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Pinking!

Bolti
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Joined: Thu Jul 28, 2022 4:17 am

Pinking!

Post by Bolti »

So chaps, the pinking issue goes on and more questions that hopefully someone can answer and may have some pointers to help others.

As you may know, I am having a pinking problem as well as what I thinking is running rich/using oil on one pot (left hand side).

So strobed up and adjusted the timing - btw, bike is fitted with Vape electronic ignition - which is right on the money now but wasn’t too far out I am thinking to give me the pinking.
So here’s a thing/question. When you fit the strobe light does it matter which side you connect the spark plug HT lead up to when doing. I think not but would like someone to confirm this. What was interesting was that I was getting a brilliant strobe from the right hand side (non timing window side), but an intermittent strobe from the left hand side. At first I thought it was my strobe light so I bought a new one but no same happened. This almost indicates to me that either the HT lead which is new along with the spark plug and suppressor cap is duff.
Being an engineer I like to work from the outside in when trying to find out a problem. So to date I have changed the plug and suppressor cap but as yet no the HT lead but still no good. That I need to do.
Now here is food for thought. If I am right in thinking and I am only getting an intermittent spark on one side, this could be the reason why I am getting slight ‘smoking’ from one exhaust and possibly why it’s pinking.

res some food for thought and wondering if anyone else has experienced this as well as does it matter what side you connect the strobe up too?

Thanks for any help chaps.

xackley
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Re: Pinking!

Post by xackley »

The original ignition was wasted spark. Fires both sides, so you can switch the cables at the coil to test cable problems.
From the wiring diagram for the Vape system it didn't look like there was a designation of left and right plug wiring, so it might fire both sides at once.

As to pinging. Carbon build up on pistons causing to much compression or bad advance unit firing too soon for rpm or advancing too far. If possible retard the spark sensor to see if it reduces pinging.

Just looked at page 14, it stated it is a wasted spark system, so switch the cables to test at the coil.
Documentation also stated they want almost no resistance to the spark plugs.

Don
1958 R69, 1972 R75/5, 1980 XS650, 1982 GL1100, 2003 guzzi ev, 2017 guzzi V7!!!
All on the road, going no where in particular in the Finger Lakes of New York

cwf
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Re: Pinking!

Post by cwf »

Well, I can't help towards solving the problem and I realise it's the sort of problem engineers want to solve, but perhaps I can put your mind at rest a little.

I bought a 60/6 new and it always pinked a bit but I was young and just got on with riding. After a few years I started travelling in countries with poor fuel quality, so I put in thick base gaskets to cope with that and, possibly, the pinking.

It continued to pink and, at about 150,000 I took it apart to change the rings and found no special damage. Perhaps the tops of the pistons had more nibbled depressions than you might expect but nothing the learned articles in magazines had warned me about and, being young, I had no qualms about thrashing the thing.

So, although it's a technical (and aesthetic) problem, practically you might not need to worry.

Charlie.
75/7+ offroad sidecar; 50/2; R 35; XR125V; XR200A; Solex; 1939 Hillman Minx DHC.

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schrader7032
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Re: Pinking!

Post by schrader7032 »

I think one should find the reason for the pinging. For the R60/6, it was high compression to begin with and had a mild cam profile which contributed to the pinging. Base gaskets reduced the compression ratio. Also, later electronic ignition systems like the Boyer had computer controlled advance curve which delayed the advance to further help with pinging.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

Bolti
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Re: Pinking!

Post by Bolti »

Well chaps re the pinking I thought I would just throw this out there from what I have found out from my bike for general discussion.

So to recap, I have fitted a Vape electronic ignition to my bike starts fantastic and runs well except when under load I.e. on hills or under load.

So here’s what I found. I fitted a digital inclinometer to the rotor - it’s one that I use to time my Lambrettas dare I say.

So I have the original timing marks on the flywheel ‘OT’, ‘S’ and ‘’F’. OT being as we know TDC, ‘S’ being 9deg BTDC and ‘F’ being full advance.

Here’s the thing, I fitted the digital inclinometer and zero’d it at OT, turned it around to S and guess what 12 deg. Turned it further to F and 41 deg.

So my question is and for general discussion - can you trust the original flywheel timing marks for accuracy in setting up your timing?

I know these are old machines and you must give some latitude for wear etc but it does make you wonder.

Now it’s probably my problem in being an engineer and being ‘anal’ about accuracy working for the Uk gov in a field that deals with Los Alamos, Sandra National Labs and Livermore where anyone that knows the business accuracy is paramount compared to my 1960 R69S but I like things to be right.

So just to finish off. I have set the ignition with a slight retard from where the strobe shows the S and now have no pinking at all.

The pre ignition could be down to the better spark from the Vape system, it could be down to the crappy 5% ethanol petrol we have here in the UK I don’t know but thought I would just share my findings with the group.

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schrader7032
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Re: Pinking!

Post by schrader7032 »

Years ago, I contacted a BMW mechanic in the St Louis area. I asked him for the diameter of the /2 flywheel. Not sure if there are more than one. But he told me after measuring one, the diameter was 222.25 mm. The math works out so that 1 degree on the edge of the flywheel is 1.94 mm. Maybe it's possible to measure the edge of the flywheel from OT to S and F and compute what the degree is to see if matches your measured results.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

Seek
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Re: Pinking!

Post by Seek »

A 12-41 degree flywheel sounds like an older model. Didn't the R69 have these numbers?

Daves79x
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Re: Pinking!

Post by Daves79x »

The R69 flywheel does indeed have different timing marks from the R50/R60, but I assumed that same flywheel was used on the R69S also? Maybe not. But the marks are more advanced. Jeff M showed a pic of the two side by side somewhere, can't remember where. The Barrington book makes no distinction between them, and it's been a couple of years since I worked on mine '55, so I can't exactly remember. I have my '56 R69 apart and will compare it's flywheel to an R50/60 one and let you know.

Dave
Dave

Daves79x
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Re: Pinking!

Post by Daves79x »

Just found the timing specs in my original BMW R50, R60, R69 owner's manual. The R69 timing specs are indeed 12 degrees and 42 degrees (plus or minus 2 degrees at full advance). So the timing marks on the R69 flywheel reflect this, and I assume it'd the same for he R69S that you have. Your measurements would be exactly correct then. Guys do complain of pinging in the R69S even when using available premium, so I don't think yours in unique. Nothing wrong with backing it off a bit though, but try using the highest octane available. My '55 R69 runs fine on non-ethanol 91 octane, but the compression is lower than the R69S.

Dave
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vechorik1373
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Re: Pinking!

Post by vechorik1373 »

The R69S flywheel does NOT have different timing marks from the R50 - R60/2 flywheel. Visually, it looks like it does. However, the R69S flywheel is smaller in diameter, and therefor lighter. Remember that , one can fit any of the flywheels to any of the engines. Who knows who has done what over the last 50+ years.
You can do a simple illustration on paper using a pencil compass to prove that I am correct if you don't believe me. Draw two circles, one larger than the other, outside the first circle that you drew. Then draw a line out from the dead center through both circles, label it TDC. Use a protractor, and lay out a second line from the dead center at 9 degrees off of the TDC line. Then measure the distance between the TDC line and the 9 degree line, and you will find that while the smaller circle the distance is less between the intersecting lines of the inner circle than the larger diameter circle, but they have BOTH have the same 9 degree marks.
The timing marks are the same on both the R69S flywheel and the R60 flywheel. But to the unthinking eye, both flywheels appear to have different timing marks.
Vech
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