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. 

A simply pull of the recoil starter should tell you if it has compression or not. Does it turn over? Does it have the lumpy resistance when turning over that is associated with compression?

Thanks Superbuick.  Gave it a good couple of pulls and I could feel some resistance. Nothing that stopped my from pulling the cord.  Do these motors have a "compression release" feature that makes them easier to start?  If that is the case, would that negate the practicality of testing for compressing by pulling the cord?

The old fuel was drained from the tank and the plastic carburetor was removed.  I think there was water inside the carb.

It was easy to pull the plastic carb off (801255 or 1009576?). As I mentioned earlier it seems to have water inside. No noticable damage caused by water freezing in the carb.

I pulled the two jets/nozzles out and cleaned them with a bread twisty and then flushed them with carb cleaner and blew compressed air through the orifices.

I cannot decide it the plastic tower on the side of the carb has a plastic top than can be pryed out or if the top is permanently sealed to the carb. Any guidance on this it would be greatly appreciated.

It's sad to see such a nice piece of equipment neglected and left outside like this.

Don't pry that piece out - its not meant to come out. There is a sticker on the side of the carb - take it off, and under it you will find another jet - make sure to clean that jet. You don't need to put the sticker back on. Also make sure the needle and seat aren't sticky - otherwise you should be good to go - the carbs are very simple and easy to clean.

Good to know. I'll leave that plug in place. I found that extra jet that you mentioned under the sticker.  Everything seems pretty clean now.

In searching the Toro manuals online I found a guide with some good information.  One thing that is not clear to me is the difference between the plastic carb on the 3650/2450 and the Snow Commander.  In reading about the R-tek engine it sounded like the higher output R-Tek engine on the Snow Commander (the one with the slotted pistons) might use larger jets.  I am trying to cross reference the part number to see if this is true. But I'm not there yet.  The previous owner was not happy with the snowblower and did not use it very much. I'm going to try to get it running and see whats what, but often poor performance can be attributed to a faulty carb.  There are replacement plastic carbs for these Toros on ebay ($50) but they don't differentiate between the three blowers. There's just one carb for all three units (3650/2450 and the Snow Commander), so that leads me to believe the jets are all the same.  Really not sure. 

I plan on picking up a replacement fuel filter and spark plug today, and hopefully try starting it on the weekend.

The briggs engine manual posted at the toro web site for Snow Commanders lists two carbs (and several different jets).
The carb used differs by date code on the engine (not on the Toro snow blower). So engines with date codes before 01060700 use carb #801255 (main jet #801425/pilot jet 801309) with a plastic body and and engines with date codes after 01060700 use carb #801396 with a metal body. It's interesting to note that the metal body carb has a overhaul kit (801427) and a lists two different main jets (#801426 and #801427). Both main jets are listed for this same application. What's up with that?
The briggs literature that I pulled this from is #3364-6 and dated 08/21/2006. When I called Toro and asked they referred me to Briggs for engine information.

I've worked on a 2450, a 3650 a 221, a snow commander, and a 726te. All but the 221 had the plastic carb, and the carbs and jets on the plastic ones were all identical - same jet numbers. The plastic carbs are more prone to surging (from warping) and i believe that is why briggs switched to a metal carb. Lawn Boys with this motor had the same issue with carbs warping - otherwise the plastic carb works just fine - just don't overtighten it.

superbuick wrote:

I'll try not to overtighten. I had a plastic briggs fuel pump that warped on a leaf loader last year.  The fuel pump looked to be made from the same material as this carb.         Is the metal carb (with standard altitude jets) an option for me if the plastic carb becomes a problem?  Or are they not really interchangable?

Does the R Tek engine have reed valves.  They would be between the carb and the cylinder.  If you can look through the intake port where the carb attaches, can you see the piston move up and down as you turn the engine over?  If you can see the piston, there is no reed block.  If you cannot see the piston, it may have reeds.  If it does, pull the reeds and inspect them for cracks and cleanliness.  If no reeds and the piston is visible, take a good look at the condition of the side of the piston.  Look for scoring (vertical lines) on the side of the piston.  If there are none, that's good.  If there are some very light signs of scoring, see if you can drag your fingernail across them.  If you feel nothing, the piston is likely fine.  If you feel bumps, the piston has been compromised.  It may still run alright and if so, go with it as is.  You might also want to do a compression test.  My machines all register in around 110 to 130 psi.  If yours is in that range, compression should be alright. 

