Installed a Bing 48 carb on my 036

[paragonbuilder]

Where does one buy a metering spring assortment and how does one tell how stiff the current one is?

Our sponsor has it.
http://www.hlsproparts.com/mobile/p...erm=W400-606&gclid=CMf6zKyY5M8CFckkhgodWd4Bnw

 

[Terry Syd]

The kit is a great way to experiment with metering springs. A 'porter' should have such a kit on hand to try and tune the carb. Once a metering spring has been chosen as the best for the given application, then it is just a matter of ordering more springs with that part number.

Perhaps someone will work out a good spring for the 036 carb and give the forum the part number. The springs are only about $1 apiece - the freaking postage will probably be more than that.

 

[RI Chevy]

Is the kit good for all Walbro carbs?

 

[Stihl working Hard]

This is my drf255 ported 036. The saw ran absolutely awesome before. I really only did the 038 carb install just to see if I could and if it would work. I already had most of the parts I needed. The end result absolutely shocked me. I wasn't expecting the gains I got

That's a truly impressive site there Mike I can't believe the gains you got well done my friend

 

[RI Chevy]

Now we just need a lesson on what springs to use and how to determine which one to use.
Maybe a webinar?

 

[Backtroller]

I will try to get the measurement/picture tonight of the L.

It was super windy last night and our power went out shortly after I posted the picture. No trees down, but the majority of the leaves fell in my yard and blew away (which is nice).

 

[Stihlbro]

Where does one buy a metering spring assortment and how does one tell how stiff the current one is?

Now we just need a lesson on what springs to use and how to determine which one to use.
Maybe a webinar?

Stiffer spring will give more resistance for the fuel draw to pull down on the metering diaphram. Shimming the spring is doing the same concept making it stiffer. Checking pop off pressure can give you an idea as long as the needle and seat is sealing properly. I have never purchased a spring kit, but keep an assortment from any two stroke carb and keep trying until I find the one that works best. It only takes small changes make a difference.

Back to the spring kits, I think they are color coded and the color represents a spring rate, but I could be wrong.

 

[Canadian farm boy]

@Backtroller thanks for stepping upto the plate here. Your pictures and other info you've shared are awesome. Thanks.

@Terry Syd I'd like to thank you for all the info and knowledge your sharing here. All great info and explained in a way that even I can understand. When it comes to "tweaking" these tiny little carbs I'am for the most part lost.

 

[Stihlbro]

Here is a zama off a 036, different set up than backtroller's. It has a aux feeder supplying the low side adjuster and a secondary transistion hole. I dug out a tillotson from a 036, but did not get a picture.


It is cross drilled to supply fuel to the low side adjustment.
There is a tillotson on eBay now and I think is worth looking into. Bigger Venturi, thinner throttle and choke blades. But slightly smaller bore by a few thousandth.

 

[Terry Syd]

Now that is a different 036 carb. When you say -

It is cross drilled to supply fuel to the low side adjustment.

does that mean that there is a passage from the corner of the carb that runs underneath that brass jet that feeds the low speed circuit?

If so, then that brass jet is an EPA limiter on the low speed circuit.

 

[huskihl]

I'm following. Kinda like the short fat kid at the end of the lunch line....but still following

 

[Terry Syd]

When modding carbs I can't emphasize enough - DO NOT ASSUME anything relating to the carb circuits. There are so many different versions and configurations of circuits that you can easily ruin a carb with a mod that you THOUGHT would work.

The carb that Stihlbro has opened up APPEARS to have a limiter jet that feeds the low speed NEEDLE. However, it may be a secondary jet that feeds directly into the airflow in the carb. If there is another access port inside the carb directly under that brass jet, then it is probably a secondary jet.

Perhaps using some WD-40 sprayed into various locations can give a clue as to the circuits. Pulling the low speed needle and shining a light in the hole may also give a clue. I've also mentioned measuring the low speed needle and seeing where the needle seat is located.

 

[Backtroller]

This is a C3A off of my red lever 036. Can't be 100% sure it's the original carb since I haven't owned it since new

This is where the low is when it's screwed in all of the way I lined it up where it would be

This pic isn't the best see the second version I posted

 

[Backtroller]

If I screw the L in all of the way and tip the carb to the side I can barely see the tip of the screw poking into the hole from the top. The largest hole that was covered by the Welch plug

 

[Backtroller]

The pic with the screw on top is more like this. Better, more accurate pic

 

[Terry Syd]

In order for the low speed needle to work, the fuel must be available to the area of the needle without the threads so that the needle seat can regulate it.

I would APPEAR that there must be a passage from the hole in the carb that runs at an angle towards that part of the low speed needle without the threads. Maybe you can find a plug on the outside of the carb that blocks off where the circuit was drilled.

Gawd, I hope this isn't another low speed circuit that is drilled from the main discharge nozzle tunnel...

 

[Backtroller]

Flashlight in the L hole has light in the hole with the lead pointing and that center hole again under the Welch plug

 

[Backtroller]

H removed has light from this hole

 

[Backtroller]

Like this?

 

[Backtroller]

Same deal different newer carb off of a 036Pro. I'm referring to the brass plug angling towards the L