Keep thinking on that. I'm out.
Too much compression
- Thread starter jwp
- Start date
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Plain and simple. with more rope on the starter it get farther away from the crank giving better leverage. For those that don't believe take the starter off and try turning it over by the center nut, then by the outside of the flywheel. More rope gets closer to the outside of the flywheel. Steve
If you don't believe it, try it for yourself. I just rebuilt a Poulan 5200. I could hardly pull it over. The rope was real short. I replaced the rope, filling up the whole pulley. It now starts like a normal saw.
sachsmo
Addicted to ArboristSite
Ever try a 143 Sachs Dolmar?
I have not. I was just thinking yesterday, I don't have any Dollars in the heard.
066blaster
Addicted to ArboristSite
I will try it on a saw today. I owned a lawn care business for 15 years with big walk behind mowers ropes broke alot while on the job we just tied the handles back on. the shorter the rope the easier the pull. Unless there's some major difference in the design.
I have a bunch of 55's so have a good base for comparison between 'em.
The last one I picked up from a guy at a swap meet with a dozen running saws and the 55 was the only one with a ? mark on the tag.
He told me it pulled over really hard (it did), he couldn't start it and figured something had to be wrong in there.
It felt fine otherwise, I got it cheap.
Put a gauge on it, 180+, doesn't look to have been machined/altered, still has a base gasket. That's very high for a stock 55, something's going on in there.
A 55 was the first saw I ever ported and machined the base to get .020 squish, it still didn't get near 180 and was relatively easy to pull over.
I haven't gotten around to pulling it apart but figure it has to be carbon build up, though looking in the plug hole, the piston doesn't appear to be exceptionally encrusted.
I'll update here when I ever get into it...
The last one I picked up from a guy at a swap meet with a dozen running saws and the 55 was the only one with a ? mark on the tag.
He told me it pulled over really hard (it did), he couldn't start it and figured something had to be wrong in there.
It felt fine otherwise, I got it cheap.
Put a gauge on it, 180+, doesn't look to have been machined/altered, still has a base gasket. That's very high for a stock 55, something's going on in there.
A 55 was the first saw I ever ported and machined the base to get .020 squish, it still didn't get near 180 and was relatively easy to pull over.
I haven't gotten around to pulling it apart but figure it has to be carbon build up, though looking in the plug hole, the piston doesn't appear to be exceptionally encrusted.
I'll update here when I ever get into it...
Maybe, but if there is that much buildup, I'd be concerned about dislodging chucks of it and scoring the piston.
Safest bet is pulling the cylinder and scraping it out, then there's also the option of adding a second base gasket if the compression really is that high with no carbon.
Anyone's guess...
You lose mechanical advantage then you decrease the distance of your lever arm (think short vs long torque wrench). Same idea with the recoil on the saw or your mower. Because the rope is coiled on top of itself in the recoil pulley when you add more rope you increase the diameter of said pulley and lengthen the distance between the crank shaft and the point that force is being applied. More leverage = more mechanical advantage = easier starts.
Matt81
Bliss: Saw full of fuel and yard full of trees!
At least some people know what they are talking about! This one's a no brainer. It is a simple application of force and leverage. I was a physics major so i hope i at least remember something of my schooling and get it right....
When you use a crowbar to lift a large rock or concrete is it easier to lift it when holding the crowbar right near the rock? Or at the end or the crowbar.
This is a different situation but the same principle applies. The further out from the crankshaft center the force is being applied, the less force required to do the same work. Therefore a longer rope filling up more of the starter pulley will be further out from center and easier to turn the saw over than a shorter rope.
Had a MS460 and the cord broke off several times from age and i kept tying it off due to lack of time to take it off and install a new rope. It got so hard to start with the shorter rope that i broke a plastic starter pawl due to the extra force i had to pull with. Looking back it would have saved more time to just put the longer rope in the first place...
