Dual plug ignition timing

Post your post 1970 technical queries here

Moderator: Moderators

Pete
Forum User
Posts: 138
Joined: Wed Aug 24, 2016 5:46 pm
Country of Residence: Fife, Scotland
Location: Glenrothes, Fife

Dual plug ignition timing

Postby Pete » Sat Apr 15, 2017 6:52 am

Hi Guys,
I'm currently replacing the timing chain on my R100R and will have to re-time the ignition as I have removed the ignition can.
The engine has had a twin plug conversion, do I set the timing with a strobe to the normal timing Mark or should it be slightly different?
What's the best revs to do it at?

Cheers,
Pete

User avatar
andyb
Forum User
Posts: 312
Joined: Fri Jul 12, 2013 9:40 am
Country of Residence: uk
Location: Notts, UK

Re: Dual plug ignition timing

Postby andyb » Sat Apr 15, 2017 11:03 am

I had to set my the ignition on my r100r retarded from standard to stop pinging. It has twin plugs and slightly raised compression by Jim Cray, and Boyer ignition...and I run on normal unleaded fuel.
I used a strobe and at1000rpm the OT mark was central in the viewing hole. At higher revs ie when fully advanced, I could not see the marks, so had to rely on this lower engine speed check.
AndyB
R100R work-day-bike
Moto Guzzi V7 Stone fun-day-bike

ts
Forum User
Posts: 215
Joined: Sat Feb 16, 2008 3:01 pm
Location: Surrey

Re: Dual plug ignition timing

Postby ts » Sat Apr 15, 2017 11:08 am

The usual advice is to retard the timing around 4 degrees at full advance (plus-minus a couple of degrees). But it depends to some extent on what set-up you have, standard ignition or aftermarket units which may come designed to give a different advance curve for dual plugging. And what machining has been done for optimising the combustion.

Some reading here, if you haven't seen it before:

http://bmwmotorcycletech.info/dualplugging.htm
http://bmwmotorcycletech.info/ignitionsingleplug.htm
http://skrunkwerks.com/skrunk/dual-plugging-1/

There is quite a bit more info on the subject out there, you can spend quite a bit of time searching and reading. And experimenting.

Could be interesting with a follow-up to hear what settings you ended up with.
ts
===========
'73 R75/5, '78 R80/7, '83 R80RT

Pete
Forum User
Posts: 138
Joined: Wed Aug 24, 2016 5:46 pm
Country of Residence: Fife, Scotland
Location: Glenrothes, Fife

Re: Dual plug ignition timing

Postby Pete » Wed Apr 19, 2017 4:53 pm

Hi Guys,
Having looked at the links, it appears that the advance/retard unit should be modified to suit the shorter burn time required with a twin plus arrangement.
I found the old reciept from the engineer who did the twin plug conversion back in 2000, (long before I got the bike) and he had charged for the timing can "mod". I spoke to him today and he confirmed that it would have been done and that I just need to set the timing up as normal. He did mention that with specialised equipment, I could check that the unit is still moving the timing to the desired position as the revs increase, but the engine was running OK before I removed the can to do the timing chain, so all should still be good.
He mentioned that if the timing was wrong, the engine would run rough.
So all I need now is my magnetic sump plug in ordered to arrive & I can get the oil in & get the timing set.

Thanks for all he info, I am now much more informed on the pros & consider of twin plugging!

Cheers,
Pete

User avatar
andyb
Forum User
Posts: 312
Joined: Fri Jul 12, 2013 9:40 am
Country of Residence: uk
Location: Notts, UK

Re: Dual plug ignition timing

Postby andyb » Thu Apr 20, 2017 9:58 pm

If the ign timing is wrong you will get pinking if too advanced. If too retarded a loss of power and possible overheat. Neither I would describe as rough running.
The 'specialist equipment' is a strobe lamp.
But as well as the mod to the bean can, the timing does have to be retarded from standard.
AndyB
R100R work-day-bike
Moto Guzzi V7 Stone fun-day-bike

Pete
Forum User
Posts: 138
Joined: Wed Aug 24, 2016 5:46 pm
Country of Residence: Fife, Scotland
Location: Glenrothes, Fife

Re: Dual plug ignition timing

Postby Pete » Fri Apr 21, 2017 8:59 am

Andy, the guy I spoke to, who had done the original conversion, told me he had a tool that measured the advance/retard in degrees. With this, he could tell if the mod to the ignition can was correct. His only concern was that, over time, there might have been a change.
I will set the idle speed on the S line then watch where the flywheel moves to going up to 3500rpm. From the links in the previous post, I should be able to see if I am getting the correct retarded timing. All done using a strobe of course. Where should the timing Mark be at 3500rpm can anyone save me some time researching this one?
If not where it should be, should I set the timing to where it should be at 3500rpm and worry less about where it is at idle?
Before I changed the timing chain, there was no pinking or overheating and plenty of power. So I'm confident that all will be OK, time will tell!
Thanks for the advice, I will be looking out for what you mentioned.
Cheers,
Pete

