The joys of prop starting

Tyger

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Why?? is the compression too high ??
Three basic reasons, in combination: 1) the compression is very high, 2) you need around 300 rpm before the electronic ignition modules will give you any spark, and 3) the latest versions all have slipper clutches.
 
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DavePA11

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Thanks Tyger. I didn’t know this about the Rotax 9 series. What is a slipper clutch?
 

Tyger

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Dave, as you probably know, there is a reduction gearbox on these engines, because the engine spins much faster than the prop ever could. Inside the latest gearboxes are interlocking "dogs" that can ride up on each other a bit; they also allow the prop to be moved 30º without actually turning the crankshaft at all (after a certain amount of friction (provided by spring washers) is overcome). These slipping dogs reduce wear by dampening torsional power pulses inherent in piston engines, including actual kickback, which can sometimes happen when starting or stopping the engine. It also allows for much lighter props.
Phil Lockwood gives a thumbnail sketch here:
In addition to this 30º "slip" feature, the ability of the dogs of the overload clutch to ride completely up on each other, while BAD for the transmission, provides pretty good protection to the crankshaft and engine itself in the event of prop strike.
 
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WaspAir

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In my early motorcycle days, I used to think that if you couldn't kick start it, you shouldn't be riding it.
 

Resasi

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In my younger days a motorbike we couldn’t pick up was one my cousins and I shouldn’t have been riding.

Two of us were 11 and my younger cousin 9. The Francis Barnet 250cc scrambler we managed, the 300cc Royal Enfield Bullet was the one that couldn’t fall over or we were stranded, and my Uncle’s 1000cc Harley was a museum piece we all used to marvel at.
 

Gyeric805

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Three basic reasons, in combination: 1) the compression is very high, 2) you need around 300 rpm before the electronic ignition modules will give you any spark, and 3) the latest versions all have slipper clutches.
My gyro in the video had the old points style ignition , which I wasn,t very fond of because they require adjust regularly so decided to install the reluctor type of distributor from Subaru , just could not get it to fire , so had to install a aftermarket ignition spark which had a great spark at any revs
 

Martin W.

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In my younger days a motorbike we couldn’t pick up was one my cousins and I shouldn’t have been riding.

Two of us were 11 and my younger cousin 9. The Francis Barnet 250cc scrambler we managed, the 300cc Royal Enfield Bullet was the one that couldn’t fall over or we were stranded, and my Uncle’s 1000cc Harley was a museum piece we all used to marvel at.
I had one of those !!!! (A bike I couldn't pick up)

It was a 650 BSA I had taken in trade on a car. I was about 16 , 5ft 8 and 130 pounds and had to use the tips of my toes to reach the ground . Hard part was starting it , I would step on the kickstart , it would go down a few inches and my body would go up lots of inches and of course the whole thing would lay over on its side.

No way I could lift it back up except it had a 36" sissy bar on the back seat and if I used it as a lever I could get the bike back up.
 

WaspAir

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I had one of those !!!! (A bike I couldn't pick up)

It was a 650 BSA I had taken in trade on a car. I was about 16 , 5ft 8 and 130 pounds and had to use the tips of my toes to reach the ground . Hard part was starting it , I would step on the kickstart , it would go down a few inches and my body would go up lots of inches and of course the whole thing would lay over on its side.

No way I could lift it back up except it had a 36" sissy bar on the back seat and if I used it as a lever I could get the bike back up.
I bought my Norton 850 when I was almost your size - - 5'9"and 125 pounds. Unlike other big displacement kickstart-only bikes I had ridden, it has no compression release and (thankfully) no manual spark advance. I had to struggle it up on the center stand to have any hope of starting it. If I stood on the kick starter, it would not move. I had to do a jump-up with the left leg and bring both weight and speed down to bear on the right. Fortunately, it was willing to start if you could get any speed into the crankshaft. Until about 4,000 miles on the odometer and some break-in, it was a real challenge. I got in the habit of patting the cylinder head with an ungloved hand to determine its temperature, setting the choke according to that feel, tickling both carbs until the fuel just started to dribble out, and then my athletics began. My belief at the time was that any would-be thief would need a ramp and a truck, because he would never bring it to life in reasonable time if he didn't know the drill.
 

j bird

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Bought my 1957 650 Road Rocket in 1961 when I was 19 years old, by that time I was 6' tall and 180#, even so, I had to get my weight on the kick starter to fire it, sometimes it was a challenge. The Road Rocket came with a single carb, this bike had special duel carb heads and a reworked cam, I could pull my buddies 1960 650 Triumph, Bonneville, up to 100 mph, the Bonneville came with duel carbs. I dumped it a couple of times riding out in the desert, wasen't easy to pick up!!!!!!!!!!!!!!!!
 

DavePA11

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I had a 1980 Yamaha Maxim 650 that I fixed up, and often would leave the key in the ignition while I did my errands. No one stole it. :)

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I had to keep my hands on the bars otherwise the front wheel would start to wooble. Never was able to figure out how to fix that. I sold it when I moved to Colorado. I want to buy a nice BMW R 1250 GS bike someday.

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JETLAG03

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Never needed an oil dipstick on my first bikes, all were Brits and if there was no oil underneath bike she needed topping up. Then went oil leak free.

SUZI 1000GS.jpg
 
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