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Post by skidro on Jul 24, 2012 9:29:13 GMT -5
This may be a "On the side of the Road" or "Stupid Trick" post but I do have a question after a long story. . So I was starting out on a short ride last evening on my hardtail when I encountered a little problem. Heading down the hill from my house I was about 1/2 mile into my ride when the hill flattened out and, after coasting, I realized that my bike didn't have any inertia. I made sure that I was gear, shifted to other gears, gave it more gas and slowly came to a stop with the bike running but not going anywhere. As I slowed to a stop I heard a very distinctive grinding noise. I turned the bike off and looked down at the chain which had suddenly become very loose. Since the rear sprocket was still attached I went right to the front sprocket. It clearly was not on the spline part of the output shaft. Since this is not a part that you can slip back on easily with the cover on I had two choices. Call my friend with a truck or push it home. I did both and ended up pushing it home - a 1/2 mile up hill in 90 degree temps and 100% humidity. It's a fairly light bike but it's still heavy enough when it's all uphill. A neighborhood kid was walking by so I paid him $5.00 (all that I had on me) to help. He thought it was cool even if the bike was broken down. After 10 minutes and profuse sweating I got the bike home. Once I got the side cover off I was happy to discover the nut and washer were still on the shaft, if just barely. I also noticed that the washer was not bent over to hold the nut in place. This was my fault. I had the sprocket off a few times and I just plain forgot to bend the tabs over. I was able to put everything back together and it's all fine now. Now for my question, what is the size of the nut that holds the front sprocket on? Is it a 36MM? I used what I had last night but I have two 650's and it's time I had the right size socket even if it's only used once or twice. Thanks, SkidRo
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Post by rikroc on Jul 24, 2012 10:53:06 GMT -5
36mm is correct...
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Post by dogbunny on Jul 24, 2012 14:25:00 GMT -5
A 1-7/16" will also work just fine, and may be easier to find and cheaper.
I got mine off the rack at Sears.
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Post by skidro on Jul 24, 2012 14:33:54 GMT -5
Thanks guys. Good info on both the metric and standard sizes.
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Post by 10ecjed on Jul 24, 2012 18:09:26 GMT -5
That's a close one Skidro. Good thing you stopped when you did. I hate to think of the damage if the chain started wrapping around the shaft.
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Post by preston on Jul 24, 2012 20:41:42 GMT -5
I hold the sprocket, still, with a small board or hammer handle jammed in place,, and use a air impact to tighten the nut... and the nut has outside and inside-sides.... be sure that is CORRECT.
yes, bend those tabs over, many of us find the nut, finger tight, and next time we have the cover off.
and Mike M, of California, says to put black silicone in the splines/groves before putting the sprocket on.
( us Maryland-ites, need to get together, and RIDE. )
best to you,,,
Preston
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Post by skidro on Jul 26, 2012 14:06:02 GMT -5
10ecjed - I agree. I lucked out with the nut still being held on by a thread or two. That allowed the front sprocket to spin freely while keeping the chain on both sprockets. Preston, thanks for the tips. As soon as I get my socket I will double check everything to make sure I have it right. I agree, one day when the weather cools down to the low 90s we should get together for a ride.
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Post by Burns on Jul 26, 2012 16:12:35 GMT -5
I just put an 18 tooth sprocket (from Mikes) and the splines are a VERY tight fit. I had to tap the sprocket in with a hammer to get it in deep enough for the retainer plate to key over the splines.
So, heads-up fellas, make sure the sprocket is in deep enough so that enough spline protrudes for the retainer to slip over. Otherwise it won't be "retaining" anything since it will be free to rotate with the nut.
BTW, here's some torque specs for that nut. If anyone knows why it varies from uear to year I'd be curious to learn.
XS1-XSB 22mm...10-12 m-kg...72-87 ft-lbs
- XSE 22mm.............5.0 m-kg...36 ft-lbs
- XS 78-80 22mm......6.5 m-kg...47 ft-lbs
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Post by grizld1 on Jul 27, 2012 9:02:19 GMT -5
Burns, Yamaha's engineers changed their minds on quite a few specs with no change in the parts, for arcane reasons we'll never know and which probably have no bearing in the real world anyway. For many years I've followed a strict protocol in torquing down that nut: I put the 3-stage buzz gun on the middle setting and give it hell.
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Post by preston on Jul 27, 2012 19:59:49 GMT -5
I can't believe Griz said that.
My Snap On Air impact wrench, is set on # 10.
( and i thought you all would yell at me, so i said nothing ).
Preston
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Post by Burns on Jul 28, 2012 11:58:56 GMT -5
There is over 50 ft lbs range from the low Yamaha number to the high one, leadng me to think the correct number is just "tight" and the critical thing is to have the retainer over the splines and bent over the flats.
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