Echo 4920 mods?

I am the owner of a new echo 4920 or I will be Monday when it shows up in the mail. The bread and butter for everything I own is muffler mod timing advance and base gasket delete. Obviously this is a clam saw so no gasket delete. However I can find very little information about these and am curious how they respond to timing advance. I've seen the one joe ported but I don't believe he mentioned timing advance in it. I'm all for taking it apart and trying it. BUT I don't have it yet and if they don't like it I wouldn't even bother. I did notice that the pistons are around 50$ so I may try a welded popup later on down the road though. Any other tips or suggested mods would be appreciated.

I haven’t heard of anyone here monkeying with the 20 yet. Maybe @Red97 has dicked with them a little bit

He posted the video of the ported one and had respectable gains. They haven't been out long but there literally is no other videos on YouTube I can find other than the 2 he has posted.

I think it’s a 44mm bore so there may be a taller piston out there.

Being a clamshell kills a lot of interest in serious mods.

I've got it just havnt got to try it yet been stuck at work but it is a 45mm bore 31.7 stroke according to the manual Wich is disappointing. I was hoping it was 44.7 and a ms261 piston would work or be similar. If I tear it down and want more compression I will have to do a welded popup

45mm is husky 353…I think the pin is different though.

It's a strato saw so no go there.

Got some time today to play around. I genuinely hate the stock Oregon chain that came with it, semi chisel safety chain. It responded well to the muffler mod it didn't care about the timing. Maybe slightly better throttle response I will probably leave it alone for now. And see how it likes it after I tear it down to port. Needs a full chisel chain bad. Squish is around .045-50. definitely getting a welded pop up eventually.

I didn't do a timing advance.

But some lower transfer work, and exhaust work really brought it to life. That was the only one I had seen/ported. Sold it off and have not heard from the customer. So I take it as no news is good news.

I have done similar to what you did along with a small pop-up I just havnt got around to making a video comparison. I'm waiting on a coil from a 4510 they are the same basic saw just different motors and coils mainly. The 4510 has a higher limit and possibly may not be limited at all Ive been waiting on the coil to show up before continuing to test.

Clarkc9743 said:

I have done similar to what you did along with a small pop-up I just havnt got around to making a video comparison. I'm waiting on a coil from a 4510 they are the same basic saw just different motors and coils mainly. The 4510 has a higher limit and possibly may not be limited at all Ive been waiting on the coil to show up before continuing to test.

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Any update on how it runs with the pop up and porting? Kinda interested if the pop up helped much.

I have done all the work and used it some and it's considerably better. I do not know what the stock compression is but it's 155-160 now. The coil didn't really make any difference. I ground a notch into the piston for 77 on the intake. The exhaust I raised to 103-104 and transfers were 121 With the addition of the porting and a full chisel chain it picked up some time in that log. I had to buy a new carb because I constantly was having to adjust the old one and eventually it wouldn't deliver fuel on the low side almost any. With the new carb it doesn't fluctuate tune anymore and runs considerably better. Goes to show difference between home owner and pro stuff. I did some timed cuts with the original carb still. It is now in the lower 15 seconds in the same log as before quite a bit from the original 19 with just a muffler mod. I havnt done any cuts with the new carb and I opened the original muffler port more. I would like to open back up sometime and match the exhaust to the casting opening because I noticed about a 1/8" difference from the cylinder. Along with play with the transfers a little more and a little higher exhaust. But overall it's decent as is.

That transfer cover looks very restrictive. I would be tempted to grind away all that divider stuff. Removing the dividers in a 365XT or 359 has good gains.

Thanks. Appreciate the honesty with the saw. There’s hardly anything out there about it except for the one Joe did and yours. I’m not huge on clamshells but echo generally makes a good machine. The spring antivibe and better air filter intrigued me. Kinda sounds like I’m better sticking to my 501p and lack of air filtration lol.

The covers are not solid unfortunately otherwise I probably would have at least made them straighter the outaide is shaped kinda like the front. If I pull it apart again I may put some jb weld on and straighten them a little more.

I wouldn't dog it to hard It seems to be reasonably well built for a clammy it has 6 pan bolts instead of just 4. The carb is a toss up my uncle's 261c carb solenoid died 4 months into owning. I definitely like the spring anti vibe but if I had the 501 I wouldn't change either. If it ever drys off I'll post a vid again in the log and in smaller wood. With just letting it self feed it holds around 9900-10200 in wood and has pretty decent torque compared to before.

Clarkc9743 said:

The covers are not solid unfortunately otherwise I probably would have at least made them straighter the outaide is shaped kinda like the front. If I pull it apart again I may put some jb weld on and straighten them a little more.

I wouldn't dog it to hard It seems to be reasonably well built for a clammy it has 6 pan bolts instead of just 4. The carb is a toss up my uncle's 261c carb solenoid died 4 months into owning. I definitely like the spring anti vibe but if I had the 501 I wouldn't change either. If it ever drys off I'll post a vid again in the log and in smaller wood. With just letting it self feed it holds around 9900-10200 in wood and has pretty decent torque compared to before.

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Yeah I hear you even the best saws break. Just the nature of the beast. Or you get some duds here and there. Nothing in life is perfect. On the covers I’m sure you’ve seen…but on the 7910’s people fill in the outsides with jb weld and then grind as much as they need on the inside. I always thought if someone cnc’d some caps for it that would be ideal but I guess they just don’t have quite the aftermarket following of Stihl and Husky.

That would be a pretty good idea after looking at them more I definitely think I will get the weird corners out. If it wasn't so much a pain I think it would benefit from a larger carb or at least larger jets at this point. The jets are both backed out alot more than normal compared to most saws I've played with. I think the low is backed out 3.5ish and the high is 2.5

Yeah it really makes it easier on the 7910’s other wise your grinding right thru the outside. And yeah I can imagine, most echos tend to suffer from small carbs.