So I'm bumping this otherwise long dropped thread to add some observations about two strokes and why it's not always good to let the CG engine overrun under closed throttle on a steep, long hill.
So first off: For Sidewinder Jerry I think most CG motorized bike riders would pull their clutch in on long descents so there isn't oil starvation issues, I know I would. Most CG engine owners don't have shifter kits. In addition, since my bike has a enrichment lever on the handlebar that opens a metered fuel enrichment circuit on the carb, I think I could do a clutch out descent without harming the engine. So it wouldn't take much of the enrichment volume, ( but you don't want to foul your spark plug either.)
Hoarses for Coarses.
Then there's this one exception though and it's one of the reasons why most of the 1960's 2 cycle road motorbike makers went to oil injection systems on their bikes around 1965~'67. The big one was less smoke out the tail pipe, the other was an oil injection system is always geared to pump oil at the same geared down speed of the engine, even at idle it's pumping a small amount, even when it going down a hill with the throttle closed but the engine spinning at road speed. But these Japanese makers also made a variable volume control linked to the throttle cable so the amount of oil given to the speed of the engine is also magnified by the volume dictated by the throttle opening.
If you ever seen a Kawasaki H2 disappear in a shrieking cloud of blue smoke while accelerating up a hill, well you witnessed their injection system pumping a LOT of engine lube oil. Most injection two strokes will fog for mosquitoes when under high RPM and WOT. I owned a couple SAAB 850 cc two strokes and their capacity to stink and fog their way up a highway grade is never to be underestimated. The oil injection ones were a little bit nicer, not by much though.
BTW did you know that SAAB had freewheels built into their transmissions for their models 93, 95 and 96 2 strokes, the 95 and 96 V4's and the first year of the 99's? The original reason was long grades and mountain roads in Sweden would often have the older, not so powerful model 92 and 93 models with the premix engines soft seizing if the owners didn't use a little choke on the descent. A few smart owners started shifting into neutral on descents. One of the clever designers at SAAB, ( they build advanced military jets...) came up with a built in freewheel for the 1953 SAAB 93 and later they designed it so you could move a small T handle under the heater that would lock out the freewheel if you wanted the full experience of the mighty engine braking of their 750 and 850 cc engines. ( there's not a lot of engine braking..) as long as you also used a little choke/enrichment on the descent. Not recommended by the owner's manual except on really steep grades in first or second gear.
So with our little, simple, premix engines we have a couple options to keep the engine from seizing from to little oil on a descent. First, disengage the clutch, you might even shut the engine off, although I'm not sure if thermal shock from letting the engine be rapidly chilled in cooler fall air would be a problem or not, probably best to let it idle,, Or you could leave the clutch engaged and choke the engine small amount. I also think disengaging the clutch and giving the throttle a couple blips occasionally with the choke partially on would be beneficent.
So another of Lewie's mini novellas, thanks for reading, and don't say DAMIEN's name 3 times in a row.
Cheers.
