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Firstly, I am loving the new bike. So much easier to ride than my 3TA. It goes well, both in a straight line and round corners and it stops well too. Nice to not have to be going flat out all the time to keep up with the traffic.

However, there are a couple of niggles that I could do with some advice on.

1. Putting the bike into 1st from neutral is far from smooth. Grinding and clunking, as though the clutch is not in at all. However, once it is in 1st the clutch doesn't seem to be dragging at all. It will tick over ok with the clutch in and pulls away smoothly. When changing down from 2nd to 1st it goes into gear smoothly (most times). When starting the bike I give it a couple of kicks with the clutch in to ensure the plates are released.

2. Finding neutral is a nightmare. I can spend several minutes clicking between 1st and 2nd. If I am stopping then often I'll just give up and turn the engine off with the clutch in, but that just defers the problem until I want to start it up again. It is just as difficult to find neutral with the engine off. Very embarrassing when you return to the bike and you have some admirers (of the bike) waiting for me to start it up!

Not sure if the problems are related? I haven't changed the primary chain case oil yet, It seems to have some in as I can feel the chain is wet through the filler hole. Wondering if it could be old or incorrect oil?

Any suggestions as to what this might be? Hoping it's not a knackered gearbox!

Many thanks
Peter


1963 3TA (TwentyOne) Half Bathtub
1968 T120 Bonneville
(Long gone - 1975 Puch VX50, 1976 Suzuki BZ120, 1983 Honda CBR125 TDC, 1991 Honda CBR600)
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Possibly a toothed clutch or if you're lucky just badly adjusted

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That clunking going into first has a part number in the parts Manual. Finding neutral is probably a clutch adjustment. I use my hand to find neutral with the motor off. Chain is wet. What with? Black snot? Time to take that cover off for a look see and cleaning. ATF works best in my 68.
PS You do have a shop Manual don't you.

Last edited by desco; 06/09/21 9:07 pm. Reason: addition

1968 T120R
1972 T120RV
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Thanks AngloBike and Desco

Toothed clutch? Not sure what that means. Damage to the plates?

It's more than a clunk, more of the sound of teeth spinning against each other. Just like trying to get a car in 1st gear without using the clutch!

I do have workshop Manual and some practice/experience with other bikes. I have the PCC gasket, so removing the cover will be the next job.

ATF? Automatic Transmission Fluid? Does it matter what type? I was going to use normal motorcycle oil designed for modern bikes with wet clutches. Is that not a good idea?

Thanks again.
Peter


1963 3TA (TwentyOne) Half Bathtub
1968 T120 Bonneville
(Long gone - 1975 Puch VX50, 1976 Suzuki BZ120, 1983 Honda CBR125 TDC, 1991 Honda CBR600)
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Since the 68 has a separate primary case ATF (type F I believe) will do a better job on the chain. A clutch adjustment should help a bit on the clunk but I don't think it will ever go away entirely. Mine hasn't in 17 years. Check the clutch center grooves for smoothness. Not toothed up (chewed up).
My 72 shifts like it's got eyes but I have had a hard time finding neutral for 35 years. Idiosyncrasies.

Last edited by desco; 06/09/21 11:13 pm. Reason: Correction A to F

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Originally Posted by Peter Williams
It's more than a clunk, more of the sound of teeth spinning against each other. Just like trying to get a car in 1st gear without using the clutch!

ATF? Automatic Transmission Fluid? Does it matter what type?
Peter


Hi Peter,

Aside from proper adjustment, a higher than normal idling RPM can cause this grinding.

As for ATF, Type F is the preferred transmission oil as far as I know.


Jon W.


1957 6T Thunderbird 650
1968 T100R Daytona 500
1971 TR6R Tiger 650
1970 BSA A65F 650
1955 Tiger 100 - Project
1971 BSA A65 650 - Project
1972 Norton Commando 750 "Combat"


"Every time I listen to AC/DC, so do my neighbors"

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Hi Peter, After adjusting clutch & changing primary oil to ATF F, as was suggested lower idle to not faster than 1000 if possible. Then try going into 2nd & then back to first. You are correct to free clutch before starting. Do it both hot & cold before every start.

Here is little video on how to adjust clutch. You don't need the fancy hollow box wrench. Use normal socket held with mole grips (vise grips) to snug nut, then final tighten nut with ratchet handle. I personally like to back off the screw 5/8 turn. I find it works a little better & gives more miles between adjustments. I recommend adjusting clutch rod with every oil change (1500 miles). That gives optimum clutch operation at all times.




After you free clutch, play with clutch lever & keep kicking kicker lever. You'll feel the friction point come in. You want a movement of clutch lever from hand grip before you feel take up on clutch plates. A good 1/2-3/4". Not hair trigger on freeing. Free, then some wiggle room works best. Then heat soak motor a good 20 + miles. Turn off, free clutch & feel the take up of lever again. When motor is heat soaked things expand & you loose left of pressure plate. So checking hot is advisable. Lever free play can be reduced to 1/64" cold as you'll get more play hot if needed.

If you can't get clutch to really free well, the pressure plate lift needs to be measured. Low lift will cause poor release. As was stated grooved/worn slots in cush hub & clutch basket will cause problems. If all that is ok, wear inside cush hub of spider & back plate will cause problems.

