Any Chinese chainsaw and chinese parts discussion

[Czed]

Not sure....I'll see if I can hold it down and get some pulls on it tomorrow and give a report.

No big deal not important.
i thought you might have a saw vice I'm going to invest in a good one like the treemonkey one.

 

[Poleman]

I sure want one, and sure liked Scotts!! Guess I'll have to get creative!! (Dangerous thought)
Instead of getting a compression reading I compared carbs to make sure they were the same as all the ones I've ordered and came in single jet. I tore one apart to get some ideas and find what I missed the first try. My initial thoughts on introducing more fuel was dashed when I tapped out the main nozzle expecting only one hole, but there were two. The Hogh side is pretty easy to figure out but the Low appears to be just pressure/velocity feed. I could not find a passage connecting to the main. There is still a Welch plug to remove but it's of a size I don't have. It look like it's above the idle/mid transition bleeds. That might be the key but of no use if you can't reseal if the mod would take place under it.
That was more my concern at the moment. I wanted to get a better look inside the carb and get an idea of passages and feeds.m

 

[p61 western]

Together and running. It has no power though.

Ported...intake and exhaust matched. Base gasket delete still only got me down to .036 squish. Pressure and vac good. .
.. but comp at 120 only .

It runs and idles...just doesn't have much power in the wood.

View attachment 67931

This kind of sucks. I'm very curious as to what you figure out is going on with it. I have one on order but it will be a while before I get it.

 

[Mattyo]

it pressure checks well...comp is a tad low, and thats a mystery... but i've seen husky 350's run well at 110 psi comp....

it is IS doing some backfiring... a little bit....

its just a freakin lazy type o saw.... I ran it a little bit today. starts, runs, idles...more or less. revs ... more or less. just lazy

 

[Terry Syd]

That was more my concern at the moment. I wanted to get a better look inside the carb and get an idea of passages and feeds.

Rich, it looks like the carb may have a low speed circuit fed by the high speed circuit off of the high speed needle. (it appears it is done this way to reduce the emissions when you drop below peak torque)

If you take some WD-40 and spray it into the various orifices (remove the low speed needle and spray in through where the needle comes in) you may be able to see where the passages lead to.

On those type of carbs, I block off the feed hole in the main discharge nozzle tunnel with a bit of GB Weld. Then, I have to drill a hole through the wet side to feed the low speed needle. Those mods will separate the circuits so they can be tuned individually (then play with the spring/pre-load to dial in the idle and transition).

It also looks like there may be an auxiliary jet to feed the low speed circuit. I can't tell from the pictures, but if you spray some WD-40 through the jets you can see where they come out. If it is an auxiliary jet, then, just like with the Zama, you can drill out the auxiliary jet to bump up the low speed circuit flow to get more low end torque.

Good luck - you're in new territory LOL!

EDIT: When you separate the circuits, you will have to dial in the idle and transition using the low speed needle (it will work like drilling the idle/transition jet on the Zama, but will be adjustable). If you get a good transition, but lousy idle, you may have to shim or change the metering spring. These carbs will be a pain in the butt compared to a Zama, but once you have the right combination, you have got some valuable information.

 

[Poleman]

Thanks Terry, I was thinking along those lines thinking about some of you other posts in other threads. I remember some of them and was going searching but you saved me a lot of time. I get rereading post and I forget what I was there for...lol.
I remembered the WD-40 trick...that was my next step to see if the H&L are connected. I was looking with my magnifying glasses and a good light and couldn't see anything but felt there was.... somewhere. I'd like to pull the Welch plug to look under that but don't have a replacement, so I'm reluctant.
We....I have some time while I wait for a tank!!!
Chef, I piped the saw over a couple time on my way to work this morning... it will be interesting to see what it is now that I've cut the base. My guess is 175 area and not broke in.....we'll see!!

 

[Czed]

it pressure checks well...comp is a tad low, and thats a mystery... but i've seen husky 350's run well at 110 psi comp....

it is IS doing some backfiring... a little bit....

its just a freakin lazy type o saw.... I ran it a little bit today. starts, runs, idles...more or less. revs ... more or less. just lazy

Do you have an oem coil and carb or even a flywheel just to try it has to be something even the four 365s were decent runner's they would have made fine everyday firewood saws.

 

[Mattyo]

I've got all kinds of goodies and ideas....just need the time to try them.

I'm desperately trying to play catchup with my youtube stuff. Got lots of vids to edit. ...especially the bolt for bolt on this 372.

I have a pile of carbs coming....ebay....including a zama.

 

[Czed]

I've got all kinds of goodies and ideas....just need the time to try them.

I'm desperately trying to play catchup with my youtube stuff. Got lots of vids to edit. ...especially the bolt for bolt on this 372.

I have a pile of carbs coming....ebay....including a zama.

Good i just mess with mine after work and on the weekend's i'd like to run them more but i don't have time hope you get yours where you like it.

 

[Terry Syd]

I'd like to pull the Welch plug to look under that but don't have a replacement, so I'm reluctant.

Yeah, I hate working with 'assumptions'. Good luck!

