Top Dead Centre

Can someone enlighten me about the monster 'L' twin air-cooled engine?

I assume that both pistons are at top dead centre simultaneously and that the cyclinders fire alternately?

Are my assumptions correct?

Will

[Pedro]

No, No!!

Best way to get it to TDC is roughly as follows:

Put bike on paddock stand.
Engage first gear and remove the spark plugs
Get a small torch and shine it through the inspection cover on the LHS of the motor.
Turn the rear wheel until a small drilled dot appears in the window.

This is where it get tricky - the flywheel has 8 dots in it. You're looking for two close together. When you find two dots, align the marker on the case to the lower of the two. Then get a skinny screw driver and poke it down a plug hole - this is to check which is at TDC.

For the other cylinder, the dots are further round the flywheel.

Check the Haynes book of lies for more info!

Ped

Thanks for the reply.

I am not trying to find TDC - just curious as to how the engine works - for best primary balance I have assumed that both pistons go in and out together - is this true or are they separated by a rotation angle of 'x' degress and if so what is this?

Will

[Pedro]

I think they fire at 270 degree spacing.

Someone correct me if I'm wrong please as I've just spent the afternoon doing valves and belts etc and really don't want to F*** it up!

Ped

[spacemonkey]

Ah, the joys of the home 'mechanic'! Everytime you hear a strange noise, or feel something weird you'll be wondering "Did I do it right?"

I have managed find out a part answer from the follwing website:


http://www.mecc.unipd.it/~cos/DINAMO...tors/twin.html

Now all I need to know is the firing order. Hmmmmmm.

The easiest twin cylinder engine to understand is the Boxer - very very elegant, perfectly balanced primary and secondary inertias, just a small rocking couple left over. Hmmmmmmm perhaps I should by a BMW twin next............................. Heresy I hear you scream in harmony!!

Will

Heresy I hear you scream in harmony!!

No cries of heresy from me

[Pedro]

Originally posted by Will
Hmmmmmmm perhaps I should by a BMW twin next............................. Heresy I hear you scream in harmony!!

Will

Fur sure, das ist heresy mein Herr!!!

You'll be wearing Lederhosen next!

Ped

PS Firing order is easy, it's just one after the other!!

[crust]

Originally posted by Will

The easiest twin cylinder engine to understand is the Boxer - very very elegant, perfectly balanced primary and secondary inertias, just a small rocking couple left over. Hmmmmmmm perhaps I should by a BMW twin next............................. Heresy I hear you scream in harmony!!

Will

lovely engines, once you get used to the 'rock' when you rev them

and perfect for winter,too. No cold toes and somewhere easy to warm your hands

almost as much fun as Guzzis take on the 90 degree V twin

Crust