Hey guys, I just got one of the "original" minibikes from from the 60s and 70s. Its got a 4-5 HP (est) tecumseh engine on it. The problem is I cannot get the enigne to make a spark. My friend hooked up a constant spark machine upto the spark plug, and the engine fired up an ran great.

I swapped the magneto out with one from a known working engine, and still no go, i even completely diseconnect the kill wire, and still nothing. I've just about given up. Then I came up with an idea to use a an ignition coil off say a a ride on lawnmower, and just use the breaker poitns in the magneto to run the coil.

Any ideas about the magneto, or should I just go ahead with the powered coil ignition? Here the general idea how it should work

 

Check the point gap and the condensor. Point gap should measure .020 at most in the open position. Also, pick up a point file at the parts house just in case they need cleaning.

 

+1!!!!!!!!


Take the shroud (flywheel cover) off of the engine and remove the flywheel.

The points and condenser are underneath an aluminum cover, the top of the 'block', against the crankshaft.

IF the engine is 'that' old, I'll wager that the points are corroded and that the condenser is bad.

Replace them (about $10.00) and set the points to .020". (Or whatever the manual calls for!)
Also, I suggest replacing the flywheel 'key'. ( $1.00 or so.)
Just for kicks and grins, replace the sparkplug and gap it to .030 - .035"

(Before buttoning up the engine, put the flywheel back on, spin the engine over and see if you have spark.)

Put the top-end back together and she should fire right up!!



EDIT: Get the model number off of the 'tag' before you buy your parts.
I have an old Tecumseh engine on a 1979 model snowblower. The tune-up kit for that dinosaur (points, plug and condenser) was $9.00 and change, two years ago.

 

Does your flywheele have magnets around the outside of it or does it have the two little prongs that stick out. If it has the magnets putting a newer style coil on it that makes spark just from the magnetics that would compleatly bypass the old points system. Ive done it on several of my old tractors and it works quite well.

 

Moved from GC.

 

I have completely swapped the mageneto out with an identacle working one, and have replaced the flywheel key. But for some reason, the swapped magneto will not well spark. It is one with the magnet inside the flywheel, well around the crank that is, but whats odd, is that the head has two bolts for theo ther style magneto that sits outside the flywheel, but I haven't checked if the flywheel has magnets around the outside edge yet. If it does, I think I can snag another magneto off a 10HP briggs.

 

Those Tecumseh internal ignitions are a bit of a PITA. I am with ooBOR. Your points are probably corroded/ dirty/ greasy and/or your condenser is shot. Also, if you removed the two 1/4 bolts that hold the whole armature in place, you have a bit of a chore in getting the ignition back into time.
Depending upon the model, your spark should occur some number of thousandths of an inch before the piston reaches top dead center. I am not positive, but I believe it is possible to rotate the armature to the point that even with good points and condenser you can't get spark because the flywheel magnets are so far out of time.
Someone posted a link to a PDF file of the Tecumseh L-head engine repair manual. I couldn't put my finger on it right away, but if you give me your spec number off the blower housing, I can look it up and walk you through the process. In fact, I think I posted directions on how to do this once before. I'll see if I can find the link.
B&S ignition parts won't work on your engine. At least not any way I can figure.
Yah. And when you set those points as far open as OOBOR suggests, you might want to wear a glove on your starter pulling hand. It hurts like heck to have that rope yanked out of your fingers when the piston fires on the compression stroke and goes backwards every once in a while.
Ya know, when a breker point magneto ignition system is working properly, you only barely have to spin the flywheel by hand to make a spark. Leave the spark plug out of the engine when you are working on it.

 

Here is the link to the Tecumseh manual. OOBlueOvalRanger had originally posted it. 2.5 mb download. Save it on your hard drive for futue use.


http://www.cpdonline.com/692509.pdf

 

I had just borrowed the coil and battery off my tractor's Kohler K341, was about to wire it up, but I think i'll look at the manual first.

I love that old kohler though, at least 30 years old and still starts up everytime with plenty of power, got to lean off the carb though, still getting puffs of fire occasionaly out the exhaust