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Motorcycle Repair/1974 honda qa50 clutch


QUESTION: good evening wayne! i just re-built a 74 honda qa50 engine,i,ve godd it all dialed in..(great compression,idles perfect,the thing sounds great....until i put it in 1st gear! then it learches foward and dies! it appears to me that the clutch is not disengaging? i had re-built the clutch springs,clutch plates,rollers...while inspecting i saw no grooves in the basket or problems with the clutch bushing? but when installed in the bike it stays locked up(engaged)? i,ve taken it apart again to re-inspect and re-installed and still will not disengage? when i took it apart the 2nd time the only thing that raised a flag was the clutch plates seemed to still be pretty dry??? so on my 3rd attempt i decided to use another clutch that i bought on e-bay,it (the new clutch)had alot of oil still on the plates so i figured i give it a try.....put it back together,started it up,put it in 1st...a lurch foward and stalls right out??? i tried adjusting....(screw all the way in then turn counter clock-wise until you feel slight drag,then back off a quarter turn)to no avail? actually i moved that adjuster every which way but loose but still....will not disengage???? i would love to hear your thoughts on this wayne because in stumped? thanks so much,rick

Hi Rick,

These clutches are quite an invention by Honda.
First off the clutch friction plates should be soaked
in the same oil you use in the bike for an hour or so.

You didn't say if these were honda oem plates or
an aftermarket brand plate. The thickness is important
to the function of the clutch.

The outer release mechanism has to be lined up
as in the manual to properly release the clutch
when the shift lever is pushed.

When the clutch unit is on the bench you should be able
to grab the gear in the middle of the clutch and hold the
outside of the clutch and turn the inner gear in one direction.

As you turn the inner gear the plates should allow the clutch to slip one way
and grab in the other as this is how the kickstarter works.

If the gear cannot be turned by hand then the clutch pack
is too tight. Was the big clutch plate snapring or circlip hard to get in
after installing the plates?

Check your assembly closely and when you adjust the screw
don't turn it clockwise very far just a turn or so.
Back it out until the resistance is very light and then
turn in 1/8 turn and lock it.

Small but tricky little clutch, let me know if you need more details.


---------- FOLLOW-UP ----------

QUESTION: hi wayne,the clutch plates are oem honda,i have the outer release mechanism lined up as in the Manuel,when on the bench the inner gear of the clutch will slip in 1 direction and grab in the other as you said.i soaked the friction plates over nite and re-installed them,they went in easy,the snap ring went on easy as well(didnt have to push down hard at all)so im assuming the thickness of plates is good? i put everything back together and readjusted the clutch as you said(a turn in,them counter clockwise until slight resistance then back in about an 1/8 of a turn. started it up,it had a rattling type noise coming from the clutch case side? the noise was fairly loud but went away in about 5 seconds! so i let it warm up a bit,put it in gear and it stalled?(still engaged)same as i tried another clutch that i have and it too will not disengage? if you push start the bike 2 feet it starts right up! runs and shifts great?(i fixed the 2nd gear slip,it does jump out of gear anymore)but it will not disengage? all the pieces on the gear shift spindle are installed as per manual,clutch lever,spring,master arm,change arm all in correct location with snap rings where they are needed? a friend had mentioned it could be a crushed center bushing as they were sometimes made of bronze? but the qa center bushing is not bronze and in comparison with 2 others i have(center clutch bushings)appears to be fine?do you think this could be a circulation problem?? maybe oil pump???? but then again the bike runs really quite valve tapping or anything like that so im not sure????? sorry for the million word question,but im dumbfounded at this point??? thank you wayne

Hi Rick,

It sounds like the clutch unit is working but sounds like a problem with the release mechanism.

When you hold the shift lever up or down all the way the clutch should be released even when
it is in gear. When the shift lever is allowed to go back to center the clutch is engaged
but only as the engine rpm goes up.

In other words if your release mechanism is working the clutch will disengage the engine
when the shift lever is held up or down.

If the lever is held up/down and the bike still wants to move then the release mechanism is not working
in the clutch case.  If the clutch releases when you hold the shift lever then the problem
is with the idle too high or the rollers engaging the clutch too soon for some reason.

That is my best guess at this point. The rattle you mentioned in the cover is curious as well.
Could the clutch not be contacting the release mechanism for some reason? Perhaps
something is not spaced right in the cover. Very hard to visualize online.


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Wayne S.


Licensed Motorcycle Mechanic, Knowledge of motorcycles from 1960 up, Japanese, British and most other brand motorcycle repairs.


Worked for Yamaha, Honda, Suzuki, Kawasaki British: Triumph, Norton, BSA Other: Most Scooters and Mo-Peds

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