bmp01

Chain is assembled from a long length of chain, cut to length and a joining link used to complete the loop. Operator is making up X quantity of chains of the same length and the bag of joining links he uses are the wrong ones. If the chains are coming direct from Oregon then that's pi55 poor quality control. I bet it's not Oregon though. Be interesting to see what packaging the chains came in.

Can you imagine the responsibility in the shop in tracing a batch of chains that are all wrong. I could easily see some engine damage from running such a setup.

Just go and put a pen mark on the chain where its clicking, wind it round and round. I can pretty match guarantee its going to be that link every time.

But if all the chains are coming from the same place. .. are they all wrong???

Come on guys, there's a link in that chain with the wrong pitch

Well, isn't the evidence right there in your picture? That drive link is different to its neighbours. .... looks like an assembly link to join the chain loop. Is it this link every time the chain goes round? Edit : Even the distance between rivets looks different.

Your carb looks straight forward, fuel in past the metering valve, fuel into engine via the single brass insert jet and fuel to primer via drilling and brass pipe. Are there any other drillings or jets coming off of the metering chamber? If not then doing the suck and blow test through the brass insert (WITH both the adjuster screws fitted and adjusted to 1 turn out) should tell you if the one way valves are working. I would repeat after feeding some WD40 into the same brass insert - sometimes that can "wake up" the valve. Blowing through the adjustment screw holes doesn't tell you anything..... A carb rebuild is usually limited to replacing the diaphragms, the little gauze filter and the metering valve / metering arm. You can replace the little aluminium plugs but it's only necessary if the passageways below are blocked and you need to gain access to clean them. So, normally it's take carb apart, clean, reassemble with new bits. ...not too hard. So anyway, you did check the diaphragms for holes ??? bmp01

Good observations. So was the metering chamber full of fuel or not? Take the pump side apart too. Fuel or not? Is the pumping diaphragm intact? IF the pump side is good, AND the metering diaphragm is sound, then the only way the air is being drawn into the fuel is through the jets in the carb. ....normally in the running engine the're flowing fuel into the engine, it's only the one way valves that stop the purge system from drawing air backwards through the jets. ....

You'd struggle to start the engine in that case. ..... the man says "it bogs" so presumably it does run when hot just badly. Deano, Wind the low speed mixture screw out a 1/8 turn then another 1/8 turn. ... Oh you've done that already? Can the engine be persuaded to higher speed when hot, if you accelerate it gently? If it were only the one carb I'd say damned accelerator pump (in the carb) but tried two carbs so I'd say damned accelerator pumps Unless one or both carbs have been tested on another saw and proven to be good, I'd say they are still suspect. Good luck, make sure you find why it seized in the first place or is going to happen again.

Ah, but did he? You're probably right but i wanted to confirm the fuel in the pipe was getting all the way to the primer and not just shuffling back and forth - seems pedantic maybe but sometimes it's not 100% certain which way fuel is flowing when it's pulsed with a primer. .... or maybe that's just me

I should have paid better attention to your original post. .. so it's been apart already . Two questions, 1) Are you seeing fuel in the primer bulb? If so, that should have filled the metering chamber with fuel.... and it should then at least cough on 2-3 pulls. If no fuel in the primer bulb then, did you get the fuel lines swapped over? Or the filter is completely blocked or the metering valve isn't opening (metering gasket upside down? Check metering lever setting). 2) Is the choke mechanism operating as it should? You need it to create the vacuum to suck the fuel in. .. If you do take the carb apart again, confirm all jets etc are unblocked with something like WD40 spray through one of those thin tubes. DON'T use compressed air at full pressure that will knacker the one way valves (one in each of the low and high speed circuits). I've got a short length of silicon hose which is very soft and can be pressed onto the entry to the drillings and sealed by hand pressure - blowing (and sucking) confirms drillings are clear and one way valves are working .... (or not). Doesn't taste the best but you learn a lot At some stage it might be worth popping some fuel down the spark plug hole, just to confirm the engine will run once the fueling is sorted.... Let us know how you get on. bmp01 -

Nope .... but if you are lucky you might avoid getting some of the surrounding crap down the holes If you're unlucky things are going to take a turn for the worse You could wind the screws in gently, then back out 1 turn each (typical factory setting) but don't hold out too much hope. ... Most likely the carbs going to need a going through, inspect and clean plus maybe new gaskets. You should also check the rest of the fuel hoses, filter etc. Thing is, if you can't get fuel to the saw with the choke on, then some thing is blocked or stuck - your not reliant on the pumping side of the carb under this mode of operation. bmp01

+ 1 Never had a defective plug ..... until the first time and now my default is new plug every time. It was visually fine, would show a spark just like normal outside of the engine but swapping back and forth between new and old plug proved beyond doubt the old one was knackered. When i cut it up it turned out the ceramic was cracked and it had been arcing inside the plug. Rare case but it does happen.

