Dual plug ignition timing

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Pete
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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

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andyb
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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
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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
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'73 R75/5, '78 R80/7, '83 R80RT

Pete
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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

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andyb
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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
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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

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SteveD
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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.
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Pete
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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

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andyb
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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


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