light ticking noise in a 99 yz400

My bike (99 yz400) has always had a ticking noise and didn't think much of it until I rode an 04 WR450 that didn't make the same noise. It doesn't make the noise when first started, but it does as it warms up.

Here's what I know:

1) The valves are in spec, I did them myself.

2) The cam chain and tensioner are stock, I haven't replaced them yet. I'm going to soon.

3) The motor is all stock, never been taken apart. It doesn't have a ton of miles on it, I'd guess I probably put on less than 20 hours a year.

4) I have a skid plate, but I don't think it's the skid plate amplifying the noise.

5) The noise is present at idle, in gear, going or stopped.

6) I thought it was an exhaust leak, but sealing the header and junction to the muffler didn't help.

Anybody have the same light ticking noise and actually solved the problem?


If it's a half-speed noise (once every other revolution, like an exhaust leak would be), it's probably valve train related. That can be anything from too much clearance to a cam that has a bit of wear on the opening ramp to a wear ledge on a lifter bore, etc. It can even be the decomp lever in the head tapping the exhaust lifter if there's insufficient clearance.

Full speed noises (once per rev) could be something like a cracked water pump gear, a loose drive gear, etc.

Good point on the frequency of the tick. Any suggestions on determining if it's once a revolution or every other revolution? Actually, I just installed a tach, I can count the number of ticks per minute and see if it matches the rpm of the tack at idle.

You've got me thinking that maybe I've got one of the valves looser than it should be. I adjusted them to be at the looser end of the spec. I know you are going to ask me if it ticked before I adjusted the valves, but I don't remember. It's been a while since I adjusted them and I don't recall. All I know is it ticked after I adjusted them, and it may or may not have ticked before the adjustment.

If it's with the decompression lever, shouldn't I feel the pulse in the lever while the bike is running?

Thanks for your input!

Yes, you usually would be able to feel the decomp lever if that were it, particularly if you touch the end of the shaft at the head. And that raises a tip about determining the frequency (half speed vs. full). Taking the slack out of the decomp lever will produce a detectable pulse in the cable at half engine speed (each time the valve closes). This is the cyclic speed of the engine, and the cyclic events (valve action, firing strokes, exhaust pulses) all occur at that rythym. Full speed is double that.

Here's a couple things to consider:

Is it most pronounced at idle, disappearing at speed, and louder in the air box? Could be a slide ticking in the carb (more or less normal)

Is it load sensitive, making more noise under light acceleration than decel? Could be piston slap.

Does a load make it go away, and taking the load off at speed make it "double up" (change from half speed to full or even double speed)? could be a rod bearing or a piston pin.

But before you get off on a hunt, go back and check the valves again, just for fun.

i have a similar problem, and it seems full speed, and it rises as the revs rise too.

it seems to come from the valve area, but i checked the valves (several times) and they are all ok (i had just put in new valves, shims, etc).

the sound is not from the water pump area, and also not from the clutch area, it's above that..what else could be wrong in the top end?

mine has the same sound. i always thought it was normal because a friend had a blaster that was new and it made the same noise. shop told him that without water jackets you can actually hear the ignition of fuel in the cylander? of course i know ours has water jackets but i just considered maybe 1: higher compression than a blaster 2: poor jetting (still workin on that one) or 3: low octane gas??

I'm planning on doing a cam chain, tensioner, piston, and rings rebuild. I'll let you guys know what I find. I'm thinking it's:

1) cam tensioner and timing chain, it's all original

2) valve with too much clearance

3) exhaust leak

Either way, I'll do a post rebuild writ up to let you guys know if I found the problem. I think it's a good idea to let people know what you find or didn't find for future reference for people doing searches.

I'm guessin that its the cam chain or a loose valve, causing that bucket to have a little bit of play and slightly bounce in there until the cam hits it down.

i've got new valves and valve seats, tried shimming ex: 30 30 in: 20 20 20, was noisy, then tried exhaust 25 25 intake 15 15 15, still noisy.. actually seemed more noisy!! now i'm going to put it back to 30 30 20 20 20 (this is clearance, in 0.XX milimeters).

the piston seems ok, and the noise seems to come from the valves... the chain seems ok, no slack (with the tensioner on).. i'm kind of loosing hope..

my noise is pretty identifiable to the valve zone, and it goes on at idle, cold, warm, running... it seems a 1x noise, i tried that with the decomp lever method, and the noise seems to be 2x the decomp pulls..

The one thing I forgot the mention is when the bike first starts up, it doesn't tick. It's after it's warmed up for about a minute or so. It seems to be related to heat (expansion of materials, etc.).

oh, mine starts right up doing the noise! so it's not related...

i tried moving the cams 1 tooth to see if it would stop, maybe timing related.., but it didn't..

i'm starting to thing this is a worse problem, like the rod or the piston pin or something.. and this time i tried lowering the idle so that i could hear better if the noise was 1/2x or 1x..and it seemed 1/2 (same as decomp)...i'm confused

anyway, are your valves really up to spec? try changing the cam chain, it's not that expensive

mine is from the time its started on. it is a full time noise. if it were a car i would guess a lifter was stuck.

so i went to another yamaha dealer, and he said it probably was the rod or the crankshaft or something there.. :ride: what should i do..this sucks..

oh and he started ranting right away, that YZFs were only for racing.. that they are torn apart after every race (lol.. yeah, it's like a 2 stroke but with 2x the strokes..)..

he talked about my bike as it were the most unreliable bike ever.. lol..

"oh yeah rod problems are common!".. lol..

sounds to me like he is trying to stick it to ya. if rod problems ask him for a copy of the technical service bulliten that says that. anytime there is a common problem with a certain model the manufacturer sends the dealers a T.S.B. technical service bulliten

yeah i though so to, when he starting badmouthin i say ok thanks bye and left..

i think it may be the CB key, and i'm going to try and check that tomorrow.. i'm searching the forum for a detailed howto eheh:)

it's sad to see that they don't even have the slightest idea of what the common problems are.. where did all the good mechanics go?

Did you change types of oil used? There is some ticking to be heard in these engines when adjusting the valves. Your dealer is wanting to make some major money off you. I would change the cam chain and adjust the valves per spec, put quality oil in and try that before going further. Just my .02 Also chech your de-comp mechanism for proper operation. When mine would stick a little, much tapping!!!

thanks, i will try changing the chain and readjusting the valves, i'm using castol gps 10w40 so i guess the oil is not the prob!

will also check the decomp, but it has like 1/2cm of slack so i guess it's not that either

take off your cylinder head cover and check on you cam chain to see if its tight, if its loose it will slap and that is probabally the sound you are hearing.

it's tight when the tensioner is on...but i don't know if it's as tight as it should be! but i think it's tight enough not to make noise, either way i have put up more than 40hours on it so i will put a new one in asap

I went out and listened to my bike again and I swear it sounds like an exhaust leak. At first it doesn't make any ticking noise, then it get's louder, softer, then louder again, until it is constant. It makes that same pitch that a leaky header makes on a small block chevy. On my bike, I have to loosen and twist the header out of the way to change the oil filter. Maybe the header pipe flange is damaged after years of doing that. I've replace the exhaust gasket before, but it doesn't make a difference.

I'm still going to do the top end and timing chain when I get around to it. I'll post what I find.

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