transmission

[cushmanscooter]

Hello All, Am working on another 305 dream. First gear problem, will not stay in gear under load. Bike on center stand, engine running, can go thru all gears up and down very smoothly and good. Bike on wheels when you release clutch transmission comes out of low with a "ratcheting sound" Doesn't really sound like a gear grind. Also, If you slow walk beside the bike you can go a considerable distance--say across the garage--before bike comes out of gear. QUESTION??? Is there any one part I need to be looking at for replacement or repair? Any input or help appreciated. Thanks and......"Keep 'Em Rollin' " Hal

[48lesco]

CMS - I think your dogs are worn. The pics show the gear sequence on a CB77 and how the dogs engage. The CA77 transmission is very similar, except that the dogs are not "undercut" like the ones shown and are more apt to disengage especially if there's some wear in the shift drum, forks, etc. and they aren't completely engaged to start with. You'll have to split the cases to find out what's worn, but you can find NOS and good used parts to fix it.

[cushmanscooter]

Exactly, what does the "shift drum" do??

[G-Man]

The shift drum contains the cams that actuate the shift forks which move the gears along their splines to engage and disengage each gear.

G

[OldScrambler]

Nice PIcs..............so one dog went for a walk!

[cushmanscooter]

Any body have a good picture of shift drum, shifter cams, shifter forks, etc.??? And, maybe the location of drum, cam, forks in transmission. Thanks again and------"Keep 'Em Rollin' "

[bamacl]

The shift drum is in the top engine case above the trans. The shift forks fit over and ride on the drum. The "cams" are not parts but machined channels in the drum that guide the forks movement for proper gear selection. Look at the pictures, top shaft / 2nd gear from left, bottom shaft / 2nd gear from right are the "slide" gears. They are the ones that move left or right for gear change. You can only see the tips of the shift forks on them. Now all that said and not to be an a-- but you really need to pick up a shop manual before you try to tackle this job. If I were closer I would be happy to help you.