You know it's going to be a long day...

when you pull the spark plug cap off and it's guts stay attached to the spark plug... I've coined a new term: Induced Maintenance. It's inversely related to Routine Maintenance. When everything is running right, do something to mess it up

In preparation for adjusting valves, points, etc., the BERU 5KΩ cap disassembled itself. There was a slight amount of moisture under the rubber sleeve around the HT lead, but there was far more corrosion than it would have generated ... so this must have been going on for some time.

Here's what I found after I dug all of the oxidized material out of the housing. You'll have to use your imagination (phone camera); the steel "screw" on the right [edit] is what goes into the HT lead from the coil; the cylindrical ceramic resistor slug; and the brass ferrule that clips onto the spark plug. The interior of the metal/plastic housing around the screw was full of flaked corroded material.



This is how it all cleaned up. I also discovered that there was wee little spring lurking in the debris (the circular item is a broken off piece of it) the clip to the left of the ferrule snaps into the groove on the ferrule and retains the spark plug end.

What isn't visible on the screw is that it actually has a hexagonal shape that engages a similarly shaped recess (inside the plug housing) which keeps the screw from rotating when you screw it onto the HT lead. Due to the heavy corrosion on the screw, that hexagonal shape is now a very loose fit into the plastic (rather than a press fit).



As much corrosion as there was on the steel screw, I'm surprised that that cylinder was even running ... but it was, and well. The spark plug color is a pleasant toasty brown. It's a happy bike.

So, with that in mind I'm wondering if I can rebuild this cap; it couldn't run worse than it is now. A new cap is only $12, but it's Monday, there isn't a BMW shop within one hundred fifty miles of me (there isn't a motorcycle shop in the continental United States that is open on Mondays) ... and it would be a week before I can get one here via UPS.

THE QUESTION

Everything cleaned up well, even the little spring. The only issue is the now sloppy fit of the parts into the plastic housing. I don't know what the operating temperature of these caps is, but am thinking that RED Loctite might suffice as a "glue" to secure the brass ferrule and steel screw into the housing.

Your thoughts gentlemen? NAPA? PepBoys?

p.s. Anyone have an infra-red thermometer that they could take a reading off of their the spark plug cap with?

Hi Lew,
Long Beach BMW specifically revised their Parts Dept schedule to be available on Mondays, but I don't know how well they stock airhead parts...
Non-factory shops may be a better bet; try Valdi's or Angel City.

Thanks for the tip Paul. I just got off the phone with their Parts guy... he doesn't have one in stock... can get it in 3-4 days.

Irv Severs down in Orange has three in stock.... of course he's not open today. All UPS deliveries within California used to be overnight. Not anymore.

My dear old mother used to say that I had the patience of Job ... I wonder where it went?

Heck, you might as well ride down to Severs tomorrow morning!

you might as well ride down to Severs tomorrow morning

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if my bike were running...

But I could drive my trusty old pickup down to Orange.... it's only 235 miles... one way.

Guess I might as well try "the fix" in the meantime. H3LL, it was running the way it was.... I couldn't do worse... . I don't think.

Grrr... Newberry Park? http://www.bmwventura.com/
There's gotta be sumpthin' closer!

actually Ventura is only 125 miles.. ..

but it just occurred to me that J-B weld is "high temperature"... 500??F oughta do it!

off to the shop goes I.. .. .

Lew, after having a few problems over the years with the OEM caps insulation failing, I switched to NGK 5K Ohm plastic caps available at auto parts stores.

No more wet weather breakdowns of the OEM caps, and a fraction of the price........Regards, Rod.

+1 for NKG caps

Rod Sheridan said:

Lew, after having a few problems over the years with the OEM caps insulation failing, I switched to NGK 5K Ohm plastic caps available at auto parts stores.

No more wet weather breakdowns of the OEM caps, and a fraction of the price........Regards, Rod.

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What Rod said! .

+2 for NGK caps too

Mine have been running since 1985. Can't say much more.

I put regular, non resister caps on a /6 with the original points system.

