airspace between your cam and valves. When the cam pushes, it first must close the gap of this dead airspace, and it "hits" the valves. This happens thousands of times a minute, and over time, can deform the metal, possibly creating a flatspot on the cam.

[pastfast125]

OK, do the hotshims kits have instructions or is it pretty simple to figure out? I've never had a 4 stroke motor apart at all, cept for a lawnmower;) Oh yea, how much do they cost? oh, and for checking clearances I need a feeler quage don't I? I think I have one, it's a keychain type thing, and it has a bunch of flat peices of metel, all labeled with different sizes. So I use those, and check to make sure it's at the right clearance? Oh, and not sure where my manual is, can anybody tell me what the clearances are supposed to be on an 05 z400?

[pastfast125]

Originally posted by wilkin250r
Oh, right. Missed the Z400 part, DOHC.

Regardless, the premis still stands.

Adjusting your valves isn't about "improvement". You're not going to see any power increase. What it does is allow your valves to last longer, as well as your cam, and all components associated with your valvetrain.

Dead space can create a "hammer" effect. If your valves are in constant contact with your cam, you cam pushes and your valves open. If you have improper clearance in there, it probably isn't too small, it will be too large. That means there is dead airspace between your cam and valves. When the cam pushes, it first must close the gap of this dead airspace, and it "hits" the valves. This happens thousands of times a minute, and over time, can deform the metal, possibly creating a flatspot on the cam.

Ok thank you, that's the kinda answer I was lookin for.

[underpowered]

on a Z400, you will not likely hear it "tick" unless it is your camchain. the Z ahs a chronic problem of sucking the valves. meaning that it does not create a deadspace, but rather eliminate what little was there. teh valves a very soft and actaully defore and get pulled through the head. You may not have any clearance and is why there is no "tick" If it s getting hard to start, i would definitally adjust them, even if it isnt, i would anyway just to be safe. instaead of going with larger shims, you may have to put in smaller ones or even have a profesional grind down the stock ones. Grinding must be done by a machinist or a profesional in order to keep it true, an alngles shim can cause all kinds of problems.

[pastfast125]

Mine is harder to start then my friends. but I figured it might have somethin to do with I'm probably a little lean, but I dunno.
So for shims what should I do? buy a shim kit or what?

[400exrider707]

Originally posted by pastfast125
Mine is harder to start then my friends. but I figured it might have somethin to do with I'm probably a little lean, but I dunno.
So for shims what should I do? buy a shim kit or what?

Its up to you. I believe individual shims were somewhere in the neighborhood of $6 a piece where you can get the entire hotcam kit for about $70 and it comes with a lifetime supply of shims in there. Just easier to do. You will want to check them at least since your down this far. The shim and bucket style is much less maintenance than the older style of tappets. (ie the 400ex). Check them and you'll probably find that they're still within spec. Also check the tightness of the chain as the Z's are notorious for stretching them.


Also Wilkin if his specs are out like you said and there is that dead space in there, then technically speaking the valves will not be opening as far as they should correct? Thus losing power? I know its probably not enough to even notice and is rather negligible, but the the theory makes sense does it not? Thanks.

[wilkin250r]

Originally posted by 400exrider707
Also Wilkin if his specs are out like you said and there is that dead space in there, then technically speaking the valves will not be opening as far as they should correct? Thus losing power? I know its probably not enough to even notice and is rather negligible, but the the theory makes sense does it not? Thanks.

Indeed, but it's even worse than not opening as far. Think about it, not only would the valves be opening less, but you would also be losing duration. They valves would be opening later, and closing sooner. This loss of duration would actually have much more impact than the loss of lift.

[400exrider707]

Originally posted by wilkin250r
Indeed, but it's even worse than not opening as far. Think about it, not only would the valves be opening less, but you would also be losing duration. They valves would be opening later, and closing sooner. This loss of duration would actually have much more impact than the loss of lift.

yeah not a good situation, but its probably not as bad as the valves not closing fully.

[wilkin250r]

Originally posted by 400exrider707
yeah not a good situation, but its probably not as bad as the valves not closing fully.

Indeed, this is going to be the worst possible scenario.

I didn't know that the z400 is known for sucking the valves. If that's true, then it's entirely possible that the valves won't close all the way, in which case you'd be REALLY down on power, if you could get it to run at all.

[underpowered]

Originally posted by wilkin250r
I didn't know that the z400 is known for sucking the valves. If that's true, then it's entirely possible that the valves won't close all the way, in which case you'd be REALLY down on power, if you could get it to run at all.

Yup, at the shop where i work, we have replaced valves in atleast 6 i know of since i have been working there in less than a year. I have yet to see one pull all the way through on a z, but have seen it on a CRF250 and it aint pretty. The Intake valves are soft and round off, causing it to be pulled farther up into the head. it is worse if you ride in very high RPM's, around the rev limiter

[pastfast125]

OK, so what exactly is the process for adjusting them? How do I check the clearences? like where at? I know I gotta pull the head/cover peice off, and then how exactly do I do it? thanks.