Carbs are carbs let them be carbs

[Naked Arborist]

Electronic carbs sucks!!!!!!!!!!!!!!!!!!!!!!!! and here is the worst case I can think of. Remember the early 80's when GM decided to put electronics on Rochester Quadrajet carbs? If you ever worked on one or owned one of these terrible designs you do see my point. They ran great till one of the many little electronic gizmos had a faulty signal or got the least bit of dirt or grime in them. We won't even discuss what happened to them when carbon came into play. If they did have any problems at all they ran like crap wasted motors and just down right wasted fuel because they would go super rich and gas wash the engine till it wiped them out. Not to mention the entire emissions
management system that went along with the whole mess including exhaust air injection ROF LMFAO. If they went lean the power was gone, mine you they did great on fuel till you smashed the pedal to the metal and the pistons became fuel. Ever seen a quarter or fifty cent piece fall through the top of a hole in a piston? Takes about three seconds to burn away, nuf said there.

Mark my words now this will happen to electronic carbs on anything and the problems will multiply as they keep adding more gizmos to control the other gizmos. I say "gizmos" so it keeps this in lay-mans terms for the masses. I you want the true opinion of a pro just go ask your over 40 years old mechanic how well the electronic carbs from early 90's GM vehicles ran in reality. This could be a whole "nother" thread at a minimum!

If they want to get it right go to a true fuel injection system and stop trying to update a time test dependable piece of good ol fashion know how like a simple (carb-a-taytor)

I retro-fitted (reverse engineered) so so so many GM cars back to the time tested GM Q-Jets or spread bore Hollies with a "curved" GM HEI non-electronic computer controlled distributor (no EST) that it became almost a full time job back then. They all, every single one of them, got better economy, better drive-ability, reduced emissions, better cold starts and a slew of other good things. It was just a no-brainer to do. Say what you want but we took them through state inspection just to prove to our customers that this was the way to go and the people just kept on coming and coming.

If your leaving the carb behind then do so and don't try to put another "gizmo" on it. If your going to true fuel injection then do so and leave that half baked TBI CFI SPI all (throttle body injection crap) in the trash where it belongs!!!

Has anyone ever seen a "DR.-erd up" carb last more than ten years in production? Bring it on...

 

[Joe Kidd]

opcorn:

 

[RandyMac]

They are pandering to the lowest common denominator and EPA, expect worse.

 

[kodiakyardboy]

Hopefully not the beginning of the end but likely is:msp_sad:

 

[Chris-PA]

Yes, GM did make crap. Still do. :hmm3grin2orange:

If you don't care about emissions then systems to control it certainly don't make sense (I do). And even non-feedback Q-jets were the most horribly overcomplicated carbs, but that was typical of GM/Rochester (they were not made by Carter). But feedback carbs on cars were not required by the EPA, that's just the garbage that the manufacturers foisted on their customers because they didn't want to invest in R&D. Then they did throttle body EFI, again because it was marginally cheaper. In fact, the feedback carbs on Fords I drove worked fine, but now they have real engine control systems and EFI that provided far better performance, along with better mileage and less pollution. The new direct cylinder injection, combined with variable valve timing is yet another huge step improvement in both performance and efficiency.

However, fuel injection offers zero advantages on a single cylinder engine, especially a 2-stroke. A carb is fine. Unfortunately, chainsaw carbs cannot even perform one of the most basic functions a carb needs to do, which is to provide a constant fuel/air ratio as load varies. They could have fixed that all along, without electronics using old standard carburettor technologies, but it would have cost a few cents more so they didn't bother, and people who used them never made a fuss - gas was cheap and no one cared about pollution, and if you tuned them filthy rich then they didn't burn up all that many engines.

Compared to a proper carb the feedback carbs offer better fuel control over a wider range of conditions, less pollution, more performance, and don't require the operator to know anything about tuning. And the system has almost nothing in common with the systems put on car that the OP complains about.

I'd rather have a good non-feedback carb, but there are none on chainsaws. So given that, I'd rather have AutoTune or M-tronic than that garbage that are passed of as carbs on chainsaws.

