November 19, 20241 yr So casings split… nothing obvious that’s broken or damaged. Using an Allen wrench on the gear change drum on the clutch side I can get 1st, neutral and 2nd… and there it stops? always had a problem when going 2nd-3rd it felt like 2nd hadn’t fully disengaged but cleared if I went back to 2nd the up into 3rd… lovely & clean inside.. no debris or any sort to be found which in some respects is very good but was hopping to see something obvious and maybe something sat in the bottom of the casing! any thoughts would be greatly appreciated!
November 19, 20241 yr Author Yes, I did snap the paw from the gear selector shaft. I welded it back together, making sure it was exactly the same position from when it snapped, also made a new paw slide pin as mine had quite a bit of wear, you could move the lever quite a few degrees before it actually started to turn the gear cam. Gear change was brilliant after… I could select every gear with ease, even found neutral with the engine running! ( I can’t upload a photo atm… file to big-don’t know why?… perhaps I’ve exceeded my allowance?) everything was great until the bike went down on its left side onto rocks. After that I had a lever that didn’t really do anything but unlike when I snapped the paw assembly off the shaft and the shaft would just move excessively up or down as far as the bash plate, it didn’t seem to have full movement… after quite a few tries I got 2nd and left it there…. At first I assumed I’d snapped the shaft again or something related to it …There were no strange noises or anything to suspect gears were eating themselves.. and no signs of that now it’s apart… my son rode the bike for a while and he too couldn’t find anything bar 2nd. He got neutral a few times. and yes I’m spinning the shafts while trying to change gear using the indent cam. im at a loss now!?
November 19, 20241 yr Author Just to add… the gear selector drum is virtually unmarked… and the pin the locates it in relation the the ident cam is also unmarked.
November 20, 20241 yr Author Yes that was my first thought that it had snapped again but it’s fine hence why I’ve now stripped the gearbox
November 20, 20241 yr Check the shift forks for slight bends or wear on the tips or binding on the shaft.
November 20, 20241 yr Author 4 hours ago, lemur said: Check the shift forks for slight bends or wear on the tips or binding on the shaft. That’s my next plan… the shafts are fine and they don’t bind on them.. I was going to put the shafts into vee blocks and check the squareness of the selector forks. Initial inspection shows nothing up..
November 20, 20241 yr I had just assembled a brand new 1995 Fantic section that would not shift at all. After a couple of days of checking the easy stuff I split the motor. I found nothing wrong at all but a blued shift fork from forcing the shift. (Side note, it was assembled without a base gasket from the factory. Plus for the tear down.) Replaced all the shift forks and reassembled. That bike never, ever had another mechanical problem. Just goes to show not all issues are clearly evident. You might fake putting the cases together to get that motor to shift through the gears before the final re - assembly. Good luck.
November 20, 20241 yr Logic I apply is that the shifter forks are the softest and most malleable parts in the transmission. ... and because I experienced the problem first hand on my 360VA Edited November 20, 20241 yr by lemur
November 20, 20241 yr Author Thanks guys…. I’ll take another good look at it all tomorrow with fresh eyes!
November 22, 20241 yr Author Had a good look over everything today… the only issue I can see or find are very slight wear marks on the crowns of the gear selector drum guides, and a very slightly notchy drum bearing… other than that it all looks to be fine… I’ll try and post pictures of the drum but I wasn’t allowed last time… if I do get them posted if anyone has any opinions on wether this would be enough to stop the gears selecting I’d be greatfil to hear your thoughts?
November 22, 20241 yr 1 hour ago, thall1 said: ... very slightly notchy drum bearing… Roller bearings should not feel notchy or they have been compromised.
November 22, 20241 yr Author Yes I was going to replace the bearing as a matter of course… not sure this could be the cause of the issue?… any thoughts on the wear marks on the selector drum?… not sure these would be enough to jam the mechanism.. they look worse than you can feel Edited November 22, 20241 yr by thall1
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