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125 timing story

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kharvey

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Kendal Harvey
And how good is the battery? Check voltage at the coil while cranking. A weak battery equals weak spark.
 

mfrade

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In his first post, he said he already checked this. Doesn't matter, because a sheared flywheel key on a K-series has no effect on the timing since the points are actuated by a cam lobe.
Not to mention I have never, ever heard of a K-series shearing a flywheel key in my nearly 20 years of working on these things.
If he's thinking his "S" and "T" are 180 degrees out.. it could make a difference. But I guess since you've seen it all, in all your years, the rest of us need not reply.
 

abthomas

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If this thing ran before I can't see that happening with a serious timing issue like being 180 deg out ? As someone said earlier I'd be checking the elec system,coil,condenser,broken wire,ect. I've had bad plug wires that caused starting issues and poor running . I've had brand new points that wouldn't pass current when they were closed and had to sand them right out of the box to make them work. Some simple checks and testing with a ohm meter will save a lot of wheel spinning sometimes ! Pretty simple engines if you got air,fuel and spark they'll usually run, and as stated earlier if for some reason you still think it's a timing issue I'd pull the head and put that to rest before pulling the engine and pan !
 

Ken Black

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i would put a lil bit of fuel in the spark plug hole... 3 or 4 tablespoons worth.... finger tight the plug. fire it up... if it pops off rite fast..
carb and or head gasket...
not sure but why is there washers holding the head near the ex valve ??? in the place they pop gaskets the most..\

just for giggles after the testing... i would pop the head and sand flat on some marble or glass. WASH IT REAL GOOD.... new head gasket. carb cleaning real good ..

would like to see the bowl and float...
 

mgonitzke

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If he's thinking his "S" and "T" are 180 degrees out.. it could make a difference. But I guess since you've seen it all, in all your years, the rest of us need not reply.
If you read his original post, you will see that he already checked the flywheel key and found it not sheared:

The key is still solid and perfectly lined up with the shaft. The gears on the camshaft are perfect with no chips.
I have not seen everything, but I can read.

The only way I can think of that the timing could be 180 degrees off on the flywheel is that the flywheel has been changed to one that does not match this vintage and spec number. There were at least 3 different variations on sight hole location over the years.

Joe-

Where in the flywheel shroud is the sight hole on your engine? It has been awhile since I have worked on a 125, but it should be either a ~1/2" round hole in the left (carb side) or right (starter/generator) side of the flywheel shroud at about the level of the crankshaft, or a notch in the aluminum bearing plate behind the flywheel on the starter/generator side.

With the engine at TDC (flywheel key facing up), where is the "T" timing mark? It should be on the same side as your timing sight hole. If it is on the opposite side, someone must have changed the flywheel at some point. If this ends up being the case, you can re-mark the flywheel and then be able to time it and eliminate that as an issue.
 

dschwandt

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Ed,
I'm sure you meant TSP!!
And even one of those would be way more than enough.
This response is mostly TIC so please don't take offense here....

3 or 4 TBSP worth!!
That's a lot of gas man!
You got 911on your speed dial phone handy??
2 ounces to be exact,
You got 911 on your speed dial phone handy??

wash down the cylinder and you will never get it started
Just a quick shot of carb cleaner in the carb is all that's needed.

If this engine was tuned correctly (as in static) it would be running before you could even let go of the key!!
 

Ken Black

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Ed,
I'm sure you meant TSP!!
And even one of those would be way more than enough.
This response is mostly TIC so please don't take offense here....

3 or 4 TBSP worth!!
That's a lot of gas man!
You got 911on your speed dial phone handy??
2 ounces to be exact,
You got 911 on your speed dial phone handy??

wash down the cylinder and you will never get it started
Just a quick shot of carb cleaner in the carb is all that's needed.

If this engine was tuned correctly (as in static) it would be running before you could even let go of the key!!

by the time you try and get it in there it be half gone all over the head hahaha....
do it all the time but what do i know..

i do know the op states it runs well once it starts... at least to me thats not timming.. i twouldnt run good or at all..
but who knows we all can arm chair it .. but i person is only way to know..

and you can spray it in the plug hole. so it doesnt have to turn over as much..
iam sticking to carb and/or head gasket.
anyways..
 

