pleasant

Joking aside...I have actually been asked that over the years. More than once. Had a guy buy a saw from us..brought it back a week later saying it wasn't right as he was getting chain oil and crap all over himself....turned out he was left handed and was holding the rear handle with his left hand and the top wrap handle with his right and was in the firing line of all the shite being thrown back from cutting. I pointed out he wasn't holding it correctly and there's no such thing as a handed chainsaw...just the correct way to hold it. Oh, and if you continue to hold it incorrectly like you are and the chain flies off it's heading straight for your leg, as you're standing on the wrong side of the saw.

As mentioned above...could be a blade binding issue, but the bearings sound really rough...certainly not a smooth operation. As its being run in the video, spray some lube on the blades...if it changes the blade speed, then look in the blade area for the issue. Gum, burred teeth..that sort of thing. To my mind it sounds motor/bearing related though

I appreciate this is top end stuff, but all should be taken into consideration for the wider picture. What compression tester are you using...it is known to you to be accurate?

Poor plug threads in the cylinder, leaking carb or manifold, rings not correctly fitted and to a lesser extent crank seals leaking??

There should be constant drive to both rear wheels when the drive is engaged correctly

iIiiiiiiiiiiiiiiiYou could but you wont be the best results turning it by hand. If you remove the blade it will most likely not start so dont try. The blade acts as a flywheel, and trying to start a mower like yours with no blade fitted when you pull the rope you with get severe kickback and the rope handle will be snatched out your hand.....very painful. If you have checked the cable is correctly attached to the operating lever on the gearbox, and you have cleaned out the pinions and lubed it all up, just reassemble it all, put the wheels back on, start it with the blade on and engage the drive if you can easily stall the drive to the rear wheels by holding it back from going forward, then stop the drive, adjust the cable up via the inline adjuster and keep doing it until the wheels continue to scrabble for traction whilst holding the mower stationary. If you can hold it back and the wheels stop rotating under load even though the cable is adjusted as far as it will go, its the gearbox........as i mentioned earlier, this is providing the belt is correctly tensioned, but if it isnt you wouldnt get any drive at all as the belt would simply slip on the engine pulley when started.

That split spacer is nothing to worry about regarding the loss or poor drive. That roll pin in the axle needs to slide easily from side to side. In the pic of the drive gear where you have circled in red on the inside of it, those three 'teeth' need to be nice and clean. Debris can build up in the corners and then the pin in the axle cannot get a good grip in the corners and can slip. Yours looks pretty clean though. It's a simple system as that's all there is to it. Assuming the corresponding larger gear inside the wheel hasn't got teeth missing then I cannot see an issue with the drive mechanism you have shown. If you are sensible, then remove both rear wheels plus the drive mechanism on the end of each axle rod...so all you have are the two rods protruding. Then lift the rear end of the mower (don't ground the deck) start the engine and engage the drive lever and then watch both axles...they should rotate. if not, then it will be the gearbox (or the cable has come unattached from the top of the gearbox- unlikely though) If there is some rotation...which there may be with zero resistance from the mower not being on the ground....then stop the mower. Re-fit the roll pins and both gears, lift the weight off the back end of the machine, start the engine, engage the drive again but get someone with a decent glove on to put gentle pressure on the drive pinions as they rotate....if you can stall the movement with your gloved hand then its the gearbox. As an aside.....you stated the belt is in place. However there should be a degree of tension on the belt otherwise it will simply slip on the pulley on the crankshaft. To check this- remove spark plug. Tip it on its side with the exhaust side facing the ground. Then rotate the blade by hand......there should be a positive grip by the belt in the crank pulley. If you can move the blade and the belt has little or no movement then it won't be transmitting the drive to the gearbox pulley. There is a tensioning mechanism on all this type of mower for the belt....mostly a tension spring on the gearbox to pull the gearbox on it's pivoting axles backwards to tension. Some have a metal bracket, which when fitted also lifts the front of the gearbox up and back...again to add tension. The springs have a habit of coming off in use, thus losing tension and then drive.

I was sitting on my bed pulling my boxers off, the wife walked in and said, 'you spoil those dogs!'

To be fair, when i was in the trade....they did that from new....and rust was standard. Taking nothing away from yours and your enjoyment, but friends i still know from back when we were selling them new, cant understand how popular they are nowadays. They were crap back in the day, and doubt they have got better

Awful, waxy, cloggy stuff. How to eff up your oiler very quickly. Especially if you're a weekend warrior who uses a saw two or three time a year for the woodburner and you leave the oil in the machine

