Great Job Explaining the carb. And it didn't take me long back in the day to figure out the Tilly metering valve "catch" on the pan handle. "why is my carb puking fuel?!?" Can't wait for the 922 build. I just rebuild my 925 over the weekend. I lucked out and only needed rings. I removed the base gasket on mine and squish was .032 and now i can' barely pull it over because of the compression increase.
Iv tried new top ends.gaskets.crank seals.carb kits oem carbs from other saws.ignition timing changes.checking choke flap springs and seals on the filters like the 038 I'm very defeated with these 2 saws iv been racking my head around this for so long.iv built alot of nasty ported saws that run amazing you have been a big part of that. The best videos for intermediate builders like my self are the chasing problem videos and knowing how to diagnose these issues. Side note tank vents and how the tanks go under vacuum if the vent line or filter is plugged and how a saw will act. And how cracking the cap will return to idle once vacuum is released.thanks for all your help these videos are great I'm going to spend more time around metering levers today and try different heights and see how these saws act
Thanks for the great tips. I have a Tillotson carb on my ice auger that was "loading" up on fuel that I bought used. Now it is tuned up nicely after seeing your video.
Great carb tips buddy thank u 4 explaining an demonstration of ur tips for people who don't understand chainsaw carbs or aren't comfortable yet messing with or adjusting carb yet. Thank u for all u do.
Another good video, Tinman. I still remember my first effort to figure out why my first ever power saw would be hard starting and also if it did start, it would run crappy. Through research, I began to learn how saws run right, how fuel systems are supposed to work right vs issues with them, and the other thing that was transformative in my education on small 2 stroke power saws and weed trimmers etc was AIR LEAKS. As I learned, a lot of times, running issues and the survival of a saw depends on ensuring there are 0 air leaks. Good Spark, Clean air in and out, Good Fuel and clean Air and fuel filters should make for a sound saw. Dirt, Leaking Gaskets, Bearing seals etc, and bad fuel/ gummy fuel lines impulse line etc will cause failures to run, engine wear and seizure, and carb issues. After replacing my fuel system in my 026 right down to another stock carb, and my saw was running like it should.
I'm glad I listened to this, searching I found my issue, (running rich) it was a loose bowl cup plug thing, was blowing air past the cup during a vac/pressure test, reseating it and new silicone grease on the H/L orings had me a well sealed unit, now it will idle all day long, and be chirpy as a canary on the throttle (ms360)
Loving the sound effects when describing how the metering diaphragm works at 9000 revs 😂. My problem with carb kits is trying to fit the metering lever, spring , pin and needle with sausages for fingers. The spring always ended up on the floor.😡
What i found with after market carb....gasket used for 2 valves side was a problem. The material used was mmm. If 4 cover screws was tightned to much carb gave issues. Loose screws ever so little it runs fine. Replaced almost clear valve gasket and runs fine. Maybe it was forced at semi open or not sealing good with material used.
You know, that makes a lot of sense. Those little "valves" are so delicate. I have found the plastic or cellophane ones seem to work better for me and last a long time, longer than the typical material they make them from. Thanks for bringing that up.
What a great and very informative video. I have almost always replaced carbs on older saws and weed eaters etc as I think they're cheap enough in comparison to kits, it's usually the quickest way to fix a problem, it doesn't always work though. I have bought bad runners too and done the same without really looking inside in case someone has made a mistake...I will look closer at these basket cases now before throwing a new carb at them.
Wow! Now we see your day job! Amazing you are a jack of all trades! That’s just awesome! You make things look so easy and you sure help us all save a few bucks along the way…Thanks Tinman now we know where you really got your name from. ❤️
So nice to see quality ducting - when I was a wee lad over 50 years ago, our neighbor, who worked for a major residential HVAC contractor, installed a new gas furnace and central air conditioning in our house, using similar all-metal smooth supply and return plenums that ran the full length of the house in the basement, with round duct pipe to all of the upstairs rooms. That system is still in operation today (the central A/C worked, with no freon recharges or compressor changes, for about 50 years with no service other than lubricating the condenser fan bearings, and the furnace was replaced once, upgraded to a condensing-style about 20 years ago). No, they don't make them that good any more! The house I live in now has a downflow gas furnace with that infernal spiral-wrap insulated plastic supply and return ducting that I absolutely can't stand. Plus rats can easily chew holes through it in the crawl spaces below and above. It has high flow resistance, is impossible to clean, and well enough said. Thanks Tinman for sharing your work with us - your pride of workmanship shows, and is an inspiration to all of us!
