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Discussion Starter · #1 ·
i just picked up a 2000 xr50, and although it's in rough shape it's ridable. so far i've found, it's hard as hell to start after being cold, almost to the point where it won't start, but once it's started and warm i've got it idling smooth and running just fine. it needs to be rebuilt for sure, cause it's severly lacking on power, but my main concern is the tranny. while in nuetral it's really hard to get into 1st, but it'll go if you raise the shift lever hard and far enough. but occassionally when trying to shift to any gear the bike will just fall out of gear all together. it doesn't do it while riding, but if you stop or try to shift sometimes it happens.



before i go putting any money into this bike at all i want to get the tranny and motor fixed and running just as good as my 03 xr does. i'm lost as to where to start in order to get this bike up to par. any ideas, tests, things to look for, anything at all that would help me figure out what's causing my tranny problem or how to fix it would be grrreat.



i've rebuilt 2-stroke motors before but haven't messed with these itty bitty 50 motors. besides a manual, is there any where i can get some information about the rebuild process and/or adjustments?



thanks again.
 

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Its possible that the shift shaft is bent and causing some issues... but its hard to say. If its hard to start... its probably lacking compression. These motors are hard to kill though. Try some simple things like turning down the idle or adjusting the clutch to get it to shift easier as well. I bought a used XR that idled way too high and it was hard to shift until i turned the idle down.



If you have the motor... you can make it work. Tear the bottom end down and check out the conditions of the gears and everything. Possible that there is a slightly bent shift fork... who knows with a r eally beat up engine. I scored a whole crf transmission for 55 dollars a while back. You can make it right if you are determined enough.
 

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Discussion Starter · #3 ·
that's what i was thinking too, as long as i have the bike and motor fixing it shouldn't be a problem.



i had it running, idling correctly, and everything last night. at first it was idling really high and hard to get into gear and when it did pop in gear would take off or wheelie. the guy tried selling it like that to me, and i told him it was a piece of **** and made an offer that he took. anyways. i've adjusted the carb, but haven't started on the clutch yet. i just wanted to get it running so we could ride last night. i guess i'll get into it more this week.



damn the whole transmission for 55? any year should work shouldn't they? i mean they are all the same motors for the most part, right?
 

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any CRF/XR 50 tranny will work... and the 12volt Z50R transmissions will work fine but you will then have a 6 spline countershaft that runs a different style sprocket. no big deal... just need a new sprocket to make it work. You could also grab a 4 speed from AHP or DRatv if they have them in stock... or yoink one out of a random chinese engine.
 

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Discussion Starter · #5 ·
cool, i was just looking around to see if i could find one for cheap. if you happen to run across one let me know. for now i'll try the clutch adjustment, and move on from there. i know the idle and everything are ok now. i have to rebuild a Z50 motor and this xr motor so i've got some fun times ahead of me. hope they're as easy as a 2-stroke.



is a piston kit all i'll need to rebuild these? well, gaskets too, but just the piston and rings, right?
 

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Depends on the shape of the cylinder. Ususally if one of my motors is in rough shape I end up upgrading it to something bigger/faster. When you can do an 88 kit for 99 dollars (DrATV OPERATES HERE) ... I wouldn't bother with boring a stock cylinder with a 20 over piston or whatever.



If you want to keep it 50cc's on the cheap... look for a take-off crf50 top end and grab a fresh set of rings. I think you can get that stuff from BBR brand new maybe? They used to sell take off parts anyways.





These engines are cake to work on. Its like a 30 piece jigsaw puzzle with bearings, seals, and gears. Just make sure the transmission pieces go back in the same way they came out and you will be golden.
 

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Discussion Starter · #7 ·
i figured they were easy, just have to get in there and start taking it apart. upgrading to the 88 kit makes sense too, and if the cylinder is jacked that's what i'll do, damn my girl will be riding a 88 kit while i'm still rocking the stock 50. wtf? lol



thanks for the help man.
 
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