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Discussion Starter · #1 ·
Ordered 16/43 for the 919, got 16/49. Its near halfway through adjustment and still not in spec and I've yet to cut the new chain. Chain cut to length by link count got .75" of slack with the adjusters all the way in. I chocked it up to user error as I haven't done a chain in a while. Posted a pic to my buddy and he noticed the 49t sprocket. Here's hoping the retailer makes things right (over a year after purchase...)
 

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McTavish
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0 miles. it's been so long since I've done chain/sprockets on the 919 I forgot that I switched to 17/43 and 17/44 in the past. Why the heck did Honda do this to us?! 2002 919 New Chain Adjustment Question
I'm sure everyone wants to know more about Hunting Tooth Theory:

I just fished around today and so far have found the following relevant info source:



hunting tooth - Everything2.com
In design of all kinds of power transmission gearing, also applicable to design of chain or toothed belt drives. A "hunting tooth" is used to ...

everything2.com
everything2.com



https://www.geartechnology.com/ext/resources/issues/0121x/Hunting-Tooth.pdf
 

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Premium Member
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2,865 Posts
Discussion Starter · #5 ·
0 miles. it's been so long since I've done chain/sprockets on the 919 I forgot that I switched to 17/43 and 17/44 in the past. Why the heck did Honda do this to us?! 2002 919 New Chain Adjustment Question
Forgot to mention the 49 stamped on the sprocket wasn't a tooth count, whats on is a 43 so it lines up with the thread. Thanks for the info @mcromo44! I'm split between sell these sprockets and go back to 17/44, or just run this until it's out of adjustment and trash the setup. put a giant banner on the chain guard "17/44 or bust!" so I won't make this mistake again.
 
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McTavish
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Forgot to mention the 49 stamped on the sprocket wasn't a tooth count, whats on is a 43 so it lines up with the thread. Thanks for the info @mcromo44! I'm split between sell these sprockets and go back to 17/44, or just run this until it's out of adjustment and trash the setup. put a giant banner on the chain guard "17/44 or bust!" so I won't make this mistake again.
I gotta laugh, I've been waiting for years to use Hunting Tooth Theory! My exposure to it was in terms of gears only, and honestly didn't know for sure if it applied to chains, but suspected it did. So, thanks for your post that got me off my butt to do some new digging instead of going by memory. So, not only is "Hunting Tooth Theory" real and valid for gears, but also chain and belt drives - although my guess is re belts, that it's for timed belts, i.e. toothed belts for toothed pulleys - like a Top Fuel Supercharger drive would use., a.k.a "Gilmer Belt". I know, I know, I'm dating myself with that one! LoLs.
 

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Old, Bold rider
2002 Honda 919, 1976 Yamaha XT500 cafe, TC-JAG TZ250
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First heard of what was called hunting ratios about thirty years ago, and have been using it ever since. Specifically, I endeavor to place a gear with a prime number of teeth somewhere in a gear train to insure that every tooth makes contact with every tooth of a mating gear. This is easier in a compound gear train where the intervening gear set has at least one prime number of teeth.
For example: in a cam drive, which obviously the ratio has to be 2:1, with a simple two gear reduction every tooth on the crankshaft gear only contacts two teeth on the cam gear. This is not ideal as the teeth take a set and wear increases. It can also cause undesirable resonances particularly in a cam drive with its cyclic loads (a modified sine curve as the cam follower climbs up the lobe, briefly pause at the nose, then down the other side) which if the backlash is even slightly too much the pinion and gear teeth will be beaten to death. A cure can be as simple as introducing an intermediate gear (called a relay gear) with a prime number of teeth, facilitating longer life and less noise. This is a common with aftermarket cam drives for high performance V8's, though they aren't much concerned with longevity!.

