English bike lovers...help!

- Z
- Zebee Johnstone
  
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posted
15 years ago

Tue, Nov 4, 2008 7:53 AM

I don't have compression releases on my Ducati 450[1] or Yamaha 500[2], and both have higher compression than the average Brit.

The trick is that you push the kickstart till you reach induction which should be the first pause in the travel.

Then you push a bit more till you get compression.

Then you lean on the lever until it slowly eases the piston over TDC. Just as it does but before the piston moves any more you release the kickstart to the top of its travel, then kick through with a clean swinging kick. Don't need to jump on it with all your weight,just need to kick right through to give the piston a decent speed.[3]

All a compression release does is to make that ease over TDC a little easier.

Oh, and stop people who think you *kick* it through compression from breaking your kickstart pawl (the Yam) or ending up being thrown through the garage wall (the Ducati)[4].

Zebee

[1] desmo valve gear means you don't get a compression release. Some valvespring singles had them but my bike doesn't even have a place to put one. [2] didn't have one when I got it, and doesn't need one. Way easy to get over TDC. [3] unless you have a Velocette when you do everything you can short of blood sacrifice to overcome the horrible kickstart gearing. [4] to be fair to my bike that incident wasn't *my* Ducati which had started and was idling happily. It was a bloke trying a new to him bike who thought that his macho required he didn't do the ease then kick thing like the *girl* did...

- G
- Gunner Asch
  
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posted
15 years ago

Tue, Nov 4, 2008 9:05 AM

Whats the difference between a AC coil and a DC coil? This has a magneto but outputs about 8 volts of AC, according to the scope.

Can a DC coil run off of ac, or does the magic smoke come out of something?

Gunner

- B
- Bruce in Bangkok
  
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posted
15 years ago

Tue, Nov 4, 2008 2:05 PM

Ain't no difference. An auto coil works because the condenser and the inductance in the coil create a resonant circuit and when the points break current surges back and forth through the primary coil windings

- in simple terms - and induces a high voltage in the secondary windings.

Someone will probably chime in with an accurate electrical description of what really happens but if you have to ask, my simplified 'splanantion should give you an idea of what is going on.

An ignition coil works perfectly with AC, by the way. Be a little careful with the voltage to start but you can create some fearful sparks using AC.

Start with a doorbell transformer......

Bruce-in-Bangkok (correct Address is bpaige125atgmaildotcom)

- S
- Stuart Fields
  
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posted
15 years ago

Tue, Nov 4, 2008 3:40 PM

Hey Zebee: I could stand on the kick starter on my Husaberg and maybe it would slowly get past TDC, but I couldn't wait for it. I weigh about 190 with gear and without the compression release the dang thing was stuck nearing TDC. I don't remember if the BSA, Ariel and KTM had similar characteristics. I had Malcolm Smith (this was before he was a national hero) put compression releases in my Bultaco Pursangs. The things were just peachy as brakes on long downhills and I would end up at the bottom with a clean plug ready to go; very handy for clearing fouled plugs. Also in a desert race I was involved in a bit of a crash and some guy jumped into the gully we were in and wiped out my rear brake lever. I completed the first loop, around 25 miles just using the compression release as a rear wheel brake. After that I had compression releases in all my 2 strokes. Including a 400 Husky prepared for Bob Ballantine by Malcom Smith. Thinking back though, I had an engine seizure at over 100mph on the Husky at the Calif. City Grand Prix. I wonder if the compression release could have had a hand in that??