Lawnmower Hardstarts

Matt Wilson /

This isn't really a moped question but it deals more with 2 strokes in general.

This spring while I was at school my dad brought our lawnmower to the shop and they did a bad job tuning it up. It worked fine before so I'm not even really sure why he brought it in originally... but now it is very difficult to start. It will start but only after like 10 pulls... how can this be fixed? Is it the idle mix screw?

Matt

Re: Lawnmower Hardstarts

Don't take this wrong... but just turn right around and take it back... if it worked better before they messed with it then I would let them fix it.

It might be the idle adjustment... try it.. you can't hurt it.

Screw it in while counting turns.. so you know where they had it set.

Then you can always go back to that setting..

annd... you don't give enough info

What were you doing wth the choke while trying to start it ?

What temperature was it (the air).

What temp was the motor ?

I don't really want to know the answer to those questions... but you HAVE to include info like that... My magic wand is being recharged at this moment... otherwise I would just wave it and make it all better eh ?

Re: Lawnmower Hardstarts

Matt Wilson /

It starts better in warm weather, and much better after it has been running. My father has already brought it back twice to the store, and both times there has been no improvement.

The last time they left it in the sun to show him that it "starts right up".

In normal weather, (we keep it in a garage, so maybe 60 degrees) it takes about ten pulls with the choke on to start.

I was wondering more about what affects how easily an engine starts in general. My scooter takes only one kick, but my puchs take about 15 sec of pedaling. Is it just because the puchs are older?

I'm probably not going to mess around with it. Its one thing to take apart something I own, but its different when its someone elses. But anyways I'm kind of interested....

Thanks

Matt

Re: Lawnmower Hardstarts

my puch starts in less than a second :)

Re: Lawnmower Hardstarts

Ron Brown /

Matt,

Much better description of the problem, Fred will be proud of you.

What usually starts a cold engine quickly is getting enough gas in the cylinder so that some of it vaporises, even though it is cold.

If you are ambitious, next time you start the lawn mower cold, give it about 6 pulls, not enough to fire, then pull the plug and look at it. Chances are good it will be bone dry.

I would make sure that the choke butterfly closes all the way and is not distorted. Even the smallest leak around the choke will decrease the vacuum in the intake at cranking speed.

If your mower has a push button primer, make sure it is working.

Ron

Re: Lawnmower Hardstarts

Garelli = Frist time, Every time.

Re: Lawnmower Hardstarts

Please take a look at this webpage: http://geocities.com/georgecohamperpro/miscpics.html

it contains technical tips, disregaurd the tips at the top of the page as they have nothing to do with mopeds, at the bottom is a list of common 2-cycle engine problems as well as possible solutions, any one of these problems can also cause hard starting as well. There are really too many things that can affect 2-cycle engines that cause hard starting for somebody to give you an answer with the only the information you have provided, but maybe this page can help you.

Re: Lawnmower Hardstarts

Ron Brown /

David,

Given that the mower starts and runs fine when it is warm, I can't find a single problem or solution on the web page for the Subaru 360 that applies to Matt's problem.

Am I missing something?

Ron

Re: Lawnmower Hardstarts

Matt Wilson /

Ron,

I was wondering about the idle mix screw on the carb. If the screw is set too lean, then perhaps the carb would not put enough gas in the cylinder, and the pull cord would need to be pulled a few times. Does this make sense?

Also what is a butterfly choke? Is it just the choke slide or is it something different? Thanks

Matt

Re: Lawnmower Hardstarts

Ron Brown /

Matt,

The idle mixture screw does not really matter until the motor is running. Also, most lawnmowers are started with the throttle fairly wide open where the idle mixture does not affect it anyway.

I may be wrong in refering to a choke "butterfly" as I have not seen your carb. Whatever "chokes" it is what I am refering to. If the choke seals correctly then the vacuum created by pulling the cord will suck gas from the carb in sufficient quantities to start it.

My neighbor has an outboard with exactly the same symptoms. We will probably work on it next week, I'll post the results.

Ron

Re: Lawnmower Hardstarts

Well, it's just been narrowed down, almost certainly a carb problem then. Maybe the choke is set wrong and the gas is not vaporizing properly when cold. This could wet the spark plug and prevent it from sparking when cold. That's what my best guess would be. Old spark plugs usually cause this to happen more often.

A new spark plug usually makes an engine start far easier, except that this mower was starting fine before it was taken to the shop.

Re: Lawnmower Hardstarts

Matt Wilson /

Does a new spark plug make an engine start easier? I was under the impression that they either work or they dont....

Re: Lawnmower Hardstarts

Well, yes.

Because after a while the center electrode errodes and even correcting the gap to make up for this doesn't really solve the problem. Also the both electrodes begin to round off, so that there is less spark, you can file them off (make flat) to make up for that. Depending on how much use the engine gets depends on when you should regap, file, and eventually replace the plug. They usually last several years for lawnmowers (I'd say about 3-4), sometimes less sometimes more. If they were "tuning" the engine they should have put a new one in.

And having an improper gap is almost like having the wrong spark plug.

But since it was starting and running fine before they "tuned" it, this is probably not the problem.

Re: Lawnmower Hardstarts

Ron Brown /

Matt,

I mostly agree with David on sparkplugs and starting. The problem I have with attributing your problem to a spark plug is that, if what you describe is correct, you pull about 9 times to start the mower. This sounds like the engine is waiting for you to get something right before it will fire. In this circumstance, the only possible variable seems to be gas.

You may want to look at the mower and see what kind of carb it has. Is it gravity fed or does it include a pump? Is it a float type carb or a diahragm type? Do you have a primer button?

Ron

Re: Lawnmower Hardstarts

Matt Wilson /

Ron

I'll take a look at the carb and fuel system when I get home. I'll let you know what it looks like, and if I can find anything wrong.

And if you figure out your outboard motor let me know.

Thanks

Matt

Thanks Ron!

Matt Wilson /

Ron,

After talking to my dad about what the lawnmower shop did, he mentioned that they replaced the choke cable.

I took a look at the carb and choke cable, and it had a mechanical pulley that lowered the choke into the carb. It was a little more confusing than a bing carb, but I could tell that it wasn't getting lowered all the way.

I tightened the choke cable, and it started first try! Awesome! Thanks again

Matt

Re: Thanks Ron!

Matt Wilson /

Ron,

Did you everfigure out your neighbors outboard motor?

I would've gotten really sick of pulling that pull start cord 10 times each time I wanted to mow the lawn! Thanks so much.

Matt

Re: Thanks Ron!

Ron Brown /

Matt,

You're welcome and good for you. Your excellent description of the history and symptoms mase it easy. I hope your dad was suitably impressed at your new found mechanical skills and paid you scate for the time you put in. : )

No I have not had a chance to work on the outboard yet, but I suspect it is a sinilar proble,

Ron

Re: Thanks Ron!

Matt Wilson /

Ron,

Why did my lawnmower start better when it had been sitting in the sun all day? I cant think of a reason why a warmer engine would start easier than a colder one.

Thanks,

Also my dad was pretty impressed, he didn't pay me, but he offered to grill up some steaks tonight, so that more than makes up for it!

Matt

Re: Thanks Ron!

Ron Brown /

Matt,

The gas vaporizes more easily as it gets warmer. When you choke an engine it gets huge amounts of gas compared to no choke. The reason it needs so much gas is that most of the gas does not vaporize.

Enjoy the steak.

Ron

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