Export thread

i have a 1980 2 stroke 21" push Lawn Boy which i love...problem is that i can't seem to keep it alive!! i have replace the ignition coil 3 times in last year, once with the high dollar original style from Lawn Boy dealer, and 2 times with Ebay Taiwan replica....the one from the dealer lasted half of a season, the others lasted about TEN MINUTES!! can someone tell me if this is indicative of the new coils or am i possibly doing something wrong with installation?? this is getting EXPENSIVE! thanks for any help you can offer. Rick

Do you set it with a business card? Placing the card between the magnet and the pick up? Heat is what takes them out usually. Hard time believing that a new part only last a few hours. Something else must be going on? Might try a different fly wheel. What is your oil ratio at? 32 to 1, can cause more heat with a lighter ratio.

are your cylinder fins reasonably clean? Heat can kill them too.

Jeff

installed each new coil with the business card method...aprox .010 air gap.....i am using newer synthetic 2-stroke oil additive (good for all 2 stroke engines) with my gas. cylinder fins are clean. this is the THIRD one in less than a year, 2 of them only ran 10min or less then died, no spark after that...what's going on here??? Rick

I would try a different flywheel as that is the only other component related to the cdi.

I do not know your machine... Do the replacements look identical to the original? The 2 strokers run high rpm and require ignition advance. This is achieved by the shaping of the "shoe" portion of the module. I saw a patent on line for this dated around 1977. I wonder how models in the 1980's differed. Were there different models of coils? You say they all work and then fail, but do they work like the original before failing? Heat does kill and although Taiwan is usually a cut above there could have been low grade parts in those . Did the plugs look normal after failure? Could you be suspecting coils when other things could be causing the problem? There are some very knowledgeable 2 stroke guys here.

replacement coils are identical to original coil.....spark plug looks fine, and works fine when coil is replaced. i ordered a replacement (used original) from ebay, and will replace it before tying another coil. is changing the flywheel a big job? any tips? thanks, Rick

razman said:

replacement coils are identical to original coil.....spark plug looks fine, and works fine when coil is replaced. i ordered a replacement (used original) from ebay, and will replace it before tying another coil. is changing the flywheel a big job? any tips? thanks, Rick

Click to expand...

Changing the flywheel to another identical one is easy peasy. Just one center bolt on the flywheel, then knock around the edge with light taps from a hammer while pulling up on flywheel. BUT....are you sure you lost spark? A good coil will produce a spark across a plug just by hand-turning the flywheel rather rapidly clockwise (looking from top). Clamp the engine brake off at the handlebar using vise-grips, or other way to keep the bail against the handlebar. Disconnect the kill wire from the coil. Take the sparkplug out and with it connected to the spark-plug wire coming from coil, hold it tight against cylinder fins, spin flywheel and you should see spark. If you get spark, then reconnect kill wire and repeat. You should STILL get spark. The kill only kills when the brake engages. You can see this function, unless your machine is old enough to be before kill switch/brake stuff. In any case, you should test for spark visually, by viewing the sparkplug. Older pre-compliance models have a separate on-off switch to ground the kill wire. Same principle. First test with kill wire disconnected, then connected, then test both on and off positions of switch to be sure it is working. Off should produce no spark.

The flywheel (its finned to act as fan blades) and shroud form a blower system to constantly push air across the coil and cylinder fins. If there is a piece missing, or any air inlet partially blocked with debris then the cooling will be poor and the coil will be more prone to failure. Often times a Lawnboy ceasing to run after it warms up is due to very bad crankshaft seals, rather than spark.

yes, i have checked for spark...no spark. even ran ground directly to coil bypassing the on/off switch....no spark. thanks everyone, i'm putting on a used original flywheel and a new coil...we shall see huh? Rick

The key on the crank can be corroded and may be a little hard to get off, just use a penetrating oil and lightly tap with a hammer, be careful to not damage the key if you plan on reusing it. The key should stay in groove in crank.

i assume bolt in flywheel is regular r/h thread?? thanks!

razman said:

i assume bolt in flywheel is regular r/h thread?? thanks!

Click to expand...

Yes, It's NOT reverse-threaded.

You sound like you know what you're doing, so pardon me for this stupid question....What are you using for a spark plug? It's not some weird one with an extra internal gap for "more power," is it?

Maybe your flywheel was replaced at some point, with the wrong one....

If it were me, and I got a fourth module, I would probably close the plug gap down to .020" inch and see how that worked out. It might foul too fast or it may make it a little easier on the module....Just an idea.

An R7070 is a cool mower, worth the extra effort!

i did buy a used flywheel, and have installed it....i'm waiting on a replacement ignition module from the vendor on ebay (i sent the other one back, and he has agreed to replace it)

i am using a standard replacement plug for the original plug...i don't remember the number, but it was recommended by lawn boy dealer, and several other forum members. i will try closing the gap a bit...thanks everyone, i will keep you posted with results of new module and flywheel! WHAT ELSE COULD IT BE??? LOL...Rick

It is so easy to check for spark, I'm sure you know how to do this before you screw the sparkplug into the engine? Just a light spinning of the flywheel in a clockwise direction, should produce a spark at the plug, with it grounded to the outside of the engine. If it won't spark, then it won't spark when installed.

yes, thanks...i know how to check spark, and i always have spark after replacing the ignition module. but that quickly changes after the module fails. sometimes it takes a few weeks, sometime just a matter of minutes!

ok, i put on different flywheel, and installed replacement ignition module....SO FAR SO GOOD! started right up, and have mowed several times now without problems! i do have one other question concerning tuning the carb. i took apart the carb last night and cleaned it out ( i noticed that float was sticking, and was able to fix that also) but as i put it back together i noticed that it does have an adjustment screw for air mixture on from side of carb. what is the best way to adjust that? just turn in slowly til it starts crappin out, and back out a little (like the old carburetors on cars??) anyone know? thanks, Rick

razman said:

ok, i put on different flywheel, and installed replacement ignition module....SO FAR SO GOOD! started right up, and have mowed several times now without problems! i do have one other question concerning tuning the carb. i took apart the carb last night and cleaned it out ( i noticed that float was sticking, and was able to fix that also) but as i put it back together i noticed that it does have an adjustment screw for air mixture on from side of carb. what is the best way to adjust that? just turn in slowly til it starts crappin out, and back out a little (like the old carburetors on cars??) anyone know? thanks, Rick

Click to expand...

Here's how I like to adjust any two-cycle carb: let the engine warm up fully and see how it performs under load -- keep making small adjustments on the needle valve until it does best. Keep in mind that how it sounds sitting still isn't the most important thing -- it's how it cuts through heavy/wet grass.