Another super helpful video @Tinman. I've been rebuilding a couple Stihl 041's with Tillotson carbs. I've tried two aftermarket carbs with zero luck getting the idle adjustment settled down (low adjustment will not tune). Rebuild kits for the original carbs are on the way, but I might play with the metering lever on the aftermarket ones just to see. Thanks for the videos you do. It's been super helpful!
@@jonathanhoekstra6174 I don't know if there are different aftermarket manufactures for the carbs or not. I've ordered the off-brands from Amazon for other small engines and haven't been able to tell the difference between one generic brand and the next. I assume it's the same or similar products just getting rebranded. Which is unfortunate. I try to rebuild WalbroI or Tilloston carbs whenever I can for this reason. When you look at other chainsaw parts we have a selection of manufactures to choose from with good reputations (thinking specifically of Meteor pistons and Caber rings). It's not uncommon at all to build a quality new saw with a mix of generic aftermarket, OEM, and third party parts. It'd just be great to have some better quality options for new carburetors.
Agree about the aftermarket carburettors and kits I bought two carburettors for a little echo ,trying to eliminate an issue I had, Both carburettors were no good and I agree the jets or the holes are no good. Thanks for going into such detail.From Western Australia
DONT KNOW HOW MUCH TIN BUT SURE LOOKS LIKE HE COULD CHUCK WOOD LOL WITH ALL THOSE PORTED SAWS 🤣🤣 GREAT JOB EXPLAINING about the metering lever be safe buddy
My name is jay small and I'm pretty new to this channel but want to say thank you so much for the help with my power saws. YOU have saved me so much money and time. Very grateful, love the channel with love God bless
Just rebuilt my first Tillotson chainsaw carb! Some one has it apart before me. I thought that diaphragm piece looked long now I see why!! It would only sputter and fuel everywhere. I think it's gonna run nice once I get that fixed!
Hi tinman, i have just watched your video on tillotson carbs. Just wanted to say i have been learning so much from watching your channel, I am big mcçulloch fan and have quite a few. Keep the videos coming i really enjoy watching them
Well done to the master, we have a 038 STIHL AV chainsaw. There is no problem with the load, but the idle is out of alignment, the idle speed drops and stops by itself. Even though I increase the idle speed, it is the same old tilitson original carb.
Buddy you just saved me 60 bucks on a new carb because of this. Used it to adjust a walbro in the same manner, and I was sure it was a goner until I saw this and you made the lightbulb go off in my head. The metering lever wasnt pulling the small pin enough to get that diaphragm moving and once I saw it sitting low, I pulled it just barely above flush of the surface of the carb, the saw now idles like a champ.
Could be ill fitted throttle shaft or housing, usually found on old saws where open and close changes as the shaft can move side to side lets more or less air suck in around the shaft . One more possibility.
Those diaphragms are used for ethanol fuels. If you change the diaphragm to a OEM black rubber style I wonder if that would make a difference. I remember seeing a Smitty's video where he said he doesn't use those diaphragms due to air leaks because they don't seal the greatest.
Tinman I had a carb doing the same thing and he took it a all part and put in the oven at 200 degrees for one hour and let it cool down and polish it inside out and put it back together and it tound great and ran awesome.
I haven’t worked on a Tillotson. when I work on walbro and zama, I make sure that after the gasket and diaphragm when sitting flat on carb are NOT depressing the needle. On some aftermarket kits, I have seen variations in the stub length on the diaphragm. Regardless of what the height gauge says, it shouldn’t be depressing the needle.
Could you do a side by side teardown, 1 original, and one aftermarket, then you could measure and compare both carbs. Also if you cave calipers you could bake both carb bodies and measure the gain to compare them, then let them cool and check the turn dimension this would show the difference in the metal alloy for expansion and contracting and why they might not work!
I have found in some of the China carbs that the crescent in the throttle plate is out of alignment with the tiny little idle circuit venture hole because the don't have the little bumps that aligne it to the throttle shaft so you can loosen the screw and spin the crescent to align with venturie which will create a tunable carburetor however the amount of turns on the jet screws will still be way different than a OEM carburetor usually low jet way out and high jet way in
Check out the ChainSawGuy's recent vids on carbs. Soda blasting the H-L seats to remove minor imperfections which I'm sure these aftermarkets are full of.