 

[albert]

I'm very satisfied with all my saw carbs. If they are in good working order and properly tuned, they work perfectly for what a saw is designed to do. They need to idle, accelerate and run wide open. If you are bogging the saw enough to go too lean, then that trouble is the operator not the carb. If you don't set them to the ragged edge, they seldom need adjustment. A saw carb does not need all the metering circuts that a car or other engine that needs precise metering at all throttle positions. I'm not knocking the new auto tune carbs, but don't understand the knocking of the conventional simple carbs either. By the way the I never thought the Qjet was an overly complicated carb. It is a very easy carb to work on and is very easy to customize to special needs. You can do 90% of any internal work rwithout removing the carb from the manidfold.

 

[Naked Arborist]

Thanks for correcting me on the Carter misprint. Bad ol' habit I have.

As far as Q-Jets being to complicated your right they were but, if you know where to look and what to tune you will never get a Holly to give as smooth of a part throttle response as a Q-Jet and they will get noticeably better economy when tuned correctly. The Holly just always has that flat spot even with the right two stage power valve installed. The Q-jet has such a smooth system for fuel delivery when using a two step metering rod arrangement and progressive rate spring under the metering rod vacuum plunger. Most folks do not know about these tuning capabilities on those carbs. Another key feature is they have down leg two stage booster in some models. The only advantage to a Holly is the angular booster that deliver a more even fuel charge to each cylinder on certain intake manifold setups. This can be corrected by angling the carb 15 degrees as is built in on most Big Block Chevy after market ones.
The Holly is joke when it comes to sealing up the bowls, metering blocks and the floats always drown when you try to make them fly through the air. I spent a lot of time inside of both and they both have some short comings.
A daily driver I'd go with a Q. For off road beatings I'd go with a Holly.

Time will tell on how well these new self adjusting carbs pan out. You will see many more smoked 2 strokes from lean outs.

 

[Tzed250]

I like my AutoTune saw...

 

[TK]

Default rich in a 2 cycle is different than in a 4 cycle.

A 4 barrel carb is plenty different (even a 2 barrel) than a saw carb.

Give it 10 years before you call it crap.

You have one example, that being GM in the 1980's. What else? You need to convince me using an apples to apples comparison.

Where's Wiggz?

Why are we talking about vehicles and TBI and the 80's?

 

[kwhite1271]

I'm not saying that new technology isn't good. But at this point seems like there are still too many bugs to be worked out. Look how long it took for the auto industry to get where they are after fuel injection became popular in the 80's. Not ready to trust my fuel mixture to some smart carb.

 

[GASoline71]

Q-pukes suck... Carter/Edelbrocks suck...

When ya wanna make power... bolt on a Holley.

Wait... were we s'posed to be talkin' about saw carbs?

Gary

 

[aus71383]

I don't think the comparison is very accurate. My first few cars were carbureted - I liked it being all mechanical, stuff I could physically change and adjust. Technology isn't a bad thing though. Almost anything can be made more efficient with a little bit of electronics and/or software added in.

Fuel injection for a chainsaw/2-stroke sort of makes sense from an air/fuel flow standpoint, but I'm guessing it would be heavier than a carb, and the carbs are working so far so why bother developing new 2 stroke technology other than adding a few sensors and a solenoid?

From my limited understanding the AutoTune and M-Tronic are basically an electronic choke, and a powerband-seeker - all controlled by a solenoid and some simple software. As long as they thought to toughen up the components I don't think it's going to cause a lot of problems. Been reading a few threads with teething problems on some of the new saws - but I bet there are a lot more saws out there not making it to internet fame because they work great and there's nothing to rant about.

All just my opinion - but I decided to buy one.... so I guess we'll find out what happens when it shows up! At least my money is where my mouth is.

Austin

 

[discounthunter]

time will tell. but also to work out bugs things need to real life tested,ie put it out in the real world. then things get improved(sometimes). id be curious as to the longivity of these new saws with electroncis in them as electronics tend not to like sitting for long periods of time in non-use states as in putting your saws up for winter or down here summer. we'll see how that works out,time will tell.

