Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

what size pulley should iput on 305cc engine there is a 51/2'' pulley on blower .it is a 36' cut blower for a lawn mower but i am modifying to go on atv .its a single stage so i want to get most power i can out of it.any help would be appreciated thanks..

I do not know what you are trying to achieve. Do you want to spin faster or slower.  if you want to spin faster you need a bigger engine pulley. if you do that your engine will work harder and may bog down. When folk play with pulley sizes the mount a bigger engine to carry the load. this will allow you to change pulleys to make your auger spin faster with out bogging down. You can then throw snow with greater distance. If you get a smaller pulley you will have more power digging through snow. Your engine will work easyer, you will in turn will not through snow as far because your auger will not spin as fast. I do not know what your engine is doing rpm wise. Todays blower impellers spin 1130 rpm and engine speed around 3600. that is about 3 to 1 ratio. If your engine pulley is 5.5" your auger pulley must be 16.5". You can try a 6" engine pulley on your engine. It may work a little better. I will not go any bigger. You engine may bog through heavy snow

thanks for info so far i tried a 51/2 pulley on both engine and auger would only throw snow a few feet and bogged down stall engine easily this is a stage one blower no fan any help would be appreciated

Don't know whether this will be of any help without knowing more about what size engine you are driving your blower with. But standard sizes for pulleys on a lot of walk behind blowers are.
2 1/2 to 2 3/4" engine pulley and around a 9" pulley mounted on the impeller shaft.  But with a single stage it is probably different because you are just driving augers no impeller.  But having said that
the augers on tractor type single stage blowers spin much faster than the augers on a 2 stage blower.  The 5 1/2" pulley on the auger shaft may be about right???. But a 5 1/2" engine drive pulley sounds
a bit to large.  What type of setup are you using to drive the blower off the ATV?

If you are bogging down you need a smaller engine pulley. 305 cc should give you good power. Try not feeding it to fast

tried a 4 inch pulley on engine today seemed better than 6 inch it seemed to blow snow not too bad but not throwing it very far maybe 4 or 5 feet.should i try a 3 inch or smaller pulley will this help throw snow farther....thanks for info so far.

josjay wrote: Stepping down from a 4" drive pulley to a 3" will slow down the auger RPM.  So, no the 3" pulley will not "help throw the snow farther"
In your first post you said that The engine is a 305cc.  Is that the size of the ATV engine? And is that engine driving the blower using some type of PTO shaft or belt?  Or do you have a separate 305cc engine mounted somewhere driving the blower?  Is the auger shaft on the blower being driven or spun by a chain and sprocket?
Does the blower have a right angle gear box on the back of it? With a shaft that has a gear on the end which drives a chain,
which drives another sprocket that is mounted on the end of the auger shaft?
It's rather hard to give any advice without knowing what type of setup you have. What brand or make and model is the blower you're trying to use.
It's also very important to have some idea what RPM the engine drive shaft is spinning at.  It's normally around 3600 on most walk behind blowers at full throttle.

you are right on with what i got.  I have a 305 CC BnS engine and a 5 1/2 inch pulley with a sprocket running the chain for auger on bottom.  On top I have a 4 inch pulley on engine separate from ATV.  Throws snow only 4 to 5 feet.  Any more help would be appreciated thanks...

sorry i forgot to say auger is driven by chain and sprockt would it make any difference to change that part of it.thanks

Yes, changing any of the sprockets or pulley diameters will effect how the blower performs.  And how the engine responds when you fill the blower with snow.

I'm trying to figure out how many pulley's and or chain sprockets you have (I'm thinking probably 4).  Does the engine crankshaft have a belt pulley on it, or a chain sprocket?  Does that belt or chain go around another pulley or sprocket that is on a shaft that goes into a right angle gear box?  Is there then another longer shaft that comes out of the gear box that has a chain sprocket on the end of  it. And a chain that goes around another sprocket that is mounted on the end of the auger shaft?  Need to know the diameter of all the sprockets and or pulley's. What's coming off the engine shaft a belt or chain?  The is no way to figure out anything without knowing how the auger is being driven.

If it's any help, my single stage runs at 900 RPM when engine is at 3600. So a stepdown of 4:1 at 10 ft lbs of torque for each 1' of auger. If you have more torque per ft you can go faster thus throwing further.