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

Guys,

I may get to go check out some SS's. One is a Yardman 21" 5hp 2-stroke. The other is a Toro CCR2000e 2-stroke.

I am leaning towards the Yardman, based on boratification possibilities. I'm guessing/hoping it has a 5hp Tecumseh, maybe the HSK850. The Toro would have a 4.5hp Suzuki engine, from what I understand. I don't care about electric start. Any reason to avoid the Yardman? I realize it's probably not as solid/durable a machine as the Toro. But if it could be ramped up more in the power department, I could live with that. Thanks for any feedback.

I like your MTD's mount, borat. That also supports it against front-back engine movement. My mount can't really do that effectively. It seems to have made a big improvement, mind you, but it's not perfect. Adding an attachment to the housing would be nice, but probably not something I'll undertake. It sounds like a lot of the machines have put in pretty robust mounts (Honda, Toro, even MTD, etc). At least you were able to replace and improve your mount, borat (the Craftsman that broke).

Red:

I didn't do anything to the MTD.  That's all stock and looks more than adequate.  Much better set up than the Craftsman before I fixed it.   

RedOctobyr wrote:
They have to, the newer machines are all 4 stroke engine that are heavier.  Some of them have 208cc which are not featherweight.  And they look pretty porky too.

Yeah, you're not kidding. I've played with some of the 4-strokes in stores, they are surprisingly heavy when you push down on the handles. Way lighter than a 2-stage, of course, but significantly heavier (or at least differently-balanced) than my 2-stroke machines. And the housings do seem to have grown quite a bit.

I saw a Husqvarna the other day that actually had LED headlights, on a SS! I thought that was interesting. It had a quick-style chute, but it used a drum with a crank on it. Two cables come off the drum, one pulls the chute to the right, the other pulls it to the left. It's a lot bulkier than Toro's QZR (?), but it seemed a bit more intuitive. It's also larger and gave the impression, at least, that it could be more robust.

The newer Husqvarna SS with the crank is more intuitive than the Toro Quick Chute.  Left to turn left, right to turn right.  The Toro is down to turn left, up to turn right.  I don't care for the Husq console with the lights, seems to block visibility to me.  And their chute crank, while intuitive, feels cheap. 

The Ariens 722EC has the crank chute that only need 180 degree rotation left to right.  This is my favorite and most intuitive system, feels robusts too.  If only they add remote deflector adjustment, like pull up and down on that same crank lever.  Anyways, I'm at SSSAS 2.  The Ariens is my next target acquisition.  :)  If only someone figured how to introduce forced induction or a nitrous shot to that 2 stroke engine.  Maybe it's a stretch to mention Tecumseh and turbo in the same sentence. 

I don't know if you can do forced induction on a 2-stroke Because the intake and exhaust ports are so "interconnected" (not completely separate cycles from each other), some of the raw intake charge, still unburned, typically goes out the exhaust on each stroke. That's one reason the EPA doesn't like them. But because both ports are exposed at the same time, if you pressurized the intake charge, I'd expect you'd just blast more of it out the exhaust (the same thing that happens normally, only worse), before all the ports were closed.

Edit- Also, because the next intake charge is in the crankcase, below the piston, if you pressurize that, it would be fighting the piston somewhat on the way down. I'm sure it's been done (someone has probably made a V8-powered desk fan), but I don't think it's as "straightforward" as it might be on a 4-stroke. You could probably do nitrous, though. Tuned pipes would also probably work, especially where the engine should be running at a fairly constant RPM. Look at what people do to chainsaws in the different classes of competitions, for other examples of what you can do to enhance 2-strokes. Some of those get pretty wild.

I'm just kidding about the forced induction on a 2 stroke. The fact that 2 stroke are powerful, simple and lightweight is enough not to mess with them.

When you think of it, these 140ish cc engines are very mildly tuned.  Even when cranked up, making maybe 10 h.p. that's relatively tame.  Back in the 60s to mid 70s, single cylinder air cooled 125 cc off road motocross racing engines were making 20 to 25 h.p. and spinning at 9000+ rpm. 

