classic motorcycle forum

Motorcycle Discussions => British Bikes => Topic started by: torridtime on September 02, 2013, 06:04:57 PM

Title: MAG engine
Post by: torridtime on September 02, 2013, 06:04:57 PM

Hello all. I just found this site, maybe you can help. I am rebuilding a 1924 MAG Aircooled vee Twin engine. I am having a job understanding the valve timing. When I line up the marks on the cam and the crank pinion. Which cylinder is firing looking from the timing chest side. left or right.?Regards. John.

Title: Re: MAG engine
Post by: R on September 03, 2013, 01:40:15 AM

What type/size of MAG engine ?
Single camshaft, or more than one ?

Remember that setting the cam timing may have no connection with timing marks or setting the timing for the magneto.
The cylinder that will be firing will be the one where both valves remain closed as the piston comes up to TDC.

On v-twins, No 1 cylinder is usually the rearmost (behind) one.
On old engines like these, the inlet and exhaust cam timing is usually near symmetrical.
So if the cam timing marks are not giving you something like this, they maybe the parts are wrong for this engine, or marked wrong ?

Title: Re: MAG engine
Post by: cardan on September 03, 2013, 04:36:20 AM

You might be interested in this one: it's one of half a dozen or so that remained unsold in a Melbourne motorcycle shop into the 1960s. It now sits in a friend's shed, having never fired a shot. Yep, a brand new 1000cc MAG engine from 1921.

Leon

Title: Re: MAG engine
Post by: rogerwilko on September 04, 2013, 02:37:56 AM

Was it Modak?

Title: Re: MAG engine
Post by: cardan on September 04, 2013, 03:58:08 AM

No, not Modak, but I think one of the long-gone Elizabeth St shops.

Leon

Title: Re: MAG engine
Post by: torridtime on September 04, 2013, 09:06:14 AM

Hello. Cardan. Did you get my P/M. torridtime?

Title: Re: MAG engine
Post by: cardan on September 04, 2013, 10:42:27 AM

Yep, just replied.