Do you mean the drive sprocket (or the nose sprocket on the bar) ? You say everything is fine with a half used chain - doesn't that rule out the new bar as the problem? Edit : but new chain on the old bar was fine too which says chain is fine. ... lol ! Is the drive sprocket in good condition, ie no deep wear marks? Could be the drive link on the chain be riding up onto the unworn surface of the sprocket? Otherwise, have a look at the drive links on the chain, any damage or burrs on the edges of the drive links that might catch on sprocket or entry to bar rails? 9 I've had that before and it does make a click noise. Put a pen mark on the chain and see if it's the same place on the chain every time .... Let us know how you get on. bmp01

Yep, can pump the primer bulb as much you like. ...still the same. ...just didn't feel right. Inflates by itself and not slowly, if anything a bit quicker than you'd expect. I started with a part full tank but quickly brimmed it - to rule out air through the filter. Lines all look good. Thanks for replies - it isn't right is it. ... Here's an update: After much head scratching I've established that the air (that's all the air) is being pulled into the fuel circuit via the jets in the carb. Specifically, through the low speed circuit. And I confirmed this by temporarily blocking the low speed circuit with bluetack (a 8ugger to clean afterwards !). It's worth noting, the primer bulb sucks from the metering chamber - so you can see how it will suck air through the jets if there is nothing to stop thIs back flow. Still surprised you can suck so much air through the tiny dia 0.4mm jet though. Further, I have a spare (high mileage) carb from a MS171 and in this one there is a one way valve in the low speed circuit (as well as the more obvious main jet /one way valve for the high speed circuit). Now, the MS171 doesn't have a primer circuit which makes me wonder why they bother with the one way valve in the low speed circuit - I can't see it serves any purpose....and pretty sure most carbs for chainsaws don't have it. Parts consistency I suppose. So, given the main jet/one way valve was fubarred (see post one) and now it seems the low speed circuit one way valve has gone the same way, I'd be tempted to say the carb has been 'cleaned' with an air compressor or maybe the engine has been 'popping' back through the inlet (due to the engine seizure).... who knows? Looks like new carb time or just live with it. bmp01

Steady. .... expected some authoritive put down not an apology The thing is, there is much to learn from those that have 'been there, done that'. Unfortunately, i have the age bit but not the other .....

Spec Saver moment there mate Beechhunter has matching bar and chain it's just the sprocket he's worried about. Presumably if the sprocket was a spur sprocket that wouldn't work, unless it was practically new, as any wear would try to guide the new chain in a bad way? But as it's a rim sprocket it will shift itself to centralise on the chain run. Think I'd run a new rim in any case for the money involved, keep the rims matched to the specific chain gauge.....

Hello all, I'm after some opinions and experience please. I've got this MS211C that I'm sorting out - its been seized so has had a replacement engine (genuine parts). I'm VERY keen to avoid a repeat engine seizure, so have been trolling through the fuel system just incase, although i suspect crap fuel was the root cause of the problem. That said i did find the main jet one way valve was fubarred so thats been replaced. Here's the thing, when i use the fuel purge bulb to suck fuel through the carb i get a surprising amount of air coming through with the fuel, was worse before the main jet one way valve was replaced. So the question, what's the usual fraction of fuel and air drawn through with the purge bulb on an MS211C? I recon I get 50:50. FYI, I've looked in the carb and can't see any sign of one way valves on the low speed fuel circuit - i think it's impossible to get 100% fuel and 0% air. In the past I thought strimmer engines etc pulled through pretty much neat fuel. BMP01

Good result, thanks for the update. I bet you're glad you persevered with it

There is a tiny reservoir of fuel in the carb so if it really is instantaneous then I'd be looking in the carb for the problem. I think a pinched fuel line or pick up issue would take a few seconds to show as an issue. It could be the metering lever is not operating quite correctly and in need of a tweek - its the only thing i can think of that gravity might affect in an otherwise sound carb. .... but that said the spring should pay the major role in controlling lever position. bmp01

I'm not sure there is much to conclude from the damaged band - with that much change to its geometry its going to adopt a different shape to a new one, plus it's bound to have got blinkin hot so it might be distorted too. I'd be a bit worried about the wear to the inside of the cover (3rd picture) - it says to me things are not aligned the way they should be, could be the cover or the machined face on the engine case. It's got to go back for repair / investigation. I'd be asking for a replacement cover as well as the brake band, hoping that fixes any alignment issue. If that doesnt fix it, then it's replacement saw time. BMP01

There was a 480 advertised on gumtree earlier in the week, think it was advertised in Corby, 29 quid, missing chain. Probably just a coincidence. bmp01

Thoroughly agree. The clever bit is establishing what value to assign to 's'.... not got there yet though

I asked the question badly. ... think i should have said 10 "drive links" not "rivets" 0.325 pitch per drive link ------> 3.25" for 10 drive links (thats over 11 rivets if you count the first one ) 3/8 = 0.375 pitch --------> 3.75" for 10 drive links (or 3.375" over 9 links, 10 rivets - most likely). My guess is it's a 3/8 pitch chain with a bit of stretch. ... can you confirm, incase someone wants it? bmp01

Hello, I'm interested in this, postage necessary though. ... Could you measure the distance over 10 rivits and tell us the number please? (in mm or inches....) thanks, bmp01