Joe Cullison

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Have not had time to look at it any more. The sight hole is on the starter/generator side about halfway up and level with the crankshaft.
The crankshaft key is solid and lines up the crank and flywheel.
I have good spark with the new plug removed and grounded.
I set the valve clearances and tried the point gap at everything from .014 to .024 with no luck.
I have a new condenser and coil wire to put on when I put the motor back in.
Turning the flywheel clockwise, compression begins with the S and T marks almost straight down, so 90 degrees past the sight hole location. I have not had a chance to see where the points open in relation to the compression.
Thank you all for the suggestions and help.
 

jstich

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Jerry Stich
Have not had time to look at it any more. The sight hole is on the starter/generator side about halfway up and level with the crankshaft.
The crankshaft key is solid and lines up the crank and flywheel.
I have good spark with the new plug removed and grounded.
I set the valve clearances and tried the point gap at everything from .014 to .024 with no luck.
I have a new condenser and coil wire to put on when I put the motor back in.
Turning the flywheel clockwise, compression begins with the S and T marks almost straight down, so 90 degrees past the sight hole location. I have not had a chance to see where the points open in relation to the compression.
Thank you all for the suggestions and help.
This is interesting information, but it would be more important to know if the T mark lines up with TDC.
 

abthomas

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I think at this point I'd be pulling the head and satisfy myself the head gasket isn't blown and as to where the flywheel marks are in relation to the piston being at the top of the block on the compression stroke of the engine, and if all of the above is good, and the timing isn't screwed up which I don't think it would have run before then with fuel,air and spark it should start,when you crank it over spray some brake kleen or starting fluid in the carb, if it fires then I'd suspect a fuel issue
 

abthomas

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This is interesting information, but it would be more important to know if the T mark lines up with TDC.
I believe the T mark on the flywheel should be at the window when the piston is at the top of the bore on the compression stroke , but with the head on you can't see that
 

jstich

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Jerry Stich
I believe the T mark on the flywheel should be at the window when the piston is at the top of the bore on the compression stroke , but with the head on you can't see that
Agreed!!!
 

Joe Cullison

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Unless I'm missing something, If the plug is in and I turn the flywheel until I'm feeling good compression, then that should be within maybe 5 to 10 degrees of TDC? Because compression happens near TDC on the compression stroke? I realize the compression stroke encompasses 180 degrees of a circle but with the ACR and the biggest amount of compression happening near TDC. That should bring the potential arc down to maybe 30-45 degrees.
I can clearly feel the compression and it is happening with the T at about 90 degrees past the hole. (straight down) Then It should be worst case between 80 and 100 degrees off.

If I'm getting compression then the valves are closing at the appropriate time to allow the pressure to build. Which should mean that the cam and crank are in harmony. But are they in Harmony at the correct position for the points to open?
I'll take a look and see when the points open in relation to where the compression is.
Thank you
 

jstich

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Jerry Stich
Unless I'm missing something, If the plug is in and I turn the flywheel until I'm feeling good compression, then that should be within maybe 5 to 10 degrees of TDC? Because compression happens near TDC on the compression stroke? I realize the compression stroke encompasses 180 degrees of a circle but with the ACR and the biggest amount of compression happening near TDC. That should bring the potential arc down to maybe 30-45 degrees.
I can clearly feel the compression and it is happening with the T at about 90 degrees past the hole. (straight down) Then It should be worst case between 80 and 100 degrees off.

If I'm getting compression then the valves are closing at the appropriate time to allow the pressure to build. Which should mean that the cam and crank are in harmony. But are they in Harmony at the correct position for the points to open?
I'll take a look and see when the points open in relation to where the compression is.
Thank you
I Quit!!!! :bash:
 

JPrattico

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Cubcadet_107
Okay, I'm gonna go ahead and try to say this calmly:

1. PULL THE HEAD. It's not even that hard to do! Just remove the fuel tank, heat shield, then unbolt and remove the top shroud cover, and there's 9 total head bolts (some of which are studs). Remove them and the head should come right off. You will need a new head gasket but it's probably a good thing to replace anyway. Plus you can inspect the cylinder bore and decarbonize everything while you're at it.

2. While you're at it may as well pull the flywheel off so you can clean the back of it where the timing marks are, just to verify that what you see through the timing hole really is the timing mark.

3. PULL THE HEAD. (see above)
 

Joe Cullison

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The points are opening at the start of the compression. Which is 90 degrees past the window. They do open just as the compression starts to build.

I will order a gasket set.
I will pull the head and clean everything up.
Then I can check all the timing marks while I'm in there.
It will probably take me a couple weeks.
I'll post what I find.

Thank you for all the help.
I did not intend to frustrate anyone.
 

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