Bean Can springs length

[R65Singh]

Hello everyone. I just cleaned and lubed the Bean Can on my bike last week and noticed a considerable gap in the coils of springs on the advance mechanism.  Is this normal or the springs are stretched?  I measured the spring length to be 18.58 mm.  Does any one knows the length of new springs?
I have always had this unstable idling problem.  The idle is set to 1200 at fully warm But wont idle when cold and dies. If revved up for a couple mins it will idle around 700 rpm and it climbs up as the engine warms..  Even when warmed up the rpm needle is not 100% stable.
I have done the following so far:
Replaced the carb to cylinder rubber adapters.
Cleaned and synced the carbs
Valves set to .06 and .08
Cleaned and lubed the bean can.

Any suggestions from you Airhead Gurus appreciated.

[Red_Hen]

Here's my 2 cents:

1) set intake valves .004
2) you can purchase new springs & gasket for bean can - I've read they do stretch over time - Motobins.
3) reset timing http://www.ibmwr.org/r-tech/airheads/R65timing.shtml
4) balance carbs if necessary - check rubber diaphragms for tears.

[R65Singh]

Thanks Ken
The Diaphragms are only a couple months old, and i did set the timing correctly using a timing light.  I am suspecting springs because I have almost eliminated most of the other causes. The springs are the only thing that are not replaced thinking that the bike has only 16000 kms on it, but was sitting in a barn for 15 years before I got it and restored it.

[Barry]

The idle is set to 1200 at fully warm But wont idle when cold and dies. If revved up for a couple mins it will idle around 700 rpm and it climbs up as the engine warms..

That behaviour sounds perfectly normal to me except the 1200 idle is a touch too fast as it's on the verge of where the advance mechanism will kick in especially if the springs are weak. BMW spec was 800-1100 RPM for your model but I think most people set toward the top end of that range. The spec for the heavier early flywheel bikes was 800 - 1000 RPM. I set mine so it idles at 1000 RPM at the end of my daily commute and it rises to an absolute maximum of 1050 when really hot.

6 thou inlet clearances should actually make your idle more stable by reducing valve overlap slightly.

[tvrla]

What Barry said! It takes a while for the engine to heat up, and if you set the carbs before that happens, the idle will climb.

Only set the mixture and idle speed after a good twenty minute run. I tend to set the idle a bit lower than most - about 800 to 900. I've found shifting to be easier at the lower settings. And it can take a while before it doesn't die on me - sometimes on cool damp days and if not riding hard or fast, it just doesn't idle right after ten or fifteen miles.

[Rob Valdez 79 R65]

New (from Motobins) spring length(s):

Overall length - ~18.8mm

Spring body length - ~7.4mm


Motobins part # 72620.
But I just tried Motobins website and it redirects to a domain-for-sale page!

And Boxerworks account has been suspended (again... )

Is this the beginning of the motorcycle apocalypse?

[Barry]

Motobins site is working ok this side of the pond.


http://www.motobins.co.uk/library/72620.jpg

[Rob Valdez 79 R65]

Motobins site is working ok this side of the pond.


http://www.motobins.co.uk/library/72620.jpg

Yep - working for me again, too.  I must have worn out my computer!