Quote Originally Posted by MotoKai View Post
The little open space: 这个叫凸轮轴减压器,作用是当摩托车起动时,让排气门打开,使起动转速快速达到规定转速,当车发动以后,这 个减压器就不起作用了
The function of the camshaft regulator (凸轮轴减压器) is only to open the exhaust valve when the motocycle starts, so that the motobike can accelerate from its start speed until it reaches a steady fast speed.
I did a quick Google search on "camshaft regulator" and discovered that it relates to sensing engine timing on EFI engines. I'm old school, and can fuddle my way around old technology, but whenever EFI or ECM stuff comes along ... it's off to the experts.

So, the camshaft regulator probably sends info to the ECM, or EFI, or both, to alter fuel delivery? I can't see how opening a valve (which is a fixed mechanical event) can be modified by the engine ... but, then again, there is something out there called "variable valve timing" (VVT) on certain cars. Who knows how that works? Maybe the cam is multi-piece and can rotate internally, adjusting the camshaft lobes' effect for valve timing?

The magic of an engine always comes down to that combustion chamber, that requires all valves being closed during the compression & firing strokes. But the timing of when intake & exhaust valves open is supposedly controlled by the camshaft spinning around, with its bumps (lobes) lifting one end of a rocker arm so that the other end of the rocker arm pushes down the valve (to open it up to allow fuel/air to come in ... or just air in an EFI engine .... or to allow exhaust gases out). Back in the old old days, there were mechanical thingies that advanced/retarded timing of ignition. I have no idea how it works now.

Re the 600B ... yeah, I saw that depressing post by nostalgia. I've toyed with the idea of swapping out the B's entire engine/tranny/controls for a regular JH600 engine. Jialing says it can't be done, but I've some contacts in the military that say they have done it. One loses the reverse gear, but that is ok.

Thanks very much for sharing your experience. I really feel helpless without an English service manual for these bikes. Bit by bit, though, we can learn from each other.

Cheers