Discussion in 'Chainsaw' started by BGE541, Apr 18, 2015.
I'd like to get the 490 done by Red97 when money allows. That guy can make the Echo's scream.
I agree from the 590's I've seen him do. He does some trick carb work to them too.
I should check the comp on mine I'm at 900ft squish is .020 ports widened with the exhaust raised to get back what was lost from machining the jug.
Hopefully we will see more videos of these saws working.
How do you go about posting videos? I'd make some if I knew how to get them on here.
Use youtube and post the link or use the "media" icon.
Upload them to YouTube then hit share, copy link, then past link here in a comment.
It was 175-185 up here I don't know how I got 195. Is your squish band cut? I'd bet yours is higher than mine was.
he said he was at .014 after machining and took .006 off the edge of the piston matching the angle of the dome to get .020
Oh nice! So I guess it has a pop up in it if you want to get technical. I want to see a video of this thing. I'll see if I can find a video of my 590 give me a bit.
The chaps were pulling my pants down......don't judge
I'll see what I can do video wise mine has a much more sedate muff mod then the eardesplitterloudenboomer so not obnoxious unless your noodleing.
@deaves61 did mine maybe he can fill in what I'm missing.
If I get another Echo I don't think I could resist the eardesplitterloudenboomer mod. It gave the most power with the least amount of work. The dual port was equal in power but was a pain in the a$$.
@Big Block and @James Miller thanks for your comments. I wasn't aware of the compression increase from running 40:1. I'm a car engine guy and am still somewhat new to modding and even properly tuning 2-strokes although I've been running them a long time with power equipment and the airplanes. The airplane engines don't get their needles touched for years after they're initially tuned. They're very very very good, but expensive. I will give 40:1 a shot on the next mix to see how it runs, or maybe I'll go ahead and see how much gas I have and calculate the oil needed to increase the mixture. I was alway's hesitant to run much thicker than what the oil is formulated to for carbon buildup reasons. I have alway's heard the Red Armor oil is great at cleaning and didn't want to mess that up. Perhaps I have it backwards and more oil will clean more. That's very possible. I am not incredibly interested in muffler mods, porting, base gasket deletes and mods like that just yet. Maybe in the future I will think about messing with that. I just want a good running, strong, and dependable saw. That's why I love Echo so much. Their products cc for cc may run faster or stronger here and their across different types of equipment but I've sure worked on way more Stihl's for my friends and family than Echo's. They are just so reliable, everything I've ever messed with of theirs at least. I've got an 11 year old or so SRM-260 trimmer with tons of time on it that runs like brand new. Very good compression and starts first pull. My CS-355T and PB-770T also start first pull.
Also, I got a chance to run the 620p some more today. I have some large logs sitting next to my burn pile out back waiting for a little rain to come around here so I can burn a little more safely. This particular log is only about 12-14" diameter but it gave me means to put a load on the saw and put some gas through it. I've got about 1.5 tanks through it so far. I will have to concede my suspicions that the coil is limited. I am pretty sure it is unlimited now that I've tinkered with that. It four-strokes really easy unloaded. It starts four-stroking way before full trigger pull. I currently have the high about one turn out (don't freak out while comparing that to a 590 carb, totally different carb) and it four-strokes about 30%-40% of the total cut. It comes and goes. I feel it's a little rich but am going to leave it that way for the first few tanks to give it a little extra mix. If I'm wrong in doing that let me know. My procedure for properly tuning the saw for the long run after break-in is a slight urge to four-stroke when in the wood. Would that be safe to say should I modify that thinking a bit? If you hold the saw on the ground and run it wide open unloaded with the screwdriver on the needle you can get the four-stroke to pretty much go away when running the high needle in about 1/2 a turn. That puts the needle only 1/2 turn out from the bottom. I turned it that far for a second or so to see if I could get the unloaded four-stroke to go away to determine if the coil is limited at all. It may be safe to say that the coil is unlimited but the saw four-strokes very easy unloaded. Absolutely no way to tune it this way.
One interesting thing regarding the coils is that there is a p/n change with a serial number split. C32026001001-C32026999999 use a different coil than the newer 620p's. I would love to know what the difference is. Maybe timing curves?
Also, today I put one of the new silver 14" bars to substitute the stock 16" on my CS-355T. It looks sexy. That's a beast of a little saw. It's a little monster. I bet it will really scream with the 14".
32:1 mix and richer is when you will start getting carbon build up. Big ported saws and mill saws usually run 32:1 and richer. The builder of my saw slapped a sticker on my fuel tank 40:1 only! So I run it in both saws. I don't think there is enough of a safety margin with 50:1. I've seen some excessive wear on it personally.
Give your 620 8-10 tanks and it may not need a retune. What you think is 4 stroking a lot unloaded may be just about right once the saw is broken in. Seems like most saws want a little more fuel as they loosen up. I run 40:1 in everything including these.
the 2 bandit motor are about to get some tweaks I picked up from the RC boat/plain crowd.
Duly noted. I'll switch to 40:1 right away and see how that goes. Would you be able to explain how Amsoil runs their 2-stroke oil at 100:1? I'm guessing possibly the oil is formulated for 100:1 as far as the concentration goes. It seems the Amsoil is a very dark color and much thicker than the Red Armor oil. Possibly it's more of a marketing thing? Maybe the concentration of the 100:1 Amsoil would be way too thick at 50:1 for example? I'm not an Amsoil fanboy at all, but the manufacturer of the engines recommended Amsoil 100:1 for years and years and years until they got an squeaky clean engine that sparked their attention one day. They called the owner and asked what oil he was running and he said Redline. They changed their Amsoil recommendation to Redline 50:1 or 40:1, I can't recall the mixture.
From what I've read there aren't a lot of people that are a fan of the 100:1 amsoil advertisement around here. Saws also tend to generate more heat especially saws that aren't cleaned regularly. They not only have the engine, but they have the clutch and bar and chain all very close that will generate a lot of heat. Add that to having sawdust and crud caked in the cooling fins and that's a bad combination for 100:1. Most airplane engines not only have the air from the flywheel but they also have air moving from the speed of the plane as well as the prop making it much cooler. They also generally run at a more constant rpm making less heat.
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That company may also be getting a kickback from amsoil as well. Just sayin lol
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