Echo CS501SXM carburetor swap?

[Lightning Performance]

The title covers my swap to something bigger in a ported saw. The wires, throttle linkage and choke I can makeup if they needed to be moved around some or swap to other shafts in the main body.

Very small carb here I just want to avoid porting that vs swapping it out to something a bit bigger.

So far cable linkages are out and most Stihl carburetors I've checked in newer models like 361, 290 or 044/460 types.

My main body needs to stay under 1.25" thick and I prefer 1.1 to 1.15 or so. Having the adjustment screws in the stock locations isn't possible most times but would be nice. If not it's time to port the tiny 11mm venturi they came with. It's 15mm out the back and my 361 measured 21mm out the back so it's a bit too big to interface with the rear ring and boot area on a stock Echo setup. I'm not changing this intake boot in this but possibly the inner ring. Stud spacing matches most 50-62cc chainsaws made without strato carburetors.

 

[Lightning Performance]

Many of you work on Echos and other brands I don't see very many of. This is kool-aid country here

Like I said getting something to fit one is half the battle. The rest can be dealt with as issues arise.

Poulan 60cc class might be a good fit here but all mine are 50cc or under in many colors. The old PP455 will get a look but likely won't be a contender. Older carbs is fine just so I get close any brand or any model.

Available new or AM is fine just not interested in resurrecting old parts here to use on a new unit except for mockup and possibly testing. New is the preferred method of madness

 

[NSEric]

The stock carb is very very similar to the carb on the chinese zenoah clones I mess with.
The best carb I found for them is off a 372. It's 5mm longer but everything else is pretty close.
I cant find one the same length that's larger dia.
They can be made to work with the stock intake but fabbing a shorter larger dia one adds more rpm/power to the clones.
Is the intake large enough for a bigger carb?
I have to add a 2mm spacer so the throttle will open on the stock clone intake, it hits, this makes the carb ever longer.

Edited to add.
I tried a 357/359 carb too but couldnt make the throttle linkage work.
It a good size dia wise. 18mm throttle blade and 18mm choke vs 16mm throttle blade on the stock carb.
It's also 5mm longer than the stock carb lust like the 372 carb.
The impulse is different but fixable, the top/bottom cover has a dimple for a fitting, add one and jb weld the stock one up.

 

[Lightning Performance]

The stock carb is very very similar to the carb on the chinese zenoah clones I mess with.
The best carb I found for them is off a 372. It's 5mm longer but everything else is pretty close.
I cant find one the same length that's larger dia.
They can be made to work with the stock intake but fabbing a shorter larger dia one adds more rpm/power to the clones.
Is the intake large enough for a bigger carb?
I have to add a 2mm spacer so the throttle will open on the stock clone intake, it hits, this makes the carb ever longer.

Edited to add.
I tried a 357/359 carb too but couldnt make the throttle linkage work.
It a good size dia wise. 18mm throttle blade and 18mm choke vs 16mm throttle blade on the stock carb.
It's also 5mm longer than the stock carb lust like the 372 carb.
The impulse is different but fixable, the top/bottom cover has a dimple for a fitting, add one and jb weld the stock one up.

Do you have any pics?

Will look into the 357/9 carb.

Not looking to use a spacer on a work tool this time. This saw will only be used for bucking so staying under the original covers does not matter for air filters but this filter cover does move air across the cylinder so part of ot has to remain in place. I do plan on increasing the filter media and possibly changing to a larger elbow inlet of the same type or a 90° design. Not too worried about throttle linkages not mating up but having one on the right or left side with a push actuator will do.

Did you make any throttle shaft or choke shaft changes?

Do you know what model or manufacturer, ie: Walbro, ect... of carburetor you used on that build?

The 372 Walbro carburetor will find a home on another build here to replace a Zama but the 5mm increase is too much for this particular build. If it was going to be a short bar racer I'd be going that route with a ported one and more intake changes.

This intake is staying stock production but the ring might change to clear the butterfly if needed.

It appears the Z5000 might be close but I doubt it will have a bigger venturi. I'm eager to find a bolt on unit but seriously doubt that will happen on this particular saw like so many others just fell together with other factory parts. Keep on looking is the current theme.

