Echo cs 490 porting

[drf256]

Ground my Venturi out to 15.00

Open and blended the intake elbow

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[drf256]

Here's where it gets bad. Started right up. Rich as hell. Spit back everywhere. Couldn't get the saw to idle right.

Couldn't richen the saw. Was screaming. Had to open the L side to richen. H side needle out 4 turns.

Flooded. Got running. Cut well at WOT. Really well. Caught a quick tach reading and only saw 12,900.

Tried to pressure test saw and found the problem

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[drf256]

I ground right into the fuel passage. So if you grind, avoid this spot. It wouldn't hold pressure, that's why it couldn't be richened. So it sprayed fuel at idle and didn't supply enough pressure to the wet side on WOT.

The saw felt even better at WOT. The piston in still perfect.

There is JB weld on the hole right now.

I'll post how she runs tomorrow.

 

[drf256]

Here's a pic of the wet side of the carb. It appears that the main nozzle is fed from under the brass plug. There is no hole in the plug.

I don't see two areas that feed file to the nozzle, but it's possible that there is a fixed hole and a hole from the H needle under the plug.

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[Moparmyway]

Its bound to happen, but at least you know where to take a step back.

Great work, and even better pictures Al !!

 

[drf256]

Its bound to happen, but at least you know where to take a step back.

Great work, and even better pictures Al !!

Thanks bud.

It's a beefy little saw. I hate to say it, but I think it might crush a ported 026. There, I said it.

It was crazy strong with the bigger Venturi. Even though it only ran at WFO

 

[bikemike]

Ok. Took my stab at the carb today. Got some measurement pics and some advice on what NOT to do.

Intake boot measurement 16.46mm

Throttle bore 15.83

Venturi bore opening 18.77

Venturi 13.49

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From the looks of the pics there not too much meat to come out before it has no venturi effect

 

[drf256]

Those are pics after grinding. I disagree Mike.

There's quite a funnel there. I'm as wide as 15.5 in a spot.

I think less Venturi will pull less fuel, I hope. That way even if there's a fixed portion of the H, it will reduce it on its own.

I couldn't figure out how to take the cap off the main nozzle under the diaphragm.

 

[paragonbuilder]

How did you jb it. Just a light skim? Or fill it and redrill the passage?


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[drf256]

A dab and some spreading.

It's on the wood stove curing.

I'll test it to 10psi tomorrow. If it holds. It's video time.

The saw was an animal at WOT with the bigger Venturi.

 

[paragonbuilder]

That's awesome! That's pretty crazy if it will smoke a ported 026!!



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[drf256]

That's awesome! That's pretty crazy if it will smoke a ported 026!!



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I said MIGHT. Let's not get crazy.

Right now it won't smoke a bow saw.

 

[paragonbuilder]

I said MIGHT. Let's not get crazy.

Right now it won't smoke a bow saw.

Too late... I'm already there!

 

[bikemike]

Ground my Venturi out to 15.00

Open and blended the intake elbow

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Looks good. Hope for a vid soon

 

[drf256]

It's getting reassembled.

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[Red97]

Those are pics after grinding. I disagree Mike.

There's quite a funnel there. I'm as wide as 15.5 in a spot.

I think less Venturi will pull less fuel, I hope. That way even if there's a fixed portion of the H, it will reduce it on its own.

I couldn't figure out how to take the cap off the main nozzle under the diaphragm.

To get that cap off you have to carefully pierce the edge with a sharp punch ground on an angle. Pop it out and replace it.

It's getting reassembled.

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Golf tee's great idea. I left my tank full, when I tore the saw down, plugged the line. When I pulled the plug it had enough pressure to spray me in the face bluck..

I said it earlier in this thread and will stick to it. I think this saw with the correct carb will run with most any woods ported 50cc.

Really hoping the carb works out for ya.

 

[Red97]

I was drilling stuff today too. Think 2 1/8 venturi would be a bit big?

 

[drf256]

I was drilling stuff today too. Think 2 1/8 venturi would be a bit big?

Mag drill?

How thick?

 

[drf256]

Sexy mofo.

And the cad keeps worsening.

Anyone want dibs on the next one?


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[Red97]

Mag drill?

How thick?

Hydraulic, mag drill, it was 24 7/8" through the middle.
Then four 2" tapped holes on the corners. Tapped with that drill too.

Sexy mofo.

And the cad keeps worsening.

Anyone want dibs on the next one?


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Lol, that is what you ment by "get a new carburetor"....