BUMP

Well, the cap went back together using J-B Weld. Worked like a charm.

As an aside...

I adjusted my valves (right exhaust was at .006", the other 3 were spot on). I pulled the points (looked a bit burnt after 2500 miles, but proved to be OK) and burnished them with a business card, checked the plug gap (both still at .028"), and reset the gap using my Northwood Points Tool.

Started right up. Went for a thirty minute ride, ran really well, and when I pulled over I had a idle RPM somewhere between 1200-1500 ... a tad high for me. I prefer something closer to 800-1000 rpm (just a hint of gen-light).

So I'm curious ... if the points gap is, say, .001" greater, or lesser, is idle affected?

Prior to this little exercise idle rpm was below 1000.

Lmo1131 said:

BUMP

Well, the cap went back together using J-B Weld. Worked like a charm.

As an aside...

I adjusted my valves (right exhaust was at .006", the other 3 were spot on). I pulled the points (looked a bit burnt after 2500 miles, but proved to be OK) and burnished them with a business card, checked the plug gap (both still at .028"), and reset the gap using my Northwood Points Tool.

Started right up. Went for a thirty minute ride, ran really well, and when I pulled over I had a idle RPM somewhere between 1200-1500 ... a tad high for me. I prefer something closer to 800-1000 rpm (just a hint of gen-light).

So I'm curious ... if the points gap is, say, .001" greater, or lesser, is idle affected?
Prior to this little exercise idle rpm was below 1000.

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Lesser gap will retard the timing, which usually slows the idle. Where is the timing now?

Seems really that you changed nothing of consequence........Yes, the one valve a bit but that would not typically change your idle..........by the way I also, we are in the minority, like my idle so the alternator light is just going in and out.......one can really tell how it is running when not disguised as a high idle RPM..........

Anyway, could it be that your plugs were not getting the fire they should have and by renewing your caps and the conductivity in them that the plugs are getting MORE fire and thereby running better at idle????????

Just sharing......NOT telling ol Bud.........God bless.......Dennis

Well this is funny... for lack of a better term. I posted an answer to melville earlier and "submitted" it, but it's not here.. . .

Where is the timing now?

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Honestly, I don't have a clue... After my mini-tune up he started better than he had previously, ran like top out on the slab, pulled well up through the twisties ... and even seemed to shift better (?).

When I finally called enough is enough (you can only scrunch down to adjust points for so long (no lift)) I thought that the gap felt a little looser than the last time, so maybe that accounts for the slightly higher idle.

I'm going out for another run this evening with some guys ... something around 80 miles. If the idle remains high (no reason to believe it won't) I'll pull the front cover and recheck the points gap. I've always "timed" the engine statically, so I will do that ... this time.

Considering the way he seems to be running mayne I should just readjust the idle at the carbs and re-synch them.

Maybe the advance unit didn't get keyed onto the camshaft the same way as it always did? Generally, when tightening the bolt holding it all together, it's best to hold the ATU to one side or the other, probably CW, so as to get it indexed in the same spot each time.

... it's best to hold the ATU to one side or the other ...

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As in, maybe there is a tiny amount of slop in that "D" hole in the ATU? In other words, "preload" the ATU CW, or CCW (machts nicht) and then tighten it down... ? And henceforth always do it the same way.

BTW... that rubber strip that seals the timing chest... what a S-T-U-P-I-D design. Once that snotty little RECTANGULAR strip gets soft, there is no way to keep it in that groove... I finally resorted to fitting a piece of 12ga. (I think it was) electrical wire into the groove. I got good compression when screwing down the front cover... maybe it will work. Either way I will have to wait until that large patch of hair on the right side of my head grows back before I try to install a new rubber strip.

DennisDarrow said:

Anyway, could it be that your plugs were not getting the fire they should have and by renewing your caps and the conductivity in them that the plugs are getting MORE fire and thereby running better at idle????????

Click to expand...

Good point to make. When I replaced the coil on my bike, the RPMs increased 200-300, and I did nothing else. Just thought I'd give a little support to Dennis's thought here.