Tillotson Q.

[bertsmobile1]

FWIW
I generally adjust the L with the H closed up fully as in theory only the L is in use at start up
IF it won't start like that then the throttle stop has been wound in too far holding the throttle too far open
Once I have it starting reliably then I play with the H
Wound out till the engine just starts to miss then in just enough to get it to run clean
Thus it will usually be a little rich
Also the head must be on and the full length of string must be out to loa the engine .

 

[oldlawnguy]

FWIW
I generally adjust the L with the H closed up fully as in theory only the L is in use at start up
IF it won't start like that then the throttle stop has been wound in too far holding the throttle too far open
Once I have it starting reliably then I play with the H
Wound out till the engine just starts to miss then in just enough to get it to run clean
Thus it will usually be a little rich
Also the head must be on and the full length of string must be out to loa the engine .

As a DYIer describing the method of 2-cycle carb tuning is like describing to a kid how to ride a bike with no training wheels. If you keep at it and keep practicing eventually a light goes off!

To help me know if I'm getting warm, I use a tach to measure rip-ems, which the pros gauge by ear.

The method of starting with the L jet and T with H jet closed really works. Then on to the H jet. The H jet still occasionally gives me grief when doing different saws-- when you get into 4-stroking, tune in wood etc. Also you may notice the saw runs different in summer than in late fall/winter which could mean a fine tune session between seasons.

 

[upupandaway]

FWIW
I generally adjust the L with the H closed up fully as in theory only the L is in use at start up
IF it won't start like that then the throttle stop has been wound in too far holding the throttle too far open
Once I have it starting reliably then I play with the H
Wound out till the engine just starts to miss then in just enough to get it to run clean
Thus it will usually be a little rich
Also the head must be on and the full length of string must be out to loa the engine .

So you mean start everything at idle? Just about everything I have starts with partial if not wide open. I added a button to hold the throttle open a hair on my McCullough 1-42 as it won't start at idle for the life of me.
This would goof up the H screw closed, no?

Oh well, I set them to default and it works 99% of the time to get it running, then I tune it.

 

[bertsmobile1]

BEing part of the white pimple on the brown bum of the world ( always loved Prime Minister Keatings description ) and not having access to much in the way of dealer information I have needed to lear ways around it
Many models span several different tiers of EPA regulations and on top of this a lot of US factories dump stuff down here so in the same year I could get 3 new engines with 3 different base carb settings and this is before the owners who "have not touched it" have set the needles to all sorts of strange positions
Old stuff is easy as most will start on a 1 - 1 setting and I can go from there but some of the EPA carbs can be as high a 3 or 4 turns as they have finer adjustments .
Chasing up the information can ( and usually does ) take a lot longer than having a stab
On CUBE carbs with 2 needles I use the set the idle first with the H closed then bleed in the H till it will run WFO and still idle
What most do not understand is both needles work all of the the time unless there is a check valve on the H jet
because of this a H that is so little as 1/12 th turn too open will dominate the idle jet
The idle jet provide fuel 100% of the time but because the H is orders of magnitude bigger anything over a fast idle it swamps the volume of fuel supplied by the L jet
If a cube carb will not start with the H closed then there is a major problem with the L setting

Mowers are different kettle of fish all together