Porting a Chinese G621 Clone

[heyduke]

i like the old school choke/throttle controls, throttle lock on the side of the handle and simple (and separate) choke linkage. every time i pick up a stihl i have to stop, put on my reading glasses, and figure out which generation of controls i'm using and the new husky controls don't really enhance my operating experience either. also they tend to be bothersome when your servicing the saw. simple is better.. it would be nice if this saw had 70cc's and closed transfers.

 

[Gologit]

Hey, I'm not down on you at all. This thing is just something I'm playing with for my own interest and entertainment. I do expect that I will be able to turn it into a decent tool for my uses, in fact I believe I already have - but I'm implying nothing about it's suitability for anyone else or for pro use, nor comparing it to high end Huskies or Stihls.

We each have to make our own decisions about what is worth spending our money on.

Hang in there Chris. You've said basically the same thing in half a dozen different posts. Do you think that eventually some of these guys will get the point?
It's your money, your saw, and your decision on how you proceed. If you're having fun and you're learning something in the process I don't see where anybody has the right to run their mouth about something that doesn't really concern them.
Screw the ankle biters...play with your saw, enjoy yourself.

 

[Chris-PA]

I contacted the seller and they are sending the inner bar plate out. So the $29 in bits I bought from RedMax will just be spares.

 

[Jeff Lary]

You make some fair points Cris. We certainly seem to agree that this isn't a saw that Joe Average could just take out of the box as is and go to the woods without being seriously disappointed. And that was really my main point. Being a dealer, if I sold something with that many issues, new or used, I'd have one unhappy customer on my hands. That was primarily the perspective from which I was posting. No matter what people pay for something, they expect that it will work. And out of the box, this thing falls short of that expectation. And for $210 there are saws out there that will actually work out of the box. And the other thing that will be in that box is a warranty statement.

But as a fun project/fight the cabin fever, why not? In that sense, it's not that different from resurecting a dead saw that's been in a barn for 30 years. And you don't have any crud to clean off. And with your interest in the EQ's, taking a look at one of these 62cc saws is a logical step. I'm also a Red Max dealer and not unfamiliar with the 621 that they are basing these things on. If they would use better materials, the design is at least sound.

Where I mentioned that better results could be realized with a quality used saw, it was not based on social/emotional reasons. It was on the basis that in most cases you would be working with a better foundation and the end result would therefore be a better saw. For example a guy finds a 257 Husky or 038 Stihl in need of a piston and some TLC. He'd end up with a good saw and have continued parts support available as well.

Gotta add here for everybody that on a site like this, whether you like the saw or not, or it's origin, this thread is informative and it let's all of us take a close look at something most of have never seen. So it's cool that Chris is sharing the whole thing with us.

And Chris aint hurting a soul have fun !

 

[Jeff Lary]

Hey Chris,,,good on ya for this one.

Seems a couple of the hard hitters with less than three weeks here seem to have it all figured out,even after never owning a chinee saw

Not enough time for me or enough post's to have established any credability,,,so opionoins worthless ,i would even respond to them

You should discuss it with people you know have something worthwhile to listen too.

Well said

 

[Chris-PA]

i like the old school choke/throttle controls, throttle lock on the side of the handle and simple (and separate) choke linkage. every time i pick up a stihl i have to stop, put on my reading glasses, and figure out which generation of controls i'm using and the new husky controls don't really enhance my operating experience either. also they tend to be bothersome when your servicing the saw. simple is better.. it would be nice if this saw had 70cc's and closed transfers.

It is a really simple design, with the carb bolted rigidly to the cylinder without any flexible couplings, etc. I assume that the simplicity contributes to the low weight. The choke & throttle are very simple, where you must take the choke off manually and the high-idle is a separate control. So far the thing starts quite easily and I have not even used the high-idle prop. A couple of pulls until it hits and away it goes - I usually can shut off the choke after it fires before it stalls.

Closed transfers would be nice, but I was not even sure it has quad transfers when I got it. I think the transfer volume is a little high, but typical for the period it was designed. I wish they had continued development and made a strato version of it.

 

[heyduke]

It is a really simple design, with the carb bolted rigidly to the cylinder without any flexible couplings, etc. I assume that the simplicity contributes to the low weight. The choke & throttle are very simple, where you must take the choke off manually and the high-idle is a separate control. So far the thing starts quite easily and I have not even used the high-idle prop. A couple of pulls until it hits and away it goes - I usually can shut off the choke after it fires before it stalls.

