Box Stock

Better engine balancing?

N

Number21

Member
I have a 212cc clone engine that I'm using for a somewhat unusual project. It's not a kart, but I don't want to talk about the details or people will get confused. I want a kart type engine. I need this engine to run from about 2000 RPM to 4500 RPM. I want it to be extremely durable, so I am going to replace several parts with things like a forged piston, billet rod, better cam, and a few other things.

I've currently been using the engine in stock form and I notice it likes to vibrate a lot more at lower speed around 2000 RPM, and when I speed it up it noticeably smooths out just a little bit. This is a currently untouched chinese made engine.

I'm wondering if I buy higher quality parts, and I take the trouble to have them balanced, will the engine be able to run a little bit more smoothly at lower RPMs? Can the factory (lack of) balance be made better? Or am I just expecting too much from a single cylinder engine? I realize it isn't going to be perfectly smooth running, I'm just wondering if improvements can be made?

Would the whole thing be stronger/stiffer with less vibration if I used a Tillotson block with all the extra reinforcements for rigidity?
 
Vibration under Load ?
That could be due to overworking the engine .
Lighter piston as stated .
A heavier flywheel would help with smoothing /dampening the power strokes .
 
Right now I have it temporarily connected to a water pump for a load. It is not being overworked, probably only around 3-4hp is all the pump uses. At typical full governed speed, it's relatively smooth for what it is, it's only when I turn down the throttle the whole thing shakes just a little bit more. This is probably "normal" for a cheap factory engine, I'm just wondering if I can solve that or if I'm just expecting too much from a single cylinder engine? It could perhaps be a tuning issue, I need to get a good adjustable carb.

I don't "need" a lot of performance parts for the sake of horsepower, but, I'm going to be replacing a bunch of parts in the name of high durability and easy repairs. I want to get the piston skirt coated with a lubricating coating and the piston top and combustion chamber/valves ceramic coated. I'm trying to make the engine as high efficiency as I can.

Is it possible to find a heavier flywheel than the standard steel/cast iron flywheel they come with? I know most people are more interested in lightening it...
 
So the water pump is a test bed ?
Whats the real end game ?
600.00 dollars of ceramic and parts for a water pump seems fruitless.
 
I suggest a stock Honda GX200 if you want durability and smoothness at that rpm.
A Briggs and Stratton LO206 engine will also be a good choice. No mods, bolt in either one and go.
By the time you have tarted up a clone you would have spent considerably more dollars.
 
The Predator is not known for quality workmanship. If you really intend for it to last a long time I would focus on things like the fasteners. Use studs for the cylinder head and sidecover, use Loctite, good locking washers and check the rod journal on the crank for roundness. Plastigage the rod/crank journal. Check crank end play, shim if required. Or, as Compu-kart suggested, get a Honda and feel good about getting a quality engine.
 
Number21 said:
Right now I have it temporarily connected to a water pump for a load. It is not being overworked, probably only around 3-4hp is all the pump uses. At typical full governed speed, it's relatively smooth for what it is, it's only when I turn down the throttle the whole thing shakes just a little bit more. This is probably "normal" for a cheap factory engine, I'm just wondering if I can solve that or if I'm just expecting too much from a single cylinder engine? It could perhaps be a tuning issue, I need to get a good adjustable carb.

I don't "need" a lot of performance parts for the sake of horsepower, but, I'm going to be replacing a bunch of parts in the name of high durability and easy repairs. I want to get the piston skirt coated with a lubricating coating and the piston top and combustion chamber/valves ceramic coated. I'm trying to make the engine as high efficiency as I can.

