Gear selection difficulty

[jamestnewsonr65]

Hi, since refurbishing my bike (gearbox / engine untouched) I have found it a little difficult to sometimes select 1st from neutral.

I have to either roll forward or backwards a little to get it to go into gear. Is there any adjustments that can be made? I've already adjusted the gear cable spacing but it nothing seems to make it any better.

It doesn't really stop my enjoyment of the bike but I would like to use it to commute to work in the warmer months occasionally.

Does anyone have any suggestions?  I have changed the original pedals to rear sets so I guess there may be an issue with the alignment?

Thanks
James

[Barry]

I have to either roll forward or backwards a little to get it to go into gear. Is there any adjustments that can be made? I've already adjusted the gear cable spacing but it nothing seems to make it any better.  

This is normal.

At a standstill it is a lottery whether the engagement dogs line up with the slots. Most times they do as there is more chance they will than they won't but in certain positions they won't engage. That's why rolling back or forward allows 1st to go in by rotating one part with respect to the other until the dogs and slots do align. Releasing the clutch and pulling it in again will have the same effect.  

The problem arises on our bikes because there are no synchro cones as in a car gearbox which help rotate the engagement dogs until they are aligned and we have a dry clutch which completely disengages drive from the gearbox.

If there is a tip that will improve the odds for you it's this: when you pull in the clutch put it in gear straight away. The idea is to engaging first while there is still a little inertia rotating the gearbox shafts which will help the dogs align. If you wait too long the shafts come to a complete standstill and it's then back to a lottery if they are aligned or not.   Wet clutch bikes don't have this problem as there is always a little drag to keep things rotating.

Understanding what is happening inside the gearbox illustrates that there is no adjustment that can be made that will fix it.

[jamestnewsonr65]

Thanks for replying and clearing that up Barry. Your knowledge has helped me greatly in the build of my bike.

I've been used to modern (Yamaha MT-07) bikes up until this one so have to get used to knowing how it rides as I didn't ride it before the tear down and rebuild.

Thanks for the info.

[Motu]

there are no synchro cones as in a car gearbox which help rotate the engagement dogs

A syncro has many dogs with tapers to help them align, 4 square cut dogs in a bike gearbox don't help at all.  My bike became difficult to get into 1st from neutral, no problem from 2nd, so easy to work around....for a few weeks.

Then one day coming out of a corner I changed into 3rd,3rd,3rd - a broken pawl spring.  I guess the partly broken spring could pick up the pin for 2nd, but the pin for 1st was too far around.  A lot of work to replace a $3 spring.  

[Barry]

A syncro has many dogs with tapers to help them align, 4 square cut dogs in a bike gearbox don't help at all.  My bike became difficult to get into 1st from neutral, no problem from 2nd, so easy to work around....for a few weeks.

Then one day coming out of a corner I changed into 3rd,3rd,3rd - a broken pawl spring.  I guess the partly broken spring could pick up the pin for 2nd, but the pin for 1st was too far around.  A lot of work to replace a $3 spring.    

It's interesting that the hard engagement of 1st was followed by the spring failure. You'll be getting James alarmed.  At least 3rd wasn't a bad gear for the pawl spring to fail in.

As I understand it in later BMW gearboxes they did adopt tapered dogs with the first part of reduced width helping to ease engagement but the down side to that is you then have to be even more deliberate with the gear change to ensure the full length of the dog gets engaged and not just the first part.

For all their reputation of Airhead gearboxes being more challenging than others I really don't find mine to be a problem in regular daily use. After a number of years I ceased to think about it.  Considering it's an engine speed dry clutch and gearbox being compared in most cases to a reduced speed wet clutch and gearboxes on Japanese machines I think our gearboxes and the quality of gear change is not that bad at all.

[Luca]

Agreed.  Once you get the technique down they really shift pretty nicely.  I wouldn't make a habit of it, but I've done some pretty quick shifts under hard acceleration where I preload the shift lever and give the clutch lever a quick pump.


James, if you do get to where first won't engage, you can also let the clutch out and pull it again rather than rolling the bike.

[mrclubike]

I find preloading and holding the shift lever up until after I let the clutch lever out has helped  a lot with false neutrals.  
I to thought there was something wrong with my gear box or clutch  until I rebuilt it and realized just how simple they are.
You just have to give them a chance to shift and learn to shift it after that they are OK.