I'm going to go check my saws out later thanks to this info. I have one in particular that is funny. It runs and idles but the muffler is always spewing fuel. I also beelive it is not reving as high as it could and that the throttle response is slow.
That is common symptoms of a metering lever that is too high. Often though they won't idle but Ive seen them idle and still have the issues you describe.
Hey tinman, iv got a hunch.... these after market carbs go out of tune because of the jet springs. Assuming these springs arnt stable, equal, tempered well, etc etc etc...they could be changing under vibrational load, temperature, memory, rebound etc and allowing the jets to turn on theor own under various circumstances. A quality spring needs to be strong enough to act like a lock washer to hold jet position. It needs to be strong yet springy enough to maintain rebound "memory" I suspect that these carbs are fine, but the springs on the jets are low quality or of an inconsistent quality...thus the run-to-run tuning issues.
I had a 576 that did that same thing and it drove me nuts so I bit the bullet and paid $200 for a new oem carb fixed the issue so I never use aftermarket carbs
Those carbs by the low speed circuit you see a little hole by there I call it the piss valve system I’ve had oem carbs act up and I can’t get into to it to fix it to tune right the aftermarket ones probably are not machined right but the basic tillitson before epa always work
My old Husky 162se gave me some grief back when it was newer and I was using it all day. Turns out I got a couple carb kits that had poor quality control on the diaphragm "hat" and the metering fork. Spring resistance might have been a factor too. So the fork was wearing the stem on the diaphragm where the needle wasn't getting the total up/down movement it was designed for. Too much slop in total. If you slip the fork onto the diaphragm stem the way it is when assembled right - how much up/down movement does the stem have on the fork? These had a lot after being run hard for a week or two. Just another thing to look at, sure enjoy your channel.
Thanks for all your wisdom Tinnman. I acquired a 288xp with a melted piston. I cleaned up the OEM cyl. and put in a meteor piston and caber ring, kept base gasket in. It runs great for awhile until you start bucking hard and building heat, then seems to run rich. I lean it out, then too lean. It's just back and forth, rich and lean like it won't hold the tune. Any ideas? I'd really like to keep this saw and cut firewood with it.
Zama carbs are my Kryptonite, I had a 575 once and just could not get it dialed in, I did sell it with full disclosure and at least I didn't lose any money on it.
DITO I hate aftermarket carbs.They never tune right and if they do it changes far to often. I put a oem 390 carb on a modded 372 and it wouldn't idle down period turn the low out 3 turns and still was running away. I adjusted the metering lever 7 ways from sunday no joy.I changed the carb and put a oem 372 carb on it runs great.Still haven't figured out why the 390 carb wouldn't idle down.Speak of breaking eggs just built a sxl925 it lasted about 40 seconds and the rod broke oh well.
Tin man, I know I asked about rifleboring carbs on saws, and you really couldn't justify any realistic power gains as to be feasible, I see on your videos and Ironhorses videos it's prudent to have the intakes "roughed" up a bit to promote better atomization on the intake ports, wouldn't it be prudent to do the same to a carb venturi, also another question in Reed valve motorbikes and snowmobiles they "boyessen" has a system called a rad valve, as far as I know it's not their aftermarket Reed kit, I use them on my snowmobiles, this is sort of a spacer that separates the venturi into quadrants to boost pressure, maybe you could explain the principle behind the system and the way it functions, I would love to see something smaller be done on saws thanks again tinman for the excellent videos!!
I have Husqvarna 359. I bet it has no more than 100 hrs on it. Walbro carb. with the accelerator pump given me troubles. Zama C3-EL42 carberator is a replacement I believe. I wonder if you need a different intake boot? Always had Husqvarna never had a minutes trouble until this one!
Tinman! Try drilling a hole in the center of the plate that covers the diaphragm. I was having the same issue with an aftermarket carb on a 357XP. Ran like a dream afterwards. I guess there’s too much vaccuum without it? Or not enough? Forget the exact reason. Worth a shot!
So when these China carbs do not work, and a lot of these old Tilly carbs are no longer available, what to do then? I am in that situation. Rebuild did not fix the issue.
