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

How do you diagnose a 2-stroke to find out if someone ran straight gas through the engine and wrecked it?

I found a Toro snow commander snow thrower (see photo). I've never used a toro single stage so I thought I would snatch it up. The previous owner said that it did not run. Apparently it ran last year but not very well. Looks like it sat out in the rain most of its life. That's all I have to go on. 

At 24" the blower is wide for a single stage and very heavy (over 100 lbs).  The 7hp engine appears to be the same InTek 2-stroke as the Toro 3650 and 2450.  I noticed that it does have an electric start feature.

Now that the blower is sitting in the garage, I realize how large it is. Think "single stage monster."  A very odd beast,  a mass of red plastic.  Toro only sold these (model 38602) blowers for a few years (2001, 2002, 2003, ?) with a list price of $960 US. There was a Toro recall in 2006 for 2001 and 2002 models. This one is a 2003 model.  I don't think they were very big sellers (expensive, hard to handle, too many parts).

I don't have any experience with 2-strokes so this is a new adventure for me. Is there an easy way to determine if someone ran the engine with regular unmixed gas and ruined the engine? Would I notice anything when pulling the starter cord?  I thought I try to rule that out first if there was an easy way to do so. 

superbuick wrote:

Would I know it if I had a surge issue?  Does it surge under load or when idling?
I'll check out the links. It sounds like 2-stroke motors have a big following especially for lawn boy. 

 

borat wrote:
This from aa335 : " The Toro manual states that it is the same Rtek engine with different engine RPM for different models.  The RPM is changed by bending the tab, as  you had mentioned.  3800 RPM for 2450, 4000 RPM for both 3650 and Snow Commander........."

Idle speed is set via the governor.  There is a metal tab on the carburetor that has a spring on it that leads to the governor.  Bending this tab either increases or decreases the tension on the spring/governor.  When you make the spring tension less, it will idle lower, and when you make the spring tension more, it will idle higher.

As far as the smoke - the mix (%) and type of oil you are running has alot to do with that.  I run opti-2 at 100:1 and have no visible smoke in the units I run that in.  They run perfectly with that mix.  As noted by Borat, even with a smokier oil and a richer mix, as the unit warms up, most of the smoke dissipates.

As to your earlier questions about the 2 stroke vs the 4 stroke, I agree with Borat that the 2 stroke is the superior type for OPE.  They are lighter, simpler, and make way more power.  They also require basically NO maintenance.  Run them out of gas each year and throw a spark plug in there about every 5 years or so and you're golden.  Realize when looking at that R*Tek and how small it is, it makes more power than the GX160 and has way fewer parts.  The theory of operation is very simple - if you go on youtube there are a ton of videos showing how a 2 stroke works: 

http://www.youtube.com/watch?v=LuCUmQ9FxMU (is a good one - shows a reed valve but piston ported is same theory just with a third port instead of a reed)

Think about chainsaws and their use profile.  They need incredible power to do what they have to do, have to be light weight to be usable by a single person for long periods of time, and have to be able to run at many different angles.  Then think of how many 4 stroke chainsaws are made....

Nice video. The combustion makes more sense, but what about the lubrication of bearings and sleeves and all those moving parts? When you open up a 4 stroke you can see how the oil has been splashing all over the place providing protection from wear and dirt.  Can a 2 stroke really protect friction surfaces sufficiently? If a 4-stroke is worked hard in dusty conditions you can shorten the oil change interval, not so with a 2-stroke.  The dirt contaminating friction surfaces might build up resulting in a short engine life. 

Because of a lack of faith I may have added a little extra oil to the oil/gas mix.  I suppose that some of the smoke may be attributable to that discretion (Can you blame me?).   

Superbuick, are you setting your idle at 4000 rpm? \

Does the Toro Snow commander in this video sound like it is doing the "surging" thing that has been spoken of ?
Video link here: http://www.youtube.com/watch?v=F0ZmkFeW28E

I don't know if your Toro has a air filter..  or if it should being a snow unit....

The biggest problems I saw with 2 stokes was dust and debris in the lower end... (other than some fool not using mix)

       In lawn equipment,  poeple would often neglect the air filter on the Toro 2 cycle mowers (Suzuki engines) ...  the ingested grit would wear the govenor shaft and bushings in the case.....Otherwise they are great engines (2 stroke)...

