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Primary Gear Noise and Solution

2 posts in this topic

After four days of riding in Moab over thanksgiving, my bike has begun to make the "Primary Gear" noise. It sounds exactly like a loose cam chain coming from low on the right side of the motor. I'm assuming it's the same noise as the others were having. (2000 YZ426)

So, the questions are:

1.) How difficult was the fix? (Scale from 1-10, 10 being hardest)

2.) Did you have to remove the clutch basket?

3.) Did you have to remove the entire right side cover to inlcude water pump and filter or just the clutch cover?

4.) How long did it take?

5.) Should this be a warranty item?

6.) Do you have to replace any gaskets?

7.) Should you replace any parts while you are already in there?

You see where I'm going? I have limited time so if it's pretty easy and does not require the clutch basket to come off I'll take it on myself. If it's pretty much a bitch, I'll have my buddy at the local shop do it. In my opinion it should be a warranty item though so the shop should do it for free. Please be specific as possible in your response.

Thanks,

Roostn in Denver

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Roostn,

Assuming the noise is related to the clutch, main gear, and CB drive gear:

1) 3 (but I have an air impact for basket, main gear).

2) Yes

3) Yes

4) About an hour

5) I don’t think so but it probably depends on your dealer

6) I didn’t

7) Yes. Main Gear retaining nut lock washer, CB drive gear if worn (check keyway), straight key if worn any at all (this is what allows the play and subsequent noise). Unless you already have one, IMO a Hinson is a worthwhile mod to do while you’re at it.

Let me add a few things. It isn’t very hard to remove the right side cover, you just have to drain water & oil, remove the water pump cover, filter cover, oil supply line, kickstart, and brake pedal. You can leave the clutch cover on. If you just remove this cover then you can check to see if your CB drive gear has play (rotational, meaning the CB shaft will turn a bit without the main, or crank, shaft turning) and your main gear retaining nut is tight. If so then you can be pretty sure that this isn’t the source of your noise. While you’re at it you can see if the basket has been clearing the cases and oil pump drive gear (this also makes some noise). If it is, it will be rubbing the case at about 2 o’clock, right where the rear head bolt boss is (I have a replacement ’00 case and it has a recessed area cast into it at this spot).

So you can check every possible noise source that I am aware of in less than 30 minutes with two allen wrenches and a few sockets. To remove the right cover two of the clutch cover bolts must come off (the ones at 1 and 2 o’ clock, more or less).

If you replace the straight key make sure it does not protrude out from under the CB drive gear it holds, this will prevent you from properly tightening the main gear retaining nut.

Hope this helps!

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