Balancer Drive

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ChrisZ

Balancer Drive

#1 Post by ChrisZ » Tue Sep 27, 2005 5:00 pm

It seems that when I post something here, I am compelled to apologize in advance for asking something that has probably been expounded upon in great detail in the past. But I'll ask anyway! The question this time: what benefit is reaped from running the motor balancer drive off of the lower crankshaft on an "earlier" model RZ? And if it is beneficial, why? Does it address a particular RPM range or running condition?<br>Thanks in advance all.
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czracerx@yahoo.com

Andy

Re: Balancer Drive

#2 Post by Andy » Wed Sep 28, 2005 8:00 am

The pro's are, your motor tends to spin up a lot quicker...<br>The cons are, that you'll increase vibration on the bike...<br>Unless you've modified your engin and got a good set of pipes on... I wouldn't do it.
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andrew.lord@vacon.co.uk

Bill Wilson

Re: Balancer Drive

#3 Post by Bill Wilson » Wed Sep 28, 2005 6:09 pm

Chris,<p>All models of RZ that I have service except the 1986 model which had the addition of a flyweight on the stator side of the upper crank have the balancer driven by the lower crankshaft. Yamaha, in their 1985 TSI bulletin referenced to service personnel how to change the drive gear from the lower crank to the upper crank. This operation in turn reduced midrange RPM, 5000-7000RPM, vibration felt in the handlebars and footpegs. Given that there is less vibration this will allow for quicker revs.<p>If your engine is that of the 1986 model replace the balancer to the upper crank, if it is not then I suggest performing the balancer modification. See Bill Pendegrass' website for my updated version of this document.<p>Hope this helps.<p>Regards,<br>Bill Wilson<br>Wilson Performance<br>Lee's Summit, MO<br>Member RZ500 Owners Group #573
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WVWRZ500N@aol.com

ChrisZ

Re: Balancer Drive

#4 Post by ChrisZ » Thu Sep 29, 2005 4:49 am

Thanks for the replies. Also Bill, the transmission work that you set me up with works great. Shifting and engagement are both top notch. As for the balancer, my bike is an '84, and an early one at that, with the balancer currently run from the lower crank. I was just curious as to why it became obviously beneficial to change the drive to the upper crank on this model; and wondered why it didn't come to light during Yamahas' R&D on this motor. I put mine back together to try the tranny fix, and to get a fresh impression of the vibration before performing the balancer mod. I need to go back in anyway to replace my clutch hub, so I figured, why not try the modification. I consulted Mr. Pendergrass' site for the instructions on the alteration- good stuff. Seems pretty straightforward; just move the drive gear itself to upper crank end after establishing correct phasing, no? I guess what I was trying to figure was whether the mod will move the vibration somewhere else in the rev range. The current vibration, as near as I can sense, feels to be a "sympathetic" one conducted out to the extraneous bits of the bike. Couldn't make a guess on it's frequency in relation to crank rotation/reciprocating mass cycle frequency. Any thoughts?<br> Thanks, Chris Z
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czracerx@yahoo.com

gareth

Re: Balancer Drive

#5 Post by gareth » Fri Sep 30, 2005 1:26 am

I have tried the balancer shaft mod a few times.<br>I have a very early 47x bike that has the balancer on the front crank..I dont notice any vibe at all on that one its a smooth as a babies ar*e.<br> I have another bike that was shuddering on the overrun at a specific rpm (what the mod is supposed to fix). I performed the mod and now I have a tingly vibe practically everywhere but the overrun shudder has gone.<br>I have just had 6 cranks rebuilt and I am going to set one bike up with the mod and one bike up stock....both with perfect cranks. As you can tell I'm not that convinced. I think out of true cranks is causing most of the vibe problems...if you get on a very low mileage bike that has never seized they dont vibe. <p>As soon as you machine the heads (make both the same) do a bit of tuning, put pattern pistons in, lighter pipes etc...I think your very lucky if you dont get a bit of vibe...especially if the carburation isn't perfect aswell.
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gareth.evans9@btinternet.com

Gareth

Re: Balancer Drive

#6 Post by Gareth » Tue Oct 04, 2005 2:07 pm

Well I thought there may be some reaction to my comments on this. What nothing....has everyone got vibey pegs and bars after the balancer mod and totally agrees with me or do they feel its better all over. I personally preferred the overrun 'judder' over constant send your feet to sleep stuff.
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gareth.evans9@btinternet.com

Art

Re: Balancer Drive

#7 Post by Art » Fri Oct 07, 2005 7:45 am

Gareth,<br>OK,I'll chip in...I think you have it backwards...Mine had a distinct "buzzing"(around 5k rpms) in the pegs and bars before I did the mod.I noticed the "buzzing" when I first got the bike and thought it had bad crank bearings or something....then I discovered the internet...then I discovered this site...then I discovered the TSI bulletins....then I got real confused.<br>Art
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