People don't try to "supercharge" two cycle engines.  As Red pointed out, that's not how to make power with these things.  The secrets for power gains is in making the air/fuel mix and exhaust flow quickly through the engine.  Easiest way is to improve air intake to make it less restrictive and same for exhaust.  Next step is to re-jet the carb to take advantage of the freer breathing engine.  A great deal of instant power can be had this way.  If one wants more power yet, porting is the next step.  However, without the thorough understanding, machining skills and equipment, Joe average, such as myself, won't be doing that kind of work. 

In addition to being "skills/tools" intensive, the end result often creates an engine that's got a power band narrower than one would want.   Not that the power band would really matter that much with an engine on a piece of OPE.  On a racing motorcycle, it would make a great deal of difference.  That's why certain very talented riders (Kenny Roberts) could ride championship winning killer motorcycles (Yamaha TZ750 two stroke) when other very competent riders couldn't manage the power band.   Back in the 70s, the TZ750 was making 140+ r.w.h.p. at 10700 rpm.  The power band was reportedly like a light switch. 

The same engine was detuned to 125 h.p. and used in a flat track race bike piloted by Kenny Roberts.   The following is an entertaining excerpt that I found in an article about the TZ750:

"It’s the bike that inspired Kenny Roberts, one of the most fearless motorcycle racers that ever lived, to utter these immortal words: “They don’t pay me enough to ride that thing!” Desperate to compete with the dominant  HD  XR750s in the 1975 AMA Grand National championship, tuner Kel Carruthers shoe-horned the two-stroke four-cylinder from King Kenny’s TZ750 road racer into a Champion flat track frame and set him loose at the 1975 Indy Mile. Roberts won that race from a near-last-place start, cementing his name forever in flat track history. The TZ750 flat tracker made 125 horsepower, had a light-switch power band, a 150-plus mph top speed and no front brake. It was so fast, and so difficult to control, that the AMA banned it from competition after just three races—before someone got killed."

Fact of the matter is that the TZ750 wasn't banned so much for worry that "someone would be killed" as much as being such a dominant machine that fans (HD fans in particular) would lose interest in the sport causing a serious drop in attendance and revenue. 

Got the Yardman reassembled tonight, in preparation for the (disappointingly small) amount of snow we're supposed to get tomorrow. Bent the governor tab to raise the RPMs from 3900, where it had been, to 4500. I have no idea what the RPM spec is for this machine, but it appears that 3700 might be the spec for the 850 (based on the info I found on the 845, showing 3700). It's nice that, on this machine, there is no lower-rear cover to obscure the engine (like in the Ariens, where it's completely enclosed). So I can make "fixed" governor adjustments with just a pair of needlenose pliers, at any time. Adding true, on-demand, boratification will come later. I want to get a chance to actually try the machine before messing with it *too* much.

Boy, I don't know how the current fuel/oil was mixed by the PO, but it sure is smoking at the moment. No risk of oil starvation, or of mosquitoes bothering me! Based on your advice, borat, I have a can of dino 32:1 that I may use in it, vs my planned synthetic (Stihl Ultra) 50:1. Perhaps when I mix my next batch of Ultra I'll go for around 40:1, so I can just use one tank of gas.

Interestingly, as an aside, the HSK845 engine is described as 4.5 hp at 3700 in the Tecumseh info document that trouts2 posted previously. That document shows nothing on the 850. But my 850 engine was right at 3900 when I checked it. If you scale the rated hp of the 845 from 3700 to 3900, you get 4.74 hp. Based on OPE engine hp math, which apparently involves an awful lot of rounding up, one could infer that perhaps the only difference between the HSK845 and KSH850 is simply 200 RPM?

RedOctobyr wrote:

   It's looking like that.  I picked up an MTD HSK845 and comparing it to a few HSK850's.  The HSK845 has the same piston, rings, crank, muffler as many HSK850's.  The carb and governor spring are different in most.  There are many models of both engines and the parts not always exactly a match but mostly are.  The HSK845 is basically an HSK850 with a carb and governor spring difference.   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.

   The one variation that seemed to vary the most was the governor spring.  Since the HSK850 is bumped to 5.5, 6, 6.5 and 7hp that's reasonable.

   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.

   While poking around I found the base level HSK830, HSK835 and HSK845 all had cast iron sleeves.