Ariel Owners Motorcycle Club

Hi,i'm looking for help timing the ignition on a 1954 vb with iron head. I have no previous knowledge of magdyno's as i have only owned 70's east european and spanish bikes. Does anyone know of magazine aticles or websites with pictures that would help a dummy like me time the ignition of a lucas m01...any help will gratefully recieved...steve...

Hi Steve, hopefully, you'll find it simpler than you expect.
You need;
1. The correct tool to remove the sprocket in the timing cover (looks like a 20mm socket with a bolt into it) . The sprocket sits on a taper. You remove the nut that holds the sprocket on the shaft, fit (screw) the tool over the (larger) thread on the sprocket itself and then tighten the bolt. This will crack the taper. The sprocket will then just fall off. Don't be tempted to try to lever the sprocket off. You will crack the inner timing cover. Honest.
2. a cigarette paper / multimeter / good eyes to check for the points just opening
3. a lead pencil down the plug hole or TDC tool ( looks like a drilled out spark plug with a moveable pin) or with a VB, just take the head off and measure! (watch valves, remember - induction / compression / ignition / exhaust)

The science is; after you set the advance to full on the handlebar, the points should just open (spark) at 5/16" before top dead centre.
You achieve this by;
1. removing the magneto sprocket.
2. moving the motor to TDC. Mark the tool, then measure 5/16" with a ruler and mark the tool again. Then, move the motor to the 5/16" BTDC point (in gear, rotate the back wheel). Go too far back, then rotate the wheel forward to get rid of backlash.
3. rotating the tapered arm of the magneto (inside timing cover) by hand until the points are just opening
4. then fitting the sprocket back on the taper.
++ The art is to get the sprocket back on without anything moving else out of place. Check and repeat (several times) until it's right.
Sometimes beer helps.

If you get stuck, ask. There are heaps of people here who will help you.

There's nothing photographic I'm aware of - but if you need a photo of something, ask.
http://www.arielownersmcc.com/members ... Guides.htm
http://www.arielownersmcc.com/members ... manual.htm

Wot Brenton said.

On OHV, we'll take out a sparkplug and then put something down the plug hole to determine the rise and fall of the Piston, you can use a piece of wood, a small scewdriver, pencil or even one of these:



You will need the rear wheel off the ground and the bike in top gear.
Get the bike on the right compression stroke, then you sit (or crouch) next to the bike. One hand on your tdc tool (to ensure it's upright) and one hand on the rear tyre, rocking the engine back and forth (which you can do as the bike is in gear and the plug is out) and squinting at the tdc tool until the piston is where it's supposed to be.

On one of these new fangled TDC tools, like the one above, then there is a graduated scale. Obviously using a pencil or something, you will have to first get the piston to TDC (lots of rocking the backwheel back and forth) and then mark that. Now take it out and measure the 1/2" (or whatever) up so you have a mark which would equate to 1/2" before TDC. When you put it back in, then you will need to rock the engine backwards.

On the VB, the sparkplug isn't over the piston though is it; which means having the plug out just removes an compression and you cannot tell where the piston is. I think there is a small nut, in among the top fins, that is directly over the piston and that becomes the entry point for your tdc tool. As the hole is so small, then it will have to be a pencil or a thin piece of wood.
The good news is that once you have the right length/width made and put TDC and advance marks on, then you can keep it handy.

Whereabouts are you ?
If you are close, then I can come and show you ?
With a

All of that is good advice.
The fuels we run lately don't vapourise as well as some of the older ones did so I find the advance figures given in the original manuals are not quite the best for use now.
When I get my engines set up and running well, I always find that you need over 30 degrees of advance or the engine's a bit "dead" and the exhaust pipe colours ( Blues) excessively.
Some engines need a lot of advance. The racing KTOR JAP's used up to 45 degrees. This is a lot of advance but with poor combustion chamber shape ( domed pistons in a hemispherical head) it can happen..
The Ariel is set up with the lever in "pull to advance" so you could give it about 35 degrees and if it turns out to be a bit much when you road test it you can back off the cable adjustment a little bit. If your setting turns out to be not enough advance, you have to "break" the taper fit again (The ariel sprocket has a provision for the correct puller to be used) and re do the timing. If iI do it on the piston travel I always give it 3/8" BTDC, but I do prefer to use a timing disc which requires removal of the primary drive cover, and go for 35 degrees with full advance. Nev

i am gratefull to everyone for their advice. Over the Christmas break i will go over it all and get down and dirty in the garage..thanx again...