250sx Third gear missing, whats the process?

[Coopart1]

hello, i have a 85 250sx that was pretty rough when i got it, but that damn good running engine, easy to start, kept me wanting to make it trail worthy. I this bike was going to be scraped for the engine to be used in another project, but here i am now really digging my three wheeler, only thing left to fix of any real matter is that not long after i started riding it around third gear popped out like twice...and now its not even there. no grinding no nothing just a blank gear like neutral. Others shift sweet and smooth, just no third..so what would be a good line up of trouble shooting to get to the problem first? Im not afraid to tear into things if i know what im doing or take my time with some kind of a guide, but frankly i have never tore into a motorcycle engine before and its a bit intimidating. All tips excepted, thanks folks.

[redsox]

well, i'm just about to do the same thing, on the same machine. i just ordered a repair manuel. $10 on ebay. you can get em on here for free if you look around. i like having the book. i'm starting the process soon, so i'll let you know. good luck.

[Flyingw]

A common problem with the SX/ES engines is the shift shaft gets bent. This is due to a heavy foot rider stomping on the shifter bends the shift shaft. When the shift shaft gets bent, all sorts of tranny problems have been reported. The place to start with diagnosing the problem is to pull the left side cover. The easiest way to do this is to lay the trike on its right side with the left cover up. Pull the starter gear set from under the oval cover. Remove the left foot peg assy. Pull the stator cover and gently pull the shift shaft out. Using this method lets you leave the oil in the tranny which is helpful because on the right side under the clutch cover is the auto-clutch lever thats on the right end of the shift shaft. By laying the trike on its right side, the lever stays in place and the oil helps keep it there.

After the shift shaft is out, put a straight edge along the shaft and look to see if the shaft is bent. If it is, replace the shift shaft and reinstall it by slowly and carefully reinstalling the shift shaft keeping it aligned to the shift drum detent pin. Reinstall the stator cover and starter gear set. Speaking of the shift shaft detent pin, while the shift shaft is out, ensure that pin is tight. They have a bad habit of vibrating loose. Thread lock that pin to be safe.

If the shaft is not bent, then the problem may reside inside of the tranny. You will probably need a new stator cover gasket and starter gear set cover gasket.

If you like, I can post a few pics of the parts I mentioned just let me know.

Manual download site
http://kb0nly.lgnas.com/

[Coopart1]

Thanks for the advice! Too bad its only Tuesday..I can only work on this project on the weekend ...but that give me time to plan my attack and order gaskets. If you have the time and don't mind posting pics of these parts im sure BOTH of us (person who posted on this topic) would like too see. I have a manual downloaded but getting things layed out for what to look for would be great!

[Flyingw]

I'll do that tonight. Don't sweat it though, pretty easy to accomplish.

[Flyingw]

Ok boys, like I said, pulling the shift shaft out and checking it for straightness is pretty easy. Once the cover is off simply pull the shift shaft out but when reinstalling it be sure its aligned to the shift drum because the auto-clutch arm under the clutch cover is splined. Some of the reports suggest the shift shaft doesnt need to be bent very much to cause problems.

[Coopart1]

This is Great! Thanks! it helps me to visualize whats going on in there and what to look for. VERY much appreciated .