User avatar
SteveD
Forum User
Posts: 2773
Joined: Tue Aug 30, 2005 1:49 am
Country of Residence: Oz
Location: Melbourne, Oz
Contact:

Re: Dual plug ignition timing

Postby SteveD » Fri Apr 21, 2017 9:14 am

Andy, the guy I spoke to, who had done the original conversion, told me he had a tool that measured the advance/retard in degrees. With this, he could tell if the mod to the ignition can was correct.
Like this?

Image
Cheers, Steve.
1982 R100RS, 2006 K1200R.
Image
Stay horizontal!

http://photobucket.com/R100RSsupergallery
https://www.facebook.com/bmwmotorcycletshirts/

Pete
Forum User
Posts: 138
Joined: Wed Aug 24, 2016 5:46 pm
Country of Residence: Fife, Scotland
Location: Glenrothes, Fife

Re: Dual plug ignition timing

Postby Pete » Fri Apr 21, 2017 5:10 pm

I had one of these when I had my B50SS!!
Nope, it was some fancy electronic gadget that measured how much the advance/retard unit moved, allegedly!?

Got the ignition strobed & the carbs balanced today, (after a good warm-up run) all appears to be running fine.

Cheers,
Pete

User avatar
andyb
Forum User
Posts: 312
Joined: Fri Jul 12, 2013 9:40 am
Country of Residence: uk
Location: Notts, UK

Re: Dual plug ignition timing

Postby andyb » Fri Apr 21, 2017 5:14 pm

Would be fun using that with a running engine!
As far as I know the only way to check the advance / retard is with a strobe.
I guess you might be able to somehow jam the ignition in the fully advanced position and then check statically but you would not know at what rpm the timing advanced, or if it advanced at all
AndyB

Edited to add.....just thought, is there something called a dwell meter???
R100R work-day-bike
Moto Guzzi V7 Stone fun-day-bike

brunocrossley
Forum User
Posts: 145
Joined: Thu Sep 14, 2006 2:04 pm
Location: Preston, Lancs

Re: Dual plug ignition timing

Postby brunocrossley » Wed May 24, 2017 1:10 pm

I twin-plugged my early R100, that originally had 'open' points. I replaced it with a Boyer set-up with electronic advance. They do one specifically for dual plugs. It has less total advance than standard. The general wisdom is that max advance should be slightly retarded with twin plugs. The cheat is just to retard the timing in its entirety. So at tickover timing would be at about TDC, giving the correct setup by the time it gets to 3-4000rpm.
A better way is to mod the mechanical advance to restrict the change. That way timing at tickover is nearer to standard, but max advance is optimum. That's what the Boyer does, but electronically.
It is possible to drive the bean can points assembly in isolation on a distributor test machine, and plot it's advance curve and total amount of advance. That's how advance curves are modded when tuning distributor equipped car advance curves. They can tweak things like the bob weight movement and the spring weights.
A strobe with a back-off control could be used to plot an advance curve. A dwell meter effectively measures the percentage of total time that the points are closed and the coil is "charging".

Hope this helps, Mark
Cheap bikes never are.
78' R100RS
14' R nineT

krankshaft
Forum User
Posts: 32
Joined: Tue Dec 16, 2014 10:53 pm
Country of Residence: switzerland

Re: Dual plug ignition timing

Postby krankshaft » Wed May 24, 2017 6:25 pm

Hi, Pete
The device he was talking about was maybe a fancy strobe light. The more expensive ones available allow you
to measure degrees of advance, you can even set the device to a specific number of degrees and check your timing
mark position. You can see one in use on Youtube.
Ride safe
Jim

IanB
Forum User
Posts: 175
Joined: Sat Apr 19, 2014 5:20 pm
Country of Residence: UK

Re: Dual plug ignition timing

Postby IanB » Thu May 25, 2017 10:26 am

If the person we are talking about is Jim Cray, he is not always very forthcoming with information - I think he feels that way you will go back to him for servicing. However, if we are talking about a Cray Stage 1 tuning set-up, the figure he (eventually) gave me was 2 degrees retarded from standard at low engine speed/idle. Seems to work OK on mine. Apparently the "bean can mod" adjusts the tabs which limit the mechanical advance mechanism, allowing the ignition timing to act as normal from 3000 RPM upwards (i.e.: returns to standard advance).