Closed transfers would be nice, but I was not even sure it has quad transfers when I got it. I think the transfer volume is a little high, but typical for the period it was designed. I wish they had continued development and made a strato version of it.

yes, when you said it was a redmax clone, i thought it might be a strato. i have a husky 575 that is a great saw, kind of funny that it sounds and feels really tame but throws chips like it has an extra 10cc's. burns gas like it had 20cc's less.

 

[Chris-PA]

yes, when you said it was a redmax clone, i thought it might be a strato. i have a husky 575 that is a great saw, kind of funny that it sounds and feels really tame but throws chips like it has an extra 10cc's. burns gas like it had 20cc's less.

I'm a big fan of strato so this thing is a bit of an aberration for me, but a 60cc strato saw is out of my range. Once I'm done playing it will be used for bigger jobs and probably felling, but the majority of my saw time will be with the GZ4000 saws. They're still my favorite and can do the vast majority of the cutting I need for firewood.

I ran it a bit today and I'm impressed with how quickly it starts, 1 or 2 pulls hot or cold usually. It feels good and has nice throttle response, and no trouble pulling the 24" bar with square ground chain. I want to try it with the 20" bar next.

 

[heyduke]

I'm a big fan of strato so this thing is a bit of an aberration for me, but a 60cc strato saw is out of my range. Once I'm done playing it will be used for bigger jobs and probably felling, but the majority of my saw time will be with the GZ4000 saws. They're still my favorite and can do the vast majority of the cutting I need for firewood.

I ran it a bit today and I'm impressed with how quickly it starts, 1 or 2 pulls hot or cold usually. It feels good and has nice throttle response, and no trouble pulling the 24" bar with square ground chain. I want to try it with the 20" bar next.

i use two types of saws 99% of the time, a 35cc top handle and a 70cc for bigger stuff, like a husky 272 or 575. or i use bigger saws when needed. we have big cottonwoods here that occasionally call for mr. diggler, my stihl 084. i have a few saws in between the 70cc and the little climbing saws but they almost never get used. still, the redmax clone interests me. it looks like 1980s technology, which is attractive to me. did you remove the cylinder base gasket? .035" is really excessive for a squish band, but common in asian aftermarket parts. the gasket is usually .020". that would give you .015". have you managed to fit it with bucking spikes? can you tell me the distance between the inboard mounting points for spikes? they look close to a stihl 038.

 

[Chris-PA]

The squish was originally 0.050"(!), and the gasket was only 0.017", leaving me with 0.033". I'd like it to be lower and I have access to a decent lathe at work, but it would take a fair amount of time to make the center support and cut it. I'd have to add a decomp then too - there is a boss. I'll see what I think of it over time.

It came with a spike of sorts:

In theory they are available from RedMax, as is a different clutch cover set up for an external spike for $30. I probably won't bother with that.

 

[angelo c]

Boy this thread sounds eerily similar to about 10 thousand posts about "my cheap Chinese chainsaw chain sharpener"

Nice job keeping your cool , Chris.

 

[heyduke]

The squish was originally 0.050"(!), and the gasket was only 0.017", leaving me with 0.033". I'd like it to be lower and I have access to a decent lathe at work, but it would take a fair amount of time to make the center support and cut it. I'd have to add a decomp then too - there is a boss. I'll see what I think of it over time.

It came with a spike of sorts:
View attachment 338263
In theory they are available from RedMax, as is a different clutch cover set up for an external spike for $30. I probably won't bother with that.

that spike looks fine for a 60cc saw.

whoa! that's a lot of squish. maybe you could find one of the botique saw builders on this site who would take another .020" off for you. however, it seems like a big change in port timing. also it's got an odd bore if i recall. was it 47.5mm? don't know if anyone would have a mandrel on the shelf. i've seen other saws run with squish bands like that. if it ain't broke...

 

[Chris-PA]

Nice job keeping your cool , Chris.

Thanks!

whoa! that's a lot of squish. maybe you could find one of the botique saw builders on this site who would take another .020" off for you. however, it seems like a big change in port timing. also it's got an odd bore if i recall. was it 47.5mm? don't know if anyone would have a mandrel on the shelf. i've seen other saws run with squish bands like that. if it ain't broke...

