ESE's works engine tuner

[41juergen]

For what engine, Jürgen? Jan Schäffer of Langtuning or Martijn Stehouwer of Emot might be able to supply you with the type of piston plug you need.
Re the material: it'd not PEEK. I wish; the stuff I finally found most suitable is a lot more expensive.
The pics show the plugs in a FOS-piston and a comparison of the Pankl RSA-piston pin and a FOS-plug.
Attachment 316978Attachment 316977Attachment 316979

Thank's a lot Frits, will contact both. They are for a TZ250 4DP (the Vee 2 engine from 1995) with a 16mm diameter piston pin ....
Juergen

[jfn2]

hello 41juergen:
When you contact these people could you ask them what size they do make the plugs for and tell us? Thanks jfn2

[TZ350]

.

Yes, contact details for piston pin plugs would be very welcome.

[Moooools]

Hi Everyone,

I have seen a bit of the discussion around crank balance going on, so I got motivated to port my MATLAB balance script into excel to make it a bit more accessible.

So far the sheet is for a single cylinder without a balance shaft only.

It finds an optimum balance factor based on minimizing the difference between horizontal and vertical RMS crankshaft vibration.
I am definitely not sure if this is the right way to go about it but if you get a chance to play around with it then provide some feedback and I might be able to make some improvements.

It just needs piston weight, con-rod total weight, con-rod big end weight, con-rod length and stroke to make it go.
Things are explained slightly more in the spreadsheet.

Most of what I got out of it was shorter conrod = more required balance factor.

Have fun.

Follow this link and click' Download through your browser' (The file was too big for KB to handle at a whopping 4.2MB)

https://mega.nz/#!dY4SlDCA!Q59zSe1Yn...1G_aWHpo228Zuk

[Sketchy_Racer]

Hi Everyone,

I have seen a bit of the discussion around crank balance going on, so I got motivated to port my MATLAB balance script into excel to make it a bit more accessible.

So far the sheet is for a single cylinder without a balance shaft only.

It finds an optimum balance factor based on minimizing the difference between horizontal and vertical RMS crankshaft vibration.
I am definitely not sure if this is the right way to go about it but if you get a chance to play around with it then provide some feedback and I might be able to make some improvements.

It just needs piston weight, con-rod total weight, con-rod big end weight, con-rod length and stroke to make it go.
Things are explained slightly more in the spreadsheet.

Most of what I got out of it was shorter conrod = more required balance factor.

Have fun.

Follow this link and click' Download through your browser' (The file was too big for KB to handle at a whopping 4.2MB)

https://mega.nz/#!dY4SlDCA!Q59zSe1Yn...1G_aWHpo228Zuk

Hey Moools,

Cool work there. In regards to balancing, how did you go about doing the balancing on your 450? Not 2t sorry guys but still very interesting.

Did you manage to come up with a mathematical solution or was there a bit of fudge factor?

Cheers,

Sketchy

[Grumph]

Without going into the file can you tell me if there's a factor incorporated for cylinder inclination ?

[Moooools]

Hey Moools,

Cool work there. In regards to balancing, how did you go about doing the balancing on your 450? Not 2t sorry guys but still very interesting.

Did you manage to come up with a mathematical solution or was there a bit of fudge factor?

Cheers,

Sketchy

It was essentially this times 3. Each piston Conrod got added up separately and the crank was ignored (because the 4 cylinder crank is inherently balanced) the weight was modelled in a similar way to how I modelled the balance factor here.

So no fudge factor at all really. I took the numbers off of the screen and put it into the bike. The hard/fudgy bit was working out what numbers to use. On the 450 I used the crossover point between front view and top view RMS rotational vibrations. Came out to a 55% balance factor for the counterweight or something.

Without going into the file can you tell me if there's a factor incorporated for cylinder inclination ?

It assumes that 'vertical' is along the cylinder axis and 'horizontal' is perpendicular to that and also perpendicular to the crankshaft axis. The effects of gravity are not modelled as they are very, very small compared to the other things going on. So no matter which way up your engine is this model will work the same. I just use the terms horizontal and vertical for ease of communication.

[husaberg]

It assumes that 'vertical' is along the cylinder axis and 'horizontal' is perpendicular to that and also perpendicular to the crankshaft axis. The effects of gravity are not modelled as they are very, very small compared to the other things going on. So no matter which way up your engine is this model will work the same. I just use the terms horizontal and vertical for ease of communication.

