Any Chinese chainsaw and chinese parts discussion

[Czed]

That's the Zama C3M twin jet. Notice there is a brass jet on each side of the welch plug. One jet is for the idle/transition circuit and the other jet adds additional fuel to the low speed circuit at about 1/4 throttle.

Thanks i will try to find some that's the one you guys had the best results with right.

 

[Terry Syd]

Yeah, that's the easiest carb to dial in. All the low speed functions can be changed independently from the other functions.

Just because a carb is marked C3M does not mean it is a twin jet. I have a C3M off of a 044 that is not a twin jet and Rich apparently has a bucket full of Chinese C3Ms that are not twin jets. You really need to pull the cover off the wet side and confirm it has the two jets.

Let's see what Rich comes up with this carb. Maybe a modded stock carb might be close to the Zama.

 

[Poleman]

I like that you numbered them.... I've done that with carbs, that way I can document by number and what I've done.
I like your wrap also!!!
Terry, I got so spoiled with the Zamas and there knock offs the other carbs can be a challenge!! Lol

 

[Poleman]

I think the stock carb has potential....if one can figure them out. The one thing I noticed with them is they have a lag during transition but run good above and below.
I'll see what happens with the changes I made and will go from there.....I have all kinda ideas....kinda process of elimination.

 

[Czed]

I like that you numbered them.... I've done that with carbs, that way I can document by number and what I've done.
I like your wrap also!!!
Terry, I got so spoiled with the Zamas and there knock offs the other carbs can be a challenge!! Lol

Those oem husqvarna wraps are still available at bailey's for 29.99 i bought 5 lol
Lefty here.

 

[Terry Syd]

Rich, once you have the Zama dialed in, then you will have a benchmark to work towards with a Walbro clone.

Did that HD-12 have an auxiliary jet in the low speed circuit? I know that the HD-5 I modded did. Perhaps if a HD-12 had the auxiliary jet, then with a bit of tweaking to the jet and the metering spring they would be a good option.

EDIT: Oh yeah, there is also the issue of the low speed circuit being joined to the main discharge nozzle. - Good luck Mate! LOL, Like I said, if I build another carb, I'm going to find an old twin jet to work on.

 

[Poleman]

Terry, the HD I'm using if off a Solo and it's a 43.
HD 43


This is the changes I did to the 43. I opened up the intake needle and enlarged the feeds into the main jet.
These carbs seem quite adaptable to different saws. I have run it on a Dolmar with a Solo P/C and it runs good but it really shines on 79cc & 84cc big bored. It produces quick throttle response on both with a slight advantage to the bigger saws but produces great torque from anything it's on. It seems like a very forgiving carb.

 

[Poleman]

I like Baileys but I had my credit info stolen a few years back when they got hacked and I have trust issues....took me a long time to get things straightened out. Still would like one tho!!! Lol
I found some note on a Zama on an 044 I forgot about..... as I recall that on worked good. Haven't done one since tho.

 

[Terry Syd]

Perhaps that carb gives you a hint. It looks like the low speed circuit has a separate feed hole for fuel from the wetside. In other words, it doesn't look like the low speed circuit is fed from the main discharge tunnel.

I would expect that having the two circuits separated would make the carb more consistent and easier to tune. I noticed when I separated the circuits on a Walbro, both the idle and WOT RPM became more consistent. I could understand why the idle was more consistent, but bugger if I could come up with a plausible theory why WOT was more consistent.

 

[Terry Syd]

I found some note on a Zama on an 044 I forgot about..... as I recall that on worked good.

The 044 carb wasn't a twin jet, HOWEVER, the H and L circuits were not joined together.

 

[Terry Syd]

Rich, my theory on why Walbro joined the H and L circuits is related to EPA regulations. They didn't want excessive emissions when the RPM dropped. The change created a carb that had to be run fairly high in the RPM range or the torque would drop off fairly quickly.

