I know this is probably an old topic for many of you, but I've not had any success finding a solution to my problem. Hopefully someone on here can help.

2003 Suzuki LTA50 won't start. Was running fine, died, and hasn't ever started again.

It has fresh fuel. New spark plug. No mods.

I removed the spark plug, and with it dangling beside the head, I have good spark when pulling the rope. Put the plug back in, and the ATV won't hit a lick.

I removed the screw in the bowl of the carb and fuel flows freely with the fuel valve on prime...stops when valve is on...(which I think is normal)

I removed the spark plug again and poured a small amount of fuel in the cyclinder, still doesn't hit.

I removed the spark plug and put my finger over the plug hole. When pulling the rope it appears to have good compression because it blows my finger off the hole fairly easy. One problem did concern me though...my finger stayed dry (no fuel).

I removed the carb and completely cleaned it. No change.

What could keep the fuel from reaching the spark plug? But, even when I spray carb cleaner or gas straight into the cyclinder, it still doesn't hit at all.

Could this be a timing issue? Such as the key being sheered on the magneto? Would it still fire at the plug but not enough to make the engine try to start?

Someone please help..Thanks.

 

That would be a good guess, timing key is sheared or even slightly sheared. It doesnt take much, and the timing is too far off.
I usually use 2 stroke oil for getting a stuborn motor to start, That way the cylinder doesnt get washed down by gas, and leaving the rings unlubed. 2 stroke oil will burn good enough, and leave no deposits.

 

Thanks hondabuster.

Do you think it's possible that I'm not getting fuel into the cyclinder for the plug to ignite?
Because I do have fire at the plug...so even if the timing is off, shouldn't I have some type of combustion in the cylinder that would indicate that it's atleast trying to start? Like I said before, when I pull the plug out and put my finger over the hole, and pull the start rope, it doesn't get my finger wet with gas at all...but it does appear to have good compression.

What causes the fuel to enter the cylinder? Vacuum? Compression? Could the rings be bad?

I did put gas on the plug while it was out, and it did ignite the gas when I pulled the start rope (while the plug was "out" of the cylinder) But when I put the plug back in, the motor doesn't hit at all.

Oh, here's another dumb question...LOL...could the automatic oiling system be dumping too much oil into the cylinder? Causing the fuel/oil ratio to be wrong and therefore not allowing the plug to ignite the fuel? I kinda doubt this could be the problem, because when I poured un-mixed fuel directly into the cylinder, and replaced the plug, it still didn't hit.

Thanks again for any and all help....I've got kids that are "not so patiently" waiting on me to get this little machine running so they can ride..LOL

 

Well, after my last post, I decided to take a closer look at the magneto and key/keeper. Everything there is just like new.

I turned the fuel valve to the prime position, cranked the rope several times, pulled the plug and it was soaked with gas. So now I'm sure the fuel is getting into the cylinder.

I went ahead and replaced the plug with a brand new one. Checked it outside the cylinder and it sparked like it should, but so did the other plug. Put it in the cylinder, pulled the rope 1,000,000 times, and still nothing!

Anyone wanna buy it cheap?!?!?! LOL. GEEZ! Whata piece of crap!

 

Is it posible, thats somethings wrong with the spark plug cap? Maybe once its bent into shape at the sylinder head, is not sparking? Is the cap loose on the wire?
I know my 50 can be a real pain to start. I wish they could be bump started.
Id try using a compression gauge, and get a real value on compression. Do it both dry, and after a few drops of 2 stroke oil.
Youve got the basics covered, has fuel....has spark....compression good enough?...spark at the correct time..

 

<div class="FTQUOTE"><begin quote>Is it posible, thats somethings wrong with the spark plug cap? Maybe once its bent into shape at the sylinder head, is not sparking? Is the cap loose on the wire?</end quote></div>

That was my next question, too. I'd carefully examine that plug wire and confirm you're getting spark when it's in the "plug position". You really should get some kind of reaction if you pull the cord after squirting fuel into the cylinder. It's not getting ignited, so you're not getting spark.

Have you confirmed it's the correct plug? Any chance its nose is too long and the piston is contacting the electrode and grounding it out at TDC? I can't remember what the timing is on these engines. I'm trying to think of things that would eliminate spark only when the plug is installed in the engine.

Try loosely screwing the plug into the head, to guarantee there's no physical interference. You should still get ignition, it just won't be as forceful.

 

Thanks guys for the ideas. I'm gonna test the compression tomorrow and see if it's a ring problem.

The spark plug is right, according to O'Rielly's anyway. I bought 2 new ones and tried them both. I had them look the plug up in their book instead of showing them what it had in it. It turned out to be the same though. I've also tested the plug for spark at different positions while out of the cylinder. It appears to spark fairly well at any and all angles. It bites me when I'm holding on to it also! LOL.

Here's something else that I have tried. I removed the pull-rope and housing unit so that I could look at the magneto and coil. Well, after removing the nut that holds the pulley on the crankshaft, I tried to pull the pulley through the exposed opening...IT DOESN'T FIT. It appears that I'll have to remove the entire magneto cover (which appears to be half the crankcase). Does anyone know for sure what I'm getting into if I remove the magneto cover? The reason for attempting this is because I'm thinking that even though I have spark, it's not enough. My nephew rode this ATV through several small mudholes, and they kept it setting outside for several months without being covered...I'm just wondering if the magneto housing got water in it and the magneto is alittle rusty and not firing properly. I've had this problem on several riding mowers before, and all it took was alittle cleaning with sandpaper to cure the problem. What do you guys think?

Got any ideas on the normal compression? Any ideas on how to test the amount of spark?

 

Its not that scientific...but I believe the spark is good, if its visable, and better if blue....and even better if you can actually hear the spark. I know that weaker than that can run a motor.

 

Well here's what I tried tonight.

I completely removed the magneto and cover..everything in there looked good, but I cleaned it real well anyway. Put it back together and the spark is still good just like before, while the plug is out.
I put the plug back in, and nothing.

Next I removed the top half of cylinder. I wanted to know why the plug doesn't appear to be firing while in the cylinder....so after I took the head off, I screwed the plug into the head to make sure it wasn't too long and was hitting the piston. It wasn't, everything was good. I then leaned the head/plug combination up near the piston (without bolting it back on) and pulled the rope..SHAZAM..it ignited on every pull. So now I know the fuel is getting there, and the fire at the plug is hot enough.

But, when I bolted the head back on...put the plug back in....and pulled the rope...NOTHING! For some reason it appears to be a lack of air in the cylinder. I know, it should have enough air to atleast ignite even if it doesn't have enough to run, but it doesn't. It won't hit at all.

I checked the air cleaner and it was clean, but I did remove the filter just in case....I tried it again and nothing.

What could possibly be restricting the air to my cylinder that is needed to cause combustion?

I truly appreciate all the help and patience with my lack of mechanical knowledge.

Oh about forgot....I checked the compression with a guage that has a rubber nipple on the end of it..It doesn't screw in, you just hold it tight in the spark plug hole. It read 90 lbs. I figured this was pretty good considering it was a cheaper guage that didn't screw in air tight.

 

Im not sure what the specs are for compression, but that seems low. Was that the wet or dry compression? was the motor at WOT for the test?
Is the little restrictor disk in the intake? If its removed...is the pilot jet bigger?
I found this thread, somewhere else, and its got some things youd be interested in reading.
http://www.allthingsmoto.com/f...uzuki-lt50-quad-13903/