sonic
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| posted on 23/9/20 at 08:04 PM |
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Why are bike engines solid mounted
a theoretical question
why carn't bike engines in a kit car have rubber engine mounts to take some of the vibration away ?
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Edwardo
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| posted on 23/9/20 at 08:14 PM |
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Good question - and one I've been pondering too recently!
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Mr Whippy
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| posted on 23/9/20 at 08:16 PM |
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Probably no good reason at all. Although I have never owned a BEC I did once solid mount a Pinto in my Falcon and my god it was horrific. Could you
not simply use rubber bushes on the engine cradle?
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watsonpj
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| posted on 23/9/20 at 08:43 PM |
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Mines on metallastic bushes is not relly solid mount but the rubber is pretty thin walled. I can't see any real reason you could have a more
flexible mount to isolate more.
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paulf
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| posted on 23/9/20 at 09:30 PM |
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They are solid mounted in the bike as they form part of the structure, as does the engine gearbox combo in many race cars but not really a need to in
a road car.
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adithorp
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| posted on 23/9/20 at 09:53 PM |
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quote:
Originally posted by watsonpj
Mines on metallastic bushes...
Mine is too. No reason it should be solid mounted. Having driven cars where they are solid mounted, I can say that even though the bushes are thin
walled as watsonpj says, they reduce vibration significantly.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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40inches
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| posted on 23/9/20 at 09:55 PM |
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I rubber mounted my ZX9R, it made a difference, not a lot but enough to make it worthwhile 
 
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SPYDER
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| posted on 24/9/20 at 12:07 AM |
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We incorporated Metalastik bushes into our engine cradle too. It still feels quite solid but they are hopefully just compliant enough to take the edge
off of the shock loads and to tame vibrations a bit.
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nick205
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| posted on 24/9/20 at 08:34 AM |
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quote:
Originally posted by paulf
They are solid mounted in the bike as they form part of the structure, as does the engine gearbox combo in many race cars but not really a need to in
a road car.
I'm not a motorcyclist and haven't had a BEC, but this was my thinking. I once drove a tin top with a solid mounted car engine and the
noise and vibration was horrendous. Short journey bearable, longer journey (20+ miles) no thanks!
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watsonpj
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| posted on 24/9/20 at 02:35 PM |
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Just like driving a BEC anyway :-) , you don't notice the engine vibration due to the +6k (at 70mph) and the noise from the exhaust and
(rattle) from the quaife reverse box when running at the constant speeds. I still love it but there are times when i kind of think that I should swap
back to a car engine (must be getting old).
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steve m
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| posted on 24/9/20 at 03:55 PM |
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Ive had many Motorbikes, and another reason i feel that engines are hard mounted, is that they are smaller capacity rev a lot higher, and will be
balanced to a higher standard than most normal car engines, hence no requirment to rubber mount them
Except for my Old Norton 850 commando, with its weird mountings front and back, that were to aid in the engine not ripping the lugs off the frame
!!!
steve
Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at
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trikerneil
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| posted on 26/9/20 at 10:03 PM |
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'79 - '81 Yamaha XS1100 had a rubber mounted engine to reduce vibration.
First mod is to fit solid mounts to stiffen the frame so it will go round corners better.
ACE Cafe - Just say No.
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coyoteboy
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| posted on 27/9/20 at 10:33 AM |
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Two obvious reasons are 1) it's a stressed member, you reduce the weight of the bike if you can use the engine as part of the chassis and 2) you
really don't want a chain drive having alignment changes under high loads - extra wear, potential for misalignment of the rotational axes.
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sonic
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| posted on 27/9/20 at 07:27 PM |
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in a car application the above would not matter as running a propshaft, take the point ab out the quaife reversing box mine sounds awfull and was
thinking of taking in out and doing away with reverse.
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