Abby’s Guide > Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) > Discussions > Yardman 5hp, 21" SS vs Toro CCR2000 SS
Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions |
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RedOctobyr
Location: Lowell area, MA
Joined: Nov 5, 2011
Points: 282
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Re: Yardman 5hp, 21" SS vs Toro CCR2000 SS
Reply #54 Feb 11, 2012 10:27 am |
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The 3700 rpm limit in the HSK845 spec page is just a limit for the way that block was configured. The HSK845 could be run at the same limits spec'ed for any HSK850 so 4500 no problem. ... Another difference from one HSK850 to another was crank weight which can be a few ounces. I'm not sure exacely what that would do to HP but for torque I would imagine that the same amount of gas would keep a heavier crank going through a load at higher torque.
So, if I'm reading that right, are you saying there were HSK850's spec'd at 4500? Just curious because that's what I currently have mine set to. If that was an officially-sanctioned speed, that would be nice to know (I wouldn't feel that I'm pushing the engine as hard). As far as crank weight, I'd expect: - If the change was to a counterweight, the change might be to help properly balance out pistons & connecting rods with different weights (but it doesn't sound like there were different versions of those?) - If it were a "nonspecific" weight change, I'd expect the extra mass would primarily act like a very small flywheel addition. It could help the RPM stay a bit more constant through small & quick loads. Flywheels only help smooth the quick bumps & dips due to changing engine loads. They won't help for prolonged added loads (a bigger flywheel will just make the engine take a bit longer to slow down). But a crank change would do much less than a true flywheel, and would make a very small difference, I'd think. - I presume the difference is not just due to differences in the PTO area (different length & diameter sticking out of the engine, etc)?
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trouts2
Location: Marlboro MA
Joined: Dec 8, 2007
Points: 1328
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Re: Yardman 5hp, 21" SS vs Toro CCR2000 SS
Reply #55 Feb 11, 2012 12:53 pm |
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So, if I'm reading that right, are you saying there were HSK850's spec'd at 4500? Just curious because that's what I currently have mine set to. If that was an officially-sanctioned speed, that would be nice to know (I wouldn't feel that I'm pushing the engine as hard). Oops, that should be 4300 Max from factory 4000 +- 300. The following from Tecumseh manuals. These manuals predate later maker models past 2002 which have mostly been rpm bumped. HSK600 Toro 290607, fixed speed top governed speed 4500 MTD 290609, fixed speed top governed speed 4700 Snapper 290607, fixed speed, top governed speed 4500 Toro 290602, fixed speed, top governed speed 4700 Murray 290607, fixed speed, top governed speed 4500 For HSK845 also listed as TH139SA (<<<---same as HSK850) MTD 290614, fixed speed, top governed speed 3800 Toro 290681, fixed speed, top governed speed 3850 Service 290627, fixed speed, top governed speed 4000 For some reason they have tied these spec's to a given crank. I have HSK600's with these cranks so it looks like I'm legal for 4700. For reference on the HSK870 to HSK850 crank difference it was 2.825lb (870) vs 2.481lb >>I presume the difference is not just due to differences in the PTO area (different length & diameter sticking out of the engine, etc)? For the SHK870 vs 850 difference I don’t know where the wight diff is. I have seen 8hp crank differences in the lobe masses next to the journals. The lesser crank was on a Craftsman so I thought it might be to cut the crank cost but just a guess.
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RedOctobyr
Location: Lowell area, MA
Joined: Nov 5, 2011
Points: 282
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Re: Yardman 5hp, 21" SS vs Toro CCR2000 SS
Reply #56 Feb 12, 2012 7:08 pm |
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I got to play around briefly today with boratifying the Yardman. I tried tying a string at the upper governor linkage connection, where it goes to the throttle plate. I ran it through an existing screw hole in the lower housing (which was already missing its screw and open- if that's not a sign to boratify it, I don't know what is ), out the side of the machine, and up to the handle, where I tried attaching it to the bail. I liked how it worked. Squeeze the bail, the RPMs climb; let go, and they drop. For the way I tend to use it (squeeze then release at the end of a run), that sounds good. I could lower the fixed-governed speed to even below-stock (for warming up, etc), and keep a high speed for doing work. I didn't have much time to mess with it, and I don't have any springs sitting around, so I need to revisit this. I'd like to add a spring, and perhaps something like a turnbuckle adjuster, or some other means to make controlled adjustments to the high-speed setting. I was at Home Depot yesterday and took a look through their OPE-parts section. They have a universal throttle assembly (lever and cable) for $7. That could be a pretty convenient way to add a control that you can simply set & forget. An advantage over simply pulling a string by hand is that the lever would reach some maximum setting. Once properly adjusted, you couldn't accidentally take it to 9000 or something (that would be my fear if I was yanking on the string manually. Have it catch on my glove or something, and send the RPMs to the moon). Heck, with an appropriate-stiffness spring between the throttle cable and the governor, you might be able to make it such that lowering the lever would give you a nice idle, and you could perhaps use pretty much the whole range of the lever to adjust your speed. I'm not knocking your approach of simply pulling on the string, borat. That's simple, cheap, effective, etc. Just trying to tweak it slightly based on what I think will work better for me. For all I know, I could get this sorted out, then find out you really need the ability to adjust the high-RPM's on the fly, for heavier/lighter snow.
