I purchased a 75 SXT125 last month. I was told it was mechanically restored. The bike starts in the first kick and ran well. After a few miles put on it the bike it does not want to shift into second or third gear. It downshifts fine but when shifting from 1st to 2nd it will take several times to engage into gear. When I squeeze the clutch and move the lever into 2nd it seems that it clicks but when I release the clutch it does not engage. Per the manual the clutch seems adjusted correctly, and I topped the oil off. Does anyone have some experience or insight??? I would really appreciate it. Thanks

 

I have no idea how those transmissions work. If it was a Big Twin I'd say it needs a shifter pawl adjustment.

 

I have no idea either I am hoping that I can find a 2 stroke expert in this forum

 

been a very long time. do you have the fsm, if not, pm me and i get you one.
does the shift lever have spring action, aka, returns center?




unfortunately the engine must be taken apart part way. i have had issues with the springs. if you can work the shifter and get it to change and the gears are solid, these are suspect.

 

try this link. this is a 250 but they share the same setup. it will give you an idea of what to look for and is a must before you decide to deframe the engine. start at the 3 minute mark, the link was supposed to start there but shinola happened.

 

I will have to check on the return to center. Didn't notice that the lever was stuck in the up position. It seemed to me that it was "clicking" up (and returning to center) into second just not engaging when I would release the clutch lever. I am new to this forum and don't know how to pm. Thank you for the help. The wheel bearing is also loose if you have any info on changing that as well. I have worked on several cars but this is a whole new ball game. thanks again

 

FYI look up Bill's old bike barn, bloomsburg pa. When I was there they had a 2000 to 3000 ft² shop full of aermacchi parts In fact everybody should look up( bills old bike barn )this man bought out 28 dealerships, he has amazing stuff in his museum, the most amazing place I've ever been to Harley Davidson wise. I have an orange 76 sx 250

 

there are a few issues
the shifter return spring should hold the shaft neutral and fairly stiff. if the shaft is allowed to sag then the shift arms will not be in position to grab the drum pins.
the pawl spring should be fairly stiff also so as not to allow the drum to rotate after the pawl arms are homed into the pins
the pawl arm ends should not be rounded with wear
drum pins in good shape and pins at correct height above flange, these pins can be replaced
shaft axial play should not be excessive as to allow shaft to move out when trying to engage arm to pins, shim it with washers.
spring 6 usually is ok but never say never. that said, look at shifter shaft end to arm hole for good fit.
most of that stuff and be remanufactured in a good home shop.

 

on the wheel, how is it loose?
not sure but if i remember, some wheels had a sorta cush drive and those rubber collars are probably shot. as far as bearing, just like any other wheel.
i believe after so many posts, you can use the pm function. if you click on my handle top left, drop box will have option for pm. i do have service info i could send direct.

 

I cannot send a pm, think i need to upgrade to a paid account. Someone at MotoItaila ,I had sent an email, called me today and told me to take off the Rh motor cover and check the I think it was the shaft that the forks ride on??? With out a manual I do not really know the parts names. He did say that he had a motorcycle that did not have enough fluid in it and this shaft had gotten rusty/corroded and the "selector part??, maybe forks??" that slide on that shaft did not move properly causing the type of issue I am having. Which makes sense bc the person I had purchased the motorcycle from said that he had changed the oil when in fact he did not or did not do it properly. The screw on the oil check hole was stripped and I had to rev drill and extract it. Then when I filled with 30w oil it took about a pint and the gentleman at Motoitaila said that it holds about a pint and half. Hopefully it is just this shaft that needs cleaned. He said that I would have to take the Clutch off to get to it.

I appreciate the offer for that manual but I am going to buy one from him to support his business. I will check all the things you mentioned in the above post and I appreciate the help very much. With the holidays it will be a little while till I can get to working on it but i will post as soon as I start. Thanks again Bustert!