Is it possible to find a heavier flywheel than the standard steel/cast iron flywheel they come with? I know most people are more interested in lightening it...
Click to expand...
Coating the piston skirt and valves in race application ceramic coatings can cost upwards of $250-$350. You will gain zero in either performance, reliability or smoothness at low rpms. Any billet part will also yield the same non-results. A heavier flywheel than the stock cast iron one, assuming you want to keep the same blower housing and magneto, will have to be fabricated from lead. I cannot imagine what that might cost IF you can find someone willing to fabricate one. Would suggest keeping the stock or getting a lighter PVC or aluminum one at the sacrifice of smoothness at low rpm. In your quest for efficiency a lighter flywheel may actually offer you a small gain. The engine will lose less horsepower trying to spin a heavy flywheel. The predators engine is air cooled and the flywheel is attached to cooling fins which has a high air resistance.
Most carbs are adjustable via changing the fuel jets. The stock predator carbs have interchangeable jets.
If you decide going with a Predator engine I would recommend trying it in its stock configuration, use a high quality air filter and engine oil. Clean the filter and change the oil every few hours and then decide on upgrades.
 
Number21 said:
I have a 212cc clone engine that I'm using for a somewhat unusual project. It's not a kart, but I don't want to talk about the details or people will get confused. I want a kart type engine. I need this engine to run from about 2000 RPM to 4500 RPM. I want it to be extremely durable, so I am going to replace several parts with things like a forged piston, billet rod, better cam, and a few other things.

I've currently been using the engine in stock form and I notice it likes to vibrate a lot more at lower speed around 2000 RPM, and when I speed it up it noticeably smooths out just a little bit. This is a currently untouched chinese made engine.

I'm wondering if I buy higher quality parts, and I take the trouble to have them balanced, will the engine be able to run a little bit more smoothly at lower RPMs? Can the factory (lack of) balance be made better? Or am I just expecting too much from a single cylinder engine? I realize it isn't going to be perfectly smooth running, I'm just wondering if improvements can be made?

Would the whole thing be stronger/stiffer with less vibration if I used a Tillotson block with all the extra reinforcements for rigidity?
Click to expand...
You can't balance a single piston engine. There is only one point it is balanced and that is when the motors rotation where the piston is in line with the crank.
 
I've heard lots of people say "You can't balance a single cylinder engine." Bull. Evidently those guys have never built a decent runner. I've seen stock engines that vibrated so bad you had to use star washers on the side cover bolts to keep them from backing out. On the other end of the scale I've had engines turn 10K+ RPM that were as smooth as silk throughout the RPM range. It's all in the balance of the crankshaft and flywheel. An unbalanced engine will shake, a balanced engine won't. If your engine builder cannot balance a single cylinder engine to run smooth, it's not the engine's fault and it's not because it can't be done. And no, there are no backyard methods to properly balance an engine. There are build habits and rules of thumb to follow that will help, but the only way to get a good balanced engine is to take the internals to someone with a computer balancer that knows how to use it. These days that's gonna cost $350 minimum. Speed costs money...
 
Oh my god so many confused people assuming things they nave no idea about...

No, this will not be a water pump engine. I clearly said that was temporary. Stop assuming things you have not been told. I'm not going to explain the final use of this engine because then you will go even more off topic. Just pretend it's a go kart if that makes you happy.

I was not asking anybody's opinion on durability, this is my department. And I never said I have or will have a Harbor Freight engine. I only asked one simple question - can it be better balanced at a lower RPM? That is the only thing I asked. I understand single cylinder engines don't usually run silky smooth, some even have extra balance shafts. I'm just wondering if it can be improved over stock. At full speed it is surprisingly smooth.

No, it does not cost $350 to have a single piston coated. I've coated more than one V8 engine with 8 pistons. Less than $100 each. They also sell kits to do it yourself if so inclined. Even if it did cost $350, I don't care.

Cost is not an issue. I am not poor, I spend money on whatever I feel like doing. Personally I think spending $1,000+++ on a race engine is silly but do whatever floats your boat. No, I'm not using a Honda or a Briggs, the clone engines are more common with more parts and a genuine Honda is not any better than a quality built clone. Especially if I use something like the Tillotson block.

I am not attempting to create huge horsepower numbers, I am improving overall engine efficiency and durability, which often includes some of the things that make more power. This is something you can do to any factory engine - even a Briggs or a Honda would be cracked opened and modified if I used one.

