Author Topic: 1st Gear Knock (Read 3991 times)

rg54669 · « **on:** November 11, 2005, 11:36:18 AM »

I just noticed a knocking sound when I take off in first gear on the '02 B12. I have not heard this sound before and I hope it is only a chain adjustment that needs to be done.
Once I am up to speed, none of the other gears make this noise. It usually knocks once or twice, but once I get the rpm's up, it goes away. Has anyone had a similiar problem and how do I fix it, it is becoming annoying.

PaulVS · « **Reply #1 on:** November 11, 2005, 11:43:17 AM »

Before doing anything else, I'd try a new tank of quality 87 or 89 octane gas and see if it still occurs.

rg54669 · « **Reply #2 on:** November 11, 2005, 12:21:35 PM »

It doesn't really sound like an engine knock, it appears to be coming from the internal drivetrain. The only problem is you can only hear it when you start to take off.

chevsuz12 · « **Reply #3 on:** November 11, 2005, 12:49:00 PM »

Mine did the same thing when I replaced the front sprocket with a smaller one. The problem on mine was the sprocket had actually worked its way loose and would rub against the clutch bracket on the housing wall. I tightened it back down and really locked the tabs down around the nut, and it hasn't been a problem since.

mike · « **Reply #4 on:** November 11, 2005, 01:07:36 PM »

I was going to suggest chain/sprocket related.
-Adjust the chain.
-Clean lube chain and sprockets.
-Check for chain and sprocket wear, in case it's time for replacing..

rg54669 · « **Reply #5 on:** November 11, 2005, 02:41:55 PM »

Thanks for the tips, will check out tonight and let you know. I have kept the new chain lubed, but have not adjusted.
About how often should you need to adjust the chain?

mike · « **Reply #6 on:** November 11, 2005, 03:43:42 PM »

I check mine once a week, just do it when necessary... It really depends on what kind of abuse you put it through... Hard accelerations, infrequent cleaning, etc.. tend to "stretch" it... After a while, you can just check the slack by feel of moving the chain up and down for play. But, if you need it, put a ruller next to it... I can't remember the exact window numbers for slack, but they're in the owner's manual.... But whatever you do, don't overtighten it and not correct it, that'll trash a chain asap...

rg54669 · « **Reply #7 on:** November 11, 2005, 10:20:03 PM »

Definitely is the chain. It may be warped, the guy I bought the bike from had replaced it once, not sure why. I pulled the cover and checked the front sprocket and it looked okay, rear is fine also. I put the bike on the center stand and tried to adjust the chain. It was much more difficult than I remember. The manual says to do it using the side stand, but I am hard headed and wanted to do it the way I used too. After fighting with it for 30 minutes, I used the side stand. Of course I have not done this in a few years, but once you align the marks it should match up, mine is still a little off and I tweaked it for at least 30 minutes.
I may take it to the local shop tomorrow and see what they say. They have mounted a few tires and done some other things for me. Will keep you posted.

mike · « **Reply #8 on:** November 11, 2005, 10:28:46 PM »

Another thing you can do to align the chain, if the marks are being a pain is:
Use a ruler and measure the gap between the tire and the swing arm on both sides of the tire until they are equal. That should help some; those marks can't always be trusted anyway... Some are good, some are bad, I guess it depends on the bike and the parts...

Good luck,
Mike :)

ray nielsen · « **Reply #9 on:** November 11, 2005, 10:51:43 PM »

It's possible that it is carbs out of sync. The application of throttle under such conditions can cause a clutch basket rattle or knock.

Just a thought.

rider123 · « **Reply #10 on:** November 12, 2005, 03:30:58 PM »

As far as the chain goes the Haynes manual says 20-30 slack on the sidestand. You can check it on the side stand and sort of figure out where you need to be. adjust it on the centrestand, then put it on the side stand to check if you need a touch more adjustment. Becarefull not to over tighten the chain as it leads to premature wear of the sprokets. Does the noise get more noticable when you take off a little faster?(more torque)

Red01 · « **Reply #11 on:** November 14, 2005, 02:21:58 AM »

Quote from: "rider123"

Becarefull not to over tighten the chain as it leads to premature wear of the sprokets.

Not only that, but it leads to premature failure of the bearings on the transmission countershaft!

rg54669 · « **Reply #12 on:** November 14, 2005, 08:05:48 AM »

I believe I finally have the chain adjusted correctly. I took it on a short test ride and there was minimal noise. I checked the slack and it is within specs of what the manual says. Thanks for all the suggestions.

Now I am waiting on parts from Ron Ayers to complete the tune up process. I pulled the tank to check the air filter and it is the stock filter with 13,000 miles. I am not sure how the engine was running with that much dirt in the filter. I held it up to the sun and could not see through any of it. Lesson learned here: If you buy a used bike, take care of the maintenance on the front end. I will be on hold for few days until I get a new air filter.

tacoman · « **Reply #13 on:** November 14, 2005, 02:47:12 PM »

You may also want to check the clutch. Is there any dragging or does the bike want to "creep" when the motor is running and you have the clutch lever pulled in all the way? Sticky/warped clutch plates can make all kinds of noises when taking off.