What causes the pullstart on a 4 stroke to pull back and rip out of your hand?

[athletichunta]

This happens sometimes, I have a huesang motor. Is there anyway to prevent it?.

I have bruised nuckles from it.

[2door]

Its called a backfire. When you pull give it a good solid pull. Don't baby it. The slower you pull the more chance the plug will fire and spin the crank backwards just as the piston reaches top dead center. That's when it kicks and jerks the heck out of your hand. You need the momentum of a good pull to keep the crank spinning in the right direction.
Tom

[Kevlarr]

A friend had one of the good ol' big cc dirt bikes back in the 70's and it backfired once while he was kick starting it. His right leg was in a cast for most of that summer and the bike got sold.

[Mac]

Yea, those XT500 Yamahas, had a little window to see the Cam, if I kicked it without getting the mark in the window, BAM!, tore me shoe off several times. I think Tom is dead on here, I would get the backfire when I was "afraid" to give it heck.

[GearNut]

Originally Posted by Mac

Yea, those XT500 Yamahas, had a little window to see the Cam, if I kicked it without getting the mark in the window, BAM!, tore me shoe off several times. I think Tom is dead on here, I would get the backfire when I was "afraid" to give it heck.

I have a '79 XT500 in my garage. It has sent me over the bars twice from kick back, even though I lined up the white mark in the window.

[2door]

Also, a backfire isn't restricted to 4 stroke engines. Try flipping the prop of a 2 stroke model airplane engine with your fingers, doesn't matter the size, you can get hurt when the little bugger backfires. The bigger the propeller, the more it hurts
Tom

[Kevlarr]

Remember the little starter springs o .049 engines? More then once the prop slipped out of my fingers while winding it backwards. lol

Dad used a chunk of heavy rubber garden hose to start anything bigger then a .25 and from the number of cuts in the hose he would have lost his finger several times over.

[2door]

I went to an electric starter when I graduated from .019 to a .40. One backfire, one chopped up finger and I never flipped another prop. When I got into giant scale and started running those monster 4 strokes I had to get a bigger battery to spin those puppies. You DO NOT want to hand prop one of those.
I had a friend with a 1/4 scale P-51 that got away from him while starting the engine. We called 911 and he was airlifted to the hospital with wounds that looked like Jaws got him. Inner thigh, calf and the top of one foot. Over three hundred stitches to put him back together.
And you thought they were just toy airplanes.
Tom

[Mac]

My piper with Enya .80 4 st. cut my hand (down from the thumb), took 3 CHUNKs out, almost hospital time, I was starting it, no backfire, pulling the glow ignitor off, right thru the prop, couldn't feel anything for a week, then I wish I couldn't feel it, I went and bought a remote glow adapter... I was down at Earnie Hubbards Helo school(R/C), in Fla. a guy with a hotrod .60 helo flew into himself from a hover, thigh slices to the bone, life flight evac, he made it but what a bloodbath! Hey, I think we hijacked this thread???

[GearNut]

Originally Posted by Mac

Hey, I think we hijacked this thread???

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