bmp01

Beginning to see why this saw got put to one side. I think you're gonna have to look at the accelerator circuit if only to confirm its healthy (or do like you said earlier, get a replacement carb). Lots of talk about the primer bulb earlier IIRC, how's that working now? Have you tried running the saw with the primer bulb circuit disconnected ? (The return fom the carb must be plugged if you want to try this). Edit: a new primer bulb was fitted, probably not that then...

Ok, nice to have an update. I take it none of the carb cleaner came out the accelerator jet circuit then if as you say ' it all squirted out of the jet in the choke tube' If so that just leaves a question mark over the check valve operation. Fingers crossed. Edit: sorry, i have no useful info regrading replacment carb.

Try this link: https://arbtalk.co.uk/forums/topic/122598-still-m181c-help/page/2/ Be nice to confirm were the fault lies before bailing on it. Pretty close now I think. Try Spuds carb cleaner treatment and if no joy I have one last test, zero cost. After that either it works or send it to me, I have a few big hammers to fix it. Usually the microscope and lathe are more useful for this sort of project though 😃

I'm not convinced either. Another question for openspaceman, when the saw was idling, is the idle screw at factory setting or adjusted way rich? I'm thinking 'check valve on high speed circuit is needed for idle operation'...if saw idles ok, this says check valve is closed at idle, either it's completely blocked or working as it should. .....200 carb has a much bigger venturi compared to these strato saw carbs....

Picture paints a thousand words. ... and it seems like what I call the main jet (with its integral check valve) you are all calling a check valve. So, Spud is right (of course), in the blue circle is the check valve. If you have any mechanical dexterity you can just tap it out with a drift straight into the carb ventrui. Even better news; you can just refit it by tapping it back into place from the metering side. I typically clamp the carb in a vice, leather on the faces to protect. Note the depth and orientation of the check valve before you start. Check valves are replacable and have their own part no. One note of caution - if the carb venturi is small you need to be confident the check valve will travel all the way into the venturi and not bump into the far wall before its released from its bore. I think i did a 211 carb which is most likely the same. Looking at the carb picture and thinking about your hose blow /suck test plus the 2 apparant feeds to the check valve....it's a bit of a puzzle. 2 feeds, the jet feed, therefore a constant fuel feed, probably suppying most of the fuel. That leaves the high speed screw to fine tune the small additional flow supplied through the second hole. I suspect when you sprayed carb cleaner through the high speed screw the stuff went down to the check valve and some of it bounced back up fix jet drillng. How about you refit the high screw and bottom it, then spray down the jet feed....does any spray come out the second feed? Your earler blowing down a hose test: with the high speed screw bottomed as you did, you should be able to blow through the check valve. You should not be able to suck through the check valve though. But wait, before you conclude check valve is knackered you need to know the accelerator circuit also feeds fuel to the check valve..... Do you know where the accelerator piston is?

And here's a sketch of how those bits go together.

Oh hang on, I've got a picture of a main jet with the check valve parts next to it. ...here you go. .... (This is not the exact one from your saw / carb but they are all the same as far as I know).

Here's how I test main jet, hope you still have it out of the carb.... Put a hose over the outlet end of the main jet.... If you try to blow through the hose that's trying to flow air the wrong way through the jet - the check valve (in the jet) should shut and stop any airflow. If you suck on the hose air should flow through the jet (in the same direction as normal fuel flow). In your first paragraph, if i have it correct in my mind you are blowing into the main jet hole from the metering chamber side ? And youve blocked the main jet hole at t'other end (where it comes into the carb 'venturi' ? And you can still blow through the hose ? I dont see how.... unless accelerator jet piston is missing. Second paragraph, the only welch plug i can picture is the one over the low speed jets, there is no check valve under there. If it's another welch plug then it's a different carb to the ones I've seen, can you post a picture?

No, that's wrong. Check valve is typically only on high speed circuit, as part of the high speed (or main) jet. So while the jet is out make sure you can blow through it in one direction , as per the fuel flow , and not in the reverse direction. Low speed circuit doesnt have a check valve but sometimes there is a one way valve on the whole fuel circuit ...I think.... Edit, the logic for check valve in high speed jet is ironically for idle operation. It stops air going back down the high speed jet, passing through the fuel circuit and out the of the low speed jet (coz that would surely cock-up low speed fueling). If you think about idling and the pressure drop across the butterly (or throttle) valve you can see: - engine side of butterfly is at a depression - airbox side is at ambient pressure That's the driver for air going the wrong way through the high speed jet.