On the end of the gearbox axle shaft inside each wheel is a drive pinion. These have a tendency to seize on mountifields. Its a ratchet system to allow for pulling the machine backwards so the wheels arent permanently locked into drive. They will be held in place with a circlip. Remove circlip and any washers and gently slide off the pinion.....i maybe seized on the drive shaft so some release agent and a pry bar will help. Depending on the set up the ratchet system will either be built into the pinion or there will be a keyway in the driveshaft with a spring loaded woodruff style key. If theres enough crud and rust the woodruff keys sticks in the keyway so doesnt lock with the pinion so it will freewheel. Needs to be removed, cleaned and lubricated.....use a light oil, not grease as that attracts the crud again. Then reassemble. It could also be wear inside the gearbox as the gearboxes are pretty lightweight for a heavy machine. Trace the end of the drive cable to where it attaches to the drive activation arm on top of the gearbox and then with a clamp, clamp the lower drive lever on the handle in the engaged position. Then get your hand on the lever on the top of the gearbox and fully push that lever right up to its stop. Then with your free hand move both rear wheels....if theres still little or no drive to both wheels then the gearbox is shot. Do this as a last resort as cleaning out the pinions may well sort it.

Yeah....and I bet the cost you'll charge me for mine will mean yours will be free! 😅

Yup.....I collect rare and/or desirable old saws. Only ones in what I would call 'shelf queen' condition. Only have around 15, but to my mind they are some of the best examples of their models. Still holding out for a Solo twin, Stihl 041G or McCulloch BP-1...or all 3!

300 tanks of fuel is an awful lot for a lightweight domestic spec saw like an ms231. That's 15 years or so use for the average specified user cutting a few logs a couple of times a year for their wood burner

Don't mess around. Honda carbs are notoriously fussy with anything other than fresh, clean fuel. If fuel has been left in the carb for an extended period sure as eggs is eggs you will have carb issues. These horizontal Honda engine carbs are really easy to remove and replace...easy access and nothing difficult. A 10mm socket and long nose pliers to remove the rods (take pics first if not sure) and off. New carb (genuine Honda) around £60-£80.......you will pay near that for just a carb clean with no guarantee it cures the issue. Just get a carb on it and be sure it will work first time out the trap. Give me the engine numbers and I will tell you what part number to get.

I remember talking to my Husqvarna rep years ago when we were main dealers for that brand I said why do you provide grease holes and Stihl don't? He said 'if you don't grease the bar sprockets through the little grease hole on Husqvarna bars from day one, then never do. If you decide to from day one, then continually do it....it's either or, but never both.

It's an industry rule of thumb that the ideal bar length is roughly one third of the saws cc's So, your 50cc 550 ideal bar length would be (around) 16" certainly no more than 18"

You are correct. Always mix according to the oils recommended dilution ratio...not what old handbooks state.

Like i said....thats because a 20 year old mountfield isnt a modern mountfield

Releasing the opc lever (operator presence control) does not 'stall' the engine. It operates the same way as a petrol car, by cutting out the the ignition circuit to the spark plug. Stalling the engine is done by artificially richening the fuel by effectively putting the choke on an already warm or hot engine.....not good for any engine. 2 or 4 stroke. As and aside.....it would have to be a pretty awful b&q job, if you consider a modern mountfield a step up as they are shite nowadays

I collect classic and rare chainsaws. If you want to pm me i can give you an idea of value. But condition can be more important than rarity. I may be interested in what you have to add to my collection

That engine is fitted with a manually operated choke via the throttle lever on the upper handle. The choke should 'flick off' once the throttle lever is moved back to the max revs position via that spring to the upper left of the pic. The plastic it is attached to on one end of the spring is the choke butterfly. You should be able to observe that plastic 'lever' flicking off when you move the throttle control off the choke position. If it doesn't move, then the choke is staying on whilst in use and will run rich which will cause the plug to foul. If not sure it is flicking off when the throttle lever is moved away from the choke position, simply remove the air filter outer cover and the filter itself and observe the choke butterfly through the intake hole inside the filter casing. If the butterfly doesn't move when the choke is taken off, then that is no doubt your issue...however in 25 years on working with Briggs engines like yours, I would be surprised. Yours is an early model hayter and there should a small slotted screw to the front of the carb that will control the fuel richness. It is actually on the front of the carb underneath that pic of the governor assembly. A small long flat bladed screwdriver is what your need to adjust the fuel flow via that screw. Anti clockwise with richen it up, clockwise will lean it off. Do a quarter turn at a time. If someone before has over richened it then you will get a fouled plug, but them may have done that to overcome another issue with the carb such as a hunting issue. Below is a pic of the type of carb, and it is the brass screw you should be looking for.....it's only the early carbs that had this....yours may not have one, in which case it is a fixed jet carb and as you have changed stuff I would suggest already then I would be scratching my head without physically seeing it or hearing it running.

I would seriously hope they aren't using that. Old engine oil is just full of swarf and various other engine deposits that will very quickly fail your pump, block oil holes and burn your bar up.

Who did the work?

Requiring a 16" bar on a 'budget' battery chainsaw is pushing it a bit...particularly for the budget. That's a lot of load on a cheapie....can you get away with a 14" or even a 12" bar?