Porting a Chinese G621 Clone

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It's not pulling enough fuel to the carburetor at wide open throttle under heavy load.
 
Maybe, but then why would the adjustment to the carb help, as it did? Definitely better after the adjustment, took longer to stall
 
Turn both screws all the way in (count the turns) then back each one out a turn. The more oil in the gas the richer the carb setting needs to be.

Start from zero, even back the idle speed screw out.
 
Also, I had a new Chinese saw, that even with the carb readjusted when at full throttle it would die down after 1-2 seconds. It ended up being a bad carb...
 
Okay, adjusted as advised, not able to go into paddock and test high speed, but idle was moving the chain after L and H was adjusted, so turned T back - fixed. Attempt to gun the engine showed the engine was reluctant, when cold, to accelerate. Tried to bog on acceleration (blade not in a cut). Got slightly better as engine warmed up. I presume L needs to be tweaked. That's all the testing I could do here, getting dark.

Interesting what the filter looks like; I've asked for a replacement. Also, I had to ream out the hole in the air filter cover so the twist screw that holds it down could meet the female part at the right angle.

filter2.jpg
 
If it still gives trouble after adjusting the carb i would look at replacing the impulse hose next. I have struck a few of that model saw that have an impulse hose that is too thin in the wall and will suck in when the saw warms up, causing it to run lean because the fuel pump will not pump when the saw is warm. I have had one that melted the plastic impulse nipple on the crankcase that caused it to run lean too.
 
The first thing I would try is to get the tuning right, but I cannot tell if it's rich or lean. It's an entirely conventional carb so tuning should be just like with anything else. Although I would not run it at 20:1! Mine is fine at 40:1.

If it can't be fixed by tuning then I'd be looking for some sort of fuel flow restriction.

Did the cover do that to the filter, or was the filter messed up to begin with? Often these things need plastic flashing cleaned up as they skip that step - just like Stihl did on my Dad's MS250.
 
Anybody tried to swapt that plastic nipple impulse from the crankcase with a metal one?
I hade my case apart but I coudn't unscrew that nipple so I lefted like that.
 
If it still gives trouble after adjusting the carb i would look at replacing the impulse hose next.

Thanks Thommo, that will be my next step if the tuning fails.

Although I would not run it at 20:1! Mine is fine at 40:1

Just following the manual.

scan0001.jpg

Did the cover do that to the filter, or was the filter messed up to begin with?

The damaged side was facing down, to the chassis. The seating area looks free of malformation problems, so ... just a bum filter.
 
Anybody tried to swapt that plastic nipple impulse from the crankcase with a metal one?
I hade my case apart but I coudn't unscrew that nipple so I lefted like that.
The nipple is a press fit. The bottom part that is pressed into the crankcase is brass with plastic molded onto it. i just pulled it straight out with a pair of pliers. I made a new nipple by breaking the plastic off the original one and making a new top half out of brass and then silver soldering the two pieces together.
 
Okay, I pulled L out another half turn and it guns easily and quickly. Needed to be slightly richer.

Raining now, so cannot go out and test H in wood cuts. But I turned it back another ½ turn (richer) because I believe it's better to be a little too rich than lean on that end. We'll see. It's still much less rich than it was.

I see from the other thread on chinese saws that one of the most common complaints is that they come set waaaaay too rich from factory.
 
It's running well now. L is out about 1.75 turns, H is out 1.5 turns.

Manual states L should be 1.25 (much too lean, won't accelerate) and H should be 1.4, which is about right (but much leaner than they sent it from factory).

Cut some big timber, drained the bar oil, drained fuel, ran the carb dry at idle, and into storage it goes as a backup in case any more big trees fall here. Meanwhile, for all the small chainsaw work, I'll keep using my little battery-driven Makita chainsaw with olive oil as bar oil. ;)

Oh, and BTW the eBay seller of the Chinese saw (Giantz brand) is sending me a new air filter, gratis.
 
Let's keep this long *** thread going. Looks like these are now being sold in the states under the x-bull brand now for 150. I put in an offer on ebay to for 135, see if they take it. Chris is yours still going strong? Also what size offset keys for the crank does this use I want to throw some in my next mcmaster order.
 
This is probably necroing an old thread but see its replied to off and on.
I have bought a few Baumr-ag saws from ebay in Australia. I bloody love them.
Once you understand its not in the same range as a stihl or husky your good to go.
Ive used a mates stihl and its definitely better but for me to cut 10 ton of wood a year for heating I couldnt justify the price.
I started off with the 66cc and then got a 62cc (knowing they probably werent that size) i think they combine the barrel and head cc's to get that rating....
Used them both for a few years then got a 75cc purely because of the better looking air filter. Then won a 92cc from a competition with the distributor edisons ebay store. So sold off the 62cc and 66cc ones.
All i done on them was tune the carbies up. I ended up selling them for more than I paid as they cost more to buy new by that stage. Both only done about 8 hours.
I run castrol power1 oil at 20:1 i have pulled the plugs out and the piston still looks new. I could probably run them at 40 or 50:1 but for the little bit of extra oil its worth it IMO.
The 75cc started and adjusted the carb and off i went.
The 92cc that I won looks like it was a return that they sent as it had some marks was missing packaging and when i started it it was having issues. I couldnt adjust the carb enough to get it to run.
Worked out it must be sucking air so 10 minutes later had the carb off and removed a metal ring that was in the rubber mount holding the carb to barrel. Figured that was causing the rubber mount not to seal properly. Bolted it back together and worked perfectly.
the chain adjuster broke on it but think that was when I had the missus adjusting the chain and she didnt loosen the nuts off...
All in all running 2 saws for under $400 (price of 72cc was $125 and 92cc was $250) when i got them a yr n half ago. I couldnt get anything close in stihl or husky and if i break 1 I still have the other one and can swap parts between. And just buy another.
Pity the price has gone up quite a bit lately and now they are also charging shipping so would re evaluate if they ever break.
 
I'm new here, but yeah,I agree with what you said.

There certainly seems to be quite a bit of difference in quality between the different brands available.
I'm also in Australia and have had a baumr-ag (62cc mk3) for a while, I recently realized I've had it 4 years, hasn't missed a beat, only issue is of course the air filter setup, I've modified it but will be fitting up a proper pleated one shortly.
I honestly think it is similar in performance to my 034 stihl, which I think is impressive, considering it was originally $159 AU delivered.
I think they are now pushing nearly $300.
I've just bought another 62 cc saw, is much the same, but is one of the earlier 62cc saws available standard in aus with the better air filter, double post chain brake handle, auto lock/release choke and just generally better build quality. It's a perla barb brand, time will tell what it holds up like but it seems good.
Cheers
James
 
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