Author Topic: How Big Can Displacement Get Without Needing A Counterbalancer?  (Read 708 times)

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TrianglePete

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BW
    What % do you balance your cranks to ?

Royal Enfield engineers put a balance shaft on

the Himalayan ??


Bullet Whisperer

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BW
    What % do you balance your cranks to ?

Royal Enfield engineers put a balance shaft on

the Himalayan ??
Hi Pete, originally I worked out the mass required to put through the crankpin holes of individual flywheels of 350 and 500 Bullets, based on a factor of 0.66 and I made up mandrels for each size of engine in order to do this when lightening the flywheels and rebalancing them between centres in the lathe.
 What I have learned over the years though, is good truing of the flywheels and mainshafts seems to be far more vital than getting the balance factor to the last few grams with the Bullet engines. There are no doubt some who would be quite horrified at the rather, shall we say, crude way I balance the flywheels, but it works and the only mention of vibration from any of my 'Asbo' engine owners to date, has been from one whose engine bolts turned out to be loose!
 I can't comment on the Himalayan, or the 650 twins, even, as I have no interest in them and I haven't really done much with the UCE engines, either and am quite happy to keep it that way!
 B.W.
« Last Edit: March 25, 2021, 11:45:33 am by Bullet Whisperer »


TrianglePete

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I agree with getting the crank true  For Sure.

I found 65% for all around.


TrianglePete

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I mean TRUE...


Bullet Whisperer

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Nice rig in that second pic, Pete, I assume that is a mandrel for pressing the flywheels up to a pre set overall width?


Richard230

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One of the claimed advantages of additional engine vibration control devices are that they allow lighter frames to be designed to withstand engine vibes and therefore save both weight and money. Plus, most customers prefer fewer vibrations, or at least a lower vibration frequency, than more. Not everyone appreciates big single vibes, but no one likes the buzz you get from some 4-cylinder motorcycles, especially when operating in hot, dry weather.

Speaking of big singles, didn't Suzuki market an ADV 800cc single some years ago called the "DR Big"? I don't think it was imported into the NA market, but I believe it was sold elsewhere for just a few years before it faded away never to be heard of again.  ???
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nicholastanguma

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One of the claimed advantages of additional engine vibration control devices are that they allow lighter frames to be designed to withstand engine vibes and therefore save both weight and money. Plus, most customers prefer fewer vibrations, or at least a lower vibration frequency, than more. Not everyone appreciates big single vibes,

All good points.

Speaking of big singles, didn't Suzuki market an ADV 800cc single some years ago called the "DR Big"?

Yes.  Lasted longer in Europe, if I recall correctly, and was a very successful Paris-to-Dakar rally racer, I think a winner in fact.  From what I understand the 800 engine was simply a DR650 engine with a bigger bore.


ace.cafe

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I would note that there is a big difference in "needing" it and "wanting" it.

The question was "could it be done".
My answer is yes it can be done effectively.
If the question is "Might some people prefer a balance shaft for comfort?"
My answer is yes for that too.
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nicholastanguma

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I would note that there is a big difference in "needing" it and "wanting" it.

The question was "could it be done".
My answer is yes it can be done effectively.
If the question is "Might some people prefer a balance shaft for comfort?"
My answer is yes for that too.

Interestingly, I'm forced to wonder if the sort of folks who LIKE vintage tech, air cooled, carbed, pushrodded big singles prefer the more visceral experience of heavy flywheels and heavy crankshafts in place of counterbalancer assemblies.

This technology is so obsolete these days even the 80s Japanese big singles are advanced by comparison. 

For instance, if some restomod shop were selling turnkey Sportster adventure hacks with 800cc "halfster" thumper engines, carbs, kickstarts, and Baker 6 speed transmissions then they'd be marketing such machines as modern vintage artifacts...and experiences.  Each machine would indeed be real world usable as a dual sport overland rig, but as an intentionally modern vintage experience too, and not just a travel appliance with an accompanying Motel 6 weekend mentality.

Ergo, anyone who actually purchased one of these things would be intentionally looking for just such an artifact and just such an experience.  Such a buyer would be intentionally eschewing a smooth modern EFI Honda machine and experience.