 

[Whitespider]

So.... does anyone remember Ford's variable venturi carburetor from the late 70's, early 80's?
And, if you remember them... did you actually know anyone who could actually work on them and make them work?
(I still have a couple of those in a box somewhere)

 

[jropo]

I keep seening the word fuel injection when I'm reading these threads about AT/MT.

Fuel Injection is not a new idea when it comes to two strokes.
The Wedge (80's) chassie Polaris snowmoblie I think its XLT had it. And most of them have been converted to carb.
because of issues, parts, battery dies and your stranded, ect.

On a saw, wouldn't you need a electronic fuel pump, and fuel pressure regulator?
How long would it take before we see "How do I convert this to carb" threads popping up.

Just give me a carb.









Said the guy that wants Holley pro-jection for his 289 Ford.

 

[TK]

time will tell. but also to work out bugs things need to real life tested,ie put it out in the real world. then things get improved(sometimes). id be curious as to the longivity of these new saws with electroncis in them as electronics tend not to like sitting for long periods of time in non-use states as in putting your saws up for winter or down here summer. we'll see how that works out,time will tell.

Exactly!!!! These things need to be put out there to see what happens so they can make improvements. Can't just leave them in the back room and expect the bugs to work themselves out!

And when someone has a problem with the saw - the manufacturer wants to hear about it! If you just get ticked and toss the saw aside it does nobody any good. That would be considered counter productive in my book.

 

[Chris-PA]

Thanks for correcting me on the Carter misprint. Bad ol' habit I have.

As far as Q-Jets being to complicated your right they were but, if you know where to look and what to tune you will never get a Holly to give as smooth of a part throttle response as a Q-Jet and they will get noticeably better economy when tuned correctly. The Holly just always has that flat spot even with the right two stage power valve installed. The Q-jet has such a smooth system for fuel delivery when using a two step metering rod arrangement and progressive rate spring under the metering rod vacuum plunger. Most folks do not know about these tuning capabilities on those carbs. Another key feature is they have down leg two stage booster in some models. The only advantage to a Holly is the angular booster that deliver a more even fuel charge to each cylinder on certain intake manifold setups. This can be corrected by angling the carb 15 degrees as is built in on most Big Block Chevy after market ones.
The Holly is joke when it comes to sealing up the bowls, metering blocks and the floats always drown when you try to make them fly through the air. I spent a lot of time inside of both and they both have some short comings.
A daily driver I'd go with a Q. For off road beatings I'd go with a Holly.

Time will tell on how well these new self adjusting carbs pan out. You will see many more smoked 2 strokes from lean outs.

Q-jets worked well when they were properly set up, they're a cross between a fixed jet and a variable venturi carb - a fixed venturi with a variable jet. The Holleys worked well too, in spite of the stupid design of the fuel bowls (they did not really leak all that often). I just prefer good fixed jet carbs with fewer moving parts and less complexity.

But this is part of my point - carbs were completely developed technology extending to complexities way past what you need for a chainsaw. There's no reason for a carb to run rich when the airflow increases, nor to get lean when it decreases. Placing the bowl vent (diaphragm vent) behind the air filter is just simple proper design, and getting this stuff wrong is just a design defect. You should not have to set the idle rich so it can accelerate, although you could make the argument that a saw is really a constant speed engine like a tractor or a mower, and an accelerator pump isn't required. On the other hand fuel was $3.89 a gallon last night, and mid grade was $4.09, so I'd really rather the fuel I use were doing something rather than blowing out the exhaust. But putting an accelerator pump on that doesn't work or fails (like the ZAMA C1Q's on the 200T's) - that's absurd.

As far as seeing many more smoked 2 strokes from lean outs - really? We're comparing a system with active control of the mixture to one that cannot control the mixture at all, and presently causes a huge number of saw failures. I'd have to go with the design that at least was intended to provide a constant fuel/air mixture, and your saw carb was not designed to do that.

