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Underdog


Joined: Oct 18, 2008
Points: 332

Diagnosing a (new to me) 2-stoke engine for trouble
Original Message   Mar 16, 2010 9:22 am
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. 

This message was modified Mar 16, 2010 by Underdog


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Underdog


Joined: Oct 18, 2008
Points: 332

Re: Diagnosing a (new to me) 2-stoke engine for trouble
Reply #2   Mar 16, 2010 2:24 pm
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?

This message was modified Mar 16, 2010 by Underdog


Underdog


Joined: Oct 18, 2008
Points: 332

Re: Diagnosing a (new to me) 2-stoke engine for trouble
Reply #3   Mar 16, 2010 9:23 pm
The old fuel was drained from the tank and the plastic carburetor was removed.  I think there was water inside the carb.

This message was modified Mar 16, 2010 by Underdog


Underdog


Joined: Oct 18, 2008
Points: 332

Re: Diagnosing a (new to me) 2-stoke engine for trouble
Reply #4   Mar 16, 2010 9:30 pm
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.

This message was modified Mar 17, 2010 by Underdog


aa335


Joined: Nov 29, 2008
Points: 2434

Re: Diagnosing a (new to me) 2-stoke engine for trouble
Reply #5   Mar 16, 2010 11:21 pm
It's sad to see such a nice piece of equipment neglected and left outside like this.
superbuick


Joined: Feb 23, 2009
Points: 138

Re: Diagnosing a (new to me) 2-stoke engine for trouble
Reply #6   Mar 17, 2010 8:31 am
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.
Underdog


Joined: Oct 18, 2008
Points: 332

Re: Diagnosing a (new to me) 2-stoke engine for trouble
Reply #7   Mar 17, 2010 9:10 am
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.

This message was modified Mar 17, 2010 by Underdog


Underdog


Joined: Oct 18, 2008
Points: 332

Re: Diagnosing a (new to me) 2-stoke engine for trouble
Reply #8   Mar 17, 2010 12:11 pm
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.

superbuick


Joined: Feb 23, 2009
Points: 138

Re: Diagnosing a (new to me) 2-stoke engine for trouble
Reply #9   Mar 17, 2010 4:06 pm
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.
Underdog


Joined: Oct 18, 2008
Points: 332

Re: Diagnosing a (new to me) 2-stoke engine for trouble
Reply #10   Mar 17, 2010 7:49 pm
superbuick wrote:
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.

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?

This message was modified Mar 17, 2010 by Underdog


borat


Joined: Nov 10, 2007
Points: 2692

Re: Diagnosing a (new to me) 2-stoke engine for trouble
Reply #11   Mar 17, 2010 10:09 pm
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. 
This message was modified Mar 17, 2010 by borat
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