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New sthil reviews

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On 09/01/2019 at 21:27, spudulike said:

It must be more than the weight of a carb, they don't weigh that much. Was the flywheel a nylon one like the MS660? Always looked at that as being a decent idea, less inertia, less weight and quicker spool up time! Reckon Stihl have thrown a lot at weight saving throughout the saw!

Interesting point that. Purpose of a flywheel - to give a more constant crank speed, primarily useful at low engine speed and crucial for starting. Not much use above idle speed, unwanted baggage. 

A key benefit of the fuel injection and engine management system (which control the sparks too I'd hope) would be much better fuel/air mixture. So starting will be more consistent and generally easier, Idle will be smoother too, both especially true from cold.  

The knock on - Stihl engineers can afford to reduce flywheel inertia (and weight). 

Nice fringe benefit to fuel injection. ....

 

 

 

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8 hours ago, bmp01 said:

Interesting point that. Purpose of a flywheel - to give a more constant crank speed, primarily useful at low engine speed and crucial for starting. Not much use above idle speed, unwanted baggage. 

A key benefit of the fuel injection and engine management system (which control the sparks too I'd hope) would be much better fuel/air mixture. So starting will be more consistent and generally easier, Idle will be smoother too, both especially true from cold.  

The knock on - Stihl engineers can afford to reduce flywheel inertia (and weight). 

Nice fringe benefit to fuel injection. ....

 

 

 

Doesn't a heavier fly wheel give more torque and a lighter one more revs with a quicker spin up ?

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I own a 462 and have run it hard for around 6 months, personally its a great saw with plenty of power but its just not well made, the anti vibes are too soft, the hd2 air filter clogs up like nothing and allows particles into the carb elbow and the rear handle came apart in my hand! plus the chain tensioner mechanism is suspect as im sure it doesn't hold tension either that or the sthil chain expands when it gets hot causing constant sag and re tensioning

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2 hours ago, Stubby said:

Doesn't a heavier fly wheel give more torque and a lighter one more revs with a quicker spin up ?

It doesn't increase the toque, that's dependent on the combustion but it stores inertia so carries power over, sort of smooths out the impulses.. In the old trials cars with fiddle brakes they would have a small engine with an extra flywheel bolted on just to allow it to run slowly but still able to power over obstacles. You want the very opposite in a chainsaw.

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56 minutes ago, openspaceman said:

It doesn't increase the toque, that's dependent on the combustion but it stores inertia so carries power over, sort of smooths out the impulses.. In the old trials cars with fiddle brakes they would have a small engine with an extra flywheel bolted on just to allow it to run slowly but still able to power over obstacles. You want the very opposite in a chainsaw.

Agreed, a big flywheel can't increase the torque of the engine. But a fast spinning flywheel has more energy than the same flywheel spinning slower. So for a short period of time the output from an engine and flywheel assembly can be more than the constant speed output of the engine. ... its just that during that time the engine and flywheel will be slowing down. That might be perceived as 'more torque' by the user.

A good example of this on a chainsaw is if you're unsympathatic with the saw at the start of a cut, or maybe if you hit a bit of hard wood. A saw with a big flywheel will drop its speed but if the time is short it might clear the obstacle,  while a saw with a small flywheel has less stored energy to devote to the cause and bogs down. (Same as the trials car). 

It's the store energy that counts.  Can't remember the formulae, but maybe that's just as well 

 

 

 

 

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A good example is when you switch from cord to a metal blade on your strimmer .  The blade takes a few seconds longer to spin up but the stored energy  , once up to speed takes longer to dissipate when off the gas .  

Edited by Stubby
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I am certainly keen to try this saw out. The 462c is a belter to use but as Steve has commented, the build quality is a bit patchy, there has been reports about the casting of the oil tank being an issue on the 500 also, there is a lip that protects the oil filler cap that is cracking off when snedding, the 572xp is a belter also so I will have to get a 500 on demo and run it against the others first.

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Surprised no one has mentioned the fact that Jonsered had the first injection saw, 1958 I think ? Looking forward to speaking to someone who has used it as in the YouTube videos I watched it seems to loose "power" easily if badly handled i.e. being dogged into the wood it seems to loose revs very easily ? Like I say probably bad handling !

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