Ignition advice on '72 WR250

[Arthur Smith]

OK...let's go over two ways to check the ignition timing...which is the exact point when the contact breaker points "open".
First, the flywheel gets re-installed and properly torqued. Before you do that, carefully remove that worn woodruff key and replace it. Also carefully dress that tapered crankshaft mating area with fine emery paper. Get it as smooth as you can. Do the same thing to the mating surface of the flywheel. Clean both with contact cleaner and re-install the flywheel with both components clean and dry.

Option 1: Use a metric dial indicator inserted into the spark plug hole. Bring the piston to tdc. "Zero" the dial indicator at tdc. Rotate the flywheel counter-clockwise about 3 mm. Slowly rotate the flywheel clockwise. If set correctly the points should open at 2.43 mm btdc. If not, rotate the backing plate until they do. I prefer an ohm-meter or a battery/bulb circuit to accurately detect when the points break. Or the analog method of tugging on a super-thin slip of cellophane inserted between the points.

Option 2: Use a degree wheel fastened (yes...I use a double-sided piece of duct tape to secure the degree wheel) to the flywheel nut flat surface. Fasten a piece of wire to the case that can be used as a pointer on the degree wheel. Bring the piston to tdc. Bend the wire pointer to match up to 0 degrees. Rotate the flywheel counter-clockwise about 30 degrees. Slowly rotate the flywheel clockwise. If set correctly the points should open at 20 degrees btdc. Adjust as needed.
For future use, carefully mark the flywheel and the engine case at that 20 degree setting.

That should do it...

Are the screws easily accessible through the flywheel slits. Seems like it's not easy to access the backing plate with the flywheel on. Thanks.

 

[Crashaholic]

Flywheel has to be removed to access the stator plate screws. Once the screws are loose the plate may not move easily. Twisting the plate back and forth an inch a few times will break the bond between the plate and engine case making things a bit easier.

Timing an old points ignition can be frustrating due to having to removing the flywheel a few times to get the timing where you want it, its just the nature of the beast. Don't sweat it if the timing is not dead on after torquing the flywheel because doing so will change the timing by a tenth of a mm, unless you're racing the bike and require the absolute best performance in which case you'll need to make fine adjustments to the points gap to dial in the timing.

All this work drives some folks batty so they solve it with a new $500 electronic ignition, which is well worth the money especially if your Femsa is driving you to the brink of insanity.

 

[DeathFromAbove]

All this work drives some folks batty so they solve it with a new $500 electronic ignition, which is well worth the money especially if your Femsa is driving you to the brink of insanity.

I paid about 300$ for my Vape for the 450, only took 2 months to get it!

 

[rob kelly]

I know it's an old thread but the engines been pulled apart this week and theres some damage inside along the lines of casings been welded, signs the piston was seized and a damaged crank. That'll probably be why I couldn't get it started.
Anyone know of a 250 or 400 engine for sale?

 

[Steve-F]

Not sure where you are but give John a call at http://www.vintagehusky.com/ He can most likely help you with your search:<)

 

[rob kelly]

Thanks for your reply Steve. I managed to source the parts i needed, most from Charlie Preston at Husqvarna vintage. The engine guy said its doubtful it would've run in the state it was as the crank was damaged and the piston/ barrel badly scored. I posted a bit more detail on another thread. If only it had been as simple as the ignition haha.

http://www.cafehusky.com/threads/72-wr-exhaust-port-inlet-reeds-and-crankcase-weld.88057/