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

Found this at an auction, bought it for $70.00.  Don't really need another blower but couldn't resist the 7hp 24" cut.  It's a 2008 model and a rare bird in design.  The ad said it didn't run but had good compression.  Looked in good shape.  Turns out it was low on fuel.  After the ride home (fuel sloshing around in the tank) and a shot of starter fluid it fired right up.  Smoked like crazy, so either it had the wrong mix in it.  Or the fuel had evaporated and left a high concentration of oil in the remaining fuel.  Will post some pics tomorrow.    I'm ready for snow already.  Hope this year turns out better than last year.
For those wanting to know.  It has a BRIGGS AND STRATTON, 084333-0199-E1 engine.

Hi-

Nice work creating the chute rotator!

I have seen both versions of the 141 cc 2 stroke (R*TEK ) internally, and yes these are different: (I couldn't find my older posts I thought I made so sorry if I'm repeating myself)

BOOST version:

Piston- two square windows in the skirt on the intake side

Cylinder- two slot type boost ports to work with the windowed piston

Porting - now has 4 intake (transfer) ports instead of 2

Exhaust port looks the same

Carburetor- all P/N the same so I beleive the carbs are same

CD Pak- same P/N so timing curve the same

muffler- same PN

crankshaft- different PN due to longer snout needed to fit snow commander chassis.

all other PN the same.

Per the TORO service manual for the boost version- the idea is to create a larger air fuel charge into the cylinder with each stroke, so the larger charge give more power!

If it weren't for the two piece connecting rods on these R-tek engines, they'd probably respond nicely to higher rpms.  Not that a two piece con-rod cannot handle high rpms.  Modern motorcycles spin at outrageous speeds with two piece rods.  However, most of them use plain bearings and high pressure oil systems.  My biggest concern about the R-tek and the two piece rod is the needle bearings/cage.  Not sure how well that combination can withstand high rpms.  The Tecumseh 139cc engines have a similar needle bearing set up but with a one piece connecting rod.  So far, the ones I own have responded very well to much higher engine speeds than in stock configuration. 

All of the high performance Yamaha two cycle motorcycle engines I've worked on have needle bearings built into the connecting rods.  The crankshafts are press fit and have to be dis-assemble to change connecting rods.  These engines easily spin to past 10,000 rpm and if used for racing, the cranks are welded to support even higher engine speeds.  

I wouldn't have any reservations spinning an R-tek to 4500-4800 rpm.  Not sure I'd want to exceed 5000.  Nonetheless, the boost version of the R-tek already makes 7 h.p. at 4100 rpm (presuming it's the same rpm as the non-boost engine).  As such, another 700 rpm or so would likely gain 1 to 2 h.p.  Very respectable for a little 141cc engine. 

From my experience with my non-boost R-tek, I've seen noticeable gains in power by increasing rpms by as little as 100 rpm.  When I first bought it, the engine was set for around 3700.  I set it to 4100 and the power gain was very much obvious but, the machine was difficult to hold back while clearing snow on the downhill grade on my driveway.  I cut it back to 4000 or so and it's easier to manage yet still making plenty of power.  If my driveway were flat, I'd jack the engine up to around 4500.    

carlb wrote:
What voltage is the battery pack you are using?

Loblolly77 wrote:

borat wrote:

When I adjusted the rpms to 4100, the machine was pulling me down the grade hard enough to give me concerns about footing.  I decided to reduce engine speed by 100 rpm increments.  After the first reduction, the machine was more manageable.  Just enough to still provide plenty of power without me falling on my a$$.  So, I guess in reality, the noticeable difference in that instance was in reducing engine speed.  I suspect it's not so much the power reduction as impeding the paddle speed that improved my ability to control the machine.  The Toro paddles are so much more effective than the Craftsman/Murray/MTD paddles.  I can run those machines at 6000 rpm without feeling like the machine will pull me off balance.  

jrtrebor wrote:

jrt, nice job on the chute conversion, as usual. Maybe you could try a 6 volt battery  instead of 12 to slow down the chute rotation. It worked for me in the testing I did. They seem to be used commonly on kids electric ride-on toys.
Cheers

GtWtNorth wrote:
Thanks GtWtnorth.  That's a good idea about trying a 6v.  Now that I've taken out the stops the speed doesn't concern me as much. 
As fast as you can whip those light single stages around maybe having the fast rotation will turn out to be an asset.