ok... still plodding on with the rebuild of my 76 DT175C
since it went back together "one" of my issues is the gear selection, am not getting all of them
unsure which gears am actually getting but basically one down and another up and neutral then nothing
i think this is possibly something to do with the cam dowel pins (i did remove these thinking it was needed for strip) or the shift selector?
or the shift arm?
imgur.com/a/Vy44Ot5
transmission went together ok as far as i could tell wasnt much to get wrong there
thanks again
D

 

Are you riding the bike?

Shafts must be turning to allow the dogs to engage the slots in the trans... bench shifting can be done if the transmission shafts are spun by hand or by rotating the rear wheel to spin the output shaft via the chain. They still don't shift well unless engine is running and you're rolling down the road.

thanks yes this was riding
i will get the clutch cover off next week and see if the dowels are correctly positioned on the cam
one is a half dowel pin for some reason (neutral perhaps?)
it selected ok on the bench as you say as long as your rotating the output shaft
hoping not to have to split cases again but prepared that i may have to

Not likely to be internal.

Can you turn the drum by hand & get 5 gears plus neutral.
Be hard turning it against the arm roller & spring & need to turn one shaft a little for the dogs to engage.
But testing that way you're checking internals to see if sitting as they should.
Think you should get neutral as well even if the short pin is misplaces as neutral is controlled by the ball & spring.
But the short pin has to be right for the claw arm to change all gears correctly.
www.partzilla.com/catalog/yamaha/motorcy...t175c/shift-cam-fork

Also that @#$%%^stupid yamaha setup on the left, you might be able to set it one spline out on #10 [just looking at the pic] & get almost no movement one way & a gear & a half the other--something like that lol. Just things to consider.
www.partzilla.com/catalog/yamaha/motorcy...6/dt175c/shift-shaft

thanks again will try that
this is what i am seeing on the shift cam clutch side
deffo something not right somewhere
imgur.com/a/bicQTf7

..also still getting bogging down on opening throttle (on occasion not all the time)
idles fine
thinking that oil seal has gone in too far due to the collar maybe?
imgur.com/a/U2AhmxB

You're not spinning the shafts so that could be the reason the linkage isn't moving the shift drum. 

Did you fiddle with the eccentric adjustment screw that sets/limits the linkage travel?   It's at the bottom, not shown in your video.  If you messed with it, or if it needs adjustment, manuals have the adjustment process which involves centering the "claw" on the drum pins.  You'll likely have to remove clutch. 

ok thanks that's good info, any not splitting of the cases is good news really
imgur.com/a/KD64zlK
is this the eccentric screw reffered to?
if so yes i did remove it to split cases realized after i needn't have done so
i did note the clutch arm was riding high
imgur.com/a/gBnQSHi

No, that's the clutch adjustment eccentric screw.

Shift linkage adjustment screw is under the clutch cover on other side of engine.