Tillotson Carb Question ?

[ZeroJunk]

On a Dolmar 120SI the carb has a shaft that runs in to the carb at about a 15 degree angle and to a lever on the outside right of the throttle trigger. You turn it maybe 1/4 of a turn. Think it might say choke , but there is no choke butterfly.

How does that thing work ?

 

[turkeybob]

On a Dolmar 120SI the carb has a shaft that runs in to the carb at about a 15 degree angle and to a lever on the outside right of the throttle trigger. You turn it maybe 1/4 of a turn. Think it might say choke , but there is no choke butterfly.

How does that thing work ?

It does not have a choke as such, it has a valve which when you turn it to choke position it lets in more fuel for cold start, they work well, if you have an IPL you will see it. That's where the i comes from in the model number, stands for injection, but it's only cold start which is injection! All the models with i have the same, 110i, 115i, 116si, 120si. Item 10a on the IPL

 

[ZeroJunk]

It does not have a choke as such, it has a valve which when you turn it to choke position it lets in more fuel for cold start, they work well, if you have an IPL you will see it. That's where the i comes from in the model number, stands for injection, but it's only cold start which is injection! All the models with i have the same, 110i, 115i, 116si, 120si. Item 10a on the IPL

Thanks for that attachment. I am putting a piston in it for a friend of mine. The cylinder was a mess, but I think I got it. This is the only Dolmar I have had and it really is well built. Really nice work on the cylinder.
I can see where that valve cams out, I just don't understand without a choke how the fuel gets up there to start with. I'll find out soon enough, Meteor piston should be here Monday.
May need your attachment to remember how it goes together since it will have been more than 24 hours LOL .

 

[L34]

More an enricher than a choke I believe.

 

[ZeroJunk]

Well, this was an aggravating repair. I got the Meteor piston in easy enough. And, I had the saw running. Then it just started to flood out.
So, I was thinking maybe I put the primer lever in upside down. Tried that. Then I put a pressure gauge on the input and the metering needle wasn't seating. I put a kit in it to start with, guess it got a bugger under it somehow.

Anyway, if anybody wonders how these work when the valve is cammed out it is a straight shot from the intake nipple to the outlet in the barrel. When it is cammed in the injection is shut off.
I'm still not sure how it pulls gas up from the tank if you run out. Guess I'll find out. I'll cut with it a little today before I give it back.

 

[pioneerguy600]

The carb pulls/pumps gas up from the tank, the choke does not. The choke depends on the fuel in the fuel bowl of the carb already being there, the choke actually increases the pull on the fuel through the orifices in the carb into the venturi. Pinch your nose, cover your mouth and try breathing in, you get the idea.

 

[ZeroJunk]

Never really thought about it. I just figured at some point of the cycle there is a vacuum in the crankcase and it would pull in fuel rather than air when the air was cut off in addition to what the impulse line is doing.
Apparently this was not a successful design for whatever reason.

 

[pioneerguy600]

The injection choke actually works better than most plate type chokes. Anyone that has run the SD saws with these chokes really loves them, me included. I ran two injector choke SD saws, the 116Si and 115i, fine saws for production cutting.

 

[ZeroJunk]

I can tell you that this 120SI is a fine piece of equipment. Half way hope the owner doesn't show back up.

 

[pioneerguy600]

Fine saws, I now own a 120Si and a 6800i but havn`t ever cut wood with them, they just make up the 8 PRO SD`s in my collection.

 

[Cantdog]

Fine saws, I now own a 120Si and a 6800i but havn`t ever cut wood with them, they just make up the 8 PRO SD`s in my collection.

Hoarder!!!!

 

[pioneerguy600]

Hoarder!!!!

Well, you know how that is, all them Johnson Red saws under the benches and stuff!....LOL
I did run SD saws for many years as our main production saws, dad ran a ported 116 and I had the 120Super non injected saw for the first couple years, then I picked up several more SD saws as the years progressed but when Makita took over I soon washed my hands dealing with them. Our local dealer was forced out of business. Left me with a very bad taste in my mouth, putting it very bluntly but not really saying what I thought.

 

[Cantdog]

Well, you know how that is, all them Johnson Red saws under the benches and stuff!....LOL
I did run SD saws for many years as our main production saws, dad ran a ported 116 and I had the 120Super non injected saw for the first couple years, then I picked up several more SD saws as the years progressed but when Makita took over I soon washed my hands dealing with them. Our local dealer was forced out of business. Left me with a very bad taste in my mouth, putting it very bluntly but not really saying what I thought.

The only saw dealer in town here sold SDs.....there are a few around but they never really caught on with the local wood boogers though I deem them to be well made units from what work I've done on them. I think it was the dealer himself that was the problem more than the quality of the saws. Not an out going fellow to say the least.

 

[pioneerguy600]

The only saw dealer in town here sold SDs.....there are a few around but they never really caught on with the local wood boogers though I deem them to be well made units from what work I've done on them. I think it was the dealer himself that was the problem more than the quality of the saws. Not an out going fellow to say the least.

We had the best of the best dealer one could ever ask for at that time, was the main reason we got into using the SD saws, the local Stihl dealer was a complete azz in every way imaginable. Dad and I bought the two SD saws on the dealers first showing.Those saws were actually well ahead of the 041, 032, and 042 I had run occasionally but were saws others were running at that time. The 034 came out around the same time, I wanted one but the local dealer did not want to order one in until he sold all his older models, mostly 028`s. I would likely still be running SD saws if it was not for the Makita takeover, when they did it just about ruined our local dealer.