2-stroke engines do not have a 4-stroke mode, that's misfire from a too rich mixture - but at least it doesn't hurt anything. It's the other direction that's a problem. When it leans out it doesn't make a distinct sound, it just damages engines. So you have to set it to be rich under all circumstances, only getting to a correct mixture under max load. If the carbs worked properly then the saws would not be near so sensitive to being a little lean. 2-strokes are not really that delicate - it's the carbs.

So.... does anyone remember Ford's variable venturi carburetor from the late 70's, early 80's?
And, if you remember them... did you actually know anyone who could actually work on them and make them work?
(I still have a couple of those in a box somewhere)

The 2700/7200VV carbs were interesting, and not really very complicated actually. I remember reading articles on them when they came out, even an SAE journal. But the 2150 worked better, even for feedback control, but that's no surprise as it was the best production carb made other than a Weber. When I still had my Jeep I was looking for a 2700VV to swap on in place of the 2150, just to play around and see if I could improve the mileage, but I never got one.

Other constant velocity carbs had long and illustrious histories, like SUs and various motorcycle carbs. Wlbro and ZAMA even made CV carbs for 2-strokes, but they controlled the jet by throttle position, not air velocity, so they're just another cheese.

 

[sachsmo]

Carbs are carbs.

Fuel injection is a little more fuzzy.

I will agree, the jury is out on AT/M-tronic, who knows what a 2-3 year sit on the shelf will do to these "gizmos".

No one likes change, but I can see the OPs point with the '80s "technology".

I for one don't like stuff that takes away the operator/tuner input.

 

[one.man.band]

cars:
carb.............screwdriver.....driveway fix
electric carb......voltmeter/sunpro.....driveway/mechanic fix
throttle body/computer....voltmeter/sunpro....fix dealer/mechanic only for first few years.....then primitive consumer code readers became available
fuel injection/computer...code readers.....fix dealer/mechanic only for first few years...then consumer code readers/programmers(10+ years later)
direct injection/computer...?

garages on every street corner started to vanish after every change of technology as customers switched to newer vehicles. most driveway mechanics went from fixing everything, to changing oil.
how many indy garages could keep up with $5000 to $10,000 computer updates? not many.

saws:
carb...yes
electric carb.....yes
throttle body...(not yet, as far as i know)
fuel injection...yes example: new stihl ts500i electronic controlled fuel injection system
direct injection...not yet

told myself i would never buy anything without a carb a many many years ago.... my opinion has now changed.

 

[naturelover]

We depend on electronics every day, and they are used in much harsher environments than a saw will ever see. And I will bet that more saws will be scored by mis-adjusted carbs or air leaks (a post here said a saw was saved from the air leak by the MT system) than malfunctioning MT or AT systems.

It seems the AT systems are having some problems as of late though, course it is a Husky..... oke: opcorn:

Yet when a few pop up in a chainsaw, some get all scared and defensive over not buying some electronic "gizmos". As common as electronics are these days, why is that?

Isn't it a little ironic dismissing electronics on an Internet message board anyways? :jester:

Can stuff be overcomplicated? Abosolutely. Will there be failures? Yea. Mine could be one, who knows? Can I get it worked on if it does? Honestly, I don't know that many dealers in this area that would know much about it....

But I am really enjoying the M-Tronic system; great fuel economy, less pollution, no worries of carb ajustments, and its always in tune, way more precise and efficient than a carb. The only adjustment I made was recently doing the calibration, which was starting the saw and letting it run for a minute.

Meanwhile in carb-land, to get the 500 back in tune, required resetting the high speed screw, adjusting the low speed screw, cutting wood, turning the high speed screw some more, cutting more wood, a finally a fine tuning of the screw followed by some more cutting wood to see if it was right.

After all that, it still won't be as well-tuned as my 441 is...

And that's a shame really, many have said the 441C is the best saw in its class, but it probably won't be the best selling because of all the unproven negative perceptions people have over its "complex" electronic "gizmos"......

My only complaint is Stihl won't offer the 241C here, me wants one..