Question about knocking / tapping sound in engine.

[perry]

Hi,
Just broke in my new quad and changed the oil and plug and put my WB eSeries on Friday. I ran it for about three hours today, and noticed that there is a knocking tapping sound coming from the engine. Its not a loud knock or tap, just able to hear it when it is idling.

Is this normal for a 400ex? Does anyone else have a kind of knocking sound or anything?

My quad is stock, save the new pipe. I didnt rejet or play with the mixture.

I run premium gas.

I have the origional disks in the pipe (8) and the quad seems to be running great.

Any idea where this knocking tapping is coming from?

Can anyone suggest a specific thread to help?

Thanks,
Mike

[AtvMxRider]

Is it a knock or a tap? There is a difference. A tap is not rweally that big a deal but a knock is a problem.

[Guy400]

Every 400EX I've ever been around has had some sort of tapping coming from the top end of the engine somewhere.

[Glamis400ex]

if it's tapping and it's a new quad also, it's probably the valves needing an adjustment.

Glamis

[sparks400]

tapping might be rockers, knocking could be that ur spark plug is to long, or piston slap. i dought its piston slap, but i just geussing with the spark plug. pull it and look at it.

[pnut420]

Most likely after putting that pipe on and not rejetting, you are running like ****. It will make a fluttery sound that sounds like it is knocking. Our bikes are known to have a little knock in the top end.

Just make sure you stay up on your air filter, oil, and plug to keep the warranty in tact. The 04's had a problem with the engines seizing, weither it was a rumor or not just be careful to keep up on maintance and they will cover it.

My buddy got dirt in his and Honda was like :rolleyes: , not covered!

[perry]

OK, first there is a definate tapping sound. When the engine warms up, there is a click, and then the tapping stops.

What is that all about?

What is left is sort of a rattle/whining sound, and then in that sound there is a sort of a knock, but a very light one.

It reminds me of a diesel engine kind of.

This could just be normal engine sounds, as I dont really remember what it sounded like before I put the pipe on. Plus, everytime my bike does something weird, I analize it. Its a pretty expensive toy, and I want to make sure that nothing goes wrong with it.

The sound I am worried about happens (when idling) about two or three times per second, and I really cant hear it unless I am down by the engine.

I dont really want to drag it into a dealer. Are there some things I could do to check it out myself?

Thanks,
Mike

[Guy400]

First off, get it jetted correctly. Secondly, check the valve lash if you've never done it (assuming you've got more than 20 hours on it). Third, when you changed the oil did you make sure and fill it with the recommended amount? Lastly, the 400EX top end makes a little noise--it's nothing to be overly worried about.

[pnut420]

Originally posted by Guy400
First off, get it jetted correctly. Secondly, check the valve lash if you've never done it (assuming you've got more than 20 hours on it). Third, when you changed the oil did you make sure and fill it with the recommended amount? Lastly, the 400EX top end makes a little noise--it's nothing to be overly worried about.

Yah most likely it is just his jetting. Its crazy how bad your engine can sound when the jetting is off. Rejet and go from there. Step by step.

Also that tapping sound at idle is usually there at idle and then goes away.

[Glamis400ex]

If it sounds like a diesel...you're in trouble...lol:blah:

Glamis

[remlapr]

This is what I suggest, get a K & N with outwear, put 12 disk in it -then rejet your carb until it is running good and the plug color looks good. For the plug color, as someone else on here said "think paper bag". I suggest the filter and 12 disk before messing with the jetting because that is really the best way to get the most out of your e-series. Then if you still think you have noise coming from the head just take it down to the dealer and warm it up and let them listed to it, I bet they will tell you it's just normal, 400ex's are just noisy, you can then put your mind to rest and concentrate on enjoying your quad!

[perry]

Checked my plug and it was white/frosted like. This means I am running lean, right?

Will this make my engine noisy?

Is there a good thread that explains rejetting? Or a website?

Thanks,
Mike

[adeptex]

sounds like your decompressor is sticking.
speed up your idle a little and see if that cures it. the decompressor will engage at low rpm.

[hondarider2006]

This thread helped me a bunch when I didn't know how to re-jet. Just look at the pictures, its real easy to do. Just follow it step-by-step and you should be fine. PM me if you need some help.

http://www.exriders.com/vbb/showthread.php?s=&threadid=19832

[perry]

Thanks Alot!

remember carb screws are soft and real easy to strip. Make sure u use the right screwdriver or bit when doing the work.