Yeah, it is 47.5mm. Turning a one-time use mandrel would not be that big a deal if I want to pull it down and do it, nor would drilling and tapping it for a de-comp valve. I have trouble with raising transfers, but I could raise the exhaust on this one to account for the couple of degrees I'd lose without bothering the transfers, as it has a 19deg blowdown as it is.

But I'm going to work with it for a while first and see if I think it needs it. I don't have much to compare it with, but I'm actually quite happy with how it runs so far, and having trouble justifying all the work it would take to reduce the squish to 0.020".

 

[Terry Syd]

As far as the transfers go, on the 029 I built with the 390 jug, I'm just going to nip a bit off the edge of the piston next to the transfer ports. I've got 25 degrees of blowdown, so I can play around a bit before I would have to look at raising the exhaust.

I've got a TS-400 piston (its slightly taller) to go into the engine, so I'm going to tweak the stock piston to see how much extra transfer timing the engine would like (if any). Then install the new piston with the best timing figures from the experiment.

 

[Chris-PA]

What I was trying to say was not to stop doing as you do ,but to try something out like a 359 or 261? then you would have something better to gage quality on? to say your no better off spending more on a saw because on paper this saw has AV/ a chain and even a bar and separate oil and fuel tanks ect ect on paper means nothing?..just saying and all ....Get something like said above saw's then go back and say how good the features of this saw are with opened eyes....True story even if Mr google dont think so lol....Like I said Chris PA Im not nocking any of this just saying it can be seen in a different light if one is open to it....Cheers and good luck with it all.....

Yeah, I understood - a saw like that would be neat, but it's just not in the budget. This is the most I've spent on a saw, and it likely won't happen again as I simply don't need any more saws.

 

[Chris-PA]

Hey, this saw is not slow! I took off a low hanging 16" walnut branch that I've been wanting to get rid of for several years now, but I never seem to get it done before it leafs out and then there is more mess to clean up. I figured with the snow cover it would help keep the yard from getting so trashed too. I had to cut at a pretty high height and my shoulder is not quite recovered enough to do it with this saw, so I removed it with the ported GZ4000 clone. Then I switched to the 62cc clone with a 20" bar and some semi-chisel chain to buck it up (and the chain was probably slow as I mistakenly sharpened it at 25deg rather than 35deg).

It really rips along nicely, it revs better than I expected (I had read that the G621 was a low rev saw) and throttle response is good. It is not peaky and has good torque. So I'm quite happy with the performance, especially as it's only had about 3 tanks through it and the rings are probably not well seated. I'd like more compression, but the port timing is good and I doubt I will mess with it further.

Now I'm going to go fix that chain...

 

[heyduke]

Hey, this saw is not slow! I took off a low hanging 16" walnut branch that I've been wanting to get rid of for several years now, but I never seem to get it done before it leafs out and then there is more mess to clean up. I figured with the snow cover it would help keep the yard from getting so trashed too. I had to cut at a pretty high height and my shoulder is not quite recovered enough to do it with this saw, so I removed it with the ported GZ4000 clone. Then I switched to the 62cc clone with a 20" bar and some semi-chisel chain to buck it up (and the chain was probably slow as I mistakenly sharpened it at 25deg rather than 35deg).

It really rips along nicely, it revs better than I expected (I had read that the G621 was a low rev saw) and throttle response is good. It is not peaky and has good torque. So I'm quite happy with the performance, especially as it's only had about 3 tanks through it and the rings are probably not well seated. I'd like more compression, but the port timing is good and I doubt I will mess with it further.

Now I'm going to go fix that chain...

nothing wrong with 25 degree chain. it cuts fast and stays sharp longer than 30 degree. i think the reason oregon has gone to 35 degree is to reduce the chance of kickback.

 

[Chris-PA]

Well, I re-did it at 35deg anyway, and I saw it needed sharpening once I looked at it properly.

The seller made good on the inner bar plate, and shipped it fast too. That should reduce the bit of oil that was dripping down inside - there is certainly plenty for the bar though! The thing really oils, even when turned down to low.

 

[weimedog]

How close are you to the Central New York area? Might be fun to have your saws at one of our GTG's

 

[Chris-PA]

How close are you to the Central New York area? Might be fun to have your saws at one of our GTG's

I'm south of Allentown on the Eastern end of the state. My saws are entertaining for me, but they're pretty dull compared to some of the new high tech equipment out there now!