You can gauge ignition timing accurately with one of these - http://www.gunson.co.uk/items/pdf/Produ ... ctions.pdf. The dial on the back allows timing to be retarded from the engine marks by a set amount. I use an earlier version of this item which does the job all OK - no more sophisticated "special equipment" is really required.

JC initially didn't want to tell me the necessary info for home servicing, and tried to sell me a Silent Hektik ignition system. I may well actually fit one of those in due course, but I won't be persuaded to buy one by subterfuge... [-X

Having said that, his Stage 1 tuning package does have certain things to recommend it, and I'm glad I got it done - I'm not sure the bike is all that significantly faster, but I do like the resulting "feel".
1992 R100RS Mono - modified a bit

chasbmw
Forum User
Posts: 1148
Joined: Mon Aug 14, 2006 9:19 pm
Location: Bath UK

Re: Dual plug ignition timing

Postby chasbmw » Thu May 25, 2017 11:01 pm

Jim was pretty open with me about his settings, he used to favour using the basic non dual plug Boyer and setting it on the full advance point on the top horizontal stroke of the letter Z. He told me that he didn't use the Boyer Dual plug module because he felt that the timing curve was not correct.

When timing a Boyer set it at full advance point, when the Boyer stops advancing, should be around 4000 revs, but ignore your rev counter, just watch the marks with the strobe and you can easily see when it stops.

This should give full advance at about 28 degrees compared to 32 degrees standard. I introduced Jim to his first Silent Hektik ignition, they are expensive but have a choice of 16 ignition curves so you can choose one that gives you something like a standard setting at idle and retarded at full advance, lots of choice out there nowadays of Ignition's for dual plugged bikes. Currently I use the Sachse unit on my 90/6. It uses a light beam switch and by using a LED to indicate when the timing has been triggered makes it easy to set up and time.

With all electronic Ignition's make sure that the system is properly grounded, ignition switches and kill switches must work well without introducing any intermittent cuts in the power supply that might be ignored by contact breakers, but will induce grumpiness in electronic ignitions. Use the correct coils for the ignition together with correct impedance in plug caps.
Charles
2016 CCM 450
1975 R90/6
1958 R50
Image

Matchlessman
Forum User
Posts: 2
Joined: Wed Apr 26, 2017 8:19 am
Country of Residence: England

Re: Dual plug ignition timing

Postby Matchlessman » Fri May 26, 2017 8:45 am

To ensure you have the optimum timing you need to run it on a dyno and adjust so it is perfect at full advance, where the engine will be doing the work and spending most of its time. Having said that, a twin plug design should be pretty efficient and tolerant of a few degrees either way. Unless you are working the engine hard it is unlikely to be damaged by a couple of degrees either way. In a racing engine it can mean melted pistons or worse....

User avatar
stevehiles
Club Member 12
Posts: 14
Joined: Sat Feb 21, 2015 6:41 pm
Country of Residence: UK
Location: East Yorks

Re: Dual plug ignition timing

Postby stevehiles » Mon Jun 19, 2017 5:00 pm

Twin plugged my R60/6 some years back in the hope of getting it to run better on modern 95 octane fuel. This was a success, after retarding the ignition slightly the motor is now much more eager and smoother at higher rpm BUT because my simple (Pirana) electronic ignition retains the original mechanical A/R unit and therefore the original advance range I cannot get equally smooth running at lower rpm. Still a worthwhile mod though.

Steve.
R60/6, K100, Triumph Trophy 900, Yamaha XS500, 650 Bandit

chasbmw
Forum User
Posts: 1148
Joined: Mon Aug 14, 2006 9:19 pm
Location: Bath UK

Re: Dual plug ignition timing

Postby chasbmw » Mon Jun 19, 2017 9:07 pm

Steve. I have heard that the original Boyer micro digital ignition curve was developed in order to help stop. The R60s from pinging, the ignition curve retards the ignition between 2500 and 3000 revs, which is a typical pinging range for a BMW
Charles
2016 CCM 450
1975 R90/6
1958 R50
Image

User avatar
stevehiles
Club Member 12
Posts: 14
Joined: Sat Feb 21, 2015 6:41 pm
Country of Residence: UK
Location: East Yorks

Re: Dual plug ignition timing

Postby stevehiles » Tue Jun 20, 2017 8:36 am

Thanks for the info Chas. Fitting thicker cylinder base gaskets (0.7mm I think) cured my pinging problems and the less than perfect low speed running as a result of retarding the ignition is only a minor irritation. Am reluctant to remove the Pirana ignition as its been 100% reliable over many years. Might try modding the mechanical A/R unit one day when I've nothing better to do.

Steve.
R60/6, K100, Triumph Trophy 900, Yamaha XS500, 650 Bandit


Return to “Airhead Q&A's”

Who is online

Users browsing this forum: No registered users and 8 guests