Still issues w/ the 750 gear selector

TeddyG

TeddyG

Hero member
Location
Portland Oregon
This message is for Pirhana who previously outlined the steps that I've followed below:

The bike is in a true neutral from the idiot light/ the main gear wheel notch is at a true 3 o'clock/ the smaller gear is inserted with notches even w the larger gear/the mounting case is first nudged back and forth before tightening the 4 bolts so there's minimal free play between the gears/ the selector arm "hooks" are centered over the dowel pin (there are 4 pins on the drum) by turning the adjuster screw and then tightening the 13mm nut/the main spring is not touching the selector arm/the outer case and lever are attached.

But I can only get into first gear and then back to neutral- when shifting up to 2nd, the selector arm is not grabbing any of the other four dowel pins since the drum is not rotating. The clutch cable is properly attached, I've tried engaging the clutch while shifting, and the drive chain is now attached.

Others have said the selector adjustment needs to be done in 4 th gear, but it won't shift that high.

I didn't want to take it apart but had to in order to remove the motor and inspect the front sprocket.

I've also looked at the Green Book, but see no additional info or trouble shooting

So Pirhana, what am I over looking?
Thank you Sir!
 
You absolutely need to pivot the rear wheel backwards and forwards while applying pressure on the shift lever. If you've seen inside the gearbox you see why: the engagement dogs on each gear will butt up against each other in certain positions and not slot into place - rocking the rear wheel allows the gears to find the position where they can engage.

The other thing is to look at the large spring while applying pressure on the lever and ensure it isn't getting caught between the eccentric adjusting screw and the selector arm. When the outer cover is not in place there's nothing to to prevent the spring from twisting a little sideways (and this can even happen when the cover is on!!).
 
Thanks again Pirhana,

After trying multiple times by starting out with the selector "hooks" evenly spaced between the drum "pin" w/ both marks aligning, and getting the same bad results, I tried starting out in neutral with the top "hook" almost touching the pin, and it's final shifting better into the higher gears. I am rocking the wheel while moving the shift lever, and shifted while sitting on the bike and pushing it. The spring prongs aren't touching the selector plate and are riding near the outer edges of the adjuster screw. When I initially removed the mechanism, the locking nut wasn't tightened and it's difficult to grab with an open end wrench, so I took an old cheap flat metal wrench and bent it to make a sort of crow's foot.

I'm assuming that the fresh oil I just put in will have to be drained if I want to take the cover off to adjust it some more?
 
You can lean the bike over a bit to still hold MOST of the oil, I like to add a safety rope to avoid dropping the bike. So proped up so the rear is off the ground and leaned over as far as possible, TAKE CARE. BTW this can be very frustrating, I once spent a bad 6 months without 5th gear before hearing all the VOODOO tricks. How good would a perspex cover be to see what's happening? I have got it right only to brake that big spring and have it happen again. Lately, on occasion, I still need to do the Laverda tap dance to get 1st. You go all the way down but still have neutral, it takes a slight lift up and then down. Not all the time just occasionally.
 
When setting up the SfQ I had hell trouble with it shifting fine with the cover off , only to persist in remaining in 2nd when it felt likeit had shifted into 3rd. Assuming it needed to travel more towards 3rd, I adjusted accordingly, only for the problem to persist. In the edn i went THE OTHER WAY! It shifted and continues to shift beautifully; while the space between hooks and pins looked fine, it was wrong - and what was actually happening was the selector was moving the drum TOO far.

I've designed in a couple of custom changes for 'insurance' to absolutely prevent the big spring going under the selector arm and eccentric. With the tools, I use the angle alu in the adjuster slot and as well as holding the screw while locking the nut, I use it to mark a line on the cover gasket face as a reference point when adjusting higher or lower.

Selector spring retainer.jpgSelector eccentric customise.jpgSelector adjustiong tools.jpg
 
Thanks guys- from setting it up multiple times following the directions with no success,I can say that the adjustment screw is finicky. When I initially took the cover off and looked at it, I knew it would be a can of worms. The bike was previously shifting into higher gears, but with some hesitation and free play at the shifter. I,ll have to experiment with different adjuster settings and hopefully get it right. I just got the motor back in after having work done to it and eager to start it up.

Pirhana- do you mean that the spring ends touching the adjuster should not move during gear changes? because I,m seeing the spring end that touches under the adjuster move and spread apart during gear changes. The spring coil is not touching the arm. Just trying to get this working properly-
 
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In the Green Book it is recommended to adjust in 4th/5th gear. And of course
check it in all the other gears afterwards.
I never had to do that, but might help in your case.
Good luck, Ernesto
 
The 4th gear thing is because it is easier to see the spacing on the Hook is an equal gap top and bottom. Where the problem is any slop in the system also comes into this adjustment as well. You need to allow for that slop or loose movement as well. Just like steering head adjustments, this brings in trial and error. Good luck, start crossing your fingers and spitting 3 times. I have had some head-banging episodes doing this, Where I end is loosely fitting it together and working the gear lever while hand-turning the rear wheel and bumping the case cover to remove any pressure or binding on the internal workings, keep it up till you confidently are getting all 5 gears. The more common problem is missing 1st or 5th, Sticking in one gear probably means one of the covers is binding on a shaft, MAYBE.
 