Note that people keep spending a base minimum of 20,000 USD on brand new Ural hacks every year, and if you peruse any Ural forum you quickly see an oft repeated standard list of wishes that the Ural factory never delivers either because of government regs or too much production cost:

- A return to carbs
- A kickstart that actually works
- A 5 speed transmission, but preferably a 6
- More engine power

Yet year after year people keep buying new Urals.  Modern vintage experiences are as important to some buyers as the modern vintage machines themselves.   :)
« Last Edit: March 25, 2021, 02:52:57 pm by nicholastanguma »


nicholastanguma

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If such an 800cc "halfster" adventure sidecar as I described above was available and I had the funds on hand I'd absolutely be plunking down a deposit with the shop poste haste.   ;)
« Last Edit: March 25, 2021, 02:24:38 pm by nicholastanguma »


TrianglePete

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BW,

     Went thru time and money to make that Jig

I can repeat 0 runout and keep small end clearance .
      The other photo is the balancer.


Richard230

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Interestingly, I'm forced to wonder if the sort of folks who LIKE vintage tech, air cooled, carbed, pushrodded big singles prefer the more visceral experience of heavy flywheels and heavy crankshafts in place of counterbalancer assemblies.

This technology is so obsolete these days even the 80s Japanese big singles are advanced by comparison. 

For instance, if some restomod shop were selling turnkey Sportster adventure hacks with 800cc "halfster" thumper engines, carbs, kickstarts, and Baker 6 speed transmissions then they'd be marketing such machines as modern vintage artifacts...and experiences.  Each machine would indeed be real world usable as a dual sport overland rig, but as an intentionally modern vintage experience too, and not just a travel appliance with an accompanying Motel 6 weekend mentality.

Ergo, anyone who actually purchased one of these things would be intentionally looking for just such an artifact and just such an experience.  Such a buyer would be intentionally eschewing a smooth modern EFI Honda machine and experience.

Note that people keep spending a base minimum of 20,000 USD on brand new Ural hacks every year, and if you peruse any Ural forum you quickly see an oft repeated standard list of wishes that the Ural factory never delivers either because of government regs or too much production cost:

- A return to carbs
- A kickstart that actually works
- A 5 speed transmission, but preferably a 6
- More engine power

Yet year after year people keep buying new Urals.  Modern vintage experiences are as important to some buyers as the modern vintage machines themselves.   :)

Sounds a bit like what you want is a Buell Blast.  :o
2011 Royal Enfield B5 500, 2018 16.6 kWh Zero S, 2016 BMW R1200RS, 2009 BMW F650GS, 2020 KTM Duke 390, 2002 Yamaha FZ1


Roeland

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I modified my uce 500 cc engine toe a 612 (Hitchcocks crank), wild cams , power commander . etc...  All beautiful - a lot of vibration but too scared to take it to max - problems with the frame I think... handle bars are starting to wobble too aggressively at acceleration - need some more work. I also was unable to kick start it so far. Sure my bike is over 200kg and will do more than 100 miles/hour but I cannot experience it for now.


AzCal Retred

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Roeland - Who did all this work? What's the cranking compression? Are the tyres stock? In good shape & rated for 100+ MPH? Are they aligned & balanced? Steering stem bearings properly lubed & adjusted? Rear shocks OK? Stock? Modified? Front fork oil clean, proper level & viscosity? Any bags, fairings or luggage bolted on, that could affect stability at speed. What's your skill level? Things happen really fast past 85 or so, it's best to approach speed incrementally. How do you really know your bike runs 100 MPH if you can't ride it? Does it have a compression release? Didn't the builder show you the starting technique?. These 612's can require 3mm or more of compression plates to reduce cranking compression to levels that won't harm the engine. Has that been done? If the cranking compression is 125 -- 130 PSI it should be as kickstartable as it was before. Talk to the builder, you need answers.
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OMFBullet

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I used to walk past a Panther combination on my way to school in the 60s.  I remember the chap who owned it used to have to give an enormous kick to start it. The Panthers were famous for knocking their big ends out at regular and quite short intervals. It was unmistakably a single, and indeed the definition of a thumper.