Cool video showing how the dog ring gearbox works.

[Thunderdawg]

My '68 Bultaco Montadero had a dog ring gearbox. It too would clunk a very little bit on shifting into first.

[PaulieG]

My theory - the "bang" is caused by the spinning parts coming to a sudden stop.

In theory the gears and shafts should stop spinning when the clutch is pulled in at a standstill. However, as cOoTeR said, there is a certain amount of friction/drag that causes the input shaft and gears to spin. When you click it into gear, you connect one of those gears to the output shaft. That cannot turn because the bike is stationary. Everything else must stop - not just the gears but also the input shaft, the clutch center hub, all the driven plates, the pressure plate, etc. Bang!

More thinking: in neutral with clutch out at 1,100 rpm idle, the whole input side is turning at 743 rpm. Pull the clutch lever and it all slows but is still spinning due to inertia/friction/clutch drag. Put it in gear and, in that short space of time, it all goes to 0 rpm. On a powerful bike like the H2/H2R/H2 SX those components need to be sturdy so that's a lot of mass to suddenly stop. Don’t expect it to click into gear like a 25 horsepower commuter bike.

Like cOoTeR, mine just feels like "normal operation". On the other hand, some riders find it worse than others so factors like oil, engine temperature and how quickly you pull in the clutch and click it into gear must all have an effect.

I like this theory and perhaps it is testable. If one were to pull the clutch in and then wait a bit for the spinning gears to slow down, I would think the Bang would be reduced vs pulling in the clutch and dropping it right away into first. The longer you wait with the clutch pulled in, the less of a bang you would experience. Right?

I am waiting on my H2 (Feb '19) but I have a '09 ZX-14 that does this bang in spades. Not sure if it works on the same principle but I will test it out today when I go home.

[cOoTeR]

My theory - the "bang" is caused by the spinning parts coming to a sudden stop.

In theory the gears and shafts should stop spinning when the clutch is pulled in at a standstill. However, as cOoTeR said, there is a certain amount of friction/drag that causes the input shaft and gears to spin. When you click it into gear, you connect one of those gears to the output shaft. That cannot turn because the bike is stationary. Everything else must stop - not just the gears but also the input shaft, the clutch center hub, all the driven plates, the pressure plate, etc. Bang!

More thinking: in neutral with clutch out at 1,100 rpm idle, the whole input side is turning at 743 rpm. Pull the clutch lever and it all slows but is still spinning due to inertia/friction/clutch drag. Put it in gear and, in that short space of time, it all goes to 0 rpm. On a powerful bike like the H2/H2R/H2 SX those components need to be sturdy so that's a lot of mass to suddenly stop. Don’t expect it to click into gear like a 25 horsepower commuter bike.

Like cOoTeR, mine just feels like "normal operation". On the other hand, some riders find it worse than others so factors like oil, engine temperature and how quickly you pull in the clutch and click it into gear must all have an effect.

I like this theory and perhaps it is testable. If one were to pull the clutch in and then wait a bit for the spinning gears to slow down, I would think the Bang would be reduced vs pulling in the clutch and dropping it right away into first. The longer you wait with the clutch pulled in, the less of a bang you would experience. Right?

I am waiting on my H2 (Feb '19) but I have a '09 ZX-14 that does this bang in spades. Not sure if it works on the same principle but I will test it out today when I go home.

The problem with this is that the gears will keep spinning even with the clutch pulled in because there is nothing to force the clutch plates apart until the bike is taken out of neutral. If you've ever tried picking up a coin off of a wet glass table top you might have noticed it seemed to stick to the table. Or if you take 2 smooth and flat surfaces and get them wet before pushing them together you'll notice it's not that easy to pull them apart when pulling straight out from the surface. It's much easier to slide them apart slightly and pry them apart. The clutch plates do the same. So no matter how long the clutch lever is pulled in the gears will be spinning until there is enough resistance to separate the clutch plates. For any example check out videos of motorcycles with the rear wheel in tthe air (on a stand) if the clutch is pulled in and the bike iis put into gear the rear tire will start spinning.

[Gadus]

To avoid the clunk I often start the bike with the clutch pulled and first gear engaged. Can this harm the clutch or the gearbox?

[Champ87]

To avoid the clunk I often start the bike with the clutch pulled and first gear engaged. Can this harm the clutch or the gearbox?

It shouldn't be a problem. However, you may find that the starter turns a bit slower since it's working against clutch drag/friction.

BTW - you can only start this way once the sidestand is up. With sidestand down the bike should not start in gear, even with the clutch pulled.

[Gadus]

To avoid the clunk I often start the bike with the clutch pulled and first gear engaged. Can this harm the clutch or the gearbox?

It shouldn't be a problem. However, you may find that the starter turns a bit slower since it's working against clutch drag/friction.

BTW - you can only start this way once the sidestand is up. With sidestand down the bike should not start in gear, even with the clutch pulled.

Yes, I notice the bike does a small movement forward when starting in 1st gear.
Of course the bike will not start with the sidestand down.

[Bengarzy]

Looks like a Moto GP box to me, didn’t take long for that technology to get into a production bike.
It is a car type shift with no synchro’s and only a few dogs to take the drive so perfect for QS operation and probably why most testers are saying it’s one of the best QS gear boxes they have used.