   As far as running an engine on slope or heavy slant...  Most 2 stroke motors (chain saws, trimmers and blowers)  have Vacuum Diaphram carbs that do not have a fuel bowl to flood...  but your unit would and could flood if tipped too far  (float bowl)...  4  stoke engines can also run on slopes depending on the carb set-up and oil lube system, but such features are not cost effective for the units, also the added weight of a 4 stroke is not the greatest on a slope..

-Friiy

Underdog - the extra lube is a waste. A 2 stroke ALWAYS gets fresh, cool, clean lubrication - it never gets old or dirty, and there is much less to lubricate in the first place (rings and crank bearings are it, basically). In my kart racing series, we run 125cc (the r*tek is 141cc) motors that make 35+ hp and go 50 hours before they need a new top end. This is at 14,000 RPM. We run them at about 50:1. All you're doing with that extra oil is making more smoke and adding extra carbon buildup in your exhaust ports. The motors are stout - just don't over-rev them (same with anything, 4 stroke or 2 stroke) That snow commander is indeed surging, and I know that because it is mine. The pilot jet (behind the sticker) had not been properly cleaned, and that surging is the result. It is also revving too high, as I had not adjusted the governor as of that point (we bought it from a gentleman who stored it outside - it was filthy and full of dirt/crud) I noticed you are a big fan of the HS621 - an excellent single stage snowblower. I haven't run one (only the HS520 - which is terrible), but a Toro 221 or 421 looks comparable (or even slightly better) based on my use of them and in comparison to that video. The snow commander, in my opinion, suffers from a bit of overcomplexity, weight, and one more paddle than is necessary (2 work fine as seen on an HS621 or a 221/421). Although the snow in that video was extremely wet and sloppy (you can see it balling up as I come up the driveway), the 221 threw it much further and didnt bog down (albeit most of the bogging in the video was a product of the too-lean running conditions caused by the plugged up pilot jet) The Commander is also pretty heavy, negating half of the advantage of a single stage in the first place.

Personally, I prefer to mix my fuel at manufacturer's recommendation or richer.  As Underdog mentioned, the engine internals have only one source of lubrication and that's what's carried in the fuel.  For some reason, people like to run oil to fuel ratios thinner than manufacturer's recommendations.  I on the other hand, prefer to do the opposite and run my oil a bit richer.  Once must be careful doing this as well.  Too much oil will displace fuel in the fuel/air mix causing a bit of a lean condition.   I know that sounds strange but it's true.   Being that I have a plethora of two stroke OPE with oil to fuel ratios varying from 25:1 to 50:1, I usually run a quality two stroke oil mixed somewhere in between around 35:1.   I use CTC brand two stroke oil (made by Imperial Oil).  I've been using it for years and all I can say is that it's great oil for the money.    

I hear what you're saying Borat, and understand the reservation, but with a good oil they can, will, and actually DO run better with a leaner mixture (as you mentioned, more oil means less gas, which means a rich mixture makes it run lean and vice versa). The added carbon buildup can cause alot of hassles and in addition, not all of the extra oil will be burnt, resulting in more goo/mess. I've been using Opti-2 at about 80:1-100:1 with no problems for 3 years now in EVERYTHING (trimmer, blower, snowblowers, lawn boys, even my RC Boat)

superbuick wrote:
Yeah, lots of people like to run a lean oil to fuel mix   I mix 100:1 for my newer liquid cooled outboards but like to keep the oil ratio a bit higher in my air cooled engines.   I've been doing that forever.  The Dead Sea was  just getting sick when I started.  

I run a bit of Seafoam through them occasionally and I've been pretty lucky regarding carbon build up.  I'd venture to say that newer two cycle engines would be more tolerant to a thinner oil mix particularly with the better quality of newer oil formulas and synthetics.  However, I'd stay on the rich side for anything that's ten to twenty years old or older.   I guess it's whatever an individual's  comfort level is.   For me, having the convenience of one fuel mix with a slightly higher oil content gives me confidence that the engine's lubrication needs are being met.  

The idea oil packaged in single use quantities is sure appealing. From the advertising it is difficult to know what ratio the pre-mixed product are..