Back ground info - did you tell us the age of saw (sticker on brake handle will say)? Also, what's your perception, is it a high mileage dog? Hardly used ? etc Can you see the fuel line while running (to see if air is coming through during running), could be the air is only due to purge bulb use ?

Thanks for the extra info openspaceman. Seems like fuel line "rot" is the common theme. I wonder if it had some nasty fuel left in it, maybe followed up with alcylate fuel when it wouldn't run right...

Well, I try to be (accurate). Thought this was going to be something juicy, a little bit out of the norm. Could have gone the replacement carb, chinese vs genuine discussion ....again 😁 But anyway it's fixed so that's a good outcome, well done openspaceman 👍

Opensaceman you are quite right in your thinking - there is nothing to stop air being drawn in via the low speed fuel circuit. But it should be a small proportion of what the purge bulb pulls through. It's easier to draw fuel (assuming the fuel filter, carb micro filter, metering valve are flowing freely ) compared to drawing are through the tiny jets in low speed circuit. Worth noting: - the one way valve in the high speed jet stops air being drawn in via the high speed jet, (one way valves fail occasionally but pretty rare). - there is possibility of drawing air from the dreaded accelerator pump circuit (accelerator pump o ring will wear out dependant on mileage). - leaking metering diaphragm is strong candidate (you say gasket was split so I'd say that was your problem). HTH with diagnosis.

Thank you. Got a couple of the progressive gauges a while back, I'll have to find time and a candidate chain (1/2 to 2/3 used) for a test.

That's exactly what I do (and expect what 99% of folk who use a gauge / experience do)..... But that ain't the progressive gauge thingee that Stere is refering to: where the depth gauge is (progressively) reduced a lot further as the tooth length reduces. Well, that's if I've understood Stere correctly ???

Are you talking about one of these steel gauges Stubby ? Might as well try to get something useful out of this thread, clearly the other numbers are gibberish.

Efco have been around a good while. Think it was a 936 (small cc's) I fixed up, lots of plastic, it had hung together until the piston ring had worn out. Bar mount plastic was pretty sore by then but bar and chain were also fubarred, short on maintenance, high on abuse sort-a-thing.

Mr Fish, have you really ground the "rakers" or "depth gauges" to 44 thou, 50 thou and 55 thou (of an inch) below the tooth cutting edge ? As stated earlier in the thread 25 thou is the nearly universal number.... None of this is new stuff, its 'run of the mill' chain maintenance, best go look at some general chain sharpening guides.

That's a coincidence, came across that again just recently. Oval pistons, 8 valves per cylinder. Honda made a very tasty looking replica road bike in limited numbers off of the back of that. .. thought road bike was bigger displacement 750cc ? I guess thats where the similarities with this story end though, the collectability and price of those bikes is sky high.

Now, pictures are for illustration purposes. That dont mean I'm in favour of risking your saw for an experiment but I sense your gonna try anyway, so if they help you decide one way or t'other that's fine. Wonder if the chain will clear the casing ? Cough, cough, (cue muffled voice).... hyper skip chain..... 😈

And a few more, K095 bar on top. Last picture is the D009 bar marked up with K095 hole positions (for the bar "tapers" equal case).

As requested, more pictures to fuel the fire .... This one with the K095 bar underneith, not sure that's of much use.

Couple of pictures for you to consider, please note these are well worn bars. Both Husky bars, from a 357XP, 390XP which I think makes them K095 and D009 mount respectively. Looks like oil feed hole and tensioner holes will need some 'thought' if you pursue the idea. In the K095 overlayed on the D009 picture you can just see the oil feed hole in the D009....

As far the stove is concerned, what about a sheet of vermiculite ? A bit fragile maybe? Was thinking further insulation around the fire box could improve combustion temperatures for a better burn. ... same as the layer of ash principle.

I'd imagine a piece of steel might conduct the heat away a bit better than stone, might find it never hats up more than a few degrees. Still, the principle is right, steel will expand with heat, stone or brick won't go the same degree so might be an issue. I've often wondered what happens to the long steels over multiple glass windows....