‘18 popping out of gear

[dan williams]

Besides in a few years they’ll all be electric and gearboxes will go the way of the rotary phone.

”Tell me again grampa, the story of how you had to shift cars and motorcycles with your hands!” “Why didn’t you let the robot do it?”

[lineaway]

 The reason for changing the gearing is first is useless. (Unless you are riding Novice) The change makes 2nd the first gear and third the same as stock second. If you ask around, shifting up to third and back down to second to keep from hitting a false nuetral has been used for a long time. Good luck.

Edited July 17, 2018 by lineaway

[dan williams]

1 hour ago, lineaway said:

 The reason for changing the gearing is first is useless. (Unless you are riding Novice) The change makes 2nd the first gear and third the same as stock second. If you ask around, shifting up to third and back down to second to keep from hitting a false nuetral has been used for a long time. Good luck.

Well that was helpful. Thanks, I’ll never change anything to my liking again. ?

[lineaway]

23 minutes ago, Nebulous said:

So , if I did ask around - and people claimed to have no idea whatsoever as to why someone would spend a hundred dollars on sprockets , simply to lose a first gear which they claimed was useless - instead , replacing it with a second gear to emulate it exactly - all because of a design-fault in gear-selectors on a poorly-constructed bike?  What then?  Would you defend your position? Could you enter into a discussion as to possible alternatives? Whilst I appreciate your method is a workaround - the introduction of a 9 sprocket on any bike is a bad move , when considering chain-life and smooth drive-capability.  That this reduces the number of available , usable gears by one - is also a negative.  That it doesn’t even cure the problem - makes it a senseless exercise , no matter what folklore you happen to believe this week.  Surley opening that gearbox and finding out what the .... is going on - would be advisable. Especially on a warranted bike. Assuming you have authority to do so , otherwise the bike should be returned whence it came  - and a replacement tested and supplied. One that satisfies the purpose it was designed for. If the company or dealer can’t do this , then you find the biggest , highest platform to stand on - and you shout your ........ head-off.   Trudging out of the dealership with a 9-sprocket is not the move of a man , or a self-respecting woman - for that matter.  Next step would be grafting the gearbox of a Junior 50 to the bike , for goodness sake.

 Actually I had your same attitude about the change of gearing. It has been a long road to finally make me happy. The bike came with a 10/42, tried 9/42, went back to 10/42, then went to 11/42 which I liked and then bit the bullet going to a 10/39. After being totally disgusted I woke at 3am one morning and crunched all the gearing ratio`s into a graph and ended up with the 9/44. Which somebody had suggested a year ago. (Like you I replied, not ME)  And now completely happy with it.  I even rode a Montesa 4Rt for a week. I rode it hard and even spent a few days setting it up for me.  My thoughts soon vanished of riding that fine oinker. So being a happy beta rider for several decades, I never had a Beta  jump out of gear. I must be lucky or just stupid. By the way I always remove the tip on the gear shift as it is just in the way 

and the folding tip is some fools gimmick.Too many moving parts wasted there!

[dan williams]

Thinking further on this I’ve had another epiphany. There are neutrals between all gears. Aside from jokes about old Bultacos, yeah I owned a bunch, there has to be neutrals between all gears because you can’t risk engaging two at the same time. I had a Hyundai Excel do that once. It wasn’t pretty, sliding through an intersection with the front wheels locked and me smashed into the steering wheel.

Looking on-line Beta has a service manual for the EVO engine and it shows the cam mechanism for the shifter. I’ve been thinking of ways to modify the cam profile to make it less likely to pop out of gear into neutral in a section when it occurred to me that I can change the index of the cam simply by drilling another hole. This should allow me to put neutral between any two gears. Say between fourth and fifth. I can hear the cries of “Heresy! Insanity!” But is it? I spend more time looking for neutral than actually in neutral at this point. You can’t tell me there isn’t a certain feeling of victory when you find neutral on the first attempt on a Beta. It happens so rarely. Aside from making it slightly easier to kick over and moving the bike around, both of which are fairly moot with a properly functioning clutch, neutral simply doesn’t seem that important. Certainly not so important it needs to be between the two gears I use, and depend on, the most.

Of course I’m going to do due diligence in figuring out what the size of the cam angle for the other neutrals is and whether I’m likely to blow the gearbox to smithereens but I suspect there’s nothing special about the 1^st to 2^nd dead zone in the gearbox. Only that it is a convenient place to put that neutral notch in the cam.

[dan williams]

Well I got my spare parts to experiment with and already have some interesting observations.

First is the finish on the cam follower arm is lousy. It's merely stamped out and not de-burred at all. This could lead to the follower not, er, following if it gets stuck on its burrs.

Second, I think Beta used too large a bearing. The picture shows that not only is the bearing not seating all the way in the cam notch but there are two contact points which is not correct as they will try to move the bearing in different directions on the initial movement of the shifter causing wear on the cam. The other thing that is obvious is the shifter action starts ~2/3 of the way up the cam. My suspicion is that the design is correct and somebody got a good deal on 16mm bearings so that's what they used figuring it was close enough. I have to think about this a bit more, contact angle and slope/force calculations but I think this is easily improved.

[lineaway]

I would look closely at the shiift shaft. The 4 strokes break the weld. I know of no 2 strokes doing this, but it makes you wonder.

[dan williams]

Let the prototyping begin. Rendering of the cam arms I'm having made. I'll fit this with 11mm bearings instead of the 16mm bearings. What could go wrong? I love emachineshop. I can design a part and see it made real in a few weeks without breaking the bank.

[dan williams]

So while I’m waiting for parts to experiment with I wanted to tighten the kick stand which is, as always, loose. So I take it off to have a look and.....

 

 

[dan williams]

Anything look familiar?

[heffergm]

Maybe they put the wrong one in your gearbox... Although I guess if they're identical, no harm done. 

[guy53]

You have to give them credit, it's kind of one part fits all

Guy

[dan williams]

“I don’t get it Luigi, We never have enough of these cam follower arms!” Luigi, who assembles the kick stands, quietly snickers.

[dan williams]

Ooooo more experimental parts are in.

 

[dan williams]

And on a slightly geekier note I think I realized why the cam profile looks familiar. It’s a sine wave wrapped around a curve.

I think only Jon will appreciate that detail. The rest of you just think I got too much time on my hands.

Edited August 2, 2018 by dan williams