I've Messed with a few of those aftermarket carbs and everyone I couldn't get to run right I found small machine shavings in passages that's why they seem like they lose tune because the shavings move around to different parts of the carb it is almost impossible to get them all out.
Too, perhaps the cheap casting expands more than the shaft creating micro leaks. if the vibration and vac pulses causes a tiny flutter in the shaft it could tune erratically. I have a factory 240 that I MUST tune only when it is at operating temp and has been in a couple cuts or, on the bench, several idle/WOT cycles. I know guys who wrench for 2 stroke dirtbike racers. They tell me the final tune MUST be made with input from the rider, from the track. They can get dang close with the bike on a stand or a dyno but to truly dial it in, it MUST be tuned in the dirt :) Dirtbikes and Chainsaws are similar. Engine/clutch/chain/load
tinman there are two things about this video that puzzle me - first you describe the gap/play in the inlet needle, but my understanding is that the fuel behind the inlet needle is under pressure from the fuel pump, therefore the gap is of no consequence as the inlet needle doesnt have to be lifted to let the fuel in, only the spring pressure has to be taken off, and then the fuel will flow in because it's under pressure - second you say that the metering diaphragm is activated by the impulse line, but the impulse line activates the pump not the metering chamber diaphragm, the metering diaphragm is activated by low pressure from the venturi which is transmitted via the high speed jet - but you are the expert - what do you think?
So I think I now have my carb figured out. I'll have to put the original back on. My metering lever was a little high but the saw would not start at one turn out on both screws. the saw flooded. i had to screw the low speed all the way in and it still ran rich.
Tinman: I’ve got an old Husky 380cd with a Tilly HS 122A carb. Won’t start now. Was starting. I want to riches the main idle. Do I turn screw clockwise or counter??
I have an old poulan 306 am trying to get running right I can't figure it out now that I've rebuilt the carb it runs out of control even with the Jets almost completely closed I'm guessing there's an air leak somewhere but I don't know where to start and finding it
I have a brand new walbro WJ-76 with the big 76mm jet for a Stihl 066 that won't pass 11,000 rmp & the H screw bottoms out,could the metering level be the problem? 🤔
Great video. New to the channel. I can’t get the pin to sit down in the groove properly. The screw holds one side of the pin down, but the other side pops up. I tried sealing it like that hoping for the best, but when I put a little gas in the tank, it immediately leaked out the air intake portion of the carb. Any suggestions would be helpful.
I got a question for you tinman. I just got a pro Mac 55. I replaced the cracked fuel line. Took the carb apart and cleaned it.runs good fires up. Once I'm in the cut for a bit on say a 12 inch log it leans out and starts to cut off. I set the metering level according to walbro. Perhaps it still needs to be rebuilt? I got a new carb coming in, found it on eBay for 40 bucks so I figured that's better than buying the rebuild kit. What do you think? It has a walbro 49 so it only has the low jet and the fixes high.
Hi, I have a Parker chainsaw, but has not had a lot of use. But I feel there is a carb issue, after taking off I found there was no info’ on it to tell you what name, number or anything to identify, it is I believe a Chinese model, which says it all. Not sure if the needle valve is to be a special setting or whatever. Can you help to say how I could find out about it, and any parts I may need. The machine did run ok but then started bogging down, I then ended up with it not starting at all so would like to restart with a replacement carb but not sure which to get.🤔🤔 Help.😒. Didn’t mention, the chainsaw is a, Parker, 20”, 62cc. model.
What if you put the impulse line on the pump side of that carb instead of the metering side? I could be wrong but i believe certain carbs have the impulse on the pump side. 🤷♂️
I have a 075 with a tillotson carb, it runs super rich on high rpm (4 strokes) and in the cut. The Tillotson manual states to check 3/6” diameter nozzle cup plug, nozzle check valve cage, is not sealing. Is this the big brass plug on side of carb with a copper washer under it?
OK, @Tinman good stuff. Thank You :-) ... NOW! Get some tin on your work bench. That should help you keep things clean between saw rebuilds :-) Or not ...I was just thinking a Tinman could find some ...Blah, blah, blah....See ya in the next one friend.
Does the metering lever affect both hi and low circuits? I have a holzfforma that runs great on the high jet/above half throttle/buried in the cut. But it won't idle, low jet screw doesn't seem to do much.it dies after a cut. OEM X torq 372 carb with 52mm top end. Thanks