Briggs&Stratton Snowblower Engine 16.5 HP

[jono252525]

I am rebuilding this B&S snowblower engine that blow the connecting rod and scratched the cylinder and the piston also.
The spec say Bore Diameter 3.300 in. (83.82 mm) Reject at 3.304 in. (8)3.92 mm.
I was able to hone the cylinder and removed the scratch but now I am at 3.304 in.
Could I get away by replacing the piston by the standard size ?
The problem is that the other option was a .020 over size piston that is NLA.
I would prefer a .010 over size piston, but no information from B&S on that option.
I cannot find an other company that would make a compatible piston for my engine.

Here the spec of the engine.

B&S engine 21M314-2470-E2 ,spec

The Briggs & Stratton engine model 21M314-2470-E2 is a 342cc Snow Professional Series
horizontal shaft engine designed specifically for snowblowers
Number ingrave in the Standard size piston = H079A 5 216413 Or B&S 793318 or 791813
B&S oversize piston .020 inch Number 793325 but NLA
And No information on a .010 inch oversize piston ( option )
Engine specifications

• Engine Series: Snow Professional Series
• Engine Type: 4-cycle, single cylinder, air-cooled, Overhead Valve (OHV)
• Displacement: 342 cc
• Torque: 16.50 ft-lbs gross torque
• Cylinder Bore: Aluminum alloy
• Bore and Stroke: 79.0 x 61.0 mm (3.12 x 2.43 inches)
• Lubrication: Splash lubrication system
• Oil Capacity: 26 to 28 ounces (0.77–0.83 L)
• Fuel Tank Capacity: 3.03 L (3.2 quarts)
• Crankshaft and starting system
• Crankshaft: 3/4-inch diameter, 2-33/64 inches long, straight shaft with a keyway.
• Starter: 110-volt electric starter with a recoil (pull) starter backup.
• Alternator: 60-watt AC alternator.
• Features for cold weather starting
  • Easy-start primer

Freeze-resistant recoil starter

Other features

• Ignition: Maintenance-free Magnetron electronic ignition.
• Carburetor: Float carburetor for reliable fuel delivery.
• Governor: Mechanical.
• Exhaust: Super Lo-Tone muffler for quieter operation.
• Controls: Manual friction/remote control and manual choke.

The engine 21M314-2470-E2 refers to a Briggs & Stratton 1650 Professional Series™ Snow engine, a 342cc, overhead valve (OHV), horizontal crankshaft engine designed for 2-stage snowblowers, producing 16.50 ft-lbs of torque, with features like a float-feed carburetor, Magnetron® electronic ignition, and a freeze-start primer for cold weather operation

I need your help to find a .010 oversize compatible piston. OR ?

 

[Auto Doc's]

I say hone it very lightly, then re-ring it and run it.

Boring to oversize is impractical and very expensive to do in a machine shop and have them do it correctly. Conventional honing with a straight sleeve hone and drill just does not work with any accuracy to maintain a true, straight bore. I have tried several times with mixed results.

 

[StarTech]

21M314-2470-F2

This is why I have ridge hones here. They remove tapers and out of round (Oval) conditions where flex and ball hones do not; they just make things worst.

 

[slomo]

Does harbor freight make a suitable replacement engine?

 

[jono252525]

Does harbor freight make a suitable replacement engine?

I need to repair the engine and I have a friend that have the special tool to do the honing for free , so Can You find me a replacement .010 inch oversize piston for my engine?

 

[Auto Doc's]

Sorry, these .010 or even the .020 pistons are nowhere to be found.

You are at maximum tolerance for the bore, I suggest you put a standard piston and rings to keep this going for a few more seasons.

Most connecting rods like this get broken when the engine has been started cold and immediately run at high RPM before a good warmup of the oil and the cold parts.

I used to deal with a lot of snow blower engine damage when I lived in central Virginia. People would often go from startup to full throttle so they could hurry up and get back inside where it was warm.

 

[jono252525]

Sorry, these .010 or even the .020 pistons are nowhere to be found.

You are at maximum tolerance for the bore, I suggest you put a standard piston and rings to keep this going for a few more seasons.

Most connecting rods like this get broken when the engine has been started cold and immediately run at high RPM before a good warmup of the oil and the cold parts.

I used to deal with a lot of snow blower engine damage when I lived in central Virginia. People would often go from startup to full throttle so they could hurry up and get back inside where it was warm.

There should be an other manufacture that make this oversize piston.

 

[Auto Doc's]

There should be an other manufacture that make this oversize piston.

You have to understand that these oversize pistons were not in high demand from the OEM and the aftermarket did not bother making them, so production was very limited for only a few short years by the OEM.

Once stocks are depleted, they are gone.

These were not high production engines like a typical automobile engine where the aftermarket produces such oversize pistons.

 

[ILENGINE]

Once upon a time there were typically .010,.020,.030 oversize pistons. Most mower engine manufacturers have dropped the .010 and .030 oversize pistons sizes, which leaves the ..020 as the only oversize option available. And in some cases there were never any oversize pistons offered. Demand for rebuild parts on small engines is very low, since to do an overhaul correctly you will have almost as much money in the rebuild then just replacing the engine.

My local machine shop that does cylinder boring won't even do a bore for a .010 oversize. .020 or larger. Since most of the time .010 won't clean up the cylinder taper.

 

[StarTech]

Plus we got remember B&S is owned by a financial investment that don't about the customers if not are not making tons of money off them. I even had two year old engine that was still under warranty that I couldn't get parts for. And Briggs comment was "Tough luck the sub contractor is out of business".

And I remember one engine that was .006 over on the top of the stroke that didn't clean up until 018 over. Boy I was getting worry about that .020 piston that I brought was even going to get used. It was the bottom taper and oval that caused the near loss of an engine.