[btour]

So, my 71 bonne is fouling (black sooty) left plug. Compression is 170 left (trouble side), and 150 right. Checking everything. Since it is winter and can not start bike, battery out, stored, etc. I was checking the electric, since I thought spark might be weak for high compression side. I followed the meridan lucas document this site, I wonder if anyone can tell me what the results mean in practical terms. Coil resistence was slightly low. Anyone measure theirs?

So here are the results:

Voltage tests:

Man it is cold in the garage. Started by testing the volts to and through coils. Everything seemed to test Ok since battery was so cold.

Except on the good running side, black yellow leads, the voltage measure to points side of the coil (+ side) was rather high, around .4 with the points closed. In fact at one point it read 12. I snapped the points open and closed a few times and it came down to .4 .

This would indicate that side b/y points are being weird, dirty, something. I cleaned them just before that result.

The bad running side gave a result of .12 with its points closed.

n the voltage test refered to above,
The test were performed:

1) From battery ground to power (or -) side of coil.

2) From battery ground to + side of coil with points open

These measurements seemed norma, but were
lower than 12V, but it was awfully cold and battery V itself kept dropping.

3) From battery ground to + side of coil with points Closed

It is on this test that I got .4 on the right side which is the good running side and .12 on the side running badly.

The expected was supposed to be 0 or at least lower than .2

I assumed that the points were just a little dirty, but after the good resistence test on them, I wonder where the voltage is coming from.

I should have done a further test to end of plug lead.

Any ideas? Sound normal?

Results of resistance tests:

Coils:

Primary windings:

Left = 3.9 to 3.4
Right = 4.0 to 3.4

Expected = 4 to 5.5

Secondary windings:

Left = 4.53
Right = 4.76

Expected = 5 to 6 K

High Tension Casing and Metal Casing

Left = Infinite
Right = Infinite

Points (and I did not know what to set meter on):

Left:

Closed = 0
Open = Infinite

Right:

Closed = 0
Open = Infinite

Condensers both tested good, runing through some numbers pausing at 20 something or other and then after no more than 2 seconds holding at infinite.

 

[OzBloke]

btour,

By the sounds of it, you have a dirty/poor connection between the coil +ve on the bad side, and the points. Check all bullet connectors (two under tank - one for each points line). Take the points out and give them a file to clean 'em up. Measure between the connector at the coil (wire off the coil) and the connector at the points spring (wire off the points) on lowest ohms range. Should read less than .2 ohms. If not, start checking from one end gradually working along the wire at each connection point looking for the higher reading.

Hope this helps

 

[btour]

Hi Oz Bloke,

Thanks for coming through for me! Couple of questions:

1) Do you think the resistance readings on the coils themselves indicate they are weak? They were done with wires disconnected, just like the lucas doc from this site.

2 ) How many connections are there for the points wires? I have taken apart the female lucas style bullet connectors located under the tank by horn and cleaned. This would be only the b/y and b/w that I have done, not the ones to kill switch.

The points are very old now, but were not used, just sat on bike. I have filed them in place, and cleaned. In fact the gap may be too big because of that and timing was set after the filing without resetting gap, by a pro, not my fault. I have no timing light.

What bothers me is that the faulty reading for the connection is on the good running side. I wonder if that could effect the bad? Or if coil is just too weak to fire the higher compression in the bad running side? Or if larger gap is contributing, to weak coil?

According to the specs, so I need confirmation they are correct, the coils are reading about an ohm less than should be.

I have never done this before. So I don't know if it is normal or not, but when testing coil the reading hit the high figure first and then settled down to about a half an ohm less. Is that usual?

I will follow your instruction to check for bad connections. I did it with the wire connected at points. It will take some time to do that because it is so cold, and I like to reconnect everything afterwards so I do not forget something.

But in the mean time, I would greatly appreciate your advice on the above questions. I know they are many.

Thank you,
Bob

 

[btour]

PS. When I ran the voltage tests, I did not disconnect the Zener diode. I notice that Glenn's manual suggests doing that. I don't know if that made a difference or not.