Check your exhuast for obstructions, water or dirt in it.  Take if off and blow compressed air through it.  Might have mouse nest in it.   In the unlikely event that the engine has an air filter, make sure it's good. 

How's the spark.  Is it good and strong?  Does the machine have the correct plug? 

If you've thoroughly cleaned and re-assembled the carb and everything else is OK, the engine should run.  Two strokes are notoriously simple machines which will run reliably with virtually no maintenance.  Just make sure you run the correct fuel to oil ratio and clean the spark plug occasionally.  That's about it.  I'd be very much interested to find out if you get the engine to run.  Also, do you have a link to a site where I can see a diagram of the engine?  An exploded view would be best.  Thanks and good luck. 

No reeds on the R*Tek - it is piston ported. The duraforce (lawn boy) is the same motor, but with reed valves. Both are extremely powerful motors for their size and fuel use. The metal carb will work on that motor. You may even be able to order a set of richer jets for it. Most of the lawn boy guys replace the 37.5 pilot jets on the duraforce with the 42.5 (or even a 47) from the r*tek. If you do a surge for duraforce surge or r*tek surge you'll likely get some more info on this. Also check the walk behind mower forum at mytractorforum.com - lots of lawn boy guys there (95% or so) that can give you jetting advice for the duraforce/r*tek.

On  my way home after work I picked up:
NGK spark plug $2.00
fuel filter $2.50
brigg 2 cycle with fuel stabilizer $1.50
gallon of gas $1.67

Then late last night I set the gap ( .030) and installed the plug, mixed oil/fuel (50/1), and installed the fuel filter (red 150 screen).
The carb is disassembled, cleaned, and ready to put back together. The briggs manual (Toro sold the R-TEK to briggs)  says to use blue loctite when assembling the nozzles and jets on this plastic (Milon) carb. 

I have read the description in the manual of how a 2 stroke engine works (three times) and I still don't completely understand it.  Relying on vaporized oil residue to provide lubrication to all the moving parts seems far fetched. And how does the engine dissipate all that heat, especially when contained within such a restricted area? Is service life an issue with 2-stroke motors? Is it common to rebuild 2-cycle motors (replace rings.pistons) or are these light weight engines considered "throw aways"? Are 2 stokes popular with their owners (because of their weight?) or do they primarily appeal to manufacturers focused on cost? Opoligies for my ignorance, no offense intended.   

When the plastic cowl was removed to reach the spark plug I was astonished by the size of the engine.  Very small, and there's a lot of room in there for something bigger (canidate for a 4 stoke GX-160 transplant?). 

The manual states that this engine is piston ported without reeds.

I could see into the piston with the carb removed however I could not reach in far enough to run my finger nail along the piston.  We'll just have to wait and see.

Are two stroke engines throw away?  Not hardly. 


A well designed two stroke engine built by any leading manufacturer will provide very long service life if basic maintenance and care are given to it.  In OPE applications, they should last as long, if not longer than the machines they come on.  Top end work (rings/piston,wrist pin and wrist pin bearing cylinder honing) is a requirement on very high service time engines.  I doubt a homeowner would need to do a top end re-build during the ownership of the engine notwithstanding a catastrophic failure.   I have a number of old Yamaha motorcycles from the early '70s. I was surprised to see how strong the engines still are.   Information I've read about the old Yamaha two stroke motorcycle engines tells me that a hard driven engine will need a top end job around 10K miles.  I moderately driven machine will be good for 25 to 30K miles.  A cautiously driven bike will provide much more.   Remember, these bikes will run at 8500 rpm in stock form.  Most OPE  engines run at less than half that. 

Regarding heat dissipation.  Two cycle engines fire twice as often and therefore should make more heat than a comparable four cycle engine.  However, due to the simple design of the engine head, minimal amount of head material to retain heat and the fact that fresh (cool) air is being circulated through the entire engine (crank case and combustion chamber), temperatures are kept at reasonable levels.  I modified a couple of my old Yamahas to put out quite a bit more power than stock.  Accordingly, I had concerns with additional engine heat.  After doing some research, I learned that modifying the engine heads by removing the squish band on the RD350 changes the air/gas flow characteristics enough to increase cooling considerably.  The next step was to   install a state of the art ignition system that allowed me to retard the  ignition at higher rpm thus moving heat from the engine to the expansion chamber. 

