066 wont start

[lone wolf]

Ill see if i can get my hands on a compression tester.

Its got fresh fuel lines and filter. The carb is in good condition. Can you replace the needles and seats? Or is that why i need a new carb?

Would a local pro shop be able to vac test it?

If you follow the chart I made to get it running it will 9 times out of ten. Not all carb rebuilds work in fact that might be easier to try first than a pressure test and seals. Well you got to start somewhere ,what ever you can do first then proceed from there. Always use OEM carbs.

 

[L34]

If you give it a shot of fuel and it won't start I say not a carb problem.

 

[lone wolf]

If you give it a shot of fuel and it won't start I say not a carb problem.

Unless its flooded or the plug is fouled but yes.

 

[Bob Hedgecutter]

If you give it a shot of fuel and it won't start I say not a carb problem.

That could have been solved at post #2 if it weren't for the saw pops in post #1!

 

[TheRockyMountainKing]

That could have been solved at post #2 if it weren't for the saw pops in post #1!

Forgot to mention it quit popping recently. Ill comp test soon.

 

[L34]

With some fuel dribbled in carb or plug hole it should run for 2-3 secs not just pop.

 

[lone wolf]

Forgot to mention it quit popping recently. Ill comp test soon.

Pull it till the needle stops rising.

 

[TheRockyMountainKing]

With some fuel dribbled in carb or plug hole it should run for 2-3 secs not just pop.

It wont run with gas poured in it.

Pull it till the needle stops rising.

Do you have to hold it wide open to get a good reading like on a sled or bike?

 

[lone wolf]

It wont run with gas poured in it.

Do you have to hold it wide open to get a good reading like on a sled or bike?

Naw just keep pulling till it stops rising. And it wont run with too much gas dumped in either it has to be a tiny amount. It has spark right? Try looking at the plug is it clean

 

[TheRockyMountainKing]

Naw just keep pulling till it stops rising. And it wont run with too much gas dumped in either it has to be a tiny amount. It has spark right? Try looking at the plug is it clean

Just a little squirt with a syringe. Spark plug is brand new. 0 carbon.

 

[Bob Hedgecutter]

Okay, so to date:

The saw does not fire, not even pop.
Will flood fuel through the system until it leeches out of the muffler.
We can assume timed correctly and correct flywheel/coil combo (although not confirmed yet by number checks and if it was not messed with before you got it).
Assume it has good spark with plug outside cylinder and earthed (although spark under compression not verified by inline spark tester).

So, that kind of leads to the compression or lack thereof theory.

If it indeed had a severe lack of compression when you got the saw, any improvement is going to feel good- but good is not always great, nor always ideal.
One rough way to disprove it, if you do not have the correct gauge to test it- is to pull the plug, tip about a teaspoon full of mix oil down the plug hole, on top of the piston- swill it around a bit, replace the plug and start the saw. IF all other ducks are in a row- the oil should give a temporary lining to the cylinder wall/rings that will boost compression and allow a saw with weak compression to start.
It will smoke like a mosquito fogger- but it should run.

 

[Mad Professor]

Too many posts......have we seen a picture of piston, through ex port yet?

 

[stihltech]

Any body else feel like we are going in circles? I know I am one of the "bad guys" (tech at a dealership} but I would have it diagnosed a long time ago. Nice to get all the tools if you know what they are telling you.

 

[Bob Hedgecutter]

Too many posts......have we seen a picture of piston, through ex port yet?

Sometimes it takes a few posts to strangle out the information needed?
A new Highway top end that has not as much as popped yet- should look okay through the exhaust post shouldn't it?
Mind you, it should also have starting compression...... that sends us back to an incorrect carb build......

 

[Aknutter]

How about the switch, contact spring,grounded out wire

 

[lone wolf]

Just a little squirt with a syringe. Spark plug is brand new. 0 carbon.

Too many posts......have we seen a picture of piston, through ex port yet?

No we have not.

 

[TheRockyMountainKing]

Compression was 125. Got at tester from friend.

 

[L34]

125 is at the low end.

 

[Bob Hedgecutter]

125 is at the low end.

And for a brand new top end- pretty bloody shocking.
Mind you- automotive tester or specific small engine tester?

 

[lone wolf]

Compression was 125. Got at tester from friend.

Hang on a minute now we need to cross check that gauge on another saw that is known to run good and be in good condition. The gauge could be wrong but this is one reason why you shouldnt use China crap parts. I am assuming you pulled it till it stopped rising.