Timing an XS2 engine without a flywheel on

[hardhat_harry]

I'm currently building my engine but I haven't got my PMA kit yet.

Can you time the engine up without a flywheel connected?

I plan to set the engine at TDC then set the Cam with the timing mark straight up as per manual.

Will that give me the correct timing?

Thanks for any advice

 

[5twins]

That will correctly time the cam, yes, but ignition is another story.

 

[XSLeo]

How will you tell if the engine is at TDC without timing marks?
Leo

 

[5twins]

Dial indicator in the spark plug hole. This is common practice on old two strokes for setting ignition timing. The firing point (the "F" mark on our 650) is often given as a measurement BTDC. You need the dial gauge to find that spot.

 

[XSLeo]

Using the degree wheel will get the static timing close but I don't think it would work well with the engine running. Maybe, I think that getting the degree wheel to stay on the crank might be tough.
Leo

 

[hardhat_harry]

I can tell Im at TDC as I have the head off at the mo.

I also have a dial gauge to hand

 

[5twins]

A holder for the gauge that fits down into the spark plug hole is needed. That's the main part of the kit I have. You can make one from an old spark plug .....

http://www.thumpertalk.com/topic/93...-15-dial-gauge-dial-indictor-ignition-timing/

..... or buy just the holder if you already have the gauge .....

http://www.ebay.co.uk/itm/GO-KARTS-TIMING-DIAL-GAUGE-ADAPTOR-FITS-14MM-THREAD-/270514237854

Of course, full kits are still available as well .....

http://yambits.co.uk/dial-gauge-ignition-timing-tool-p-12695.html

 

[gggGary]

I think hardhat is speaking of "timing" the cam to the crank. No need to time the ignition with no flywheel installed.

 

[TwoJugs]

You need a degree wheel and a way to find TDC, A piston stop or dial indicator in the sparkplug hole will find it. If you have points and a test light you will be able to set up your timing. Race motors use this procedure when they have no alternator system installed, your marks are gone.