spudulike

My money was on an FS400:lol: reset the H screw as I described, hopefully it will get it back!

You can use a quality pair of side cutters on the screw thread if the cross head has failed - there is no guarantee the head won't come off though! The cutters should be vertical to the carb and the cutter ends embedded in to the head on either side if that makes sense!

The back fire leads me to believe it may be the flywheel key has let loose or possibly the coil is shifting the ignition timing. A back fire will occur when the ignition is very retarded or in laymans terms - when the piston is on the way down and not just before top dead centre. Excess fuel in the exhaust can also produce a bang or two. I would pull the flywheel and inspect the key for starters. If the engine has compression and isn't knocking badly, it sounds like it has life left in it. Also check the exhaust hasn'tgot unburnt fuel in it. Interesting one - be careful running it before checking the flywheel - ignition happening out of time can cause piston melt down!

The mesh strainer sounds very likely, check the fuel line isn't holed and before you write the ignition model off, try regapping it with slightly less gap - sometimes if the gap is slightly too large, they can spark when cold but go when warm. Worth checking the rest of the carb over as well.

Your description sounds a little vague, it could be that the needle valve has been glued in - now that is a strange one, never heard of that before!! A deep ultrasonic clean may well do it, depends on the power of the cleaner and if it is heated.

Try turning the H screw (furthest away form the Engine) all the way in and then out 1 - 1 & 1/4 turns what the feck is B400 anyway:confused1:

Get carb kits from Hugo at Rowena Motors - damn good value and helpful as well:thumbup: Usual delivery is 24hrs as well!

The best non OEM piston will be the Meteor one, I have fitted many and with no issues. The real cheap ones are.....well.....really cheap so is it worth risking bad circlips or brittle rings??? Meteor ones are circa £25-30, a bad piston could take the top end out and result in a real expensive repair and more importantly, downtime!! The carbs - I have only ever had to replace one carb. Faults can often be fixed by the more experienced tech but some will fit new just as it is easier and quicker for them to do so. I can spend an hour on one to resolve a running issue as I just give a fixed price repair - my time my choice! The main thing to do is to verify the parts do need changing and the cost of them makes for a viable repair! Some may just fit them as "it may be the issue" rather than KNOWING it is the issue!

You were lucky to split the muffler cases, most will not split!

Thats a welch plug, it covers the low speed jets, if it leaks you will get an uneven idle and it should be a tight fit in the hole. if it leaks really badly, the saw won't start. Put a little superglue around it. trying not to get it on the jets and then work in a little more around the plug. any leakage is bad news and is a common issue on all types of carbs with these oval plugs!

These ones are about the easiest ones to do, put on the safety specs, place the bent end in the plastic moulding and feed it in holding it in place with both thumbs, it really isn't difficult:001_rolleyes:

get rid of any aluminium by cleaning it with solvent and abrasive paper followed by acid or alkali to get rid of it and then use a very light hone if needed. The piston will be an issue due to its domed top - unusual with modern saws. you will need to match the dome height, crown to pin centre and the height of the piston - all are critical to making compression and timing. The diameter will obviously also need to match!

The bore is chrome plated aluminium, there is no way that can be rebored. Put a pic up, is it really that bad. Most of the time, these can be saved if they are not too bad, The ones that I have had most trouble with are the real high revving Huskys, the 550XP and 346XP have a tendency to score the cylinder as well as transfer aluminium. If the bore is fixable, the next job is to try to get a similar piston and then modify it to fit!

I am sure Wes will be about soon to give an opinion but thought he rubs a mix similar to mine:confused1:

I'm ok at the moment, thanks

Got two Aspen conversions coming up, a MS250 and MS210, both have been run on Aspen but are playing up a bit so will change the carb diaphragms and fuel lines, clean the carb and tank then retune - this should sort it! Barries Aspen stickers are going well:thumbup:

He must be in lurrrvvveeee with a girleeeeeeeee:thumbup:

Taking the clutch off a MS260 is pretty easy, the Stihl plastic double ended stop is good and the clutch has a hex nut on the end so spins off well - remember it is clockwise to undo!! Just thinking, you have located the chain on the rim drive correctly - if it is to one side, you could get this effect!

I understand what you are saying but using that theory, if I setup a saw on 50:1 and set max revs at say 13,000 If I were to use 25:1 mix, do you reckon the saw would scream to higher revs or sound like a strangled cat and smoke like hell??? IMO, it will be the latter - see what I am getting to, I guess you could prove it but I personally reckon a 40-45:1 mix with the saw set to the correct revs will give the engine more protection than using a 50:1 mix considering our fuel wil proably go the same way as the US with more ethanol content in time! Just my opinion:001_rolleyes:

Don't know Barrie - I think if you ran a 1:50 fuel to oil, that may never seize the engine as it would never start:lol: The point I was making was that if the saw was tuned to the correct max revs and was running say a 40:1 mix Fuel to Oil, you now have the same amount of fuel (oil & petrol) vapour going in to the engine but with a higher oil content and this must surely protect the engine against seizure as it is the oil and not the fuel that lubricates the engine. Sure, the amount of PETROL that is going in to the engine is less so it may not run quite the same power but the oil would protect the saw more. Would you say this is "Lean"........ not sure as the same amount of vapour will be passed by the carb (making allowances for the viscosity of the mix) and you usually say an engine is running lean if the fuel/oil MIX entering the engine is not enough but this won't have changed?? It would be interesting to run a saw with 50:1 and 30:1 and register the differences in output, max revs and heat generated - just my ramblings on a slow Thursday:blushing: I run 45:1 mix on all my saws for the record, even the hot ones!

So what you are saying is that with the saw going flat out, when it hits the wood, the revs stay high but the chain stops spinning. If that is so, it sounds like the clutch is worn or tight and not making good contact with the clutch drum. If the saws revs plummet and bog down when the chain hits the wood then it sounds more like fuel or compression issue!

I have heard a few say that putting more oil in the fuel "Leans" down the mix. Well.....it does as far as the fuel/oil to air mix goes. It also makes the oil content of the fuel/oil to air mix GREATER so it is less likely to seize an engine - that's my take on it and would like to hear if anyone doesn't agree:001_rolleyes:

I have been working on a 550XP this week, well two actually. One came in for repair as it was seized, the cylinder was shot and I know of a low mileage one that had been clouted by a tree, the auto tune gave me concerns on the first machine so a deal was struck between the two owners and I stripped the first one and used the crankcase for the second that had busted chain brake lugs. The first saw had been off to Husqvarna on a warranty claim and had come back saying the piston had been damaged by carbon from the exhaust port - this was a load of sphericals as the only "carbon" in the exhaust port was in fact, the aluminium scraped off the front of the piston as it fried!!! They had said the crankcase was pressure checked and had then taken out both crank seals.....WHY???? It just means I ended up having to purchase another two:001_rolleyes: I guess they didn't pressure check it and just took the seals out to cover their tracks. The machine was then returned completely in bits - even the flywheel had been removed and the clutch, oil pump etc...WHY??? I know they need to be thorough but you can test for leakage without dismantling the machine - you only do that if it leaks!!!! I wasn't happy for the original owner - I think the most likely case of failure was lack of oil in the fuel but more about that in my next post.

I think it is when the big lump at the top gets cut off and it hits the dumper below dislodging the first ladder leaving him stranded up the tree:001_rolleyes:

Not sure if this has been posted before - classic!