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Question on setting ignition timing

JaapDeurloo

Forum Website User
Non-VOC Member
Hello all,

I am getting near the end now of the restauration of my 49 Rapide, and I am now at the point to fit the overhauled Lucas magneto and fire it up after 50 years.

but I have some doubts about stting the ignition timing, looking from the left side of the bike, the magneto (rotating counterclockwise) has two lobes the bottom one and then
the next one 310 degrees later.

When looking at the article "setting your ignition timing" in Whitakerpedia setting ignition timing it says that the bottom lobe corresponds with
the rear cylinder, but should that not be the front cylinder, because the engine (looking from the left side) rotates anticlockwise which means the front will fire 360+50=410 degrees after the rear cylinder has fired.

My question is which lobe corresponds with which cylinder, because I think the bottom lobe corresponds with the front cylinder, and not the rear one.

thanks,

Jaap
 

chankly bore

Well Known and Active Forum Website User
Non-VOC Member
A common error is to fit the cam ring housing 180 degrees out. Check your ignition timing with a degree plate on both cylinders. Nowadays it is better to go with about 35 degrees full advance. See recent threads on "Ignition timing and modern fuels."
 

teunvandriel

Active Forum Website User
VOC Member
Zet de achterste zuiger exact op BDP, zijn bij PCB handige apparaatjes voor te koop, zet de vervroeger op volle voorontsteking met behulp van een stukje hout van een wasknijper en stel mbv een voelermaatje van 0,01 mm en een goeie gradenschijf gemonteerd op zo'n conisch asje wat afgebeeld staat in de Vincent boeken de ontsteking op 35 graden voorontsteking. Weet je zeker dat de conus van de vervroeger goed past op de magneet, was bij mij niet het geval waardoor de vervroeging verliep en een gat in de zuiger brandde, controleren met pruisisch blauw of zo iets. Heb je een ouwe camring dan kan het zijn dat de voorste cilinder een graad of 5 later staat, vroeger keken ze niet zo krap, ook even controleren dus, dan moet je een beetje middelen, tegenwoordig worden die dingen op een graad nauwkeurig gedraadvonkt. Teun v Driel
 

JaapDeurloo

Forum Website User
Non-VOC Member
bedankt voor je antwoord Teun, je methode is me duidelijk, ik zat/zit alleen te twijfelen of de beschrijving die ik tegenkwam wel correct was, tussen de onderste en de bovenste nok zit 310 krukgraden, dan zou de onderste nok niet bij de achterste cilinder horen maar de voorste.

Hierbij een plaatje.

Google translate suggests: thanks for your reply Teun, your method is clear to me, I sat / sitting alone to doubt whether the description that I encountered was correct though, between the lower and the upper ridge is 310 crank degrees, then the bottom cam would not reach the rear cylinder but hear the front.

Here is a picture.
 

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vibrac

Well Known and Active Forum Website User
VOC Member
Zet de achterste zuiger exact op BDP, zijn bij PCB handige apparaatjes voor te koop, zet de vervroeger op volle voorontsteking met behulp van een stukje hout van een wasknijper en stel mbv een voelermaatje van 0,01 mm en een goeie gradenschijf gemonteerd op zo'n conisch asje wat afgebeeld staat in de Vincent boeken de ontsteking op 35 graden voorontsteking. Weet je zeker dat de conus van de vervroeger goed past op de magneet, was bij mij niet het geval waardoor de vervroeging verliep en een gat in de zuiger brandde, controleren met pruisisch blauw of zo iets. Heb je een ouwe camring dan kan het zijn dat de voorste cilinder een graad of 5 later staat, vroeger keken ze niet zo krap, ook even controleren dus, dan moet je een beetje middelen, tegenwoordig worden die dingen op een graad nauwkeurig gedraadvonkt. Teun v Driel

Plenty of translators on the web:....
Put the rear piston exactly at TDC, when PCB handy devices for sale, put the advance unit at full for inflammation using a piece of wood with a clothespin and set using a feeler gauge of 0.01 mm and a good degree disk mounted as' n conical shaft which is depicted in the book Vincent ignition at 35 degrees for ignition. Are you sure the cone of the advance unit fits on the magnet, was not the case with me making the advance went and burned a hole in the piston, check with Prussian blue or something. Do you have an old camring it may be that the front cylinder 5 degrees later, earlier, they looked not so tight, even just check so, then you need a bit of resources, those things gedraadvonkt accurate to a degree today. Teun v Driel
 

Martyn Goodwin

Well Known and Active Forum Website User
VOC Member
Plenty of translators on the web:....
Put the rear piston exactly at TDC, when PCB handy devices for sale, put the advance unit at full for inflammation using a piece of wood with a clothespin and set using a feeler gauge of 0.01 mm and a good degree disk mounted as' n conical shaft which is depicted in the book Vincent ignition at 35 degrees for ignition. Are you sure the cone of the advance unit fits on the magnet, was not the case with me making the advance went and burned a hole in the piston, check with Prussian blue or something. Do you have an old camring it may be that the front cylinder 5 degrees later, earlier, they looked not so tight, even just check so, then you need a bit of resources, those things gedraadvonkt accurate to a degree today. Teun v Driel

Cripes! I reckon the original double dutch made more sense!

M
 

Monkeypants

Well Known and Active Forum Website User
VOC Member
I tried using one of those web translation services to aid in purchasing a Rapide in Argentina. I attempted to make an offer on a Rapide, however as near as I could tell from the seller' s reaction in broken English, it appears I may have proposed to his sister.
We are very happy.

Glen
 

A_HRD

Well Known and Active Forum Website User
VOC Member
Jaap,

There is something wrong here. I am not surprised you are having a problem.

I think your cam has been put in backwards! Remove it and fit it in the other way around!

Using the the same orientation as your picture, the front cylinder points (no.2) will open with the upper cam opening the points at approx 10 o'clock. The lower cam (No.1) will be at approx 5 o'clock.

I have checked all 3 of my KVF magnetos and they are all the same as this.

Cheers,

Peter B
Bristol, UK.
 

JaapDeurloo

Forum Website User
Non-VOC Member
Thanks Peter, I had the feeling it was not like it should be.
Do you think the camring needs to be turned 180 degrees ?, can this item be pressed out and in, or can I loosen the whole housing and turn it 180 degrees ?
 
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