In any case when selecting first from stand still, push the lever down like you mean it. Don't kill it down, but don't gingerly select 1st. Every shift should be quick & with authority.


I doubt your transmission is bad. However the shift lever centering springs may be weak, rusted or broken. Rust in outer cover, especially the centering spring area is very common. I'll say 100%. No cure, just what it does. Don't use springs in 650 Manual. Use late T140 springs. 57-7051. They are much stronger & give a more positive center. I've found it helps to find neutral.

Also at standstill motor running, blip throttle lightly. Just as RPM rise begins to fall the gear dog splines are unloaded & slide out of gear easily. Just at the right moment shift to neutral. This takes a bit of practice to get the feel for. Once you get the knack it's works really well. I do it every time. the

Once you set primary oil level with the level check plug, you can take a dowel or screwdriver & reach down through filler hole behind chain & feel bottom of chain case. Pull out & measure oil on your "dip stick". That is what full will be. An easy way to check for now on.

Check your trans oil level also. You can use the level check bolt on drain plug per shop Manual or a flash light looking into trans filler hole you can see oil level. There are 2 shafts. The one where the kicker crescent goes to when you move kicker lever, the main shaft & the other below it is the layshaft. No gears or anything on the end of layshaft. It has a center drilling in the end of shaft. 500 cc will bring oil level to center of center drilling with bike setting level on it's wheels. On center stand block up wheel as needed to hold bike level. These days most use a gear lube 85w-90 or the like. Look at makers web site & make sure it's no ferrous metals compatible. Some newer/modern gear oils are not compatible & will erode the bronze bushings in our transmissions. Be especially careful of GL5 oils.


End of day your learning why 650 was such a great selling bike. They really do work well. Like all machines they need to first be sorted, then maintained.
Don


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it souds like the clutch is dragging , so some amount of rotational Force
is being passed through to the tranny main shaft with the clutch pulled .

it could just be out of adjustment
It could be some clutch parts have passed there prime

in neutral
the tranny mainshaft spins at 1/2 engine rpms
and in neutral the layshaft isnt spinning at all .

when you pull in the clutch the tranny-main still spins
with a a "varying amount of torque " , depending on how good or bad
the clutch releases .
( even with a good clutch some spin Transfers across the clutch
this can be seen with the bike is on the centerstand and the back wheel slowly spinning )

when you shift out of neutral to 1st the spinning main shaft is engaging the stationary layshaft
and you get the traditional Triumph snick of gear engagement .
or you get the extra loud Triumph clunk that signals something is out of adjustment .

if you rev the engine and then let it fall , the main shaft spins up the tranny oil
a little like an automatic transmission torque converter , and the layshaft spins a bit .
when the rpms fall ... first gear can be easier to engage , as both shafts a spinning
... and the gears can mesh while moving ...and without a big , or as big of a clunk .
( there is only a magic moment as the rpms fall where this works )

a lower idle rpm helps ... the tranny mainshaft isnt slamming into the layshaft... in 1st gear
and so does a clutch that disengages ... there's less torque tranfered with the residual spin .

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@TR7RVMan and @quinten - thank you both for taking the time to provide such comprehensive suggestions.

I will have a look inside the PCC at the weekend (hopefully) and see what the state of the clutch is. Will also replace whatever fluid is in there with ATF.

Once that is done I will try to "learn" how to use the gearbox correctly.

Thanks again
Peter


1963 3TA (TwentyOne) Half Bathtub
1968 T120 Bonneville
(Long gone - 1975 Puch VX50, 1976 Suzuki BZ120, 1983 Honda CBR125 TDC, 1991 Honda CBR600)
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As quinten says it makes a big difference on my bike if I pull in the clutch and then wait a a few moments before engaging first. However, because you say it is hard to find neutral, I agree that your clutch could be dragging.

I think a "toothed clutch" might mean that wear has occurred in the chain wheel and centre's grooves in which the plate tangs engage which stops the plates moving properly. Adjustment at the handlebar and pressure plate is the first step as others have said.

Dave

Last edited by dave jones; 06/10/21 7:34 am.
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@ Peter Williams: A good choice of bike, although my preference would have been for the single carb TR6 for the real world performance advantage wink

I'm sure you'll have been through the usual checking or changing oils and filters etc. My Triumph twins were all afflicted with the mysterious loss of tappet inspection caps within a few days of ownership, so that might be worth checking; various locking systems are available. Greasing the swinging arm spindle is another frequently forgotten task.

How do you find the vibration compared to the 3TA?

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Originally Posted by Dibnah
How do you find the vibration compared to the 3TA?
To be honest I think there's less vibration. I haven't ridden the 3TA for a few weeks but I certainly didn't get on the T120 and think this vibrates a lot!

I'll have to ride them back to back and see. Carb rebuild on the 3TA at the moment (when the right bits arrive), so it wont be for a week or so.


1963 3TA (TwentyOne) Half Bathtub
1968 T120 Bonneville
(Long gone - 1975 Puch VX50, 1976 Suzuki BZ120, 1983 Honda CBR125 TDC, 1991 Honda CBR600)

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