If this is your first two stroke, I'm certain you'll learn to understand how and why they are a superior engine in a number of ways.  Their incredible simplicity, reliability, compact size and outstanding power to weight/displacement ratio will garner your appreciation.   That R-Tek will blow away any four stroke OPE engine of equivalent size.   Put it back together, get it running a be prepared to be surprised with the power it will make.      

A lot to learn for such a simple looking device. I'll let it soak in.

Its not all back together but I was impatient and put some gas in anyway. It started right up. Lots of fun. Noisy and if you watch closely you can see that its smokes.  Still, it was quite a thrill to see it start. 

http://www.youtube.com/watch?v=DZpSxnqzic4

Nice thrower... what did you end up paying for it?

-Friiy

Good going!

Sounds pretty healthy but if that was idling speed, it's set too high.   A single cylinder two stroke should idle around 1200 rpm or so.  Put a tach on it to see what it's running at then adjust your idle screw to bring the revs down. 

borat wrote:

Idle screw. I did not see that any place.  Is this screw attached to the carb? I will look again. I think I remember seeing a photo of a a governor control in the manual.  If my memory serves me, the idle speed was to be 4,000 rpm.  

What about smoke? Am I within an acceptable limit for smoke or is there such a thing?

Thanks for helping me work on this little motor. The kids all jumped up and down shouting when it started. Very exciting. Then at dinner I was told it was "too loud and  too smelly."    You can't please everyone.  

All two cycle engines smoke.  The newer ones with catalytic converters produce very little.   Older engines produce quite a bit when cold but tend to thin out as they get warmer.   Your engine will probably emit less smoke once it warms up.  Four thousand rpm for idle speed doesn't sound right.  That sounds more like max operating speed.  The idle screw is often a screw that puts force on the throttle linkage to open up the butterfly or slide (depending on carb type).  I suspect your carb has a  butterfly.  If so, see if you can find a screw or spring that sets the butterfly opening while at idle.  Something I just thought of now, is that your engine may not have a controllable throttle.  It may be running at max operating rpm upon start up.  Maybe that's what the manual means by "idle" speed.  

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..

I agree on alot of what you guys are saying about oils.....  All 2 stokes require the same lube requirements,  oil are of diffrent quality...

       Opti oil 2 (I remember the original)...  100:1 mix Is a GREAT oil...  The problem is sloppy mixing of fuel...  If you have a guy working for you that does not check the ratio of the oil to gas as he mixes it, ( mixing too little oil or too  much fuel).. you may have mixed fuel that falls short of the 2 stoke engine's needs..  at about 1.7 oz per gallon,  a small error gan make a the fuel mix around 140:1... 

When Opti oil was big news 20 years ago,  I went to a few oil  shows and asked some questions ...  Most oil suppliers told me they could / have made their oils 100:1 or even 200:1 (some using Murcury metal) , but the consumer will not follow directions closely enough to protect the equipment, and packaging for one gallon mix containers is wasteful...  Hence, a 40:1 or 50:1 ratio is widly accepted as OPE norm and hard to screw up for the end consumer.

-Friiy

 

The R-tek is reading 4138 on the tachometer.  I took several reading and they ranged from a high of 4138 down to 4128 rpm.  I measure the rpms on the shaft that comes out this side of the engine and drives the pulley  

At those kind of engine speeds, with proper lubrication, that engine should last forever.  I've got 35 year old, vintage, two stroke Yamaha twin cylinder motorcycles that have the rev limiter set at 10,000 rpm.  They can spin up to that speed without hesitation and being as old as they are, that should be a testament to their durability. 

The small individual oil bottles might be appealing but you might want to compare the price of their contents to that of a quart or a gallon of high quality two stroke oil.  For your application, having one two cycle machine, it might be worth while using the small bottles.  However, a small plastic measuring cup or calibrated turkey baster will readily measure your oil requirements.  Many two stroke oil bottles have a mixing scale printed on the rear label.  It's handy if the quantities they have printed match your mixing needs.  Otherwise, you'll still have to do some converting.  For those with multiple mix requirements, a custom made chart would be handy. 

