pleasant

Using your post muddy, as an example, you can see why, as a dealer it is cheaper in terms of labour to simply replace failed parts as a unit rather than trying to repair. Get a lot of carbs with issues...cheaper for the customer for us to simply fit new. Customers ask 'before you fit a new carb, can you attempt to repair the old one as it will be cheaper' No it won't if you have to pay us to remove, re-build, re-fit, then potentially remove again and then fit new, you are looking at two lots of labour plus the cost of a carb kit which didn't improve things. As Muddy is not costing in his labour, then not an issue and will be interested to see how it all pans out, but pricing up the labour involved to do what muddy has done so far would be eye-watering in a workshop. (Just a very mild rant at some of my customers that think labour cost nothing)

It includes tyres? There's a novelty...I know the 661 can be quite heavy, but putting wheels on it is taking things too far.

This could simply be wear in the pumping mechanism...is it the original pump? If so, then it's getting on. The reason it's not pumping is because the internal pump 'gearing' teeth are worn I should imagine. See it a lot on these 460's. You can blow air through so no blockage, but still not pumping, because it isn't actually a blockage, but the gap between the mating surfaces of the pump have worn down to a point that they aren't actually doing anything. New, genuine Stihl pumps come out at around £75 plus vat.

Has to be pre 1989 due to the early metal riveted nameplates instead of the later grey plastic ones, and most tellingly the stihl metal badge on the recoil cover has made in west germany on it. West germany ceased to exist when the wall came down in 1989

Right. I sent the photos to customer last night explaining we know what is wrong, but cannot work out why. I asked if he has had some work done on it recently elsewhere? Customer rings me this morning to inform me he took it somewhere else last year and had a new drum fitted by them and has had issues with it since then! Would seem the previous repairer may well have fitted an incorrect drum. I am now going to order a correct genuine drum and compare. Keep you posted.

Replied.....thanks. Things have moved on since last night after I text the customer. See my comment below.

Strange one today, so any advice and suggestions would be welcome. We have taken in an Echo CS420ES saw. We aren't familiar with them as we are other brands, but a good customer who also has brands we are main agents for, so didn't want to upset him by not at least offering to take a look. Guy said on idle the chain was still spinning. Removed the chain cover and bar and chain and could see the chain had 'slid' off the sprocket teeth on the drum and was effectively on direct drive hence the spinning. This during recent use has caused the chain drive links to grind out a groove in the alloy oil pump body as well as wearing down the nylon oil pump drive gear teeth. Removed the clutch and drum and really couldn't find anything wrong per se. However despite replacing the clutch and tightening it right back up again there is around 4-5mm of 'end float' between the teeth on the sprocket and the teeth on the oil pump gear in the body of the saw. You can pull the drum in and out-thus, away from the nylon oil pump gear teeth- this is why the chain has come off and got jammed and would be why the oil pump isn't working as the gears aren't meshing. I will attach some pics of the air gap between the two. No washers are missing and the teeth on the sprocket don't look worn down in terms of width, although not knowing these saws too well I am not sure how wide the sprocket teeth should be...they do look quite short compared to the ones I usually deal with but the face of the teeth between the drum and the body don't look ground down shorter than factory? Ideally i need a sprocket with wider drive teeth to take up the play between the drum and the body, but never had to address that before- ever.

They are interchangeable as long as you change both the bar and the chain as a pair, as the 171 runs 1.1mm chain and the 181 runs 1.3mm, so be careful

There are always loads of the 181 on the bay. Either complete for spares or separate parts available......a popular budget saw. Parts are generally not rare or hard to come by. I note you say you like saving saws and know theres no money in repairing a 181, so why dont you just buy what you can't find, new from a dealer?

Avoid the 290/390/291/391 saws, they are the farmer range of saws and are beefed up domestic style saws in the stihl range. The engines are clamshell (cheap, and bastards to work on) construction same as their domestic stuff and the power to weight ratio is poor. A really nice late ms260 would be superb. If you get offered an early ms261 then walk away as they have clutch bearing issues.....later ones are all sorted, but will be dearer than what you probably want to pay

Loads.....not knowing how you took it apart and how you put it back together it is nigh on impossible to know exactly what has caused these issues. Anything now would be a guess out of the dozen plus reasons you have this issue now. Sorry.

Agree with ADW. Although you need to establish the reason you have had this failure in the first place. If it's a simple case of you adding a weak fuel/oil mix, then a new piston and barrel will sort it. However if you have an air leak somewhere, then just fitting an new piston and barrel means the same will happen again.

Well, as I say to my customers EVERYTHING is repairable. Comes down to how much you want to spend and whether what you spend stacks up against a replacement machine.....that is what affects all repairs. The Husqvarna as you probably know is very much a budget saw in their range, so doesn't take a lot of labour before a repairs is uneconomic...unless like you, you can repair it yourself. However having done that you still have a saw with some serious issues now. If time isn't an issue for you, then sure spend some more time investigating and repairing, but my gut feeling is sell it on the 'bay' as a spares machine and invest in a better, new or newer saw. Particularly if you rely on one.

That ring groove is badly smeared

True. National minimum wage is £11.44 for over 21's , so an 8 hour day stacking shelves in tesco is going to get you nearly £100 a day.....more if you work evening hours.

Stihl oils, lubricants and fuels are made to their specification by a company called OMNI Speciality packaging based in the USA, Louisiana. They produce bespoke products for a lot of well known brands. If you go to their website, and then click on the videos tab at the top, then watch the corporate video you will see Stihl motomix at the 37 second mark Omni Specialty Packaging WWW.OSP.CC Omni Specialty Packaging (OSP) manufactures, markets, and distributes lubricants and chemicals to automotive and...

Is it fitted with a rim sprocket? It's possible the drive teeth aren't located in the corresponding holes for them in the rim, so with the side cover loose it will allow the chain to move, but when tightened as the chain isn't correctly located it will clamp it up and not allow it to move?

Yes, it is running within acceptable parameters. As ADW has said, by modding the exhaust all you have done is make it a bit lighter.....so every cloud and all that

1.3mm and 1.5mm is the thickness of the drive link that sits in the groove of the bar. It may not sound a lot of difference and both will sit in the groove when cold, but as the chain rotates through use, the metal bar and chain will get hot and hot metal expands-this will cause a 1.5mm drive link fitted to a 1.3mm bar groove to jam and either simply lock up or throw the chain.

Just like the police force nowadays. 'vunerable people' 'duty of care' etc etc.

I don't recall that. I've been dealing with various brands as a dealer for nearly 25 years now, and a Stihl main dealer for the best part of that, and I don't recall a Stihl fitted with a re-badged Honda 4-stroke unit. I have sold brush cutters that were from a manufacturer that decided to fit the excellent Honda GX25/35 4-stroke engine to their machines, but if definitely wasn't Stihl.

errr...ok.

Why?

Here you go: Compression pressure should be between 7.5 and 8.5 bar. Here's the page from the WSM: