IamRooster151 My Rides (2) Posted November 8, 2015 Long story short, my 14 yz250 ran great the last time I rode with was about a week and a half ago. Everything was in sync and it was flawless. Then today when I went out for the first practice and noticed the skipping and slipping in 5th gear. It does not do it in any other gear but fifth so it got me thinking it was the clutch (which is stock) or something in the tranny. I read in other threads that this is frequent in the YZ's. I read about the 5th gear being bent or the dogs or something like that or it was the shift fork. I guess my question is 1) What exactly is goin on? 2) What do I need to do to fix this? I just honestly think it is a little strange that this would happen this a fairly new bike since the stock clutch from the factory is still in spec Share some knowledge and information if you have experienced this first hand or heard about this or just have knowledge about what is the issue. PS the bike has about 60 hours and is maintained well. Here is the bike Share this post Link to post Share on other sites
adam8781 Posted November 8, 2015 sad to say but 5th might need tobe inspected. Ever split cases before? drain the oil and check very very carefully for any chipped teeth Share this post Link to post Share on other sites
yz250474 My Rides (2) Posted November 8, 2015 how do you change gears? use the clutch? Share this post Link to post Share on other sites
SmokinJoe90 Posted November 8, 2015 It's a known issue with the gear box the 3rd through 5th gear wear out. The gear dog ends wear down and the gears won't stay locked into position. The gear dogs are 3 posts that are rectangular shaped on the ends of the gears. When you change gears the gear dogs ends slip and lock together. Over time the edges of the gear dogs wear down causing it to slip or jump out of gear. The gear that is the problem is probably your 4th gear. Ignore it and you'll just make it worse and it will start wearing out your shift fork ends or worse break a gear. Share this post Link to post Share on other sites
dazza1968 My Rides (2) Posted November 8, 2015 Sorry to hear and yes i had to do third gears selector was all rounded .....split case job Share this post Link to post Share on other sites
adam8781 Posted November 8, 2015 Im running stock internals on a 06, im surprised to see this happen to such a new bike 1 Share this post Link to post Share on other sites
yz250474 My Rides (2) Posted November 8, 2015 It's a known issue with the gear box the 3rd through 5th gear wear out. The gear dog ends wear down and the gears won't stay locked into position. The gear dogs are 3 posts that are rectangular shaped on the ends of the gears. When you change gears the gear dogs ends slip and lock together. Over time the edges of the gear dogs wear down causing it to slip or jump out of gear. The gear that is the problem is probably your 4th gear. Ignore it and you'll just make it worse and it will start wearing out your shift fork ends or worse break a gear. 01 660's had a bad problem of breaking them off 2nd gear they only had 3 dogs, they added a 4th on 02+ models.... seems they would do the same if it was a huge problem... how are you guys shifting? using the clutch? Share this post Link to post Share on other sites
dazza1968 My Rides (2) Posted November 8, 2015 Im running stock internals on a 06, im surprised to see this happen to such a new bikerare isnt it Share this post Link to post Share on other sites
EYY Posted November 8, 2015 Imo, having the 5th gear dogs undercut would likely solve the problem much cheaper than new gears. Something to look into. Share this post Link to post Share on other sites
IamRooster151 My Rides (2) Posted November 8, 2015 Yup I use the clutch every time I shift. Share this post Link to post Share on other sites
IamRooster151 My Rides (2) Posted November 8, 2015 So if I am ordering parts tonight, which parts should I get? A new fifth gear and shift fork or just a new fifth gear. Or should I split the cases and take a look first? Share this post Link to post Share on other sites
SmokinJoe90 Posted November 8, 2015 Split cases first you could need all 3 gears and forks. Share this post Link to post Share on other sites
frettie Posted November 8, 2015 I'm going through the same ordeal right now. I went ahead and split and inspected before ordering parts. Glad I did, cause I found wear on several gears along with all the forks. Don't forget to order all new circlips for the main and counter shafts. Don't reuse the old ones. Share this post Link to post Share on other sites
Snider Posted November 9, 2015 What kind of gearbox oil was used? Share this post Link to post Share on other sites
Diehard2stroker Posted November 9, 2015 I had the same problem with my old 125. Turned out to be a piece chipped off the gear and went in a bearing and caused it. I ended up replaci the dogs forks and the bearing and it runs like a champ Share this post Link to post Share on other sites
IamRooster151 My Rides (2) Posted November 9, 2015 So a few more questions of mine are once I get this fixed, how many more times with this happen? Do you think I had a faulty gear or something? And will this next set of parts be stronger? Share this post Link to post Share on other sites
IamRooster151 My Rides (2) Posted November 10, 2015 I'm going through the same ordeal right now. I went ahead and split and inspected before ordering parts. Glad I did, cause I found wear on several gears along with all the forks. Don't forget to order all new circlips for the main and counter shafts. Don't reuse the old ones.What else are you replacing besides the clips and the gear? Should I go ahead and replace the crank bearing and seals also? Any other parts I should know about other thank the gear and clips? Share this post Link to post Share on other sites
dazza1968 My Rides (2) Posted November 10, 2015 What else are you replacing besides the clips and the gear? Should I go ahead and replace the crank bearing and seals also? Any other parts I should know about other thank the gear and clips? at such low hours i would say you shouldnt have to worry about bearings......your unlucky....i did mine a while ago and had done a truck load more hours...reckon it was because i had pivot pegs on the bike and when lifting the front doing wheelies it knocked into next gear a bit....and it was my loan bike to mates every now and then. Now i dont lend it out and drop my foot back on wheelies just to make sure! Was the selector between 3 and 4...i changed them all as it wasnt to expensive. . Share this post Link to post Share on other sites
frettie Posted November 10, 2015 What else are you replacing besides the clips and the gear? Should I go ahead and replace the crank bearing and seals also? Any other parts I should know about other thank the gear and clips? Mine has under 50 hours. I am replacing all seals, but the bearings are still smooth. May as well replace top end while its apart. Share this post Link to post Share on other sites
IamRooster151 My Rides (2) Posted November 10, 2015 Mine has under 50 hours. I am replacing all seals, but the bearings are still smooth. May as well replace top end while its apart.I replaced to top end about 10 hours ago, I'll just have to tear it down and inspect everything I guess, Just ordered a case splitter clutch holder and a crank puller online. Share this post Link to post Share on other sites
