MTD Tractor Starting problem

[lefty]

Arkie,

We got a good start at .009...ish. .009 to .010 I should say.

So you're right on the money. What does this mean and what are my marching orders? I have no problem with cranking at that setting. Starter and battery seem to be fine with it. Do I just run it at this setting or do you suggest a repair? I'm ok either way. It's my machine. I'm ok with running it if that's the advice or doing work on it as I could use the experience and it's kind of a play machine for me anyway. Does this mean that the cam is worn?

[Arkie]

Another thing.


Is that the type engine carb/throttle set-up that for choke the throttle on the dash has to be full throttle? Some single cylinder Briggs engine Nikki and Briggs carbs use this type throttle choke on single cylinder OHV's.
(or is the choke separate)

If it's the type that the throttle lever has to be full throttle for full choke if you have not already done so look at these two choke operations. (test the last one no matter what type choke you have)

Look at the choke operating arm wire behind the carb next too the engine block that the throttle metal lever arm lever pushes on for choke at full throttle. With the engine not running push the throttle lever on the dash to full while watching the choke operating wire that the throttle linkages pushes against for choke. See if it pushes it too full choke. (reason I say this is some of them have a linkage bend adjust for full choke)
and some won't go to full choke unless a small machine screw is removed from the throttle plate.

If it seems to be full choking, no matter what type of choke it has the next time the engine is running apply the same amount of choke that you have when it's cranking and see if the choke smothers the engine, makes it blow smut and act like it's choking good and wants to kill or upset the engine good..

Each of these tests will let us know if the engine is getting full choke during crank. Some of them Briggs engines have to have a good full choke to start up when the engine is both hot and/or cold, even though when engine's hot choke it's only a momentary good full choke.

[38racing]

If upping the valve clearance seems to fix it I doubt that it's a worn cam as I posted earlier my logic says reducing clearance would make up for worn cam. I also assumed that the choke operation had previously been verified.
At least you are further ahead than I am on my Kohler problem. been too hot to do much.

[lefty]

It is the one with the choke that gets actuated at full throttle with the wire lever getting pushed by the throttle. I have verified that it is fully choked when set. It does cause a rough condition, almost stall, when engaged during normal operation.

[Arkie]

Arkie,

We got a good start at .009...ish. .009 to .010 I should say.

So you're right on the money. What does this mean and what are my marching orders? I have no problem with cranking at that setting. Starter and battery seem to be fine with it. Do I just run it at this setting or do you suggest a repair? I'm ok either way. It's my machine. I'm ok with running it if that's the advice or doing work on it as I could use the experience and it's kind of a play machine for me anyway. Does this mean that the cam is worn?

The compression release is coming in later and should/maybe result in an increase in the compression, due to the dump later in the cycle. Maybe the compression is little weak or the intake cam PROFILE is not quite as it should be????(the engine should be trying to kick back when cranking with the intake valve lash set higher and out of specs)
Just wondering if you used the thin steel OEM type head gasket or the multi-layer type thicker head gasket?
Not that it makes that much difference in compression, just wondering?

You asked: what are your marching orders? AT EASE

We need a second and third opinion??????????????

Stay Safe and Cool.
Hot and high Humidity (humility) in this area.

[38racing]

I still don't see how the compression release prevents fuel from entering the cylinder as it only comes into play after all the fuel should have entered. If anything it would allow fuel to be pushed back into carb. Has this engine ever been apart?

[lefty]

The engine has an interesting story. Since it came under my ownership, it was apart for this problem, although less pervasive. It was intermittent, 1st rearing its head during a hot start. It then happened during a cold start but again, intermittent. So I took the head off, inspected and lapped the valves because I was loosing a little out of the intake during leak down.

After that, it ran great for about a couple weeks before the problem started happening again, this time, more frequently...almost all the time. So that's where we are at this point.

Before all that, it came to me from my brother. He purchased from a nearby mechanic who had just put a 20HP briggs onto an old MTD tractor. The engine is obviously much newer than the tractor. As far as anyone being in it before that, I wouldn't know. I do know that my brother never really had this problem over the 5 or so years he had it. Just the occasional carb issue after sitting over the winter. In fact, it had sat over winter when he gave it to me. I rebuilt the carb and started using it for a few weeks before the problem started.

[Arkie]

I suspect sometimes Briggs engines does stuff like that just as a brain teaser to make you think and see if our heads will produce a wood burning smell!!!!!!!!!!!!

I've got a friend that just hates Briggs engines, really anything with Briggs name on it, he says Briggs has left a bad lingering taste in his mouth several times, the type of taste that just won't go away. He has given me lots of Briggs stuff and I tell him I've fixed it and it's running good. He says enjoy, Briggs just aggravates me.

Stay Patient.

Stay Safe.

[38racing]

I once had a flat head briggs whose rings were so bad it would not start due to low compression. Maybe this unit is so marginally with bad rings that compression release just puts it to the point failure. Mind you the leakdown should show that. Square one.
I had a snowblower with none closing exhaust so it would still start but die under load.

[lefty]

Do you think I should inspect those components again? Valves, springs, etc?

Maybe replace the valves and the springs?