Miller Mod Saws and the CS-500P

I'll be back to discuss this build later but here's some eye candy till than. Some of you may now this wood. Ain't nothing that will kill a saws power faster than Hedge in my neck of the woods.

 

Yes saws turned out really nice imo! Light and fun to run now. As I worked my way threw the recipe I settled 108 exhaust with around 15 degrees blowdown and don't touch the intake.

And that all said on saw 1 which is my saw I did epoxy the intake for trial puposes.

 

Before I throw out the numbers to far I'm hoping fordf150 jumps in here. These saws flat run outta carb. To go any further they would need an upgrade. Lol.

Nate is there a chance one of the bigger echi saws has just a little bigger venturi but will still bolt up fairly easy?

 

Saw #1
.030 taken from the base and squish cut at a 3° angle and reset to .020.
Numbers 108/123/75ish
This saw is the better runner of the 2. As there both holding around 11800 in the cut but this one holds the rpm better.
But that said it also has more runtime on it.
The exhaust is at 65% width and on the exhaust outlet I raised and lowered it about 1 mm each and blended back.
The intake is at 62% width. And epoxied!

 

Carl I looked these carbs up and it's 13.5mm venturi, same as a 5105 IIRC. That being said, from my vantage point not all carbs will flow the same even if they have the same venturi size. The nozzle in some carbs is flush while others it's sticking half way into the venturi, that can't be good for max flow.

Carb size is not always a good determining factor in total volume.

I haven't jumped into porting a chainsaw to much so I really don't know if this is a good example but

I built some 400/460 engines years ago that even though shift points were set at 6000/6500. We had better times running a 600 over the 750. That is contrary to conventional wisdom.... 460 cubes turning 6500rpm should be drawing enough air to use 750/800 cfm carb.

 

I thinned the carb screws on saw 1 to get more flow but still not enough. Saw will only turn a little over 13k unloaded and it's simply lack of flow. It just gives it up. Lol. I was hoping one of the 590 or something had a similar carb set up that could almost be directly bolted on. 14-14.5 venturi. I could get an hd12 or 7900 carb to bolt up but there big enough I'd have to change the intake boot as well and I'm not wanting to go that big. Lol.

 

Saw #2
I took .035 off the base. 3° squish band reset to .020. Exhaust outlet the same.
Intake is untouched!
108/124/86 is the numbers in this saw.

Comp landed just over 200.
Both saws ended up with dual port mufflers.

 

Saw #2 is headed back to the customer. The other is mine to play with for a bit. Hoping to find a tad bigger carb just to try.

But these are a great fun saw to run once ported! Light and hold good rpm in the cut!

I may have left something out so if any questions. Fire away!

 

I will take a look at the 590 carb vs 490. I should have a 590 carb on the shelf to compare to the 490.


5105 with a 13.5 venturi turns 14k no problem.... Is the 490 using that much more air or is it the different carb design that's not letting it get enough

 

I'm not sure. I've gotta order a new 5105 next week as I sold mine here so I can't pull it and check. But the carb is pretty plugged up on the way threw. That's why I thinned the carb screws hoping for more flow. I maybe wrong on the carb but if I found an easy enough bolt on I'd like to test it and see. Don't get me wrong. Nit sure there will be enough gain to justify. Just more out of curiosity.

 

620 carb is what i keep on the shelf but sold the last one a week ago and they are on BO. 620 carb is 15.88mm venturi, 590 is slightly smaller but almost double the price. carb body is going to be too large i think. If i get a chance today i will pop the 2 saws apart and look

 

At first I thought this was a loaner demo to you reading this. I thought" they let him part their loaner"!!!! " do they know!!!???" Haha

 

Well you may have to pry it away from my son. I have 2-11 year old sons and 1 of them has feel in love with this saw. Theses 500 are light and nimble. So I'm gonna show a little daddy pride her. I'll have to get one of them running the echo and 1 running the 421 and take a vid. Lol. Sorry for the crappy vid but I'm gonna show it anyway! Lol.

 

What I meant was I thought Echo or whoever loaned it to you to use and your ported it!

 

O I got ya. Lol. No this was a dealers demo saw and I bought it off him! My bad! Sorry! Lol. I'm assuming he's demoing the 490 now. Maybe he'll be tired of it before long. Lol.

 

good news is that cylinders are cheap for these so you can go back in and experiment a few times if need be without spending a fortune.

millermodsaws have you dug into a 6100 yet?

 

I have. They are awesome ported!

 

I will have to wait till its light outside but I went in tonight and opened the venturi up to 14mm and thinned down the carb and choke rods. I think it had some gains but let me test before I confirm. Lol.