Lawn Mowers

Bit of an upper cylinder lubricant on the old Honda eh Kev?, it will run fine they do need a decoke though the 2 stroke oil leaves some nasty deposits around the valves and ports. The first sign is a loss of power.

TIP. go to your local light aircraft / heli field with a petrol drum and buy some Aviation Fuel [ av gas ] never have carby diaphram issues etc etc again.
also use a good full synthetic 2 stroke oil not the stock junk like Sthil / castrol etc etc. some of these oils can be mixed at a ratio of 100 to 1 , not like the oily 25 to 1 smoko.

Remember BP Zoom?, that was true donkey piss even worse than our diesel.

I've moved all these posts into this new thread. The first post doesn't really make a huge amount of sense, but we were staying so far off topic in the other thread it was looking like I was unemployed.

Let the discussion continue!

I actually got Harry out (anyone who knows me knows I am fostering a special needs child and he gets a thrill out of my garden equipment being named - Harry is the Honda) yesterday afternoon and did some mulch-mowing with him. That's after I'd done the primary area just near the house with my Ryobi Cordless mower. Mine's the model before that one, and I wouldn't mind the newer brushless version, but I shelled out plenty of cash for the one I've got and it still works fine.

Anyway in mulching mode the thing does such a fantastic job you can hardly tell I've left the grass on the ground. So impressed with it that if I had my time over again, I wouldn't waste money on all the others I've owned over the years.

The topic is now where it should be, thanks admin. Any thoughts or queries on outdoor power equipment ask here.

I'll start it off, never buy a Honda copy, some look the same but poorly built and no wty from Honda should a problem arise.

Standard rev's on any new mower is set to 2600-2800 rpm to comply with emission laws, increasing that to a safe 3600rpm will put the motor in it's real torque area dramaticly improving cutting and catching ability.

by mem about 3000rpm is the optimum for cutting grass. faster isn't always better. it depends on blade width, you want blades to be going within a certain speed range.

jonney said:

TIP. go to your local light aircraft / heli field with a petrol drum and buy some Aviation Fuel [ av gas ] never have carby diaphram issues etc etc again.
also use a good full synthetic 2 stroke oil not the stock junk like Sthil / castrol etc etc. some of these oils can be mixed at a ratio of 100 to 1 , not like the oily 25 to 1 smoko.

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not sure why you think stihl oil is junk since i have been using that on my MS290 chainsaw since 2004 i bought it and runs perfect everytime, havent replaced anything yet, just spark plug so far. and its a pretty high powered chainsaw as well.its a big boy no doubt.
unleaded 95 petrol works well for me.

Stihl oil is just Castrol or another mob that lay claim to the name. 25/1 is fine with cheap mineral based oil, but it results in much more performance, and less deposits if you run a leaner ratio such as 50/1 with a synthetic oil.

tweak'e said:

by mem about 3000rpm is the optimum for cutting grass. faster isn't always better. it depends on blade width, you want blades to be going within a certain speed range.

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Not at all mate, faster the better gets the better results and fills the catcher. Below 3000 most slip out of their sweet spot and lose all grunt.

happy john said:

Not at all mate, faster the better gets the better results and fills the catcher. Below 3000 most slip out of their sweet spot and lose all grunt.

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happy john said:

Not at all mate, faster the better gets the better results and fills the catcher. Below 3000 most slip out of their sweet spot and lose all grunt.

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it was something to do with high blade tip speed rips the grass rather than cutting it. i'm sure some manufacture will have it written down somewhere.

The manuals are shit, the lift of the blade is what cuts and throws the grass. A Honda fitted with 4 blades has lost near 1hp as compared to 2 blades on the same model.

Higher revolutions introduce other issues. First and foremost is the increased fuel consumption - imagine if you needed 1ml of fuel per power stroke (just picking that number because it's easy, not because I want an M1A1 lawn mower although thinking about that, you'd never have a complaint mowing at 2am any more). At 3,000rpm in a 4-stroke motor that's 1.5 litres of fuel per minute. At 4,000rpm that's 2 litres of fuel per minute.

The second problem is debris. Small stones and sticks are just minor irritations at normal revolutions, but if the mower is revving much higher, those small items turn into projectiles. What's worse is that the steel blades could chip or break.

The governor could be fiddled with but you'd want to adjust ignition timing and carburettion especially if you change fuels. It's possible to run a whipper snipper, for instance, on methanol+castor oil just like the small model aircraft motors. RPM can be expected to rise from a nominal 2800 to over 10,000 (it's been done). At those RPM you'd want a bloody good line but even with crap line, it eats through grass like no man's business. Very dangerously - it throws stuff everywhere.

The loss of power is just natural for having to drive a larger object around, but the 190cc engine seems to manage really nicely.

happy john said:

Stihl oil is just Castrol or another mob that lay claim to the name. 25/1 is fine with cheap mineral based oil, but it results in much more performance, and less deposits if you run a leaner ratio such as 50/1 with a synthetic oil.

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i run 50:1 ratio and 1 litre is enough to get me past 2-3 winters depending on how much ton of wood i need for the fireplace. i dont know what brand is it, all i know is that its red and cheap, not sure i have seen much red 2stroke oils, all i have used so far are brown (for the chain etc) but still, i dont like to lose sleep over it i just go to the local dealer and buy it from there.

Chain oil is just a thick and tacky compound designed not to fling off the bar and chain so easy. Many of the tree guy's would use old sump oil to save money. The fine particles left in the old oil would grind and wear the blade, we would have to machine the bar back and fit a new chain. There is a little grease hole for the sprocket at the tip of the bar that needs a squirt fom time to time too.