why are saw motors so weak????

[rmihalek]

When I used to race dirt bikes, some guys would have to change the rings after putting about 10-15 hours on their engine. The big ports just wore the rings out fast. I don't think most loggers or arborists would want to have to change rings every other work day just for the pleasure of having a 20hp 80cc saw.

Also, when that guy Simonizer was on this group, he was saying something about the crankcase in most saws was too small to allow for high HP. I'm not sure exactly why he said this but it's true that the crankcases on dirtbikes are bigger for a similar displacement (look at the crankcase on an 80cc dirtbike cersus an 80cc chainsaw). Dirtbikes also have tuned pipes, bigger carbs and water cooling to remove the excess heat that high power output generates.

 

[ShoerFast]

my 800 cc snowmobile motor came from teh factory with 150 horsepower.

My 80 cc saw motor came from teh factory with 6.3 horsepower. The math doesn't make sense.

How come saw motors are so inherently weak???? Diminishing return and 2 stroke theory says small motors shoudl make a lot more horsepowre then they do.

Anyone know how much horsepower they get from teh hotsaws for racing??? 20 for a 5 cubic inch reasonable, or is that high?????

Thoughts????

There is an inherent efficiency in "big" , look at the old poppen-Johnnie's , 2 huge pistons, ran all day just sipping fuel. Trains and ships use the "big" idea to add longevity and efficiency to there engines. Another way to put this is look at a 100 HP car, getting passed by a 500HP car transport with 10 cars on it. (it could happen)

With saws, that idea of big just wont carry well. Every engine has to support it's crank, and own crankcase, but by adding more throws to a crank, sharing crank-case support you really in effect are running and extra engine, for the weight penalty of a 1/2 an engine, the effeisnacy is multiplied.

Comparing the HP : Cuibes , of a multi cylinder mounted engine to a hand-held engine is a little like comparing an auto engine to an aircraft engine, granted, some will interchange, but the trade off is longevity ~ reliability / efficiency. Sleds to saws is, sleds needs raw speed / power, the saw needs portability. Give a think to saws built with two long handles and a wheelbarrow tire?

 

[PES+]

Would you believe

"Give a think to saws built with two long handles and a wheelbarrow tire?"

China is making them right now and Gravely used to have an attachment for a chainsaw or a large circular blade. Heck of a brush cutter and the lit is a riot they show a guy cutting down an 8 inch tree with it

 

[pinus]

water cooling allows to get more HP-s. Now most from the high end, racing motobikes are on liquid cooling for this reason

 

[Gensetsteve]

Pest
I had A Honda ss50 sports moped in uk cant remember if it had pedals but it was 4 stroke.

 

[oldsaw]

Substitute "chainsaws" for "mopeds" in that sentence. :hmm3grin2orange:

Now that's getting personal....But saws are useful, mopeds are....mopeds.

Saws are TOOLS, and being so are a whole different animal.

mark

 

[PES+]

But

Mopeds are transportation and even modded up get pretty fair mileage. Full race built no but then full race would most likely not be a relable form of transport

 

[Chopwood]

Now that's getting personal....But saws are useful, mopeds are....mopeds.

Saws are TOOLS, and being so are a whole different animal.

mark

Plus, you know what they say about mopeds and fat chicks.





















They're both fun until your friends see you riding one.

 

[PES+]

Old days

The town I grew up in used to cite us for going over the legal speed limit for mopeds I never got a ticket but a friend got cited for 62 mph on a slight down grade and the cop wrote him up for both the moped violation and the speed limit violation and he got stuck for both fines

 

[Marco]

Snowmobiles have to be tinkered with all afternoon for a 10 minute ride. I wouldn't care for a chainsaw like that, the horse would walk back to the barn on me.

 

[Freakingstang]

Pest
I had A Honda ss50 sports moped in uk cant remember if it had pedals but it was 4 stroke.

Gen Set Steve....

Does the name Aggreko mean anything to you?

 

[spacemule]

Snowmobiles have to be tinkered with all afternoon for a 10 minute ride.

So do women, but that hasn't stopped any of us yet.

 

[PES+]

10-4 on that



HAAAAAAAAAAAAAAAHAHAAAAAAAAAAAAAAAAAAA

 

[bwalker]

Snowmobiles have to be tinkered with all afternoon for a 10 minute ride. I wouldn't care for a chainsaw like that, the horse would walk back to the barn on me.

Maybe so in 1970, but not today. I havent messed with mine since I bought it other than a yearly plug change and exhaust valve service, neither of which are really needed.

 

[timberwolf]

Thats the truth ben, I remember carb fiddling and messing with plugs nearly every day on some of the 70s early 80s stuff, the new machiens are pretty much pull and go and hope nothing goes wrong (repair bills). The most I have had to do on a modern sled is go to a differnt heat range plug.

 

[oldsaw]

Plus, you know what they say about mopeds and fat chicks.

They're both fun until your friends see you riding one.

Nasty. However, if you are 16 and have a moped you better be looking for the fat chick to ride. That or just quit the charade, go shopping for an "outfit" and spend the evening watching "Will and Grace" and eating Cherry Garcia. IF you know what I mean. Oooh, what color is that shirt...ecru? That is thaaa bomb! Pass the Village People CD, are you ready?....

 

[Chopwood]

Nasty. However, if you are 16 and have a moped you better be looking for the fat chick to ride. That or just quit the charade, go shopping for an "outfit" and spend the evening watching "Will and Grace" and eating Cherry Garcia. IF you know what I mean. Oooh, what color is that shirt...ecru? That is thaaa bomb! Pass the Village People CD, are you ready?....

YEEEEAAAHHHHH, BOOOOOYYYYY! How's those cherry logs going Mark?

 

[Gensetsteve]

Gen Set Steve....

Does the name Aggreko mean anything to you?

Yes I worked for them for two years in 1988 but I dont shout about it.
Do you have a connection with them ?

 

[Lakeside53]

Confession time... In the '70's I rode a Honda 50 scooter for three years.. but it wasn't a "moped". Moped stood for MOtorwith PEDals.. in my day...

I also rode a 1960's Sach-DOLMAR (YES, see, I have owned a DOLMAR) moped for a couple of years until it blew out it's spark pug one day.. My first two stroke love.. It was a dog to start though - pedal like crazy and drop the clutch... keep pedaling and ... sailing... ..sailing... oh... the 60's and 70's were good to me..

 

[Lakeside53]

Nasty. However, if you are 16 and have a moped you better be looking for the fat chick to ride. That or just quit the charade, go shopping for an "outfit" and spend the evening watching "Will and Grace" and eating Cherry Garcia. IF you know what I mean. Oooh, what color is that shirt...ecru? That is thaaa bomb! Pass the Village People CD, are you ready?....

:hmm3grin2orange: :hmm3grin2orange: :hmm3grin2orange: