Driveway Port Toro S200? (Tecumseh) -pics

[Moddoo]

Hello all.
Not a chainsaw, but small 2 stroke anyway.
I picked up this snowblower for $20 this summer.
Cleaned the carb, and it runs great.
Then today I decided to tear it down for the heck of it and see how it's built.
I find that the ports are simple drill holes in the jug.
The transfers from the case to the intakes are uncleaned cast openings.
And the head gasket is thick paper.

I plan on cleaning up the transfers and shaping the port "mouths" to promote better flow.
The exhaust pipe needs a lot of work near the port to remove the 'wall' it creates at the gasket.
Also thinking of ditching the head gasket or using a thinner one to increase compression. I may do some math and measuring to determine how far to go with this.
I don't plan on changing port timing at all at this time. Since I am unsure of where to go with it.
I may decrease the volume in the intake manifold where it creates a transfer port on that side.
Anyone else ever mess with one of these little snow throwers before?

 

[Moddoo]

More pics
All port pics from inside were taken at BDC.

 

[PES+]

Move cautiously

That block has rather large potential for power the huge problem you have is the connecting rod and big end and small end bearings.

Check the big end bearing carefully because it appears to have few rollers if any (some of these Tec's have a plain big end bearing)

You can see gains by cleaning up and matching the ports but attempting to raise the RPM significantly will be short lived fun.

Also use a good synthetic oil at 50 to 1 or 40 to 1 if it is a plain sleeve big end bearing (no rollers)

That carbon you see on the piston and in the ports causes all manner of headaches and should be minimized any way possible

 

[kevlar]

That block has rather large potential for power the huge problem you have is the connecting rod and big end and small end bearings.

Check the big end bearing carefully because it appears to have few rollers if any (some of these Tec's have a plain big end bearing)

You can see gains by cleaning up and matching the ports but attempting to raise the RPM significantly will be short lived fun.

Also use a good synthetic oil at 50 to 1 or 40 to 1 if it is a plain sleeve big end bearing (no rollers)

That carbon you see on the piston and in the ports causes all manner of headaches and should be minimized any way possible

That is exactly what I was about to type!Huge potential for power after just cleaning those ports up but that bottom end was never made to handle them!

 

[Moddoo]

Thanks for the info.
This motor does have the needle bearings on the crank. The wristpin bearing looks to be simple.
I will inspect them before assembly.
Have you 2 ever increased the compression on one of these?
It is an AH520 engine I believe.

The governor is adjustable, but I may add a finger throttle to get more rpm only when I need it.

I have used these blowers plenty of times in the past, and they work pretty well for being so simple.

 

[ned coed]

when i worked in a small engine shop 20 odd years ago these engines were quite common. aspera made a very similar av520 av600 model with torrington needle big end but were not very strong so be careful. if i remember correctly the head was fixed with six 3/16 unc bolts. one day we had a vicar/padre who kept complaining that his old rotary clinton two stroke was not going like it should. cos i had some time to kill i opened his transfers,cut the base gasket to match. widened his intake a little and raised the exhaust a few mill. he came back again but only to say that it was cutting grass like a goodun. the guys had a laugh when i told them what i,d done.

 

[PES+]

Thanks for the info.
This motor does have the needle bearings on the crank. The wristpin bearing looks to be simple.
I will inspect them before assembly.
Have you 2 ever increased the compression on one of these?
It is an AH520 engine I believe.

The governor is adjustable, but I may add a finger throttle to get more rpm only when I need it.

I have used these blowers plenty of times in the past, and they work pretty well for being so simple.

You can......but again don't go overboard.
When you raise compression it puts much higher load on the rod bearings and you have the flimsy aluminum rod.

I have been looking at some of these motors recently myself and need to investigate the older model rods which were steel and see which will fit.

If you raise the RPM too high the rod will break right below the small end.

If you raise compression too high and load it hard you will wear the big end eye and break the cap.

 

[oneoldbanjo]

Well I am going to sound like an old guy here (maybe because I am getting old)! I have one of those Toro snowblowers.....and after 33 years it still runs fine. In those 33 years the only thing that has required maintenance is the replacement of the fuel line that got dissolved by the alchohol in the new fuel. The snowblower sits for 10 months at a time between uses and only runs for a few hours each year. The blower still has the orignal carb diaphragms and I believe the sparkplug is the original. The engine has adequate power for running the rubber blades of the snowblower - and I can't imagine that there is much need for increased rpm or power from this cheap little engine. The snow blower works well in light snow that is up to a foot deep - or in wet snow/slush that is only a few inches deep. When moving snow with this blower sidewalks can be cleaned really quickly by going along the length of the sidewalk and blowing snow to the side by angling the chute to either side. For driveways it works best to clean a path down the middle and then work the driveway sideways while blowing the snow straight ahead to the edge of the driveway - try to avoid blowing the snow in a location that you will have to clear again as the snow keeps getting compacted and heavier and harder to move each time you run it through the blower.

This is a cheap, light little blower that works great on sidewalks and small driveways in light snow - heavy and deep snows are going to require something bigger. The only big complaint I have is the muffler blows the exhaust behind the snow blower - which is where I am standing . The 32:1 fuel/oil mixture is a bit rich by modern standards and the blower does smoke heavily and the operator smells like exhaust after using the blower. I am going to try the Mobile 2T at a 40:1 mixture in it this year and see if the nasty smell can't be reduced a bit.

Don't get too crazy modifying this cheap little engine or trying to get higher rpm's - the snow blower really doesn't need any more horsepower and seldomly bogs down. It will occassionally bog down in heavy wet snow and on occasion I do stall the engine - but I imagine the rubber blades wouldn't be able to do a whole lot more work even if the engine was more powerful.

 

[Moddoo]

I got it done.
it runs strong.
I'll post some pics tomorrow.

 

[Moddoo]

Here are some pics of the porting.
I left the head gasket alone for now.
It's running great, and I had to mod the tensioner for the drive belt to put the power to the snow.
I have another engine coming for free.
I may get a little more radical on that one for fun.

 

[booster]

I'm doing the same thing to my s200. Any suggestions for cleaning out the crankcase and jug before reassembly? Any preferred 2-cycle oil? Synthetic?
Thanks for posting the photos they were helpful.