I need help with my magneto

[Tattooo]

Ok so I set up mag and timing mark like you suggested it’s sounds and runs a lot better than before but still carry’s a backfire! I had a buddy double check all my shit and made sure compression stroke was good by checking pushrods and it fired right up! Dialed carb in but it still has slight backfire in rear cylinder! Should in therory by moving timing mark further back in the hole give it more throw in the mag and retard the timing a bit or do I need to advance the timing by moving the timing mark forward!!! Sorry I forgot to take pictures of what’s going on this weekend

Now you have a carb problem........... Intake leak to lean etc?????

[Biscuitboyftmc]

I’ll look at jets sizes may have to go down in sizes

[Biscuitboyftmc]

No intake leak sprayed and checked nothing cutout on it

[farmall]

Manifold pressure checks work MUCH better than spraying carb cleaner (or propane, which is safer and works better). Image search "panhead manifold pressure tester" for examples to make your own. They are very simple.

Post your jet sizes for advice before changing jetting.

Your timing can be fine tuned by ear now you've got the engine running. Moving the mag body (move a very small amount) in the direction of points cam rotation retards spark. Moving body opposite direction of points cam rotation advances spark. No need to pull the timing plug for that since the engine runs. Marking your starting point using a Sharpie is wise.

[Biscuitboyftmc]

Will do thanks

[Dragstews]

Advanced .. ^^



Retarded .. ^^

[Kickstarter]

What about on a 78 1/2 ?

[Jonas]

Fighting with unreliable spark here on my MM3 Mag. Pretty sure I have the timing right, but what I read here had me wondering. At the advanced timing mark will I want to have points just open (as Morris Mag write in their manuel) or just about to open as written below?

Also, when setting the point gap to 0,015" in what position is this done? I have done this in the advanced timing position, which seems to be wrong?

5)...Take the magneto and set the points gap at 15thou and plugs gap at 25 thou.

6)...install the magneto with the narrow cam lobe just about to open the points, this will be fully advanced (35 Degrees BTDC)

[JBinNC]

Point gap is at the tallest spot on the lobe, and you should check it at both lobes to see if there is any difference (you may have to split the difference, one may be .014 and the other .016, for instance).

With the front cylinder on its compression stroke (intake valve has opened and closed, and piston is coming up) and the advanced timing mark in the center of the hole, when you install the mag fully down in the hole, you should be able to rotate the mag and get the points to start to open. You can check point opening with a buzz box, or with the cellophane and rubber band trick. If you have an auto advance mag, you have to advance the point cam to its stop when checking advance timing.

Jim

[Guest]

on the front cylinder compression stroke (remove the front cylinder intake pushrod cover off & tie it up tofind the compression stroke)
with the magneto set at full advance, when the timing line starts to appear in the timing hole, the points should JUST be about to open.
this can be done using a magneto timing light as sold by Morris Magneto, great bit of kit to have & only $89 here .. https://morrismagneto.com/accessories.aspx
or with a multi meter to show when the points JUST open.
if it sparks off the bike by simply spinning the magneto over you dont have a bad magneto, but when you do spin it by hand you MUST tape the 2 plugs together metal to metal,then hold them to the magneto body, if you try to do it with just one plug & lead on it for testing NOTHING will spark as the both need to be grounded to a common ground,... I ususlly justhold the 2 wires in one hand & spin it as the jolt you get at hand spinning speeds don't hurt, but if you mount it lightly in a vice & spin it in the correct direction) with a power drill with both plugs grounded to the magneto body DONT touch it then as you'll get the full wack of 20,000+ volts going down ya arm !! hahahahah... I have always used Magnetos & they rearely go wrong, if you need new points or a condensor it's worth buying from Dave at Morris Magneto as he don't sell shit & avoid Joe Hunt & anything that V-Twin Mfg sell as it's usually shit & cheap made in China crap,.... Daves a great fella & will always help if you have any questions, his Numbers in the link I posted above,... good luck & let us know how it goes, & Welcome to ChopCult.........

[Jonas]

Thanks both JBinNC and tzienlee! much appreciate it after some days doing the timing over and over again.

Just one thing I need to be sure about - am I understanding it correctly that on the advanced timing mark the point are just opening? or should they still closed but just about to open? thanks for spelling it out to me :-)

[JBinNC]

Thanks both JBinNC and tzienlee! much appreciate it after some days doing the timing over and over again.

Just one thing I need to be sure about - am I understanding it correctly that on the advanced timing mark the point are just opening? or should they still closed but just about to open? thanks for spelling it out to me :-)

The best final check is to set the timing with a timing light (strobe light). Then you can get it dead on the money and be SURE that you have it right. The little clear plastic plugs for the timing hole are very helpful to keep oil out of your face while doing that.

Jim

[Guest]

NOT at any 'ADVANCE TIMING MARK', but the timing mark,
with the magneto set at full advance,
points just about to open, which is best done with a MAGNETO TIMING LIGHT,...
they have a light and when the timing mark is (for me) 1/2 way from appearing in the hole on the right & being in the center of the hole, do not move the motor from that point,
Then you advance the magneto by turning it towards the sharp cam lobe on the magneto,
as soon as the light goes out..THAT is full advance,
so without moving the magneto from that point, or the flywhhes from moving, you set your magneto base advance stop screw, there so it cannot advance any more,
then retard it by hand about 15*degrees or rotation & do the same for the retard stop screw..this isnt as important as the advance stop as too much advance can damage any engine & usually you only need it retarded to start it or if you want the slow put put-put put-put put idle beat ....
this must only & always be done on the FRONT CYLINDERS COMPRESSION STROKE & on the POINTED LOBE of the magneto cam this is a short film of a mate on my shovelhead, towards the end of the film you see when the magneto retards itself & the slow idle that sound so good.... https://www.youtube.com/watch?v=zapYrI8o4Y8

[70fatster]

Gauging your timing by when the points are about to open by eye can have a wide range of results.
I disconnect the condensor and use a 12 volt test light connected to the points. The light is on until contact is broken. This is the point where a spark will be made.
I've always used this to get close, then use a timing light once the engine is running. At normal engine speed it is usually a bit off from the test light method, but very close.