Crank balancing

Ps113r

New member
I am building a mod clone, need the crank balanced, anyone know anyone who does that kind of stuff, I am located in central Kansas preferably but I can ship it if necessary
 

flattop1

Dawg 89
Single cylinder engines do not balance well.
Search the tractor pulling folks .
I've seen where they do it .
Do you have a balance factor in mind?
 

"J'-remy

Member
there is no such thing as balancing a single cyl one-piece crank. save your money. anyone claiming they will do it is just taking your money not to mention if tech sees holes or grinding on your crank you'll probably get tossed
 

95 shaw

Site Supporter

Here is a pretty good series of explanations about primary and secondary balance forces. And what it takes to get the most from your balance job.
 

ABR #69

Member
The balance in single cylinders is moved to be balanced within it's usable power range. So that it's out of balance at it's lower RPM and more in balance when in it's higher RPM. Specifically the RPM range it see's the most under power. It's absolutely still done in ALL types single cylinder engines. It's been done since the invention of the engine.
 

"J'-remy

Member
ok how does that work in an engine that is operating at a different rpm every mili second?

or have you "balanced" crank engine and start it and run it on without it being bolted down in its balanced rpm range. it should not bounce around right?
 
Last edited:

"J'-remy

Member
It's called tuning.

Beyond that, everthing is a compromise.

Matching the rpm range to best suit the needed powerband.

Most of that learned from 'sperience.
and some people believe the world is flat. most gullible people on the planet are guitar players and motorsport racers

do whatever you think is fast
 

ABR #69

Member
and some people believe the world is flat. most gullible people on the planet are guitar players and motorsport racers

do whatever you think is fast
The big thing on the other side of the crank shaft opposite the piston, that's a counter weight.... To balance the crank shaft.... Lmfao.

You do realize that changing the bore of an engine requires you to balance the crank? They have to be balanced from the start, they're not perfectly balanced from the factory. They can be "tuned" and balance better. You "tune" for an RPM Range. Or did you not read that part? The Range covers your mili-second problem.
 

CarlsonMotorsports

Site Supporter
You absolutely can balance a single cylinder engine.
The problem is that you have less weight to work with and can really only balance the rotating assembly (with flywheel) to a specific rpm.
From the factory, most of our industrial engines are static balanced to 3600 where they were designed to spend much of their life. At 3600 rpm, the balance doesn't have to be very precise, but at 10,000 rpm, that balance had better be a lot closer than where it was from the factory if you want that engine to live. Big surprise that we have to loctite sidecover bolts on a clone turning 7000 rpm with stock factory balanced parts.
Now, throw in different bore sizes, different piston and ring packages, different connecting rods, and then throw a light weight billet aluminum flywheel on it, and you'll see that the factory "balance" is a long way from perfect with your new rotating assembly.

We spent a LOT of time testing a balanced flathead years ago through the clutch alone. Was it worth it? Not really. But then again, the engine was $600 as raced. Take a small block open that's turning gazillion rpm and costs upwards of $2500, and I think you'll want to at least consider having it professionally balanced. The benefits are real -- the return on investment may vary for your application and budget.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
www.youtube.com
34 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 

rainman

Site Supporter
Single cylinder 2 strokes are actually balanced, since they are a 2 piece crank and you do need to make sure you mount it right and aligned or otherwise vibration will destroy the engine, and it won't run true in the cases, and other than through alignment they can be balanced through the crank halves plugs too. They is a reason why V-blocks are used.
 

flattop1

Dawg 89
I am building a mod clone, need the crank balanced, anyone know anyone who does that kind of stuff, I am located in central Kansas preferably but I can ship it if necessary
Screenshot_20221117-174034.png
 
Top