Knockin 426

I have a 2000 426 that knocks at idle and quits as you rev the engine. I have checked the valves and they are fine. Is this normal for this engine? It runs fine but the knock has me worried. Any feed back will be appreciated.

To me when you talk about knocking in the motor it is a gas thing, what kind of gas do you use? Like in Cali it is 91 now, before it was 92 octane, so I am using an octane booster. I know the manual says to use 95 octane. I think I may use octane booster in my streetbike because ever since octane rating has gone down, it is running like crap as well.

does the noise change when you pull the clutch in? where does the noise sound like its comming and from and what does it sound like take a good listen

Originally posted by KANSAS:

I have a 2000 426 that knocks at idle and quits as you rev the engine. I have checked the valves and they are fine. Is this normal for this engine? It runs fine but the knock has me worried. Any feed back will be appreciated.


I've heard that the Canadian models tend to start this noise after about a year of normal noise and then they blow up after a few rides. Be Careful and get it to the dealer! Just kidding, this is Rob, it's about time you found this website. Hopefully someone will be able to help you. Send me an email at


PS I will be coming out to Utah soon so we can attack Cherry Creek some more.

My 00' 426 has similar if not the same symptoms. Haven't got it to the dealer yet. When I was in Colorado I had Larry Roseler listen to it (really) and he recomended that I not ride it on the CO. 500, so I rode a backup bike instead. He also said to send the motor to him and he would fix her up asap. How long has your motor been making the knocking noise? I seem to think its due to low oil pressure at idle because as soon as you rev it up a bit the knocking goes away. My 2 cents and some change.

Interesting, Huge

I ride with Kansas and think he did a crappy job at explaining the noise(no offense Kansas). It is a rattle/knock coming from the left(I think) side of the engine. It does it at low RPMs like he said, in gear or out of gear, clutch in or clutch out. I am pretty certain it is not in the transmision but rather in the head or cylinder. This is just my impression of the noise. could it have anything to do with the timing chain? Any ideas? Bt the way, that was a good one Roberto!

I'm thinking it is the natural mechanical noise the bike develops after some time. My friends 426 sounds like that at idle, and im sure many others do. Huskys and some KTM's make the same kind of noise. Guessing these engines were not built to run quiet as possible, because that wouldn't be a major consideration for the bikes intended purpose. Just my uneducated opinion.

Some have had the key in the crank drive gear (counterbalancer drive gear?) develop slop and make a knocking noise on their '00.

Yamaha got rid of the key and went to a spline in '01.

This problem hasn't surfaced on my '00 (yet).


Holeshot's Page

[This message has been edited by holeshot (edited September 14, 2001).]

I would look 1st at the keyway on the counterbalancer drive. Many threads about this problem some time back. My '00 developed a knock but the symptoms persisted throughout the rpm range (you could hear the knock better at idle). Upon inspection of the counterbalancer drive gear, there was noticable slop. A new key, some red loctite, and a lot of torque to the nut and the problem hasn't returned in over a year.

Bingo! These two guys got it. A search for CB gear will fill in the details.

SWEEETT, I hope thats all it is. How hard is it to replace the key. I will look at the archives maybe my answer is there.

thanks, huge

I just finished a CB key job on my bike about an hour ago.

It was making all kinds of funny noises and you cant really tell where they are comming from, sometimes it goes away when it warms up, sometimes it gets worse when it gets hot.

I was getting pretty worried about it last week so I tore into it tonite before going to the track tomorrow. Took about maybe two hours as I took my time, not a hard job. When i got the side cover off, I could feel the slack in the CB drive gear. Not a lot but it was there. The key had been wobbling and was grooved on the sides. Didnt have a spare key but it is square so I just cleaned it up and turned it 90 degrees. Fired it back up and it not a peep from the engine other than the exaust! Yipee!

Fortunatly I consulted the manual to see what direction one of the gears went on becuase if I hadnt, I would not have realized that the CB gears must be aligned to each other by a dot mark.

I remember someone saying they made keys out of some hardened bar stock. Who was that and how has it worked out?

Dave S

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