Another example is if you want a 2:1 ratio it can be done with the same number of teeth on both ends of the gear train by using an intermediate gear set with one prime number of teeth coupled to a gear with twice the number of teeth. Specifically 29 teeth driving 74 teeth coupled to a 37 tooth gear driving two 29 tooth gears through a relay gear, again with a prime number of teeth. Left illustration.

Another way to implement a hunting ratio is to have the drive pinion an odd number of teeth and the driven double the number of teeth with a relay gear of a prime number of teeth. For an illustration of this take a look at the Moto Guzzi V8: the cam drive uses this method. IIRC in this case the relay gear had a prime number of teeth (No, not 277!) and also served to drive the coolant pump. Right illustration.

This also applies to chain drive, where one or both sprockets ideally should have at least an odd number of teeth, and preferably one prime number. The reason? Roller and Hyvo chains by their nature have an even number of links, and it can have a small effect on longevity if either of the sprockets has an even number of teeth. Of course there are a number of other factors effecting wear if the chain is not enclosed in a housing with an oil bath as many scooters are.

Frankly, I have not looked into toothed belts and what if any factors have a negative effect on MTBF.
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Rob
 

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McTavish
Joined
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6,545 Posts
First heard of what was called hunting ratios about thirty years ago, and have been using it ever since. Specifically, I endeavor to place a gear with a prime number of teeth somewhere in a gear train to insure that every tooth makes contact with every tooth of a mating gear. This is easier in a compound gear train where the intervening gear set has at least one prime number of teeth.
For example: in a cam drive, which obviously the ratio has to be 2:1, with a simple two gear reduction every tooth on the crankshaft gear only contacts two teeth on the cam gear. This is not ideal as the teeth take a set and wear increases. It can also cause undesirable resonances particularly in a cam drive with its cyclic loads (a modified sine curve as the cam follower climbs up the lobe, briefly pause at the nose, then down the other side) which if the backlash is even slightly too much the pinion and gear teeth will be beaten to death. A cure can be as simple as introducing an intermediate gear (called a relay gear) with a prime number of teeth, facilitating longer life and less noise. This is a common with aftermarket cam drives for high performance V8's, though they aren't much concerned with longevity!.

Another example is if you want a 2:1 ratio it can be done with the same number of teeth on both ends of the gear train by using an intermediate gear set with one prime number of teeth coupled to a gear with twice the number of teeth. Specifically 29 teeth driving 74 teeth coupled to a 37 tooth gear driving two 29 tooth gears through a relay gear, again with a prime number of teeth. Left illustration.

Another way to implement a hunting ratio is to have the drive pinion an odd number of teeth and the driven double the number of teeth with a relay gear of a prime number of teeth. For an illustration of this take a look at the Moto Guzzi V8: the cam drive uses this method. IIRC in this case the relay gear had a prime number of teeth (No, not 277!) and also served to drive the coolant pump. Right illustration.

This also applies to chain drive, where one or both sprockets ideally should have at least an odd number of teeth, and preferably one prime number. The reason? Roller and Hyvo chains by their nature have an even number of links, and it can have a small effect on longevity if either of the sprockets has an even number of teeth. Of course there are a number of other factors effecting wear if the chain is not enclosed in a housing with an oil bath as many scooters are.

Frankly, I have not looked into toothed belts and what if any factors have a negative effect on MTBF.
View attachment 159051

Rob
Very nice addition Rob and thanks for taking the time to do it.
 

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Old, Bold rider
2002 Honda 919, 1976 Yamaha XT500 cafe, TC-JAG TZ250
Joined
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2,494 Posts
While crunching some numbers it occurred to me that if I wanted to experiment with a more proper hunting final drive ratio instead of the stock 16/43, where the chain rollers are constantly engaging the same countershaft teeth, by going to 17/45 sprockets. In this way the chain would hunt on both odd numbers sprockets, and as I like the stock ratio the new ratio would only be an insignificant ~1.5% difference. It would be interesting to see if there is any change in the wear, and possibly any other aspect.

Rob
 
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