Teddy. The eccentric - there are different diameters - is it possible a larger one has been mixed-in on your bike and is therefiore limiting the max throw of the lever? Or vice versa?

In orther words - these 2 items - if they are mismatched you will get too much, or too little, throw. Both will bugger up the change quality.
delme 750.jpg

(Don't worry about the black stuff folks - just an experiment with Moly)
 
Thanks again guys,

All the mechanism parts have been left alone and not changed since the bike was ridden last, and the smaller pinion gear will in turn rotate the larger gear (when the hook arm engages w/ one of the 4 drum dowel pins). I haven't tried it manually with the selector arm disengaged but I'll try that next. The problem is that as a higher gear is selected, the "hook" isn't synched with the next dowel pin. I think the whole mechanism needs that concentric adjuster positioned just so, and I've tried multiple settings. I'm wondering if possibly that 50 yr. old smaller spring may be worn out and causing the problem?
I'll show it to a friend w/ mechanical bike experience and hopefully we can figure it out.
 
It won't be due to wear. There should also be no play up-down in the lever shaft when the spring is over the eccentric, which would indicate that the spring legs are too wide apart. Both legs should contact the eccentric - the slop could be preventing the hook slotting over the next pin.
 
Thanks once again Pirhana,

The spring tangs are initially gripping the adjuster screw, but I recall the lower tang moves away from the adjuster as the shift lever is moved up or down. A friend helped and tried different settings on the adjuster, and it seems to be working better. She said it's designed better than the Norton equivalent. I'll know more when I take it out for a test ride tomorrow. The rebuilt motor fired right up and sounds healthier with more exhaust back pressure.
 
Cool! You've had start-up, Ted. Fingers crossed it's a fine running machine that just needs a little fine tuning and ashort run in. Don't pussy it running it in. Plenty of throttle will give you the combustion pressure to help bed in the rings.

I reckon a spacer over the splined lever shaft to act in place of the cover while it's off would be a good setup tool - keeping the spring in exactly the place it will be when the cover is back on (no twisting). Have you go the eccentric turned so the long side is at 3 oclock and not 9 oclock? This offers slightly more travel than the other way around. Not relevant now that you've closed her up but if you do have to readjust might be worth checking then. I lean my left clipon against a doorway upright to give me enough angle to remove the cover without oil going everywhere.
 
Thanks again Pirhana- the motor should now perform as it should instead of struggling to reach 50-60mph. My friend tried slight variations and the slot was at @ 1 o'clock and I don't recall the lobe orientation, but it seems to be shifting into the higher gears. I'll see how it does during a test ride.

Question on properly setting the cam chain tensioner- I installed a new nylon wheel and rubber bumper, and compressed the spring and plunger and locked it down. The unit requires a little force to seat into the motor opening and it's then bolted in place. The plunger lock bolt is released but I see no movement from it, nor when the motor is advanced a few times. Before hand, I checked that the plunger is moving freeley and lubed it. So how do I know if it's pressing too hard against the chain- should it fit into the opening with no pressure? One Laverda expert recommends shaving down the rubber bumper so that the tensioner easily fits in place, and the Green Book doesn't offer much info.

Opinions on this?
 
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With the motor rotated forward so the slack (if there is any) is on the rear side of the chain, the tensioner shouldn't require anything more than gentle hand pressure to seat fully against the barrel. So depends how much pressure you're needing, if you deem it excessive you can shave the rubber down or fit a second gasket. It doesn't matter if the plunger doesn't move inward when you loosen the bolt because you know there's positive pressure on the chain. There are a couple of crank positions in which the slack in the chain is greatest (or tension on the front of the chain is highest - same thing).

Don't forget to nip it up again and secure the locknut.
 
Thanks Pirhana,

Now that the cylinder and head have been correctly torqued down, there is some slight slack in the cam chain (which is good). With the tensioner spring fully compressed, when it's fitted into the housing, it sticks up at the top @ 1/2 an inch and requires a little bit of pressure to seat in fully. I've kept the old gasket in place and added a second. With the plunger unlocked, it doesn't move in or out when the motor is advanced a few times, so I'm thinking it's OK. When I received the bike, the lock nut was loose (like several other things on the bike, including the lower motor mount bolts and a dangling enricher plunger, etc). With all the work I've done to correct lots of things, the bike should now run properly, and it's been satisfying to see the progress. These are beautiful machines!
 
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