Valve Spring Constants R11

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dBDawg
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Valve Spring Constants R11

Post by dBDawg »

More technical questions on lifters and valves.

Is it necessary to have to two springs per valve as noted in the parts list.

If so, what is the combined spring constant and how is it divided between the two springs?

Also, is there any preload with the lifter?

Many thanks again to all that help.

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Twocams
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I would say yes to both. They

Post by Twocams »

I would say yes to both. They designed the engine to have 2 springs. Which manufactures have been using off and on for 100 years on internal combustion engines. usually one spring is lighter and is placed inside the other. I havent seen your engine, but if there are springs involved then there will be preload on the lifters. At some point anyway. IMHO

twocams
Twocams
92 R100RT/69 R69S
2004 Aprilia Atlantic 500cc single cylinder Scooter
83 Honda V65 Magna, fastest production bike in1983

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dBDawg
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TwoCams, Thanks for the

Post by dBDawg »

TwoCams,

Thanks for the reply. My engine is more or less the same as an R12 engine except with geared timing. When I took it apart it only had a single spring per valve, and I had missed the call out in the parts book for two springs until just this past weekend. I was just wondering if anyone could explain the mechanical advantage of two springs to one and if this was an absolute must. Otherwise I thought it might be good to know what the spring constants were for possible vibration problems.

Thanks

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Twocams
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I guess you could use just

Post by Twocams »

I guess you could use just one spring if you had the right spring tension of 2 springs. But if you should have 2 springs and only have one. Are their calculations correct. Keeping the right spring tension on the valves is very important in their opening and closing and operation.

twocams
Twocams
92 R100RT/69 R69S
2004 Aprilia Atlantic 500cc single cylinder Scooter
83 Honda V65 Magna, fastest production bike in1983

speight1823
Posts: 142
Joined: Fri Oct 27, 2006 3:00 am

Why 2 valve springs ?

Post by speight1823 »

Why two valve springs ?
Only reason I can think of is that if one spring breaks the valve will not drop into the engine and destroy it but will alert you to a problem as you should develop valve float.
Anyone think of another reason ?
I would have a problem with replacing 2 springs with one .
Bill

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dBDawg
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Side valve opposed

Post by dBDawg »

Bill,

It's a side valve, opposed 2 cycle, so it's impossible for the valve to fall into the engine any father than the closed position. But the redundancy theory is a good one. Might make sense for that time period. Thanks for the input.

Jason

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Ian R11
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Joined: Sat Oct 22, 2011 1:00 pm

I can't add anything re the

Post by Ian R11 »

I can't add anything re the technical side to your question. If it helps to know, I've fitted available new supply twin springs sets to both R62 and R11 engines. If I remember correctly Huggett supplied the R11 ones and it works great, several other suppliers have them and not expensive.

I don't know the individual spring rates but both the new and my originals feel soft compared to other engines I've done. That said these engines don't rev very high.

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caker
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Location: Haddonfield, NJ, USA

My understanding of two valve

Post by caker »

My understanding of two valve springs has to do with spring rates. Having two different springs with different spring rate properties means a reduced chance of valve float through the RPM range.

-Chris

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Diablo
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Joined: Sun Mar 27, 2016 5:39 am

2 springs on valve

Post by Diablo »

I don't know why 2 springs are used , but this is common on a lot of engines . I rebuilt my car engines , Lotus Elan , Ferrari 250 ....all have the 2 prings . Perhaps the different flexibility of the 2 springs help the function.
While we are on this subject , can anybody tell me if there are marks on the distribution for its timing ; I need to dismantle my R11 engine because of a bad noise from the crankshaft . Anybody has a factory book for this engine ? I only found the user book and the spare parts book . Thank you for helping .
JC
Diablo

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Ian R11
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Joined: Sat Oct 22, 2011 1:00 pm

Not sure what your asking re

Post by Ian R11 »

Not sure what your asking re timing. Are you wanting to know about crank timing marks or magneto timing? This would also depend on which engine you have, gear driven or chain driven cam.

I've never seen any workshop type books for these bikes, would be nice if there was.

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