Forcing to shift

I have a 70 commando with 6000 miles the bike ran fine with no issues. The motor was taken apart because of oil leaks. The engine was sealed and everything was put back together and now have 1 issue I have to use force when shifting gears. Any thoughts on what needs to be done? Help!!

Primary chain too tight?

˄˄ +1

Over tighten primary chain or clutch adjustment or sticking plates is usually the main problem with hard to change gears, if set right it should be just a light click and smooth change and easy to find neutral, but I say it be over tighten primary chain.

Ashley

Debo said:

I have a 70 commando with 6000 miles the bike ran fine with no issues. The motor was taken apart because of oil leaks. The engine was sealed and everything was put back together and now have 1 issue I have to use force when shifting gears. Any thoughts on what needs to be done? Help!!

Click to expand...

There is so much to know.
(I'm still learning)
Crankcase check valve to reduce oil leaks.
As mentioned above, a misadjusted primary chain will cause drag on the mainshaft= hard shifting. Clutch has many subtleties as well.
Tell us more...
Did you do the engine work yourself?
Your skill set?
What (level of mechanical work) are you wanting/willing to do to solve the problem?
It will help us to know how to proceed.

The long version of +1 on tight primary chain

Chain adjustment is an art form. It only takes one tight spot in the run of the primary chain to make it too tight for the gearbox. Chain has to be checked all the way around more than once during assembly. Fortunately it's easy to adjust after the fact without removing the primary cover. Move the gearbox forward incrementally in small steps and test until shifting feels right. You have to adjust/check both the primary and rear chain at the same time more or less. Rear chain should be adjusted with rider weight on the seat feet on the pegs, but you can fake it till you make it. A little loose is always better than too tight.

If you worked on the gearbox while the engine was apart, that could be part of it. Could also be the clutch not disengaging from the gearbox easily. Clutch center notched too much, excessive gear oil leaking onto the friction plates, over torque on the big nut holding the clutch on the gearbox main shaft. I'm not that familiar with Commando clutches. Many after market manuals sight around 20 ft lbs too much torque, or so I've been told.

Primary and secondary chain adjustments are counter intuitive. The Rider's Handbook goes through it pretty good.

And yes a primary chain that's too tight will cause this issue and is hard on the trans shaft. Don't leave it like this.

Debo said:

I have a 70 commando with 6000 miles the bike ran fine with no issues. The motor was taken apart because of oil leaks. The engine was sealed and everything was put back together and now have 1 issue I have to use force when shifting gears. Any thoughts on what needs to be done? Help!!

Click to expand...

Debo:
I have been working on British bikes since building a 60's Bonneville engine at age 16. Unfortunately, not much Norton work.
However, I have a question and few thoughts: What did you use to seal the oil leaks?

A few years ago, I had forced shifting after a gearbox rebuild. I had shimmed the mainshaft to .010" end float as recommended. Shifting was very hard; so hard it quickly wore the shift forks. Subsequent disassembly revealed a star field of swirling metallic bits in the gearbox oil. A bent shift fork spindle was noted as well--don't know if this bent spindle was a contributor to the shifting issue or a result of forcing shifts.

Replacing the worn/bent parts and resetting the mainshaft clearance to .030" helped some, but thoroughly cleaning the clutch plates in acetone solved it. Smooth shifting ever since. Now running ATF in the primary and using Dyno Dave's clutch nut and seal.

I am not suggesting this is the issue with your Commando, but it was the issue with mine. Certainly, between your diligence in tracking this down and the collective knowledge of the folks in these forums, the issue will be resolved at some point.

Regards,
998cc

After you put the gearbox together, did you spin the main-shaft and counter-shaft to check there was no drag, which might have been due to mis-assembly ? Most people know how to check chain tension.

Norton's like a bit of end play, after 46 years and well over 160k miles on it my gear box still shifts smoothly.