What Grumph was trying to communicate is horizontal cylinder engines such as an old Honda step through and an Aermacchi vibrate in another plane altogether
The balance factors used on them are totally different altogether than a vertical cylinder. He has no doubt learnt this from experience.

[Moooools]

What Grumph was trying to communicate is horizontal cylinder engines such as an old Honda step through and an Aermacchi vibrate in another plane altogether
The balance factors used on them are totally different altogether than a vertical cylinder. He has no doubt learnt this from experience.

Well I didn't know about the different balance factors in those engines. Learn something new every day.

I can say with relative certainly however that this has nothing to do with the engine cylinder orientation alone. The forces due to gravity are just too small. My guess is that it is likely a lot more to do with how they were mounted to the bike, and interacted with the very bendy (in the vertical direction) chassis. It might have been better to sacrifice a bit of balance in the 'cylinder axis' direction in favour of balancing the the vertical (with respect to bike) forces, and reduce overall vibration within the engine-bike system.

[Flettner]

What Grumph was trying to communicate is horizontal cylinder engines such as an old Honda step through and an Aermacchi vibrate in another plane altogether
The balance factors used on them are totally different altogether than a vertical cylinder. He has no doubt learnt this from experience.

What you are saying is balance factor in a (non balance shaft) single is a compromise anyway, so you can either have the engine shake up and down or forward and aft OR a compromise of both. On a TT500 for example the shake is bias compromised forward and aft so although they seem relitively smooth at the handlebars they are in fact vibrating forward and aft a LOT.
In a lie down engine the compromise bias I guess would be the other way round, assuming it's running in a bike.

[husaberg]

Well I didn't know about the different balance factors in those engines. Learn something new every day.

I can say with relative certainly however that this has nothing to do with the engine cylinder orientation alone. The forces due to gravity are just too small. My guess is that it is likely a lot more to do with how they were mounted to the bike, and interacted with the very bendy (in the vertical direction) chassis. It might have been better to sacrifice a bit of balance in the 'cylinder axis' direction in favour of balancing the the vertical (with respect to bike) forces, and reduce overall vibration within the engine-bike system.

The chassis and the mounting and harmonics or resonance of the chassis and materials all play a part. Steel is a better damper than Aluminium for instance. but I believe its the direction of the vibes and how they are mitigated as why the Laydowns are balnced to different factors.

What you are saying is balance factor in a (non balance shaft) single is a compromise anyway, so you can either have the engine shake up and down or forward and aft OR a compromise of both. On a TT500 for example the shake is bias compromised forward and aft so although they seem relitively smooth at the handlebars they are in fact vibrating forward and aft a LOT.
In a lie down engine the compromise bias I guess would be the other way round, assuming it's running in a bike.

Correct my understanding is as well as the it being a compromise in regards to the rev at which the engine is static balanced to run at what is deemed by the rider as being acceptable.
The direction at which the vibrations occurred ie for or aft or up or down (and are balanced to mitigate) are also is important in how the vibrations are actually perceived by the rider.

[Moooools]

What you are saying is balance factor in a (non balance shaft) single is a compromise anyway, so you can either have the engine shake up and down or forward and aft OR a compromise of both. On a TT500 for example the shake is bias compromised forward and aft so although they seem relitively smooth at the handlebars they are in fact vibrating forward and aft a LOT.
In a lie down engine the compromise bias I guess would be the other way round, assuming it's running in a bike.

That is a nice explanation. I would presume that the stiffer your chassis gets (read: more modern) the more the balance shifts towards an outright compromise between fore-aft and up-down.

Correct my understanding is as well as the it being a compromise in regards to the rev at which the engine is static balanced to run at what is deemed by the rider as being acceptable.
The direction at which the vibrations occurred ie for or aft or up or down (and are balanced to mitigate) are also is important in how the vibrations are actually perceived by the rider.

