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4mil Whining Sound


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Hey guys I am new to the site but have read multiple different threads to help me out through the years. I finally have a problem that I cannot find any discussion on. I just rebuilt my motor and put a 4mil with a max load and TZ bearing on it. I also did straight cut gears and a billet clutch basket. I got the motor together and it fired right up. The only problem is that it is making this terrible whining noise out of the bottom end. I actually pulled the motor back apart to see if I did everything right and found nothing wrong. When I put it back in the noise was still there. I have no idea what could be wrong and why it is making this whining noise. Any help please!

Thanks

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When you went to the straight cut primaries did you change to 2.68 ratio? If you did then I'd check the thick washer on the water pump shaft. The oversize gear will rub that washer and make a terrible noise. You can carefully grind it down for clearance.

Another thing that you might not be aware of is that you need to use a little silicone sealer on the crank key or slot so air doesn't get sucked in causing a lean condition in the right cylinder.

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The ratio is 2.86 so I take it the problem is not that washer but I will check anyway. I think that it might be the TZ bearing. When I split the motor for the second time and spun every bearing in my hand all sounded fine accept for the TZ. It made a little noise. Have you experienced one of these being bad right out of the box?

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The washer clearence should be fine with 2.86 ratio but it's worth a look.

Through the years I've run a total of 12 TZ bearings in my asphalt bikes and never had a new one make any noise when spun.

Straight cuts can make a little more noise than stock but not "terrible" as you describe. Don't hear mine over the OOF drag pipes lol.

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The ratio is 2.86 so I take it the problem is not that washer but I will check anyway. I think that it might be the TZ bearing. When I split the motor for the second time and spun every bearing in my hand all sounded fine accept for the TZ. It made a little noise. Have you experienced one of these being bad right out of the box?

 

if the bearing made noise in your hand it needs replaced! they should warranty it.

 

strait cut gears will sound different than stock.

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So I figured out what the problem was. I took off the straight cut gears and when I pulled off the crank gear it was really tight and made a screeching noise as I pulled it off. When I put on the stock gears and started the motor it was fine. I am going to send back the gears or try to take a little metal out of the center of the gear so it fits better.

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