R65 running high when hot

[Aristotle]

Hello: I have a 1986 R65 that I've owned for almost 22 years. It'll be23 this coming May.
Of course, when you buy a bike more often than not, the bike including all of it's internal components age over time.

However, for the last few years, I've had my baby run pretty high. Sometimes as high as 5000 RPM.
Which is totally  not normal.

Most of you are familiar with the normal idling speed of R65's to be at around 800-1100 RRM.

I know that it is in most cases, just an adjustment to the idling speed, but that doesn't always seem to help.

I was wondering if any of you would have other suggestions or if you've also experienced this same problem.

thanks in advance for your replies.  

[montmil]

Let's see what my "souvenir" T-shirt sez...

Sticking advance weights in the bean can; ignition timing; air leaks at the rubber connecting tubes between carb and head; valves need clearance adjustment; leaky O-rings at throttle butterfly shaft; weakened return springs under carb dome; throttle cables need adjustment and/or synchronization, and...

Who else has some ideas to add?  

Monte

[Bob_Roller]

Has a carb synchronization been performed, just before this high idle problem occurred ?

[Aristotle]

yes. in many instances after the bike got it's tune up at the BMW shop, there were carb syncs.
And also, about what montmil mentioned about valve clearances needing adjustment, that might definitly be.

But I didn't know about the possibility of the return springs under the carb domes needing adjustments. That's an interesting idea.

How might the springs under the carb domes interfere with the correct idling speeds if I might ask??

[montmil]

...But I didn't know about the possibility of the return springs under the carb domes needing adjustments. That's an interesting idea. How might the springs under the carb domes interfere with the correct idling speeds if I might ask?

Just replaced the springs in the Bing 32mike-mikes on my '81. New springs from Motobins were very economical. Bits arrived this week and before installing the new boingers, I measured them against the old springs.

The old springs had serious wear on the outer edges of the coils. Metal was worn away on the perimeter of every coil. Twenty-nine years may do that... A gram scale and a totally unscientific test showed the old springs to have less tension than the new ones. Old ones perhaps had also been stretched as they were unequal lengths and longer than the replacement springs..

All this tells me the old springs were shot. Perhaps not doing their job as well as the new ones most certainly do.

Earlier non-spring equipped Bings were often retrofitted with the springs to assist in the complete closing of the slide.

Monte

[Aristotle]

a very interesting notation you made there montmil. That makes me wanna go and check my springs as well which I think I'll check in with the old Hayne's manual and see how it's done and see about ordering them. My bike is going to be 22 years old this year and I'm sure those springs weren't checked much over the years. Thanks montmil for your good advice.