Most importantly I'm not hunting RPMs like so so many others do. This is being built for torque and not HP. Certain aspects will make more RPMs in this tool but it isn't the target goal here. Not worried about making fuel or impulse lines match. They can always be moved around easily enough.

Zenoah is not a Chinese company as far as I know it was Japanese manufacturing but I could be wrong.

Thanks for your imput and help with ideas

 

[NSEric]

 

[NSEric]

Another pic.

 

[NSEric]

I was hoping this 357carb would work for my 50cc saw as the 372 one is a bit much.
This is the same size on the choke side as the little stock carb.
You can see my impulse fitting in this pic. I could have made this work if I cut and welded the throttle linkage but didnt want to do it. It's a work saw I dont want anything on it that could fail, the 372 carby lines up pretty good with a different intake on my saw.
Every carb I have is chinese.

 

[Lightning Performance]

I was hoping this 357carb would work for my 50cc saw as the 372 one is a bit much.
This is the same size on the choke side as the little stock carb.
You can see my impulse fitting in this pic. I could have made this work if I cut and welded the throttle linkage but didnt want to do it. It's a work saw I dont want anything on it that could fail, the 372 carby lines up pretty good with a different intake on my saw.
Every carb I have is chinese.
View attachment 1050436

I brought home another new 600SX Shindiawa today to see how the smaller 59cc carb will fit up. My next look will be the 590 and 620P or now defunct 600P. They all play with same type parts on similar platforms although the insides are quite different from model to model.

 

[Lightning Performance]

@NSEric
You should look more towards something closer from a different design that is bigger but has a better lay out or make your primetime thing a working choke and swap the throttle shaft to one of hundreds available on many models. Longer shafts can be shortened. They are fairly easy to work with. Linkage rods are the easy part.

 

[NSEric]

Im waiting to see if you can find a bigger bore carb that fits like stock for yours. The stock echo and china 5800 zenoah carbs will swap, the only difference is the way the fuel fitting is pointed.
I'd like to find a slightly bigger carb that bolts onto the stock intake like stock for the 50cc versions.
I have two 54.5cc saws built/sorted with the 372 carb. They run pretty good, you cant tell the carb is huge.

 

[Lightning Performance]

Im waiting to see if you can find a bigger bore carb that fits like stock for yours. The stock echo and china 5800 zenoah carbs will swap, the only difference is the way the fuel fitting is pointed.
I'd like to find a slightly bigger carb that bolts onto the stock intake like stock for the 50cc versions.
I have two 54.5cc saws built/sorted with the 372 carb. They run pretty good, you cant tell the carb is huge.

Manners or how it works as a felling saw isn't my concern. Maybe by tonight I'll have something figured out that will work for both of us as a bolt on option. If your running a carb bigger then the intake it should have major issues if the fuel map isn't close. My plan is to change that and dial in the fuel circuit to my liking.

 

[NSEric]

My new intake is 21mm, 1mm bigger than the carb bore, it seams it work well.

 

[Lightning Performance]

My new intake is 21mm, 1mm bigger than the carb bore, it seams it work well.

I ran down all your work from 2019 in a few threads around the forums. The intake deal I worked out about 30 years ago on swapping parts around so using an oval boot or different bolt-ons with a custom intake pipe was already in my mind. Those cheapo jugs are NOT doing you guys any favors or the short stroke in those clones. My reading confirms the 45cc to 65cc clones are all running undersized carbs. Feeding this ported 50cc intake with about 3mm more carb venturi is about the limits for decent signal under a heavy load. I also have the benefit of machine work and a stock domed piston not all cut up to make timing numbers. I'm using closed quads so my intake could use a bigger 372 carb but the idol qualities will be poor at best. I've decided to go in another direction and try with larger dual port older carbs for testing off pro series tools. My choke isn't going to work but I can dial in a better low speed and midrange fuel map first on something closer to a 13mm venturi. The 14mm+ is a bit overkill for my long bar saw.

