2hp vs 3hp Briggs crank differences

[isaac_halverson]

Are they the same crank or does the 3hp have a little extra stroke?

Sent from my MotoG3 using Tapatalk

 

[Slideaway]

Are they the same crank or does the 3hp have a little extra stroke?

Sent from my MotoG3 using Tapatalk

Im also interested to know if you can swap a 2hp crank into a 3hp. Im sure someone here knows if its atall possible

 

[Richard Trotter]

You can swap crank, rod and piston as a set but don't mix and match.

 

[Havasu Dave]

Richard Trotter is ON IT!

I'd hate to guess what it costs to get one shipped to the UK, along with import tax, VAT, etc.

 

[Slideaway]

Richard Trotter is ON IT!

I'd hate to guess what it costs to get one shipped to the UK, along with import tax, VAT, etc.

Luckily i have a spare 2hp with a smashed up valve seat, but crank, rod and piston are perfect so may do this swap on my 3hp with no keyway on the output shaft. Will there be a major performance loss though?

 

[Dr. Shop Teacher]

Luckily i have a spare 2hp with a smashed up valve seat, but crank, rod and piston are perfect so may do this swap on my 3hp with no keyway on the output shaft. Will there be a major performance loss though?

It all depends on the block. If the 2hp was a Kool-Bore (aluminum bore) and the 3hp is also a Kool-Bore, shouldn't be an issue. However, if the 3hp is steel sleeved, then you'll need the correct piston for a sleeved bore engine. You are losing 1hp, so there will be a loss which can be made up by sacrificing speed and using lower gearing (mini bike, I presume?).

As to Dave's note, I just ordered a Tecumseh stator from the UK through eBay and the shipping/fees were quite reasonable. Might be a tad more going the other way.

 

[Havasu Dave]

It all depends on the block. If the 2hp was a Kool-Bore (aluminum bore) and the 3hp is also a Kool-Bore, shouldn't be an issue. However, if the 3hp is steel sleeved, then you'll need the correct piston for a sleeved bore engine. You are losing 1hp, so there will be a loss which can be made up by sacrificing speed and using lower gearing (mini bike, I presume?).

As to Dave's note, I just ordered a Tecumseh stator from the UK through eBay and the shipping/fees were quite reasonable. Might be a tad more going the other way.

Looks to me like he's losing .25 of stroke. From Richards comments, it looks like the crank journals and wrist pin sizes are not the same. Only the bore is. They would both be aluminum. I can't answer the question definitively because I don't know enough about the years, and he didn't supply model numbers for both engines. I was originally tagging you in this post actually, but then noted Richard had answered.

With regard to the UK, it is far more expensive for them than "US," as they have to deal with a VAT tax that is pretty steep.

The OP needs more crank shaft, and a key way. NOTE: I have used an extension on the crank with a shoulder bolt going in to the PTO on Tecumseh. I used an old crankshaft piece to the extension, and threaded it to the PTO.

 

[Dr. Shop Teacher]

The OP needs more crank shaft, and a key way. NOTE: I have used an extension on the crank with a shoulder bolt going in to the PTO on Tecumseh. I used an old crankshaft piece to the extension, and threaded it to the PTO.[/QUOTE]

Now that's a slick idea...I didn't even consider that with one of the Briggs Cousins. I have used a steel spacer for short extensions.