How much pullrope are you using?????

madprofessor

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I've read many posts and seen videos about people nearly getting fingers broken by the violent "snatchback" of pullropes. Experienced some of that myself on hotrodded Predator 212 @ 12 hp., and recently with my current 212 @ 15+ hp.
Many people have automatically thought about there being excessive timing advance when that happens. I myself went to the flywheel, looking for a broken advance key spinning the wheel, or anything else obvious. The 28 degree PVL flywheel got a #6 advance key, which was still okay. I put the OEM key (no advance) back in, so just 28 degrees total when trying again.
Still snatching back, but then I lost my balance yanking on it, stumbled backwards, and saw a bunch more rope come out. Had been pulling far enough to get through a full cycle, about 3'. The snatchback always was right at the end of that.
Measured my pullrope and found there's "51" of rope there to pull on! Purposely stepped back a bit from the motor to make room, yanked a full 4', and it hasn't snatched back on me since! As long as I don't allow the pull to stop at just 3', the motor fires forward instead of backward.
So when you're pulling, step back and force a nonstop longer pull.
 
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Willie1

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I've read many posts and seen videos about people nearly getting fingers broken by the violent "snatchback" of pullropes. Experienced some of that myself on hotrodded Predator 212 @ 12 hp., and recently with my current 212 @ 15+ hp.
Many people have automatically thought about there being excessive timing advance when that happens. I myself went to the flywheel, looking for a broken advance key spinning the wheel, or anything else obvious. The 28 degree PVL flywheel got a #6 advance key, which was still okay. I put the OEM key (no advance) back in, so just 28 degrees total when trying again.
Still snatching back, but then I lost my balance yanking on it, stumbled backwards, and saw a bunch more rope come out. Had been pulling far enough to get through a full cycle, about 3'. The snatchback always was right at the end of that.
Measured my pullrope and found there's "51" of rope there to pull on! Purposely stepped back a bit from the motor to make room, yanked a full 4', and it hasn't snatched back on me since! As long as I don't allow the pull to stop at just 3', the motor fires forward instead of backward.
So when you're pulling, step back and force a nonstop longer pull.
Never really had this issue with the 212's I've worked on.
BUT . . .
Since pull starting doesn't agree with 63 year old shoulders with multiple surgeries, I try to make the most of every pull. I learned THE HARD WAY from kick-starting motorcycles years ago that to avoid "shin-cripplers" to ALWAYS start the kick at the compression stroke - so I learned from this and tighten the cord up to the compression stroke before pulling the cord.
Another thing to ponder - most of the 212's I deal with have stock - as in heavy - flywheels. I would guess that since both the engines you mentioned are modified, they have lighter billet flywheels which would carry less inertia and may be more prone to kick-back.
 

madprofessor

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Willie1, I can still feel your pain from kicking those bikes over, I also am 63 years ancient. Can recall being thrown over the handlebars of a Superglide at about 14 years old.
I also pull a rope to the start of backpressure on the rope, noting that the actual compression release doesn't kick in until you pull a little more. Starting there allows an easy pull and gets the whole momentum going. You are correct about the lighter billet flywheels reducing momentum, but I don't give them a whole lot of credit insofar as being causal to the backward firing motion of the engine. Any engine that can snatch my meathooks hard enough to make me quit for a day could very easily spin a cast iron stock flywheel backwards and has in fact done that to me a lot on the first 212 build.
Truly you know what I'm talking about on the continued force applied to the pullstart after the plug fires 35.2 degrees in advance of TDC, and I must stand behind my assertion that the longer pull (force applied until and past TDC) is the best cure available. Remember that the old 74's only had enough stroke on the kick to get around one time, and that a compression release lever became a must-have option. Hell, by the time I got the single-banging thumper 650 dirt bike there was not even a compression release option available anymore, and guess what, no kickstarter available either. Nothing but electric start, too many lawsuits.
 

Willie1

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Madprofessor, yeah I think the secret to pull starting is finding the sweet spot between what the engine likes and what our bodies can do. 30+* of timing advance is probably more than double what the engine realistically needs at starting RPM's, but with our fixed timing ignition systems we are at the mercy of compression releases and our pain thresholds (LOL) to start our occasionally temperamental "children". One thing that hasn't been mentioned is having a comfortable handle on the pull rope. A friend that works at a small engine shop always saves the pull handles off scrapped snowmobiles, snow blowers, etc. since they are usually running bigger bore engines, and the handles are sturdy and big enough for a gloved hand.

But back to your original post - getting the most out of your physical ability to fire the engine by simply adjusting where you exert your best energy is a great tip. Fine tuning what the engine likes and using the proper parts can also make waking up an occasionally temperamental Demon Child less of a chore.
 

madprofessor

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a comfortable handle on the pull rope
Very good point. The T-handle type of standard pullhandle does hurt between my bony fingers. Put a D-handle on something once, don't remember what, but it was a real good idea. Seems there was something or other negative about it, but I only really remember how nice it was not having that bone pain between 2 fingers after repeatedly yanking on a T and maybe getting kickback too, ouch.
 

Hemiwoodworker

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I'm not running anything radical. Billet flywheel and rod. Stock cam 212. I always rotate the engine with the pull rope until I hit the compression stroke. Then reset the pull rope back and give her a good yank. Since I've started doing this I've never had a problem.
 
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