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1976 YZ175 Difficult to shift

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Recently acquired 1976 Yamaha YZ175 in pretty good condition but has trouble shifting from 2 on up, just wont do it. New oil, new clutch fibers, new clutch springs, existing steels. Ask only starts with a bump-start, after its warm it starts with the kick starter (if that info helps). It looks like there's a shifting adjustment that can be made in the service manual that I haven't tried yet. Any ideas? Thanks.

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there's a chance the linkage is hitting the case on up shifts.   this is the easier of the 2 fixes.

 

left side:

remove shifter lever.

remove shift cover.

reinstall shifter.

 

pull up on lever to see how the linkage works.  if you have it indexed wrong, it can hit the case on up or down shifts.- you'll see it....  if so, just remove circlip and remove linkage/reindex so it doesn't hit.

 

 

if this doesn't fix it.   take clutch cover off, clutch, etc.  look at how the selector arm is centered along the pins of the shift barrel.  should be centered.  there's an eccentric adjuster pin the return spring rides on.  loosen locknut and adjust pin until the selector 'fingers' are equally spaced between the shift barrel pins. play with it until it shifts best.  tighten locknut.  put it all back together.

 

 

 

 

 

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there's a chance the linkage is hitting the case on up shifts.   this is the easier of the 2 fixes.

 

left side:

remove shifter lever.

remove shift cover.

reinstall shifter.

 

pull up on lever to see how the linkage works.  if you have it indexed wrong, it can hit the case on up or down shifts.- you'll see it....  if so, just remove circlip and remove linkage/reindex so it doesn't hit.

 

 

if this doesn't fix it.   take clutch cover off, clutch, etc.  look at how the selector arm is centered along the pins of the shift barrel.  should be centered.  there's an eccentric adjuster pin the return spring rides on.  loosen locknut and adjust pin until the selector 'fingers' are equally spaced between the shift barrel pins. play with it until it shifts best.  tighten locknut.  put it all back together.

Thanks! I actually did both and it is working better, not perfect yet but at least I can find all the gears. Still probably need to tweak reindexing the shifter but much better than before at least.

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Some of the detents on the shift cam plunger had a hole in the center, instead spirals on side.  This tended to wear and seal creating a "hydraulic lockup".  Its a hex head on bottom of engine, when removed you'll have a plunger & spring.

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Some of the detents on the shift cam plunger had a hole in the center, instead spirals on side.  This tended to wear and seal creating a "hydraulic lockup".  Its a hex head on bottom of engine, when removed you'll have a plunger & spring.

Having trouble locating the parts, is it something in one of these diagrams? If not I can post others. Thank you.

image.jpg

image.jpg

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First image, #9 "spring screw". It's showing a ball bearing; but that's not necessarily what's in there. Pull to check, if spring binding or dirt will also result in stiff shifting

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on your crankcase there's possibly 2 holes in the left case top with bolts in them - 1 is the shift detent stop spring/pin/bearing setup, 1 is unused - i assume for a neutral indicator - i can't remember if your cases had 2 or 1...

 

also spring 15 and 16 in 'shifter 2'  on the fiche can wear out and cause other shift issues.    as yzmann said, clean shift detent/spring really well - it gets sludged up, and can make it really notchy/hard to pull up on the shifter..

 

also the shifter cover hole that the outer shift shaft goes through, it can wallow out, and make shifting difficult - when you pull/push on lever it tweaks the angle/leverage on the linkage and can make it hard to shift..

 

 

if bike only starts cold with bump, there's an issue with your carb - pilot,choke circuit,  or slide cutaway.  or your ignition sucks.  these should start 1 kick cold/hot/anytime.  the primary gear ratio on these is really good, so the piston gets plenty of revolutions on each kick to get them running...

 

if for some reason you decide you don't like the bike, i'd gladly take it off your hands :)

Edited by nyabinghi
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on your crankcase there's possibly 2 holes in the left case top with bolts in them - 1 is the shift detent stop spring/pin/bearing setup, 1 is unused - i assume for a neutral indicator - i can't remember if your cases had 2 or 1...

 

also spring 15 and 16 in 'shifter 2'  on the fiche can wear out and cause other shift issues.    as yzmann said, clean shift detent/spring really well - it gets sludged up, and can make it really notchy/hard to pull up on the shifter..

 

also the shifter cover hole that the outer shift shaft goes through, it can wallow out, and make shifting difficult - when you pull/push on lever it tweaks the angle/leverage on the linkage and can make it hard to shift..

 

 

if bike only starts cold with bump, there's an issue with your carb - pilot,choke circuit,  or slide cutaway.  or your ignition sucks.  these should start 1 kick cold/hot/anytime.  the primary gear ratio on these is really good, so the piston gets plenty of revolutions on each kick to get them running...

 

if for some reason you decide you don't like the bike, i'd gladly take it off your hands :)

I've gone through all the recommendations - thanks!

What I'm left with is:

1) the Change Shaft Assy 2 ( outer shift shaft) does have some play both in and out and "up and down". I assume to remedy that I would need to replace the Oil Seal ( for the up and down wobble)? Is the in and out play ok and if so - how much?

2) in the SHIFTER 1 diagram the 3. Side Plate has some nicks on the outer edge presumably caused by the top claw of the 14. Change Shaft Assy (SHIFTER 2 Diagram) which is pressing directly on the edge of the Side Plate and possibly popping over the edge at times when it seems it should ride more toward the middle of the dowel pins. Any ideas on how to get the Shifter Shaft Assy closer to the middle of the dowels?

Thanks for everyone's help.

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I've gone through all the recommendations - thanks!

What I'm left with is:

1) the Change Shaft Assy 2 ( outer shift shaft) does have some play both in and out and "up and down". I assume to remedy that I would need to replace the Oil Seal ( for the up and down wobble)? Is the in and out play ok and if so - how much?

 

 

2) in the SHIFTER 1 diagram the 3. Side Plate has some nicks on the outer edge presumably caused by the top claw of the 14. Change Shaft Assy (SHIFTER 2 Diagram) which is pressing directly on the edge of the Side Plate and possibly popping over the edge at times when it seems it should ride more toward the middle of the dowel pins. Any ideas on how to get the Shifter Shaft Assy closer to the middle of the dowels?

Thanks for everyone's help.

 

 

1) you need to either bush the cover, or find a better cover.   the seal does nothing to fix the wobble.  in and out movement of the shaft the shifter lever is on?  there are 2 shims (8) that keep it tight, but there will still be some in and out movement..

 

2) in image 2 is circlip (11) tight and the groove not wallowed?  is plate washer missing(12)? also, spring (15) could be totally worn and not keeping the arm tight against the barrel..

Edited by nyabinghi

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Plate washer 12 was on the right side of the engine instead of left causing the shift shaft assembly to be misaligned. Guess the previous owner didn't have the shop manual I do!

Edited by motopitdad543

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Plate washer 12 was on the right side of the engine instead of left causing the shift shaft assembly to be misaligned. Guess the previous owner didn't have the shop manual I do!

do you have digital copy of shop manual?  i could really use one..

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do you have digital copy of shop manual?  i could really use one..

Sorry nyabingha but I bought mine off ebay from an Austrailian seller that took the original manual and supplements, scanned them then enlarged to 8.5x11 and bound in zebco format it's nice to have it that large, but it's nots digital. I could upload some pics of specific pages like I did above if needed.

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