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Author Topic: KIT ENGINE, First impressions--  (Read 35992 times)

aqmxv

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Re: KIT ENGINE, First impressions--
« Reply #15 on: August 23, 2006, 05:08:52 PM »
Um, Darren, I think that's was just what xyzer said.  The only issue is that since you have two flywheels, and each (probably) has a different balance, you have to balance them separately, or you end up with a rocking couple between the flywheels, an over-compensated crankpin mass, or both.

I'm thinking a good place to start might be figure out the compensation mass, divide by two, then do the lever arm math for the rim of the flywheel from the crankpin.  Then add that amount of mass to the rim of one flywheel in the right place and statically balance it.  do the same with the other.  Then bolt them up.

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slowspeed1953

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Re: KIT ENGINE, First impressions--
« Reply #16 on: August 23, 2006, 05:59:00 PM »
Um, Darren, I think that's was just what xyzer said.  The only issue is that since you have two flywheels, and each (probably) has a different balance, you have to balance them separately, or you end up with a rocking couple between the flywheels, an over-compensated crankpin mass, or both.

I'm thinking a good place to start might be figure out the compensation mass, divide by two, then do the lever arm math for the rim of the flywheel from the crankpin.  Then add that amount of mass to the rim of one flywheel in the right place and statically balance it.  do the same with the other.  Then bolt them up.



Sorry brother I did not realize that he described what the rotating and reciprocating weights are and what there relationships are to on another.

I also didnt note the mention of balance factor or how it effects engine vibration in his post. Again sorry!

Quote
I'm thinking a good place to start might be figure out the compensation mass, divide by two, then do the lever arm math for the rim of the flywheel from the crankpin.  Then add that amount of mass to the rim of one flywheel in the right place and statically balance it.  do the same with the other.  Then bolt them up.
 

Or even better you could...

Quote
So in order to achieve a 50 percent balance factor add 100% of the weight of the rotating elements to the crankpin along with 50% of the weight of the reciprocating elements, than with flywheels installed zero balance the assembly by removeing material from the previously zero balanced flywheels equally

But as usual what do I know? Im just a dumbass reiterating other peoples proir posts.

Peace&Love :D, Darren

aqmxv

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Re: KIT ENGINE, First impressions--
« Reply #17 on: August 23, 2006, 06:26:26 PM »
Just one difference in detail - I was talking about *not* zero-balancing the flywheels first.  They have gaps in the rim mass to act as crank counterbalances.  Zeroing this out would be a bad idea, because then you'd have to add it all back.

Nah, start with the unbalanced flywheel, add the compensating mass (all of big end of conrod and crank journal, 1/2 of piston and small end of conrod all divided by 2), then balance.  I suspect that in my case, at least, it's probably not that far from where it should be.
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slowspeed1953

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Re: KIT ENGINE, First impressions--
« Reply #18 on: August 23, 2006, 06:32:05 PM »
Just one difference in detail - I was talking about *not* zero-balancing the flywheels first.  They have gaps in the rim mass to act as crank counterbalances.  Zeroing this out would be a bad idea, because then you'd have to add it all back.

Nah, start with the unbalanced flywheel, add the compensating mass (all of big end of conrod and crank journal, 1/2 of piston and small end of conrod all divided by 2), then balance.  I suspect that in my case, at least, it's probably not that far from where it should be.


When you zero balance the flywheels simply wire on some fishing weights as this way there is no additional machining.

If you use your method there is no way to balance out the imbalance inbetween the flywheels which if present will cause twisting/flexing of the crankshaft.

Peace&Love :D, Darren
« Last Edit: August 23, 2006, 06:34:09 PM by slowspeed1953 »

xyzer

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Re: KIT ENGINE, First impressions--
« Reply #19 on: August 23, 2006, 06:36:05 PM »
Darren,
You explained it just like it said in all the research I found to balance my first 6/1. The problem I found the hard way is they never mentioned in all of my looking how to deal with 2 flywheels. I treated them as one......I kick myself all the time for not seeing that in the first place...oh well.....I am convinced you have to balance each flywheel with 1/2 the rotating mass+1/4 the reciprocating mass mounted on the rod journal. It sounds good anyway ???  Correct me if someone knows better!!!!!
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slowspeed1953

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Re: KIT ENGINE, First impressions--
« Reply #20 on: August 23, 2006, 07:38:33 PM »
Darren,
You explained it just like it said in all the research I found to balance my first 6/1. The problem I found the hard way is they never mentioned in all of my looking how to deal with 2 flywheels. I treated them as one......I kick myself all the time for not seeing that in the first place...oh well.....I am convinced you have to balance each flywheel with 1/2 the rotating mass+1/4 the reciprocating mass mounted on the rod journal. It sounds good anyway ???  Correct me if someone knows better!!!!!

No brother thats not what I said. What I stated was that the flywheels need to be independantly balanced prior to final assembly balancing. Again here's a quote of what I said the first time.

Quote
So in order to achieve a 50 percent balance factor add 100% of the weight of the rotating elements to the crankpin along with 50% of the weight of the reciprocating elements, than with flywheels installed zero balance the assembly by removeing material from the prevoiusly zero balanced flywheels equally.

The flywheels must FIRST be neutral balanced by what ever method tickles your fancy. I personally would use a tempory add on weight like stick on wheel weights or whatever you have handy.

Doing this insures there will be no crankshaft distortion as the way you said "I" descirbed LOL.

Look heres the bottom line if you guys want your shit right do it the way Ive reccomended. If you dont want it right than follow a different method. By the way 48%!

