Gearbox Stuck - The last straw?

[SeanFD]

It took me 5 years, off and on, to go from this:

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to:

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The last couple of weeks have been frustrating as the bike seemed determined to stay in the garage. One little problem surfaced after another; it would run one day, and then not start the next; it fell over breaking the tail light lens ....

Finally I got everything sorted and took a short ride up and down the street, then around the block. Everything seemed fine. Got myself properly dressed for a longer ride, and ... the starter was dead!

I checked everything, found nothing wrong, tried the kickstart again, and it started! 🤷‍♂️ Starter was now working too!!

I started off down the road, slowed and changed down for a junction, and then couldn't engage 2nd gear. And that's how I rode, thankfully not far, home.

So now I can only move between 1st gear and neutral. The clutch engages and disengages with the bike in 1st. But no second gear.

My plan is to check clutch adjustment as a first step, but before I start taking covers off, has anyone any suggestions as to the possible cause of theis latest gremlin!

If it comes to splitting the cases, she's going back on the shelf!

[Johnny4428]

That’s a lovely looking resto Sean. Seems it is trying your patience a bit but there are always niggles with the newly restored/rebuilt. I would go for selector mech.

[Athame57]

I started off down the road, slowed and changed down for a junction, and then couldn't engage 2nd gear. And that's how I rode, thankfully not far, home.

So now I can only move between 1st gear and neutral. The clutch engages and disengages with the bike in 1st. But no second gear.

I had this issue for a few days and discovered all I had to do was reposition and tighten the gear change lever. 

[Athame57]

Finally I got everything sorted and took a short ride up and down the street, then around the block. Everything seemed fine. Got myself properly dressed for a longer ride, and ... the starter was dead!

I checked everything, found nothing wrong, tried the kickstart again, and it started! 🤷‍♂️ Starter was now working too!!

I'm having this issue intermitantly myself even now, on the list for things next visit to garage. I had it once before, I'm not sure what the mechanic did but the issue was with contact when I pressed the starter button, maybe he just cleaned something for me. Don't panic! 

[SeanFD]

Oh, the starter is working now!

That's why this has been driving me crazy. One minute things are working, and then not!

[SeanFD]

I started off down the road, slowed and changed down for a junction, and then couldn't engage 2nd gear. And that's how I rode, thankfully not far, home.

So now I can only move between 1st gear and neutral. The clutch engages and disengages with the bike in 1st. But no second gear.

I had this issue for a few days and discovered all I had to do was reposition and tighten the gear change lever. 

Checking the clutch is actually No 2 on my list. The pedal is No 1; it is too low now - it was hard to get my foot under it to change up before the problem started - so I'll adjust the position and see.

[K2-K6]

Ordinarily the clutch .... shouldn't  .... affect the gear change mech on bike engines, that's without a very obscure coincidence.

They are, in essence, a pretty crude device. The selection should work regardless of any clutch adjustment.

With it on msinstand, rotate rear wheel back and forth while trying to select and go through ratios. If it's refusing that, then probably next inspection is selector mechanism which I recall is behind the clutch on these  ?

It may be something very simple displaced or snagging.

[taysidedragon]

My 400f doesn't like changing gear or finding neutral when the clutch adjustment is out of spec.

I suggest slackening off both ends of the clutch cable and remove the triangular cover on the clutch cover. Adjust the screw and locknut on the clutch release first, then the cable at that end. Lastly adjust the free play at the lever end.
When you check the gear lever make sure that the dot markings are in the right position on lever and shaft. They can be really hard to see on old parts. Also lubricate the rose joints. Any stiffness affects the gear lever action. 😉

[florence]

I agree with going through the gears, without engine running, by turning rear wheel and operating the gear lever by hand.  If this doesn't work then the selector will be at fault.  My 350, which is a similar design, decided to stay in top gear on a run once.  I had to ride all the way home in fifth.  Once at home, when I took the clutch cover off, I found that a bolt in the selector had come loose and the selector fork couldn't engage properly.  I would start there and see how you get on.

[Bryanj]

Most common problem with bad 400 gearchange is the operating lever on wrong spline of gearchange shaft and physically hitting something

[SeanFD]

I adjusted the position of the pedal - no difference.
I adjusted the clutch - no difference.

So reluctantly I took the clutch cover off - again – and this is how things are moving, or not, behind the clutch.

https://youtube.com/shorts/EwoXVoCQp5g?feature=share

I am moving between neutral and 1st gear and back again, and then unsuccessfully trying to shift into second.

I guess I'll have to remove the clutch as the next step?

[Bryanj]

You need to spin the rear wheel whilst trying to select a gear

[SeanFD]

I did; made no difference.

Even tried it with the engine running - before I took the cover off.

[Bryanj]

Remove the clutch the try turning both the clutch shaft and rear wheel whilst trying for a gear.
If still no joy look carefully at the detent mechanism and pins plus trying to turn selector drum with staked screw on end.
If still no gears, sorry something is incorrect internaly

[SeanFD]

OK, thanks.

I'll try that once I get the clutch off. Trying to find someone with a castellated socket; I'm here with 4 spanners, a screwdriver and a vise grip!