There is no difference in the design, it is just simple physics 101. There is a difference between less energy to do the same thing ( which is what a longer rope will do ) and a shorter rope being what YOU prefer. Everyone likes to have things the way they feel most comfortable with. Some people like a slightly shorter rope some like a longer rope. Doesn't matter, either way a longer rope filling the starter pulley will make the saw (or anything) much easier to start.
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There are rules and laws in my world.
Speeding is a rule.
Gravity is a law.
Your opinion does not recind the laws of physics.
You can't break the law.
Think thru it slowly.
Have a good one.
066blaster
Addicted to ArboristSite
ReadyStart® starting system
No priming. No choking. No worries. Just pull for power. The ReadyStart® starting system is a mechanism that automatically senses engine temperature to deliver the appropriate air/fuel mixture under all starting conditions.
• ReadyStart® starting system automatically supplies the right amount of fuel to the engine for easy starts
• High-output ignition coil for more charge with less effort
• Shorter pull rope maximizes leverage, minimizes effort
got this off brigg's web site
ReadyStart® starting system
No priming. No choking. No worries. Just pull for power. The ReadyStart® starting system is a mechanism that automatically senses engine temperature to deliver the appropriate air/fuel mixture under all starting conditions.
• ReadyStart® starting system automatically supplies the right amount of fuel to the engine for easy starts
• High-output ignition coil for more charge with less effort
• Shorter pull rope maximizes leverage, minimizes effort
got this off brigg's web site
Thats inaccurate statement. With less rope on the recoil you will get the engine to turn over (slightly) more given the same length of rope pulled verses having more rope in the recoil but its going to take more arm strength as you have less leverage.
Your bike analogy in your earlier post was incorrect also but could be used to explain what we are talkin about. To compare a bike chain/gears to the chainsaw recoil you have to only consider the rear sprocket and ignore the front sprocket it stays constant. Your legs on the bike are like your arm pulling the recoil on your chainsaw. Move the bike chain to the smaller smaller rear sprocket (less rope) and you have less leverage and pedaling gets hard so you have to do more work to keep the same speed. Move the chain to the larger sprocket (more rope) and pedaling get easier but you have to pedal like mad man to maintain speed. Understand?
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066, you cannot use a Briggs 4-stroke engine and compair how it pulls to a 2stroke. Everyone knows that Briggs engine have automatic compression release built into the exhaust cam lobe. It slightly holds the exhaust valve open during the compression stroke to effectively lower cranking compression. At running speed the cam profile does not effect performance. Briggs calls it easy spin starting. They have been doing it since the 60,s. Please understand all physics laws before defending your argument. You are thinking backwards as if a smaller wheel on a car is eaiser to spin by the Axel. But when yo want to spin the Axel by the wheel you want a larger wheel.
naturelover
Tree Freak
Course what could have happened was they increased the size of the rope pulley and used a shorter rope.
ReadyStart® starting system
No priming. No choking. No worries. Just pull for power. The ReadyStart® starting system is a mechanism that automatically senses engine temperature to deliver the appropriate air/fuel mixture under all starting conditions.
• ReadyStart® starting system automatically supplies the right amount of fuel to the engine for easy starts
• High-output ignition coil for more charge with less effort
• Shorter pull rope maximizes leverage, minimizes effort
got this off brigg's web site
Sent from my iPhone 5 using Tapatalk
half_full
ArboristSite Guru
I couldn't agree more!
066blaster
Addicted to ArboristSite
Well I tried it on my 290. Took several pics but it says their to large to upload I will have my wife figure that out later. Anyway the rope was frayed so I pulled hard on it and it actually broke on its own and coiled inside . Took off the recoil and fed the end through the eye hole and reatached.leaving 6 inches of extra hanging above the handle. So I shortened it about 12 to 14 inches. So I give it a try . Easier to pull. But knowing you only have a foot of rope you have to pull gentler. And doing this makes releasing the initial compression a bit harder. All you nae sayers look at the spool size and gear size on winches tell me you need big gears for leverage. The concept most of you are missing is acceleration !!!!!!
I see where I messed up and agree with you, I think we agree about the same principal I just mispoke. I corrected my post. Thanks!
