SEM RETARD IGNITION..?

[Bigbill]

We never got into what a SEM retard ignition does?

Does this ignition retard electronically when it's not running so it starts easier then advances after it fires up?

 

[jo360]

Never heard of it but 2t should retard advance then retard again.

 

[Bigbill]

Years ago there was a thing called roost boost. This was back I believe when some ignitions didn't have advance in the timing and lost amperage as the rpms increased. (I think) we're going back to the mid 80's and back. I installed roost boost in our 125cr Honda. The more modern ignitions came with the features so roost boost was a thing of the past. Funny how some stuff comes and goes.

 

[dukkman]

The 85/86/87 SEM's I have here are fixed with no advance or retard.

 

[fran...k.]

You (post 1, this got bumped) started a thread a month or so ago about or it had a lot about aftermarket ignitions. With the knee stuff you post on here I would think one of those new ignitions and a compression release would be in order for the larger displacements you seem to like to discuss on here. Unless the idea is to wait until fuel injection and ignition all in one computer comes along.

As for SEM The only one I have in operation is on the 88 510. Just looked up the data on it, says 33 degree (8.0mm) advance. I wonder if that one has retard for starting. It starts good cold and does not kick back or if it does it isn't dangerous.

Now there are map switches things may only seem like they go back to what once was.

 

[jo360]

My sem is crapping out, very hard to start even with decomp valve but once running is fine, re epoxying magnets and cleaning things up until i get my electrexworld stator replacement, hoping the extra kick start windings will let me use the original cow horn kick start lever.
Would love to strip and rewind the sem but the epoxy encapsulated windings would be a clean up.

 

[Bigbill]

The 85/86/87 SEM's I have here are fixed with no advance or retard.

If you look at the spec/tech sheets most of the brands of the orginal ignitions have timing advance built in.

 

[justintendo]

If you look at the spec/tech sheets most of the brands of the orginal ignitions have timing advance built in.

oh yeah, like which ones?

 

[fran...k.]

I have only had a light on the mini 6 and it does not advance or retard. You must have found specs from the manufacturer not Husky? Post 5 contains the figures from a file that was downloadable on here a while back. Is the advance you believe in digital or analog? This is the vintage left kicker section. Maybe you are thinking of the older single cam or something another Italian Husky you had.

 

[dukkman]

The 85/86/87 SEM's I have here are fixed with no advance or retard.

My mistake , "The 85/86/87 Two Stroke SEM's I have here are fixed with no advance or retard".
Sorry.

 

[Bigbill]

The SEM as listed for advance,

'85
Motoplat
125 15 degrees wr/ XC, 12 degrees cr

SEM/ motoplat
240/250 10 degrees XC,wr, cr

SEM
400 17 degrees

Motoplat
500 cr/XC 16.5 degrees

From 85 to 88(cajiva) they all have timing advance on the spec sheets.

As far as I know the Husqvarnas were ahead of there time. The early hondas had no timing advance.(60/70s) I read it somewhere. I installed the roostboost in our built 85 125cr Honda. It wasn't for a novice rider. The upper end came on like gang busters. But all the porting tricks were done also.

 

[justintendo]

The SEM as listed for advance,

'85
Motoplat
125 15 degrees wr/ XC, 12 degrees cr

SEM/ motoplat
240/250 10 degrees XC,wr, cr

SEM
400 17 degrees

Motoplat
500 cr/XC 16.5 degrees

From 85 to 88(cajiva) they all have timing advance on the spec sheets.

As far as I know the Husqvarnas were ahead of there time. The early hondas had no timing advance.(60/70s) I read it somewhere. I installed the roostboost in our built 85 125cr Honda. It wasn't for a novice rider. The upper end came on like gang busters. But all the porting tricks were done also.

thats where you set the mechanical timing, not an advance curve.

 

[Bigbill]

There's a static timing setting BTDC that's seperate. I guess then the advance in degrees is for using a degree wheel static setting.

 

[justintendo]

There's a static timing setting BTDC that's seperate. I guess then the advance in degrees is for using a degree wheel static setting.

correct, both are btdc one is for measuring at piston or measuring at flywheel with a wheel or timing light

 

[Bigbill]

Sorry I miss understood it.

 

[dukkman]

Wop a timing light on them and they don't move at all.