I have a 2004 z400, with vibrations coming out of the engine. It seems to start at about half throttle to full throttle. Engine runs fast and fine, just vibrates. I had originally thought it was skid plates or nerf bars, so I started removing things. It turns out they were rattling, but because of the engine vibrating and transmittin vibrations everywhere.

So, anyone know what would cause engine vibes in this way? I checked the valves about a year ago, and I would say there is less than 20 hours since checking. I have found lots of threads regarding timing chains stretching, so I am guessing that is probably the problem and will be pulling the machine apart.

Anything else I should be looking for?

Tom

Has it always done this? i dont think you can get a single cylinder engine to be perfectly smooth tho.

The timing chain stretching is more of an audible ticking sound.... I don't believe that it really causes any vibrations; At least not as noticeable as you make it sound. Are your crank bearings possibly getting worn out? I am thinking that something like that would be more of a likely candidate for the vibrations you are describing.

This is my second z400. I had a 2003 that I sold to buy this 2004 about a year or so ago. My 2003 didn't make this noise.

The 2004 vibrated a little when I got it. I always just thought it was a loose skid plate. I loaned my quad to some friends for a few weekend trips, and now the noise is much worse.

I actually had it up for sale, I haven't ridden it myself for over 6 months, so I didin't know the vibration got so loud. I met the guy at my friend's house where the quad was and he took it for a ride. I was surprised myself at how loud the vibrations were. Obviously, he didn't want to buy it, so now I am stuck. I just want to fix this thing properly and get it sold. It runs and rides great, just has this noise that doesn't sound right. I am not a person who likes to dump used items on people and would try and sell it like this unless somebody was fine with the noise. Right now, I don't think I can sell it.

One other thing we noticed is that when it is pulled on trailer, gas leaks into the oil as the quad bounces around. It was being ridden with the oil level very high - full of gas. We changed the oil out and now disconnect the hose whenever transporting. Two more questions:

1 - I am assuming I have to replace the petcock...it is not normal for it to leak, right?

2 - Could runnning the quad for a few hours on overfilled, gasoline thinned out out have damaged the motor?

Tom

ok, wait a minute. you are using the teams "noise" and "vibration" together. Now my engine "vibrates", but does not make noise. so which is it? to me the two are a separate term. Does it do both? what kind of noise is it? can you post a vid so we can hear it?

Sorry, I was using them both together. It is a vibration as far as I can tell. I will try and get a video up later today.

Thanks for the replies and offereing to give it a listen! I really appreciate it.

Tom

I had a similar problem, so I took it to the dealer, and they placed a silicone type gasket around the skid plate and it solved my problem.

Here is a video that shows the noise. Of course Youtube reduced the quality of the video so it is hard to tell.

Give it a listen and please let me know of any thoughts. My friend thinks it is the timing chain...

http://www.youtube.com/watch?v=yNxYg35kzjY

Honestly I cant tell, the sound is not very clear. Do this: take the 12mm bolt out of the tensioner, be careful its under spring tension...its gonna want to pop out. After you take it out, remove the tensioner. Then very easily and carefully pull on the plunger one click at a time. Count the clicks. report back.

Depends on what kind of vribration.
Could be an unbalanced motor, crank problem.. (hopefully not, but mine was)

ever had the fly wheel off? maybe that thing came loose. ive heard of it happening.