 

[CommandoRdster]

Bravo,B. Now you should get more answers,less lectures. :upthumb:

P.S. Was not ignoring your request. SRE
:chug:
Cheers
Bruce

 

[OzBloke]

btour,

Seems I mis-interpreted you first post. Been up to my armpits in daughters car (engine change) over the last few days.

To answer you questions (no lecturing ??)

1) Coil resistance readings are good for 12V coils.

2) For each coil - One connection at the coil, and a short wire from there to the condenser. One connection under tank (you've done that one). One connection at the points. I re-read your first post, and apart from the .4 ohm reading on the good side- seems a little high. May be a wire with broken strands near a bullet or spade connector, or where the two wires (b/y & b/w) enter the casing behind the points well.

3) Leaving the Zener connected will not (assuming the Zener is OK) affect normal voltage readings. It may affect resistance readings from coils to earth.

If it's fouling a plug, and not running rough or running one one cylinder intermittently, it's probably not the electrics.

IMHO, if you're sure the carbs are set properly, and you still think it's an electrical problem, I think your best bet from here is to start swapping bits from side to side. Start with spark plugs, run for a while, and check to see if problem changes sides. If not, swap the plug leads and check after a run. If it still stays on one side, swap the coils over from left to right and vice versa. If it still stays on the original side, it's a carb or oil causing the fouling.

Pete.

p.s. Bruce - maybe I'm thick, but don't understand where the "lectures" comment came from.....

 

[CommandoRdster]

Sorry Pete! That comment was not aimed at you in any way,shape, or form.What I meant was, now btour will get actual answers to his questions,instead of just lectures,like he seems to have been getting elsewhere. It should be taken as a complement. I apologise to you, and btour for any misunderstanding.

:chug:
Cheers
Bruce

 

[btour]

Hi Pete,

Looks like you have hands full with engine change. Thanks for helping me.

That is kinda bad news for me, that coil resistance was fine. I was hoping it they would be weak, and so new coil would give me hotter spark and solve the problem.

I guy I respect told me an old trick was to file the side electrode so its tip lined up even with center electrode. I am going to try that when it warms up.

And I think I better check that zener diode too. I did not mention it but when checking voltage my results were lower than I wanted, I just assumed the cold was dragging down battery, quickly. Started with 13 something across battery. 12 something first side coil and then 11 something after.

Anyway, I will try to isolate where the b/y is leaking, if it is. I think you gave directions to do that. If it is in the case behind points plate is it possible to tape new wire to old and pull through to run a new one?

I have swapped coils, and leads, and coils and leads test the same too so testing confirmed having no effect.

New plugs make it run great. Plug on one side fouls over time. New slides and new needle jet, and hotter plugs ngk7's projected all helped make that time period much longer. Plug looks black sooty not like oil. Compression is 170 on bad side. Plug looks to blacken one side first in vertical line. Could be splash fouling? Maybe I just have a really dirty intake? Now the breather tube shrank and pulled off the connection, and I left it like that(thinking it was a cool chain oiler), not thinking that was where the carb was breathing.

I was trying to eliminate the electric. Actually the good running side does seem to miss intermitently, and briefly sometimes, but it is not bothersome.

If you are positive those coil readings are OK, then I will clean and or replace points, set gap, and retime. Then if still trouble, I will swap carbs side to side, and then if still trouble, I will take the darn top end off.

Are you absolutely sure that secondary reading is OK? I am praying not, cause it would be so easy. Last night I tested my friend's 71 bonne, and his primary coils were right were expected 4.5 ( see mine were 3.4, I mean reading started at 3.9 but quickly dropped and held at 3.4 ) His did not do that, read higher and then drop lower. His SECONDARY windings tested at 9.5 WOW way higher than expected 5 to 6 and way way higher than mine at 4.5

I know this is a real lot of info, all over the place.

I can't really do much at this point, it is too cold to wrench and test. But I really appreciate your help.

