This idea started several weeks ago at the onset of another round of postings with the same basic theme running through them... "My R65 idles too high... sometimes."
On occasion, my 1981 has done the same thing. Not always. Sometimes. The 1983 R65 does not display this random high idle phenomena. I'm satisfied with the tune-up on the Bings. Easy starting, good performance, excellent fuel mileage and the plugs look ab fab.
Today, I checked valve lash as it had been 500+ miles since they were lasted touched. No changes. I have a pair of new springs for the bean can's advance mechanism laying about so decided I'd swap in the new ones to see what happens. I had not opened up this particular ignition trigger unit before so in just a few minutes, there was nothing left inside the aluminum can.
Check the photos. I was surprised to see that the OEM springs were no longer closing up the wound coils. They were more of an open coil with not as much strength as I thought they might generate. I poked a white pipe cleaner through a new spring for comparison with the near thirty-year old original. Look closely and I think you'll be able to see the gap between each coil of the old spring.
Spent some time cleaning gunky stuff out of the ITU can and lubed what needed it. New springs in, reassembled and eyeballed the timing. Road test.
Seemed a bit "hot" on the timing after a few so circled back and dialed in a little retard. Better. The engine idles down as it should but I will confirm timing this weekend.
Motobins sells R65-specific advance springs should you want to dig into the ignition in our ongoing quest for UJM-type performance.
Monte
Original bean can advance return spring on top. New Motobins spring below. Note the different lengths due to "stretch" in old spring.
See the gaps between coils?