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trouts2
Location: Marlboro MA
Joined: Dec 8, 2007
Points: 1328
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Re: Yardman 5hp, 21" SS vs Toro CCR2000 SS
Reply #58 Feb 17, 2012 4:58 pm |
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It's 50+ here and feeling like summer. Out putzing with the machines and noticed the MTD 7hp SS had the cowling bolt but no support bracket. It's an earlier model like Red's. They probably did not come with with engine supports like later models. The bar the clamp is on is a stablizing bar welded to the side of each intake housing side. The brown bar is the wheel axle. In later models they removed the stablizing bar and left just the axle which is where the bracket runs to on later models. The bracket connected the axle, engine and back of the intake housing making a nice brace. The added bracket is a RedOctber-like motor stablizer out of a steel steel. Can't see the bolt and nut very well as they were slimed with grease. The brace dampens the engine considerably and even noticable at the handles. Probably would never had added it if I did not see Reds. It's a 7hp now as it got update 803554, RMP Enhancement String Kit.
This message was modified Feb 17, 2012 by trouts2
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trouts2
Location: Marlboro MA
Joined: Dec 8, 2007
Points: 1328
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Re: Yardman 5hp, 21" SS vs Toro CCR2000 SS
Reply #60 Feb 18, 2012 10:02 am |
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Borat, I"ve actually been looking for better string like a tight braded nylon but thin. I had set a few of the machines to have a base rpm higher than normal and the string to max it from there. Running it like a chainsaw seemed a good idea so I lowered one way down and ran it like that for a while. Funny stuff as it is like using a chainsaw and gives the engine a break so I set the other machines the same way. It's 40 here in the shade today so will probably get to the low 50's. It'll be in the 50's next week also. It's looking like no possibly snow here at lest into March. Very frustrating.
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RedOctobyr
Location: Lowell area, MA
Joined: Nov 5, 2011
Points: 282
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Re: Yardman 5hp, 21" SS vs Toro CCR2000 SS
Reply #61 Feb 18, 2012 11:08 am |
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Nice mount, trouts! I thought about using sheetmetal, but I didn't really have something like that handy. So, ironically, making it out of aluminum was almost easier. It was more fun, at least, I got to machine it I'm on board with what you found, in terms of raising RPMs. I haven't yet gotten to play with my string setup any more. But I did pick up a spring to add to it, and a turnbuckle for easier adjustability. I want to add them to the machine, then maybe I'll try to get some pics. I have the string going to the bail, so as the handle gets close to fully squeezed, it raises the RPMs. I haven't yet lowered my governed-RPM speed, but that's on my list. I took the governed speed from 3900 to 4500. I will probably lower it back to 3900 (stock), maybe even lower. And try to adjust everything so that squeezing the bail is enough to crank it up to a feisty operating speed. I'm using general purpose braided nylon string. Excuse me, Ultra Performance Turbocharging RPM Adjustificator Space Age Polymer Cabling. My string is just white. But if I dyed it red, that would add another 0.25 hp and 1" of cut width right there. You did have me wondering what 7hp MTD you were referring to, until you listed the part # and explained the upgrade And borat, you're probably right, the mono line will give you better fuel economy vs braided, as it reduces weight, and will have less wind resistance. If you polish the line, that will also help reduce drag as the machine is moving forward. +10 points for bragging rights, however, if the line you're using has a tensile strength greater than the weight of the machine.
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