Peace&Love :D, Darren

rjcroc

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Re: KIT ENGINE, First impressions--
« Reply #21 on: August 23, 2006, 07:54:03 PM »

Sorry to make this worse but have you checked to see if the counterbalance weight on the flywheel is directly opposite the journal location. On my 6/1 there is a slight difference of about 2 degrees. the only good part is that one side is clockwise and the other is counter clockwise so I hope that they balance out. This should make balancing a real pain in the a**. Someone should teach a broaching class in India.

Rick
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hotater

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Re: KIT ENGINE, First impressions--
« Reply #22 on: August 23, 2006, 08:01:28 PM »
I can weigh parts to a gram and I can balance a flywheel to less than that, but the math escapes me.

*I'M* interested in a definitive, TRIED and PROVEN formula for balancing THESE engines.  I have one to do, but I'm not interested in chasing theory right now.   ;)
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xyzer

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Re: KIT ENGINE, First impressions--
« Reply #23 on: August 23, 2006, 08:14:28 PM »
Peace&Love , Darren


 OK....I see your way after reading it several times......you are doing the same thing except I believe it is a bunch more work....
Your way

1-balance each wheel to zero(you need a straight shaft to balance each wheel)
Getting them perfect is a bunch of work!

2-add 100% of the caculated bob weight

3- mount both flywheels

4-carefully remove weight equally both sides till balance is achieved
More work.....be careful!

5-Now you have to replace the band-aid weights with securely fastened weights of the same weight and location.

Did I get it right brother?

My way
1-add 50% of the calculated bobweight to crank

2-mount 1 flywheel and balance with actual weight needed and fasten

3-repeat #2 on second flywheel

Oh....By the way I'm sure I'm doing it the right way....and the easiest way at the same time....Your way..Is right also but a bit more involved in my opinion.

« Last Edit: August 23, 2006, 08:17:17 PM by xyzer »
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xyzer

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Re: KIT ENGINE, First impressions--
« Reply #24 on: August 23, 2006, 08:25:39 PM »
Tater,
I am dealing with the same engine supplier as you. I should have mine in a couple of weeks. The method I use is not theory but standard method to static balance 1 cly engines...... except we have 2 flywheels. I'm sure you are way ahead of me on your engine project. I am going to use the 1/2 bobweight , one flywheel at a time method. I'll let you know how it turns out.
Dave
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Halfnuts

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Re: KIT ENGINE, First impressions--
« Reply #25 on: August 23, 2006, 08:28:49 PM »
Jack,

I don't think there is any easy to do this.  The wheels show evidence of having been balanced in India by the drill marks.  

On my 6/1  moving 7.5 oz of lead around on each flywheel rim had very little effect on the balance of my engine mounted on a 4x6" wood/steel trolley on casters.  I bet most of the motion that is blamed on balance issues is actually torque puses in the plane of the flywheels.  

Halfnuts

Timbo

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Re: KIT ENGINE, First impressions--
« Reply #26 on: August 23, 2006, 10:00:47 PM »
Easy way to tell if it is balance issue vs torque is to run it up to speed, note vibration and then shut off the fuel rack and open exhaust valve.

Immediately after fuel shutoff, during coast-down the nature of the vibration will change - motion at this point is balance related and not due to the powerstroke.

Try it - it's very noticable (for an engine not bolted to a ton of concrete).

Intuitively, the "chalk" method as described in "balancing out the bounce" thread seems easiest - and it appears that people who have done it have smooth running machines afterwards.


Timbo


gpkull

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Re: KIT ENGINE, First impressions--
« Reply #27 on: August 24, 2006, 01:19:57 AM »
do what ever balance method you choose. run a roid balanced or not on anything but a "TON" of concrete then take the same roid and bolt it down. you will be amazed. it will run smoother your multi groove belt will stop flying off the pulley of your driven acc. and you will drive off any moles. dont really care why but after its bolted to the crete it will coast on shut down twice as long as before. i think the dead giveaway is the 2 foot rods with a hook on one end and threads on the other that u get when u purchase a roid. thats all folks carry on smartly

xyzer

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Re: KIT ENGINE, First impressions--
« Reply #28 on: August 24, 2006, 05:21:32 AM »
gpkull,
I agree....we all have our own use for these things, off grid, toy, whatever....If I waited for the power to go out I wouldn't use it much. So I dream up ways to use it just because I can. If I didn't balance it I would find it in the lake the next day...or I would have concrete slabs all over the place.....Balanced or unbalanced both ways take a lot of work......haul your ton of concrete or screwing around to get it run smooth....pick your poision....I pick mine and it coasts down quite nicely....I know I can make it appear to run smooth with a ton of concrete....they even debate how the concrete should be done....well I am going to balance mine and use the concrete for something else....
                            Balanced and portable...
 
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slowspeed1953

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Re: KIT ENGINE, First impressions--
« Reply #29 on: August 24, 2006, 06:16:30 PM »
gpkull,
I agree....we all have our own use for these things, off grid, toy, whatever....If I waited for the power to go out I wouldn't use it much. So I dream up ways to use it just because I can. If I didn't balance it I would find it in the lake the next day...or I would have concrete slabs all over the place.....Balanced or unbalanced both ways take a lot of work......haul your ton of concrete or screwing around to get it run smooth....pick your poision....I pick mine and it coasts down quite nicely....I know I can make it appear to run smooth with a ton of concrete....they even debate how the concrete should be done....well I am going to balance mine and use the concrete for something else....
                            Balanced and portable...
 

Good eye brother!

The concrete is a bandaid. Being that the engines run at a steady state RPM there is no reason that they can not be perfectly balanced without compimise.

Peace&Love :D, Darren