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eric05gto

Engine RPM Sunstar Command 20HP

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eric05gto

Some observations/conformations needed regarding the engine rpm on my Sunstar. I have a 1995 Command, 20HP, 60” deck. Using a Tiny Tach for RPM readings.

First, RPM is set without load, correct? Right now I’m set at 3600 without load.

Secondly this summer, while cutting the yard every 7-10 days (not a hayfield) with these conditions:

Under load, level ground, in low range, at 3/4 ground speed, I noticed my RPM was all the down to 3400 RPM +/-100. My usual rpm had been 3500 =/-100. Also while using my Vac collector, at about half ground speed, the RPM’s dropped another 800 or so rpm, down to 3320. Is this typical of other Sunstar owners? My quality of cut had diminished all summer long.

I just went through my fall deck cleaning & greasing & blade sharpening. I noticed the belt on the deck I was using was very loose / worn out. The idler pulley was already in the ‘second’ position. I decided to just keep on using it as I had said to myself since I purchased the tractor 3 years ago.

Well, my next use the belt broke. I have a spare I have not put on yet.

So, are there any points from motor PTO to Deck blades or anywhere in between that would contribute to my RPM’s dropping and lowering cutting performance? I am hoping that the new belt will bring my RPM’s back up (less belt slop ), and in return, I’ll be able to cut at full ground speed once more.

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Check to see if you have loose cable clamp at the governor. And by industry rules of governing engines you are stiil running within 5-7% difference of no load rpm to partial and/or full load operation. The engine came from the factory set 3600 plus or minus 100 rpm no load. A sloppy belt would not typically drag down engine speed.

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