Has anyone ever had problems with their sprocket bolts on the '00 yz's? I bought the bike, and noticed that the bolts kept coming loose. I ended up replacing the sprocket and getting new bolts...I made sure to use lock-tite as well. I made sure that I checked the bolts before every ride with the new setup. Well, on about my fifth ride with the new sprocket something weird happened. I landed a jump at the local track, and suddenly heard a loud noise and had my back wheel sieze up. I look down and find my sprocket bent in half with part of the hub torn off and the spokes broken. After taking it apart, I found only 3 of the 6 bolts still in the sprocket (with the hub still attached...sorry to say) Anyways, I'm almost positive this happened because the bolts came lose again. Has anyone had similar problems? I'm getting my wheel rebuilt, and would hate for this to happen again because of bolts coming loose. Any suggestions or info?
2000 YZ250 Rear Sprocket Bolts
- Thread starter sraser
- Start date
B
biglou
There have been some issues with the 426's breaking hubs (ask Nikki and Red, and Predator), but I haven't heard of any of the 2T's breaking them. Like Layton says, once you loctite and tighten a bolt, you can't adjust it. If you check it and it's loose, take it out, clean it and re-loctite it before you tighten it back up. I stayed on top of my sprocket bolts on the 426 for the first few rides, but never found them loose. I have since gotten a little lax about keeping my eye on them. So far, though, I have had no problems with mine.
Sprocket bolts loosen, loc-tite or not. Check them often. This is a comman problem on ALL bikes, sprocket bolts are not prejudice to brand, however a bigger bike with more torque or vibration can accelerate this problem. Check often and be careful!
jmics19067
LIFETIME SPONSOR
- Jan 22, 2002
- 2,097
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Although I probably am not as fast as most of you and do not stress parts of the bike as much , I have never had a problem with sprocket bolts.
These are the things I do and look for when I change sprockets though.
1st of all clean everything well, take a small screwdriver and dig out the allen heads and also a small wire brush and run it over the exposed threads of the bolts on the back side. Spray a little loose juice on them<wd 40, crc etc.> . If you use red loctite<I don't> get out the propane torch and heat up the bolts a bit to break down the loctite. Use a box end wrench and break the nut loose first before you use your allen wrench and spin the bolt out. I have had some older bikes that the hub was actually threaded and the nut was nothing more than to lock it tight. <not a bad idea and I would like to see it more often >
Once you have the sprocket off the hub check it around the bolt holes and see if the aluminum is being pulled out a little bit<most common on threaded holes though> and chamfer the holes a bit if needed. Get your old toothbrush out and clean around that little lip that the sprocket sets around. Take a good look at the hub side of the sprocket and make sure there is no rough/sharp edges that are protruding into the bolt holes of the hub or that center ring. Clean and inspect the bolts for damage and stretching. If you are buying aftermarket bolts make sure that the countersinks are the same angle as the holes in the sprocket. Nylon locknuts should be thrown away after each use, the crimped locknuts every 4 uses<although I don't>
After I know that the sprocket sets flat on the hub and the bolts are sitting in the countersink right, I actually use anti sieze on the bolts. Run the bolts up snug alternating them ie.,run one up snug ,skip one ,snug,skip, snug, 1/2 way across,snug ,skip, snug etc etc. I folow up witha torque wrench when I think I am about close to final torque. Once I have the bike back together I take it for a nice easy ride dragging the brakes to make sure that they feel right I double check the torque , brake clean off the back of the bolts and use the penetrating loc tite on the nuts and bolts.
Now using a torque wrench on bolts that have anti sieze increases the actual tightness of the bolt that is why it is imperative to check for bolt stretching during inspection. I do not have any problem with my bolts coming loose but if I did I would use a paint marker or something and mark the nut and the bolt. That way it would be a lot easier to tell if the bolts are actually loosening or the sprocket,hub and countersunk bolts are just seating themselves. No amount or type of loctite on the bolt /nut is going to cure a problem of the parts seating.
These are the things I do and look for when I change sprockets though.
1st of all clean everything well, take a small screwdriver and dig out the allen heads and also a small wire brush and run it over the exposed threads of the bolts on the back side. Spray a little loose juice on them<wd 40, crc etc.> . If you use red loctite<I don't> get out the propane torch and heat up the bolts a bit to break down the loctite. Use a box end wrench and break the nut loose first before you use your allen wrench and spin the bolt out. I have had some older bikes that the hub was actually threaded and the nut was nothing more than to lock it tight. <not a bad idea and I would like to see it more often >
Once you have the sprocket off the hub check it around the bolt holes and see if the aluminum is being pulled out a little bit<most common on threaded holes though> and chamfer the holes a bit if needed. Get your old toothbrush out and clean around that little lip that the sprocket sets around. Take a good look at the hub side of the sprocket and make sure there is no rough/sharp edges that are protruding into the bolt holes of the hub or that center ring. Clean and inspect the bolts for damage and stretching. If you are buying aftermarket bolts make sure that the countersinks are the same angle as the holes in the sprocket. Nylon locknuts should be thrown away after each use, the crimped locknuts every 4 uses<although I don't>
After I know that the sprocket sets flat on the hub and the bolts are sitting in the countersink right, I actually use anti sieze on the bolts. Run the bolts up snug alternating them ie.,run one up snug ,skip one ,snug,skip, snug, 1/2 way across,snug ,skip, snug etc etc. I folow up witha torque wrench when I think I am about close to final torque. Once I have the bike back together I take it for a nice easy ride dragging the brakes to make sure that they feel right I double check the torque , brake clean off the back of the bolts and use the penetrating loc tite on the nuts and bolts.
Now using a torque wrench on bolts that have anti sieze increases the actual tightness of the bolt that is why it is imperative to check for bolt stretching during inspection. I do not have any problem with my bolts coming loose but if I did I would use a paint marker or something and mark the nut and the bolt. That way it would be a lot easier to tell if the bolts are actually loosening or the sprocket,hub and countersunk bolts are just seating themselves. No amount or type of loctite on the bolt /nut is going to cure a problem of the parts seating.
- Thread starter
- #12
Thanks for the detailed info. I am going to watch these new bolts extra carefully. I have all my new parts ordere and the new wheel will be built by Friday....hopefully I'll be on the track by Saturday morning :aj: Thanks again for the help guys...this site is great
No problems here with my 2K YZ250. When I installed a Renthal sprocket in place of the stock sprocket, I noticed the factory used blue loctite. I used blue when I swapped sprockets and I haven't had problems. For what it's worth, I did add one tooth when I changed sprockets.
