setting timing

[pdg]

I'm sorry to ask help for something that's probably very basic to everyone else, but ...

Having had my magneto rewound, I need to set the timing, and need some advice about how best to do this.

My problem is knowing where 3/8" BTDC is. I've put a dial gauge through the spark plug hole and found TDC with both inlet and outlet valves "loose" so I know it's the compression stroke  .

At the moment, to go back down 3/8", I've put the bike in gear (3rd or 4th) and turned the back wheel in reverse to take the piston back down. One problem is that because I've still got the petrol tank in place and only a short 1" dial gauge, the dial gauge is at an angle, I can't get a true measure of 3/8". My thought is that I will need to get an extension for my dial gauge and take the petrol tank off so that I can set the dial gauge vertical and measure the 3/8" accurately.

Is this the right approach or am I making a meal of it?

Many thanks, Peter.

[morris]

Get a timing disk. They're widely available and much more accurate.
With a bit of imagination it can be temporarily fixed on the crankshaft's timing side, and a pointer is quickly made out of a piece of steel wire.
That's how I do it. Works great.
From memory I'd say that 32° btdc with atd fully advanced is ok. Unless someone's got a better memory than me. Which is bound to be...

[RichardL]

Here is another alternative, probably not as accurate as the timing disk, but has worked for me. Granted, it always takes me several attempts, mostly because I have to re-train myself on best mag gear tightening technique. As described in the post, the picture shows an aluminum tube with a paper graticule glued to it. What I changed since the picture was to put a screw in the top of the tube for added weight.

One good thing about a using a disk might be that the primary case is open, which allows you to turn the crank with a breaker bar and socket, assuming you have the SRM cush nut.

Richard L.

http://www.a7a10.net/forum/index.php?topic=8301.msg58614#msg58614

[pdg]

Many thanks for the advice.

What is the recommended way to turn the engine over? I'm currently putting it in gear and turning the back wheel  .

Thanks, Peter

[muskrat]

G'day Peter.
If your doing the timing with the timing cover off, the crank nut. Be careful as the crank nut is left hand thread so winding the motor clockwise (the way it spins) you may loosen it.
Cheers

[pdg]

Many thanks. I think I'll go for taking the primary cover off. Would I then use a C spanner to turn the engine over?

[duTch]

Would I then use a C spanner to turn the engine over?

   Yeah but then you stand a chance of loosening the cush nut ....but not if it's tight ...I use the rear wheel method you've been doing, but just make sure if you need to start over,  to get rid of gear lash either go right around (4 strokes/2cycles) or go back further and come back up

[Topdad]

Bah humbug ,you load of technos you !! Where you going to find a dail guage away from home and garage    ,I'm still using my pencil method      ,  last  set about 3 yrs ago still starts first kick even when left over the winter , Bob

[muskrat]

Yep, I can't remember the last time I did my timing, a few years at least. Electrick ignition, set and forget .
Cheers

[RichardL]

Bah humbug ,you load of technos you !! Where you going to find a dail guage away from home and garage    ,I'm still using my pencil method      ,  last  set about 3 yrs ago still starts first kick even when left over the winter , Bob

My graticule tube is, basically, just  the "pencil method" with a bit of graphics. You could easily keep it in your tool box (along with a pencil). Hmmm, "away from home and garage"? Better throw in a ratchet wrench,  plug socket, allen key, socket for mag pinion nut, rolling papers (and accessories), spanner for valve-cover nuts, spare outer timing cover gasket, spare valve cover gaskets and gasket sealer. (I suppose you can find a twig by the side of the road to block your ATD into fully advanced.)

Richard L.

[bsa-bill]

rolling papers (and accessories)

All sort of problems with that gear these days

[Topdad]

Point taken Richard , but at least stuck out there in the middle of nowhere I'm pretty sure if the timing slipped I'd more likely borrow those tools from someone rather than a dial gauge   

[duTch]

(I suppose you can find a twig by the side of the road to block your ATD into fully advanced.)

  It's been known for that to be stored in the oil tank.....

[RichardL]

(I suppose you can find a twig by the side of the road to block your ATD into fully advanced.)

  It's been known for that to be stored in the oil tank.....

Wow! You have a good memory. Are you sure you're old enough to be a vintage bike enthusiast?

Richard L.

[duTch]

 Some things can't be forgotten nor unread...