Now that you have your carburetor sorted out, I recommend you pull the muffler off for an inspection and cleaning if necessary.  Some two strokes have a fine spark arrester screen in them that tend to clog up over time.  It's unlikely that there would be a need for one on a snow thrower but you might want to take a look nonetheless.   I know you had your machine running nicely already so, the exhaust is probably fine.  After a period of storage, you never know what what take up residence in a muffler.  

Several years ago I had left my old Suzuki ATV at camp unused for several weeks.  When I went to fire it up, it was reluctant to start.  Very unusual for this machine.  After a  minute or so of intermittent cranking at full choke and full throttle, the machine began to occasionally pop.  I cranked it over for a good ten seconds straight with it popping with regularity.  Suddenly there was this big "kaboom" and the engine started.   When the blast occurred, I saw something flying out of the back of the machine, out the garage door and onto the ground.  It was a mouse nest with three half grown mice rudely scattered about in the driveway!  

I'm assuming that the explosion was caused by raw gasoline accumulating in the header pipe and being ignited by flames from one of the engine pops.  Either way, it certainly cleared the exhaust system.    

I will check the muffler. Its easy enough to do. In fact everything seems easier to do with this motor. I'm still withholding judgement until the snow comes. But it is reassuring to hear of the longevity of some of these motors.

Is a measurement of RPMs at the output shaft representative of the engine rpms? Is there gear reduction that would create a difference between the two (engine/shaft) as there is on the Yamaha 4-stroke snowblower?

The output shaft from the engine should be the end of the crank shaft.  Accordingly, that's a good place to measure the engine rpm.  I usually use an electronic tach .   With those, you just wrap a wire around the spark plug lead and it reads engine speed.   Don't know anything about gear reducers on the four stroke Yamahas.  Never been exposed to one.

Here's a trick for cleaning the carbon out of a muffler:

Remove the muffler, place it on a hot charcoal (or even gas stove) and heat it to the highest possible setting for about 15 minutes.  Any carbon inside will turn basically to dust and you can simply tap the muffler lightly and watch it fall out.  Works great on old Lawn Boys which used to run at 16:1 and 32:1 back when oil quality was mediocre at best.

The motor will have more than enough grunt for just about any snow conditions.  I have one on my 2 stage PowerMax 726te and it will chew through nasty nasty snow that bogs down even much bigger 4 strokes.

superbuick wrote:
Will the high heat burn off the galvanized coating on the muffler and cause it to rust out?  Or is 15 minutes not enough time to do that kind of damage.  My charcoal grill can reach 500 degrees F without much trouble.

The exhaust gases passing through the muffler can attain some very high temperatures.  Chances are that the coating will not be effected.  Another way to clean the exhaust is to put an ounce or so of diesel fuel into the muffler,  shake it around, ignite it with a butane torch and keep the flame blowing through it until it's burned out.  Either process will get the job done.

It's probably unlikely that the exhaust will need to be cleaned.  If you don't see an accumulation of carbon right around the exhaust port or see carbon accumulations inside, it's probably not in need of cleaning. 

Hasn't burnt off the coating on any of  mine, but Borat is spot on - its unlikely it needs cleaning.  If it does, though, either of those methods work well (on 2 or 4 stroke engines).

It's been a year now, how's it running?  I recently got a very similar unit (CCR 2450 - 38413) with the R Tek 5hp for free but the thing won't stay running.  After the first time you start it, it will run under a load for several minutes and then die (can't do anything to save it like primer or choke).  On subsequent startups it will die very quickly.

This is why I got it for free.  The guy I bought it from said it worked perfectly but was leaking gas before he brought it in for service at Acme tool.  Acme found the recall with the cracked gas tank and replaced.  When my friend received it, it wouldn't run.  Then Acme rebuilt the carb and it still wouldn't work.  The tech at Acme said that it was due to low compression ~100 psi and it should be 130.  Now it's in my lap.

I've pulled the carb apart and looked for anything outside of the ordinary, cleaned it and put it back together.  I noticed remains of a sticker around the pilot-jet but finished cleaning the carb and replaced.  It ran exactly the same, no joy.

Recaling the tape remains around the pilot jet, I put a piece of tape over the pilot jet..  It worked perfectly, for about 10-15min (much longer this time) and then died again.  Now it's possible the tape came off??  What did you do with yours?  Did you have to tape over that pilot jet?  In this discussion forum thread I've seen someone suggest that you don't have to cover the pilot jet but I've also seen in the R tek service manual that it's one of the differences between the R Tek engine and the DuraForce engine.  What did you do?