My theory is that once the revs were up and the carb was flowing through the main discharge nozzle, then if engine revs were pulled down, there would be less fuel available to the low speed circuit. This is because the main discharge nozzle is creating a low pressure not only on the H needle, but ALSO on the low speed circuit. The low speed circuit just can't flow like it would if it had direct access to the wetside.

By going back to separate circuits, each circuit can be fed directly from the wetside. You may get more hydrocarbon emissions, but you will also get more torque down low. You will also get less interaction between the two circuits pulling on each other and thus a more stable fuel mixture.

 

[Adamski]

View attachment 70160 I used a 372 mahle cylinder and just cut the 268 piston down flat topped with base gasket to around .20 squish I've got three more 268 pistons to play around with.
Ran a tank through today has descent torque and a good topend.
I need a tach it revs high seems a lot higher than the double ring huztl that was in it .
I was worried that with the piston being shorter it would be hard to tune no problem at all holds tune good no idle issues no dead spots i will have to try it and the other mahle at the same time to feel the difference. View attachment 70161 View attachment 70162 View attachment 70158 View attachment 70159

How much do you recon you took off the 268 piston? I am seriously wanting to up the compression on my 372xp w/ a base gasket delete it is still the same old aweful squish. What brand of 268 piston did you use?

 

[mdavlee]

If you don't mind $110 for a piston the Dominant wiseco has a popup on it. With a gasket delete they are coming in around 170-175.

 

[Adamski]

If you don't mind $110 for a piston the Dominant wiseco has a popup on it. With a gasket delete they are coming in around 170-175.

If you are replying to me I am all up for DIYing everything I do. It's all a learning curve and fun, I think I will buy a cheap china £5 piston, do the maths and the machining work on it and then see if it runs, If it does then I'll invest in a Meteor one and repeat the process.

 

[mdavlee]

I was just throwing it out there for info. It is a little salty but compared to machine work, new piston, and shipping it's not that bad.

 

[Adamski]

I was just throwing it out there for info. It is a little salty but compared to machine work, new piston, and shipping it's not that bad.

yeah no problemo, wasn't trying to be *b-wordy

Just wanting to get my 372xp up to and past the torque levels of my ported 038 mag so that the saws don't keep having a d**k measuring competition with each other every time I wanna cut some wood. Would just like my 372xp to eclipse the Stihl and me done with it.. Currently it does not..

 

[mdavlee]

yeah no problemo, wasn't trying to be *b-wordy

Just wanting to get my 372xp up to and past the torque levels of my ported 038 mag so that the saws don't keep having a d**k measuring competition with each other every time I wanna cut some wood. Would just like my 372xp to eclipse the Stihl and me done with it.. Currently it does not..

I've never been impressed with a 038 or a stock 372.

 

[Czed]

How much do you recon you took off the 268 piston? I am seriously wanting to up the compression on my 372xp w/ a base gasket delete it is still the same old aweful squish. What brand of 268 piston did you use?

Around .30 give or take even though it's a mahle they all vary of course the huztls have large squish on all them.
2.93 huztl website pistons they are pretty nice especially for the price.

 

[Rob Stafari]

I like Baileys but I had my credit info stolen a few years back when they got hacked and I have trust issues....took me a long time to get things straightened out. Still would like one tho!!! Lol
I found some note on a Zama on an 044 I forgot about..... as I recall that on worked good. Haven't done one since tho.

I wasn't part of the hack, but that's why I didn't order a wrap for my 394 when they dropped the price. From what I understand you can pay with paypal which offers some protection, but I don't have one of those set up as of yet and not sure I really need one other than to order a wrap handle.

 

[Czed]

I wasn't part of the hack, but that's why I didn't order a wrap for my 394 when they dropped the price. From what I understand you can pay with paypal which offers some protection, but I don't have one of those set up as of yet and not sure I really need one other than to order a wrap handle.

Prepaid credit cards is what i used to use it just takes a few minute's to set up my paypal account in thousands of purchases no issues at all.