Missing.

[SteveD]

Charlie, Mal and me camped out at Dargo last night under a clear sky by a mountain river with an fire with hot food, grog and banter. We missed a few regulars!

However that's not the missing I'm writing about.

My 11/1981 R100RS ran very nicely. However about 60kms from home, @ highway speeds of 110kph, it "missed" momentarily on 5-6 occasions. Running well, then a quick stutter and the tacho needle would flicker. One miss, likened to 3-4 consecutive misses, saw the tacho go to zero.

I moved into the slow lane and reduced speed to 95kph for a while.

All good, got home without any further issue.

Tomorrow I'll check the coil earth and HT lead connections on the dyna blue coil. The ICU is the new dry version matching the newish EI.

Any other suggestions? The fuel cap was covered with a cloth under a magnetic tank bag. Float bowl volumes are around 28mm.

Plugs are light tan, and I used 44 litres over 630kms @ 14.3kms/litre.

Fuel taps were replaced recently. No filters in line except the Germa inline screens.

[fubar guzzi]

HALL SENSOR

[montmil]

The tachometer dropping to zero may be a clue to the stu-stu-sutttering issue as the instrument takes its feed from a coil terminal. Go over all the connections to and from the ignition coil. Clean and add a swipe of dielectric grease to add. Check grounds.

[Bamboo812]

A friend here on the island had a similar issue including the dropping tach. Turned out to be dirty contacts in the kill switch. Removed switch and sprayed contact cleaner in there and all is good.

[tsa]

The other week I took my R80/7* out of hibernation. It started up OK, but on nearly all trips it ended up having series of "ignition kill switch backfires" when the engine was under moderate load, whilst at low revs (approx. 2-3 000 RPM). The electronic rev counter dropped towards zero during each of those misfires, indicating failing LT supply to the coils. On one longer trip (40 miles) at a relatively steady 3500 RPM it ran without any backfires, but when getting off a major roads, and varying revs at lower speeds, the backfires/cut-outs reappeared.

Previously, I've been left stranded twice due to total ignition failure. Then there were no backfires. The cause was quicly found to be vibration that fractured the 12 V pos supply from the battery to the EI "black box" - at an inline 8 A fuse held in place with screws directly into the lead inners (no clamp on the outer plastic insulation).

Now, I also checked my right handlebar switchgear, which looked without any corrosion. Is the cause now likely also to be poor connectivity at the LT connections of e.g. the coils? Or a component (EI, or coils) failure?

*standard except for aftermarket Boyer-Bransden Micro-digital EI fitted.

[SteveD]

Good point re: the ignition switch. I do regularly flick it in both directions so that it stays "used" hoping to avoid corrosion on the moving parts.
Having a close look at it, the rubber dash just touches the tip of the switch. I'm wondering if there may be some movement of the switch from that when riding along.

The earth at the coils is fine, the HT leads are all well connected. It all looks ok under the tank.

I think I'll reposition the right cluster a tad to the right, or shave a wee bit from the dash pad.

[Mal S7]

Did you fix it Steve?

My bike (R100/7) had the hiccups all the way home. Missing and stuttering between 2000-3500 rpm all the way from Hobart.
Strong and smooth once up to cruising speed.

[SteveD]

Not yet Mal. I'm doing graveyard this week. Life otherwise stops then you know! I'll get it up on the lift on Sunday and pull the EI, inspect, reinstall and hope for the best.

It was happening at 110-120kph which is a bit more vibration prone. Cured itself at 100kph. I'm hoping for something loose. I also need to get some good electrical cleaner and ensure the kill switch is clean.

Did you have a crack at cleaning the slow running passages?

[ME 109]

Did you have a crack at cleaning the slow running passages?

Mal didn't mention any health issues at Blue Duck, Mal? Compaction from too many days riding maybe.

[Duane Ausherman]

The other week I took my R80/7* out of hibernation. It started up OK, but on nearly all trips it ended up having series of "ignition kill switch backfires" when the engine was under moderate load, whilst at low revs (approx. 2-3 000 RPM). The electronic rev counter dropped towards zero during each of those misfires, indicating failing LT supply to the coils. On one longer trip (40 miles) at a relatively steady 3500 RPM it ran without any backfires, but when getting off a major roads, and varying revs at lower speeds, the backfires/cut-outs reappeared.

Previously, I've been left stranded twice due to total ignition failure. Then there were no backfires. The cause was quicly found to be vibration that fractured the 12 V pos supply from the battery to the EI "black box" - at an inline 8 A fuse held in place with screws directly into the lead inners (no clamp on the outer plastic insulation).

Now, I also checked my right handlebar switchgear, which looked without any corrosion. Is the cause now likely also to be poor connectivity at the LT connections of e.g. the coils? Or a component (EI, or coils) failure?

*standard except for aftermarket Boyer-Bransden Micro-digital EI fitted.

Here is where I wish to get on my soap box again. The BMW wiring contractors did a terrible job of installing the terminals on the wires. We saw some fail in the first couple of years. By 5 years many were failing, or ready to fail. This was all before I understood what a proper crimp was. Now, with my long time in cellular wireless work, I know far more about crimping. Go to my site for more info.

In my obsession, I do a far better job than the wireless standards demand.