 

[Lightning Performance]

My new intake is 21mm, 1mm bigger than the carb bore, it seams it work well.

The step helps with reversion waves. Stick with it if it worked for you with the bigger intake area. I'm not trying to make more RPMs in my build. It will get there just fine if tending to business as usual

 

[NSEric]

I've built better clones since I posted about building them in 2019. Back then I blind ported them based off what someone else did to theirs.
I did very little grinding on my joncutter5800 (54.5cc) and it out cut my other over ported saws.
Once I put a degree wheel on em I realized raising the exhaust was a mistake, they're too high stock.
I have a 50cc one that rips with a stock carb, I dropped the cylinder until the squish was .025 which got the exhaust down to 104, which is still high for 50cc. I had to raise the transfers and jb weld the intake after dropping it over 1mm.

I only want cheap saws, I dont mess with expensive stuff. My saws live on the front rack of an atv, they could get destroyed at any time. If im out 200 bucks for a clone I dont care, if im out 800 for a new pro saw im pissed.

 

[Lightning Performance]

I've built better clones since I posted about building them in 2019. Back then I blind ported them based off what someone else did to theirs.
I did very little grinding on my joncutter5800 (54.5cc) and it out cut my other over ported saws.
Once I put a degree wheel on em I realized raising the exhaust was a mistake, they're too high stock.
I have a 50cc one that rips with a stock carb, I dropped the cylinder until the squish was .025 which got the exhaust down to 104, which is still high for 50cc. I had to raise the transfers and jb weld the intake after dropping it over 1mm.

I only want cheap saws, I dont mess with expensive stuff. My saws live on the front rack of an atv, they could get destroyed at any time. If im out 200 bucks for a clone I dont care, if im out 800 for a new pro saw im pissed.

I'm just setting up new tools at a decent price point to start building them. This is the first one and I have to make some decisions this week. It appears if a bolt-on wider carb venturi can be found I'm switching to some better inlet elbows more common and much bigger. That allows the filter be be much better. These saws are being built for a commercial environment bucking constantly. Longevity and low maintenance is the goal with decent or better parts not cheapy tools. After reviewing many aftermarket and OE parts available now the AM stuff is half junk by design and will only make this worse not better from a flow standpoint. Now it needs volume being ported and much much more inlet area on the filters. Cutting this intake boot or swapping it out is always an option. This can be cut and clamped but it can be expanded a bit bigger in the stock mount. I might keep all that and make my own intake pipe. After that the throttle blade is a none issue with the short intake or the stock one possibly. Moving back 5mm like it's setup now will use stock bolts minus the stock plastic brackets for the old now leaving elbow. Having a custom elbow and intake might be required not sure yet. Carb parts can be made-to-order or stock but fit much easier then keep looking at stuff either out of date and no support or not acually made in the size venturi I need. The other 600 saw is a none issue. It's left side adjustment setup with a bigger boot of a different design is a different layout. My last option is to switch this saw to right side adjustments. Less work and parts saves time and money if they bolt on with no mods on the intake end. The original stuff may get sold as is or cannibalized for bits. That hurts the bottom line cutting them up. Again this isn't a hobby I'm looing at a model as the whole package finished but new. It might be a bust based on time. No one else is doing it with newer Echo or Shindiawa saws I've found. Good tools when done right they will last with proper maintenance.

 

[Lightning Performance]

Tonight is five saws to compare in three models some are different model years. So far none of the 60ish cc carbs are a direct swap. Two can be converted and one is too big out the back like 2mm too big without intake adjustments. The good news is more carbs came to look at on this model and one is rigged just like it. Some interesting options available for clones with dual choke lever assembly built in. Looking mainly at OEM clones to get the real thing new.

 

[Lightning Performance]

The carb swap isn't going to happen right now. It's getting ported and put back. Had a piston issue with a supermarket tight wrist pin and three razor sharp edges on the skirt back cut.
Has anyone addressed this issue?

 

[Lightning Performance]

All better now.
Pita

 

[Lightning Performance]

Both clip bores had a major bur and crap jammed in them from the factory.
Pin bores were worse as you can see before honing.