Pull the head off and see if the piston is dished out on top or burnt. Also can run the piston down and check some of the cylinder for real deep scratches. Or take the exhaust off and take a look see in the port that the rings arent scraped over

I have to think that if it ran perfectly before my friend brought it in for service on a gas tank issue, it should run perfectly after a gas tank service.  Would there really be a need to pull the head off at this point?  I'm hoping for a an easier solution...

It's difficult to get an accurate compression reading on these machines if they have a compression release mechanism.   Chances are the compression is fine.  Your problem is likely all fuel or carburetor related.  If you have the basic skills required to clean it, I suggest you pull it off yourself and go over it.  It may need to be thoroughly cleaned.  Just because someone said they cleaned it doesn't mean it was done right.

Another thing to look for, is to make sure the fuel cap vent isn't blocked.  if you get the machine running and it starts to falter, loosen the fuel cap to see if you can get air into the tank. 

If you clean the carb and it still doesn't work, look for a new (preferably metal) carb to replace it.  Ebay might have one for around $20.00 or so.  Either way, it's a great machine that's worth a bit of expense to get running right. 

Will the engine turn over?  If some one ran  gas through it , it would throw a rod or weld it self together. If it is locked up , i would not bother with it. It may be welded or rusted up.From your pics your carb is messed up and i'm sure your ignition is too . Just buy another engine. You will make out cheaper.

Wow - I appreciate all of the suggestions! I'm with you (Borat) on the compression thing, I can't see that being an issue when it runs perfectly under load but then when it seems to really warmup, that's when it dies. Weak compression would not manifest itself like that (I don't think). As I mentioned earlier, I did take the carb apart, removed the jets/nozzles and sprayed it down good through every orifice. I think on this model that the pilot jet needs to be covered. I did put a piece of tape over it and got it to run much longer. I talked to the coworker today that gave me the machine and he gave me another clue - He said that when he originally brought it in that the repair person at Acme told him that the fuel filter was installed the wrong way and he switched it around. Note, it worked fine for almost 10 years the way it was. I did try removing the fuel cap to check for vapor lock, that made no difference. This leads me to believe I might have a couple of things to look out for. 1) Instead of putting in a new one, he just changed the orientation of the filter which would allow any accumulation from the last 10 years to go into the carb! The good news is that the little plastic carb has a screen on the main jet and it doesn't appear to have any issues with the needle/seat like I'd expect. This is good. But is there anything special about the fuel filter on these things? Does it have a check valve. I blew through it last night and there didn't appear to be any restriction but I blew from the carburator into the fuel tank, not the other way around. That would explain the quitting after a few minutes and then not staying running if it was starved for fuel and burned what was in the bowl along with the line after the fuel filter and then wouldn't stay running untill it sat a while until gravity filled the float bowl again. I could test this just by blowing into the gas tank after it quits and see if it extends the run-time to let me know if I'm on the right track (a trick I learned on snowmobiles to get the fuel into the bowls after you've drained them!). 2) I'm still thinking about the 'plug' to the pilot jet on the side of the carburetor. I was reading in a service manual for the R-Tek and it's sibling the 'DuraForce', one of the differences it specifically stated was that the pilot jet had a plug. By plug I'm sure they are referring to the decal that originally was placed over the top of the pilot jet. Last night when I tried plugging the pilot jet it worked perfectly for about 10-15min (much longer than before). So it's possible that the piece of duct-tape that I slapped on there came loose. When I open it up tonight to put in a new fuel filter, I'll clean the side of the carb with alcohol and put a good piece of tape over the pilot jet to see if that changes anything. I know, I should only change one thing at a time but taking that shroud off is a royal pain and running it under load without the shroud means leaving the carburetor's intake exposed to the elements - I personally don't get how that engine doesn't fry when it's no doubt sucking in ice crystals. This is the big thing that all the warnings on snowmobiles scare you about and use multiple foam filters that mice love to eat. Finally, if you know of a metal carb for this that will work, I'm open to suggestions. Plastic carbs don't exactly inspire confidence. I'm willing to throw some bucks at this thing, it works great on this spring snow where it cleans all the way down to the concrete vs. just leaving a thin layer like my bigger snowblower does. It will also work great on my ice rink where it's imperative to clean all the way down the ice before resurfacing. This thing could save me a bunch of time!