What brand Sprocket and chain??

Woah,....I learned so much more right there about measuring chains then I have ever learned about anything in school.

Thanks Grayracer and Jay. :):D

Oh, I use Sidewinder Ti sprockes and chain on my YZ 250. Have held up fine for me. :)

...an astounding statement, given your oft-stated predilection for precision. One percent of 5.85 is .050" (1.01x5.85=5.901), which I suppose is a fraction (13/256), but it's smaller than 1/16", and bigger than 3/64", making decimals somewhat more convenient.
...exactly why I provided a more precise method.

...The measurement from outside to outside would compress the wear out of the pin/bushing unions so that the difference in the two would be the .400" roller diameter plus the wear at the pins. The arithmetic is more complicated, and the method only provides accurate information when measuring a new chain, or one in which the plates have stretched, but in which there is no pin wear, a very unlikely scenario.
...you should always measure a chain with the section taught. Your assumption is incorrect on this one. The method provides an accurate measure no mater if the chain is new or worn. The taught chain is putting the chain in it's actual length, the only thing you are compressing is the roller against the bushing. It also accounts for any wear between those two items as well. This, btw..is the preffered method by Tsubaki, the largest chain mfg in the world. But hey, what do they know?
...Apart from that, I think that by far most common vernier calipers are capable of a 6" maximum reach, and cannot measure the 6.25" pin-to-pin length of a 5/8 chain, nevermind the 6.74" outside roller measurement that would be required to know that a chain had reached even your 1.5% wear limit using that method (6.25+.094(1.5%)+.400).
...I think if a man is apt enough to manage a vernier caliper, he is apt enough to realise that the method works for ANY amount of chain reels, since we are dealing with percentage. Simply measure a 8 space section if all you have is a 6" caliper.
...The method shown in the manual has merit because it uses common tools, is accurate, is difficult for the marginally competent to screw up, and involves no math, unless you need to understand where they got their numbers from.
I would refer you to section 2-14 of the manual. When going to the specification page for information, there is no method provided, only data. And "Chain Length (10 links) is not 6", unless the unconventional method for measureing chain is provided for the average Joe to understand, which it isn't. The only thing that provides you a clue as to what they are reffering to is a picture in section 3.

Again, I might have missed the assumption chapter though.

...exactly why I provided a more precise method.

...you should always measure a chain with the section taught. Your assumption is incorrect on this one. The method provides an accurate measure no mater if the chain is new or worn. The taught chain is putting the chain in it's actual length, the only thing you are compressing is the roller against the bushing. It also accounts for any wear between those two items as well. This, btw..is the preffered method by Tsubaki, the largest chain mfg in the world. But hey, what do they know?

The method is valid enough for a chain still in place and/or held taught, but Yamaha choose to give their simpler method instead. Doing it this way requires infromation not in the manual and requires four additional steps (taking the second measurement, calculating the average for the actual pin-to-pin length, calculating the proper length of the section measured, calculating the percentage difference in the two)
...I think if a man is apt enough to manage a vernier caliper, he is apt enough to realise that the method works for ANY amount of chain reels, since we are dealing with percentage. Simply measure a 8 space section if all you have is a 6" caliper.
The trouble here is that it requires the person doing the job, who in very many cases, most even, will be a person who is not a professional mechanic or engineer, to analyze the entire situation until he understands what he should be measuring, do a bunch of calculations using information not included in the manual, offering him a chance to make another error, and then, once again understand that the chain must be held taught on both measurements. Unless there is any demonstrable fault with using the simple method Yamaha provides (and there isn't), it's just far easier for most guys to take one measurement and see if it meets the required specification. It's simple, accurate, and it's a single step.

You do have a point about the lack of a reference from the spec page to the section showing the measurement technique, though, and that isn't the only place that happens. There really should be one. A decent index wouldn't hurt, either. A little more effort on the part of their technical writers would serve their customers well. :)

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