Hey! I have the AC 400 fis manual tran, it makes a knock while it is idling. The noise seems to be from the bottom of the engine, or there about, not sure what it is. Also I have noticed a chattering type of noise while riding, when I hit the throttle to speed up. I only notice this until the rpm's of the engine are reved a bit, sorry no tac to get actual rpm's.

Can anyone tell me what this is and should I worry about it.

 

Have you gotten your valves adjusted?? Is it a knock or a ticking?

 

It is not the ticking of the valve tappets on top, but a knocking noise while it is idling. Also any idea what the chattering is?

 

I also have an 0/4 400 mannual with a thousand miles on it now... have had the same noise from day one...( sounds like the connecting rod is going to let go) had it to the dealer twice for service , told them about the noise, they say it is normal sound for Cats. But did not tell me what the noise was. After searching a.c. forums I found that this sound is common and normal for most cats which can be spark knock , and you can`t ajust the timing. Also they have a decompression valve that can raddle and make the same sound. The 500`s also have this issue, so i think your cat is normal. doesn`t hurt to get it checked by the dealer. How many miles on your quad??

 

I have the similar noise on my 03 400I manual trans. It was much worse when it was newer than it is now. I also noticed it more after I adjusted the valves around 1000 mile mark. I now have approximately 1600miles and don't notice it any more unless I am towing something heavy. Its still there I just don't notice it.

I origianally thought it might be my clutch slipping when it was new and called the dealer. They said it was the compression valve and its normal. I have also heard that they have quited it down on newer models but I am not 100% sure on that.

If your machine is still under warranty I would take it to the dealer and have them look at it. Which would not cost you much but the time and would give you a liitle piece of mind about the noise.

SJ

 

Thanks for the imput doober ArcticBrat and swampyjunior.

Yes it still has 1¼ years on the warranty, with about 900 KM's. I was beginning to think I bought a lemon glad to see that this sound is common and normal for most cats. I'll
still bring it to the dealer and see if they can shine some light on the noise. It's do for an oil change and going over anyway.
If they have any additional info on the noise I'll post it where everyone can see it.

AC never enough mud!!

 

Wish you luck with your bike MudMerc... you know cat's have 9 life's........ just don't get to close to a grizzly...lol[img]i/expressions/face-icon-small-shocked.gif[/img]

 

I had a knocking sound in my '01 AC 400 manual. I could really hear it when I unscrewed the oil fill cap. A biker buddy told me to put Risolone in the oil. That helped...for awhile. I mentioned it to the dealer when I took the machine in for routine maintenance. He increased the idle speed and put in synthetic oil. No more knocking.