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High Performance Bicycle Engine Tips and Motorized Race Bicycles We all want our bicycle engines to push our bikes faster. Get exclusive engine modification tips and suggestions from us. Also check out some of our racing members builds

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  #11  
Old 07-10-2012, 06:00 PM
multipaul multipaul is offline
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Join Date: Mar 2012
Location: Germany
Posts: 75
Default Re: Crankshaft balancing and truing (part...)

(Part 4b)

Only when I worked at a higher temperature, there were noticeable improvements. I used a soft gas flame, which is intended for brazing copper solder. But I remained below 200 C (390 F), so that the steel did not change its color. (The hardened crankpin should not be heated so much!)

Here is my final result:


Initially I wrote readings directly on the disc. After some attempts that became a bit messy and confusing. Later I made templates to assess improvement (or worsening) more effectively.



If you have questions or critical comments, no problem. Perhaps there is another and also better methods. In this regard, I am open minded and happy to learn.

If parts of this posting are not well understandable because of the language and the used technical terms, the moderators may change my sentences to make them clearer where necessary. It would bei nice, if they would keep me informed about changes.

Finally I'll post a video that shows the achieved results. Remember, we worked down from 0.4 mm runout on the main bearing journals.

Up tp now that was a complex but cheap pleasure.

Multipaul
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  #12  
Old 07-10-2012, 06:33 PM
ivan H ivan H is offline
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Join Date: Oct 2011
Location: australia
Posts: 619
Default Re: Crankshaft balancing and truing (part...)

Hi Multipaul, condition 1 u show is "indexing" of the crank, not a home job, & u'd like 2 hope the crank manufacturers got it right. Condition 2 can b caused when assembling the crank in the cases. For this reason, the crank spindles should b "pulled" thru the cases. U can do this with packing washers & the nut/bolt on the spindle ends, it just takes a couple of goes at each side. Great thread, well done. Cheers
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  #13  
Old 07-12-2012, 10:11 AM
multipaul multipaul is offline
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Default Re: Crankshaft balancing and truing (part...)

Hallo Iwan

Thank you. In the meantime I'm not sure about this thread. Probably too long and too complicated in some parts.

Finally I had to do some changes on the little video.
It shows how I balanced and how I measured the results of the truing. It is about 4:15 minutes.
http://www.youtube.com/watch?v=ONbEV...ature=youtu.be

Working on this thread, I got some clarity about relationships. For me, there are some conclusions:

1. The lifetime of the bearings
The limiting factors are the max dynamic load on one side and the fatigue load limits on the other.
Barings which are loaded maximal quit their lives (statistically) after 1 Mio revs, which are 70 miles.

2. Balanced engines compensate forces internely.
Balanced motors compensate internal forces, although they are still there. They just can't reach the outside. This generally doesn't generate additional power.

3. Trued crankshafts generate more useable energy than not trued ones.
Vibratory plates also need a separate drive.

4. What is the role of the gases. I wrote pretty much none at all.
Anyone can check this by opening the gas at a certain speed and closes. Changes?

5. A bicycle should not vibrate stronger while driving at any speed than with the clutch pulled on the stand.
Otherwise, the vibrations coming from somewhere else. Mostly of the drive, chain, sprockets.

Multipaul
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  #14  
Old 07-12-2012, 06:53 PM
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Goat Herder Goat Herder is offline
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Default Re: Crankshaft balancing and truing (part...)

Quote:
Originally Posted by multipaul View Post
Hallo Iwan

Thank you. In the meantime I'm not sure about this thread. Probably too long and too complicated in some parts.
This is a great thread! Thank You kindly Sir for sharing it too. Been following it and have enjoyed all technical aspects of this whole set up here immensely .
__________________
Still gotta have a since of humor.
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  #15  
Old 07-13-2012, 01:01 AM
ivan H ivan H is offline
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Join Date: Oct 2011
Location: australia
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Default Re: Crankshaft balancing and truing (part...)

+ 1 GoatHerder, I think its a great thread, & ur right on that last point MultiPaul. I think a lotta vibration comes from that chain tensioner. Also, notice the countershaft bearing stayed in the left case half. Did the right side bearing stay on the countershaft, not in the case. I think its a kinda loose fit in the case 2 overcome that the cases provide no means of aligning this shaft. If, upon assembly, u align it properly & seat the bearing in the case with loctite bearing retainer, u'll notice a lot less rattle from the motor. Cheers
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  #16  
Old 12-12-2016, 11:29 PM
Bonnygirl Bonnygirl is offline
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Join Date: Dec 2016
Location: Australia
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Default Re: Crankshaft balancing and truing (part...)

Hi multipaul. Great post but should there not be an allowance made for the radius at which the weight is removed? It was removed from 2 locations either side of TDC which compensates somewhat for the radius being greater than the crank pin but I still think you have removed more mass than is needed for a 50% ratio. My guess (looking at your pics) is that your balance is probably about 70-75% of the reciprocating mass.
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