If the H & L are joined and you seal off the L port in the nozzle tunnel, you then have to drill through the wet side to feed the L speed needle. It looks like there may be a 'dimple' on the carb to indicate where that hole should be. There was a dimple in one of the other carb threads.

What you need to do is bottom the L needle and measure how much needle sticks out of the carb. Then remove the needle and lay it on the top of the carb to see where the needle seat is. Hopefully, that dimple will be spot on to drill a hole about 2mm away from the seat (you don't want to bugger up the seat).

When you drill the hole, I mount the carb in the vice so that the L needle hole is pointing downward. That way if there are any shavings that drop into the hole, they can drop down AWAY from the welch plug (you don't want any shavings to go under the welch plug if you aren't going to pull it). Then give it a spray of something to flush out the needle passage.

 

[Poleman]

Czed, only was 150 with assemble lube in it......

 

[Poleman]

Ok, so far I haven't found a channel between the H & L. What I have found this is the feed for the L. It goes from here to the needle channel where it's richened or leaned going into the area beneath the small Welch plug where it's drawn into the air mix going through the carb and this draws the mix out the bleed holes. The main one measures .50mm. The transitions are smaller adding fuel until it moves to the H circuit.



Now comparing this carb to the Zamia C3M, it has very similar design just without the jets.


Two Zamas sandwiching the Hutzl carb. One Zama with jets and Welch plug the other stripped down to show similarities with different use of jets and Welch plugs.
Thoughts here....drill a small hole in the Welch plug for more feed. But there is a chance of pressure loss and back feed.
Second, increase the size of the bleed hole to .55mm slowing more fuel to pass.
Those are the two ideas so far.

In reflection this carb is simpler than the twin jet....just need to figure out how to improve it in a simple way so it can be easily duplicated by others.

 

[Poleman]

Oh ya.... gave the saw a squirt of mix before I put the plug in....fired and ran a couple seconds first pull....I need a taaaannk!!!! Lol sounds like a runner!!!

 

[tp2177]

Maybe a dumb question, but how would you guys think one of these would hold up to milling? My biggest saw is a cs-590. Would these be ok for nothing bigger than 18 inches milling or would keeping my eyes out for a 288/390/395 parts saw be better?


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[Terry Syd]

My 77cc Big Bore, with the modded Zama has heaps of torque for cutting Ozzie hardwood. I run a 24" bar and an 8-pin with bar buried. With a 7-pin it would run a longer bar.

As far as cooling, I prefer to run with the 'air injection' system blocked off. I just fill the plastic intake to the flywheel with liquid rubber. Here's why - when you bump up the power on these saws (like going from 65cc to 77cc, and a muffler mod) you are pulling more air into the engine. That air comes through the 'air injection' system. - As you increase the power, you increase the heat of the engine, while at the same time you are SUCKING MORE AIR OFF THE FLYWHEEL! - You're increasing the heat of the engine at the same time you are reducing its ability to cool.

If you block off the air injection system and put a few holes in the back of the air box, you will be blowing more air across the fins than a stock saw.

A cooler running two-stroke not only is more reliable, but it makes more power.

 

[Terry Syd]

Rich, I've never seen circuits like that before (WTF!) So you've got two holes in the nozzle tunnel - I expect one hole leads to the High speed needle to feed the nozzle, but what is the other hole for??

Also, looking up the carb throat, I see the idle port and then two transition ports in line with the idle port. However, I can't see where the idle port could fit under that welch plug.

OK, you may have to pull that round welch plug and see what is underneath. I wouldn't worry about the availability of having another welch plug to replace it. Just take a thin piece of metal (even a piece of tin can) and make a lid to put over the area, spread a thin coat of GB Weld around the open area, put on the lid and add a bit more GB Weld around the edge of the lid.

I really don't like the look of that carb as it doesn't have an auxiliary jet to bump up the low speed flow. You may have to source a different carb to get the performance you're used to.

What about that HD-12 you had? Does that have an auxiliary jet for the low speed circuit? If so, maybe some Chinese HD-12s might be a good choice to mod.

 

[Poleman]

See Terry what we're all up in arms about!! This carb replaced the twin jet. I took a run at this one last summer with results but not consistency. I framed it unworkable and quit messing with them.
The nozzle only has one hole from the H, the low doesn't go into it or the H channel. It looks like the idle and trans all are fed through the bleed holes that are fed from under the Welch plug from a channel from the L needle which is fed by the hole on the wet side. That hole is covered by the Welch plug on the C3M's.

 

[Czed]

The mahle is on it's second tank both 50mm saw's set up excactly the same new 18 inch bars and chains that came with.
both huztl double ring pistons one huztl one mahle cylinder the only difference the mahle has a little more torque midrange wfo they are close in my hands neighbor said the same.
I did work on the huztl cylinder a lot comp is not impressive 120-130 on both but i need to try another gauge because both of these are a *b-word to start.

 

[Czed]

 

[Czed]

I didn't cut the base on any of them nobody around here does it.
I've got a bunch of oak and pine to cut.
I will keep running the first saw to get as much time on it as i can so far nothing at all is wrong with any of them.