I have been pondering why it seems from complaints I have read it is 98% of the time the LEFT side that fouls plugs? Any ideas

 

[btour]

Ps, Pete.

I don't know if you want to get into what might be my problem, but...

Last known what it was doing was, and that was after switching to bpngk7's, and re fiddling the carb screws: The left side was not firing when first starting at idle range, or miss firing like 8 cycling, and then clearing out and running fine, and idling fine, until shutting, and restarting after sitting.

I also plan to try to remove the freeze plug in that carb and clean real good, and replace that freeze plug, though I hear it is a real trick and I have no idea how to do it, ( do you ?) and finding a screw in pilot jet and fitting that. I figure that carb is toast if that is problem, as it is, and I might as well give it try to re-build it, and learn something, before giving in and buying a new one.

I have one other really big concern, but will save that until you decide to accept this impossible mission.

 

[GrandPaulZ]

btour:

Go down to the nearest Auto parts store and buy a one-gallon can of Berryman's Chem-Dip, it comes with a dipping basket inside.

Pull the carbs completely apart and soak all metallic parts for 1/2 hour - 45 minutes.

While they are soaking, plug in your air compressor and fill the tank, have your blaster nozzle standing at the ready. Also, fill a bucket with water and leave the hose running right before you take the parts out of the Chem-Dip.

Yank the dipping bucket from the sauce and run the hose over the parts, then toss the whole batch in the bucket of water. Leave them rinsing with the hose in there for a minute or two, then start fishing the parts out and blasting them dry.

Re-assemble with all new gaskets and o-rings, fresh plugs and a fully charged battery.

Don't neglect your valve tappet adjustment.

 

[btour]

Thanks grandpaulz,

I appreciate the instruction on cleaning carbs, and the berryman's to use. I will try it.

I had the carbs professionally cleaned, so I think it may need something extra, like removing the freeze plug and really cleaning the primary air chamber, but I need to know how to replace that freeze plug without a problem.

Remember these carbs sat for 30 years with gas in them.

 

[GrandPaulZ]

I don't know how some professionals do the job, but some are not as good as others.

It won't hurt to try this, and that Chem-Dip is DEFINITELY good at getting WAY into the nooks and crannies.

 

[OzBloke]

btour,

I took a good long look at your postings, and my gut tells me your plug fouling is not an electrical problem. Although I am a bit perplexed by the primary coil reading going from 3.9 to 3.4 ohms. I'm assuming you tested your friend's coils with the same multimeter, and the battery in the meter is OK, and that you're testing with no leads connected to the coils - power, points, condensers and high-tension (plug) leads all disconnected.

GPZ is pretty smart, and gives good advice, so don't discount the "deep soak" cleaning routine. I'd be inclined to ensure the carbs are perfectly clean, and properly tuned before pulling the top end apart.

Somewhere on the web there's a site that shows you how to take out the blanking pulg on the Amals, and one of the threads on this forum had a link to it - about 12 months ago if I recall correctly.

EDIT - found the site - goto http://www.jba.bc.ca/Bushmans Carb Tuning.html

Pete




[ This message was edited by: OzBloke on 2007-02-12 23:47 ]

 

[btour]

Hi Pete,

Your assumptions about my coil testing are correct. It was the same meter with brand new battery. Coils completely disconnected from bike.

So the dropping resistence is NOT normal?

I had found the Bushman's site. I do not see anywhere in it the directions for replacing freeze plug, the about 5/16 round pressed in thingy. If you saw those instructions and come across them, could you link me to them, please?

Also, I have a question aobut what he means when he is talking about tapping in a blanking screw. He says:

"A better method is to actually drill out the blank plug on the opposite side from the air screw and physically probe the jet so that you can see with your own eyes that the jet is clear. The drilled hole is tapped 10/32 (in real life it should be 2BA) and install a blanking plug (an old air adjuster screw cut to size) with Loctite."

My question is what does he mean by : "(in real life it should be 2BA)"?

But even doing what he says there, I do not think, does not give good access for scraping the air chamber. So I want to remove and replace the freeze plug.

Thank you.