I also need to point out that the weight of a flywheel has nothing to do with the "horsepower" or efficiency output of the engine. It effects throttle response, but once it's spinning it does not matter if it weighs 1lb or 100lbs, it's not wasting HP. The part that wastes HP is the blower fan, but it's kind of required.
 
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Number21 said:
Oh my god so many confused people assuming things they nave no idea about...

No, this will not be a water pump engine. I clearly said that was temporary. Stop assuming things you have not been told. I'm not going to explain the final use of this engine because then you will go even more off topic. Just pretend it's a go kart if that makes you happy.

I was not asking anybody's opinion on durability, this is my department. And I never said I have or will have a Harbor Freight engine. I only asked one simple question - can it be better balanced at a lower RPM? That is the only thing I asked. I understand single cylinder engines don't usually run silky smooth, some even have extra balance shafts. I'm just wondering if it can be improved over stock. At full speed it is surprisingly smooth.

No, it does not cost $350 to have a single piston coated. I've coated more than one V8 engine with 8 pistons. Less than $100 each. They also sell kits to do it yourself if so inclined. Even if it did cost $350, I don't care.

Cost is not an issue. I am not poor, I spend money on whatever I feel like doing. Personally I think spending $1,000+++ on a race engine is silly but do whatever floats your boat. No, I'm not using a Honda or a Briggs, the clone engines are more common with more parts and a genuine Honda is not any better than a quality built clone. Especially if I use something like the Tillotson block.

I am not attempting to create huge horsepower numbers, I am improving overall engine efficiency and durability, which often includes some of the things that make more power. This is something you can do to any factory engine - even a Briggs or a Honda would be cracked opened and modified if I used one.

I also need to point out that the weight of a flywheel has nothing to do with the "horsepower" or efficiency output of the engine. It effects throttle response, but once it's spinning it does not matter if it weighs 1lb or 100lbs, it's not wasting HP. The part that wastes HP is the blower fan, but it's kind of required.
Click to expand...
Well it certainly seems like you have a lot of experience. Maybe you can teach us a few things.
 
No such thing as a balanced single cylinder. Any flywheel should be balanced to x rpm. Ran a briggs stock flywheel in a motor that did 9700 rpm without issue never balanced anything.
 
Number21 said:
Oh my god so many confused people assuming things they nave no idea about...

No, this will not be a water pump engine. I clearly said that was temporary. Stop assuming things you have not been told. I'm not going to explain the final use of this engine because then you will go even more off topic. Just pretend it's a go kart if that makes you happy.

I was not asking anybody's opinion on durability, this is my department. And I never said I have or will have a Harbor Freight engine. I only asked one simple question - can it be better balanced at a lower RPM? That is the only thing I asked. I understand single cylinder engines don't usually run silky smooth, some even have extra balance shafts. I'm just wondering if it can be improved over stock. At full speed it is surprisingly smooth.

No, it does not cost $350 to have a single piston coated. I've coated more than one V8 engine with 8 pistons. Less than $100 each. They also sell kits to do it yourself if so inclined. Even if it did cost $350, I don't care.

Cost is not an issue. I am not poor, I spend money on whatever I feel like doing. Personally I think spending $1,000+++ on a race engine is silly but do whatever floats your boat. No, I'm not using a Honda or a Briggs, the clone engines are more common with more parts and a genuine Honda is not any better than a quality built clone. Especially if I use something like the Tillotson block.

I am not attempting to create huge horsepower numbers, I am improving overall engine efficiency and durability, which often includes some of the things that make more power. This is something you can do to any factory engine - even a Briggs or a Honda would be cracked opened and modified if I used one.

I also need to point out that the weight of a flywheel has nothing to do with the "horsepower" or efficiency output of the engine. It effects throttle response, but once it's spinning it does not matter if it weighs 1lb or 100lbs, it's not wasting HP. The part that wastes HP is the blower fan, but it's kind of required.
Click to expand...
This may help you some. https://4cycle.com/karting/threads/balancing-arc-crank.118579/post-855322
 
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