I can understand the perception that engine balance changes through the RPM range given a set static balance. I think everybody has had a bike that shakes at X rpm. However all major engine vibrations increase with RPM^2. There is no change to the balance. The perceived change in balance through the RPM range is all a function of how the engine resonates with the chassis. By changing the compromise between fore-aft and and up-down vibrations with the balance factor, for instance, you might excite different frequencies in the chassis. A chassis might have a 100Hz natural frequency for and aft and a 200Hz natural frequency up and down. If you shifted the balance factor to produce more fore aft and less up down you might reduce excitement to the 200Hz chassis frequency and start exciting the 100Hz chassis frequency. It would then feel like the engine vibrates at low RPM, when in reality it is just the chassis vibrating at lower RPM.

[Tim Ey]

Hello everyone.
As discussing balancing factors at the moment is a thing:

I agree with Husa - different cylinder angle needs different balancing factors.
A friend of mine got used to this fact while mounting a rotax 100ccm kart engine horizontal. It nearly ribbed the bike to pieces. After rotating the Engine to standing Position, it ran pretty smooth.

I know an "old dog" Kart Tuner who says for a horizontal mounted cylinder, a Balancing Faktor of 20-35% might be the best option. From benchmarking serveral engines, also he knows that modern Motocyles like the Honda RS125 or some "Agriculture" 125cc Engines got the Factors around 66-74%

My questions:
1. How is a chainsaw ballanced?
2. How do I balance a V2 Engine like the RS250? Do I deal with it like the cylinders are two single engines? I know that there are some forces which might be killing itself. Also I know where I have to read to get an scientific answer, but I wanted to know if anyone of you guys got experience with it.

Cheers
Tim

P.S.
Frits, do I read your drawing correctly - I do not see any clips in there?! Is only the Cap holding the wristpin in tis place?

[husaberg]

Hello everyone.
As discussing balancing factors at the moment is a thing:

I agree with Husa - different cylinder angle needs different balancing factors.
A friend of mine got used to this fact while mounting a rotax 100ccm kart engine horizontal. It nearly ribbed the bike to pieces. After rotating the Engine to standing Position, it ran pretty smooth.

I know an "old dog" Kart Tuner who says for a horizontal mounted cylinder, a Balancing Faktor of 20-35% might be the best option. From benchmarking serveral engines, also he knows that modern Motocyles like the Honda RS125 or some "Agriculture" 125cc Engines got the Factors around 66-74%

My questions:
1. How is a chainsaw ballanced?
2. How do I balance a V2 Engine like the RS250? Do I deal with it like the cylinders are two single engines? I know that there are some forces which might be killing itself. Also I know where I have to read to get an scientific answer, but I wanted to know if anyone of you guys got experience with it.

Cheers
Tim

P.S.
Frits, do I read your drawing correctly - I do not see any clips in there?! Is only the Cap holding the wristpin in tis place?

I think the factors if we take both those figures you posted away from 100 percent there is a direct correlation with cylinder angle from vertical.
Hondas offset crankpins four stokes ie Hawk /Bros /Revere/Transalp used a simple formula which I wlll post it .....here tomorrow. That made them balanced like a 90 degree v twin
The two strokes whether V 2 or v4 also do as well I will post ......something tomorrow

[Frits Overmars]

I agree with Husa - different cylinder angle needs different balancing factors.

So do I. Vibrations in the horizontal plane (i.e. in the riding direction) are much less annoying to the rider than vertical vibrations, so engines with a horizontal cylinder get a balance factor of less than 50%; 30% may be a good value. Engines with vertical cylinders get about 60%. But these factors also depend on frame stiffness.
For example a kart chassis is about as stiff as a wet newspaper in the vertical direction, so kart engines get about 70% balance factor to minimize the vertical vibrations.
Note: all of the above is null and void for engines with a balance shaft.

How do I balance a V2 Engine like the RS250? Do I deal with it like the cylinders are two single engines?

More or less; you treat a 90° V-2 like two single cylinder engines that were both equiped with a balance shaft.

Frits, do I read your drawing correctly - I do not see any clips in there?! Is only the Cap holding the wristpin in tis place?

That's right. It saves some weight. But it requires that the caps' protrusions are precisely matched to the clip grooves in the piston.
In the past people have fitted caps that were designed for a Vertex piston, in a Kreidler piston. The wrist pin diameters were the same but the clip grooves weren't,
so a cap worked loose. The material of the cap is such that the cap could disappear without doing any harm to the piston or the cylinder, but then the wrist pin started moving sideways, damaging the cylinder.