spudulike

Why, unless a crank or main bearing has grenaded, there is very little to gain from doing this apart from destroying the machine.

You my old mucker are a wanker....I made a splitter and also some kindly gent gave me one like in the pic!!

I would really avoid splitting the cases. It is worth checking there is no play in the crankshaft but if there is, throw the towel in. For simplicity, take the impulse line and carb boot off and check them out carefully. TO fully check them, you need to seal off all the crank openings and check with vacuum and pressure with a Mityvac or similar but they are £60-80 hence my comment. look for damage or splits/holes and replace if found to be faulty. Start with this and as far as the cylinder goes, use acid or strong alkali to shift it....battery acid, brick cleaner or caustic soda/strong oven cleaner can work well! Apply, let is stop fizzing, rub with wet and dry and start again.

The "A" means it is slightly smaller in bore size, "B" means slightly bigger and was from the days cylinders and pistons were matched.

The markings on that flat plate are EXACTLY the same as Stihl use on their pistons and some of their cylinders. Aftermarket cylinders very rarely mark their cylinders A or B. The plating may be chrome, more liable to chip but still strong. 80s bikes were Chrome bores hence this view.

I am sure we can give it a go. Legendary status...I just do my thing, I am not on Facebook so probably miss most of it but just sort out issues and get saws working as they should or better....people are happy...all good!

Sorry Rat....you are wrong, that is an OEM part. If the OP can learn a bit, the best option is to strip the cylinder off, strip the transferred aluminium from the bore and then hone lightly (or rub the bore with wet and dry) then fit a decent aftermarket piston...Meteor or Hyway are your best bet. Best find out where the crankcase is leaking as well - the impulse line is probably the most likely, seals tend to leak a little with age, you can visually check the boot - someone may have stuck a screwdriver through it or sometimes the clamp splits the boot.

When you fit the new inlet manifold (Bellows), fit it without the plastic bits on it and make sure the nipple that pushes in to the hole below the inlet port is pushed home nice and snug before the plastic parts are fitted. This is the correct way, pre assembly tends to squash the nipple on fitting and YES STUBBY....I did say NIPPLE Good luck with the clamp - I use a pair of mini plumbers adjustable grips!

Has that cylinder got anything stamped on that flat near the spark plug and is there any identification near the bottom of the cylinder either side - like Stihl, Mahle, Gilardoni, Tecomec etc? The cylinder looks a bit aftermarket to me. As others have said, the leak may be the impulse line, inlet manifold or crank seals.....depending on your abilities decides the fate of the saw.

Could be a leaking crank seal The most common issue is a split impulse nipple on the top of the manifold. The second most common is the manifold has been fitted incorrectly and the impulse nipple is distorted, after that, leaking manifold, dodgy crank seal (Although that NEVER happens) and the impulse line between the carb union and cylinder union can come off. My money is on a split manifold or badly fitted one - the former isn't easy to see!!

Pretty much agree with this, I have seen a few worn crankshafts without these issues.

The L, H and LA screw really need to be adjusted together but on this saw, thankfully, the L&H screws are independent and don't impact on each other. You have set the H screw...fab.......if the L screw has the limiter still on it, it is probably pretty much OK but the usual method is to wind it in until the revs rise and then drop back until the saw either stalls or is close to it. You then turn the L screw anti clockwise and the revs will increase and start to fall.....as the screw is undone, the revs will go from even to slightly uneven and you may feel the saw starts to rock or judder slightly - the point this starts is bob on where it needs to be and you then adjust the idle speed to 2500 rpm - slightly faster if the saw is stalling but not so fast the chain is pulsing forward. Stalling after a high speed run can be down to an over rich carb but if the H screw is set correctly, it is probably the Idle setting.

Saw this and think it very apt and to the point...plus a great song.....

Never seen one like that, looks like the gudgeon pin is soft and it has had a hard impact. Strange on the piston crown. I would have expected damage somewhere from where it ended up. May have been lucky and ended up in the exhaust. It would be worth inspecting the big end cage - the normal way is to lubricate it, shove the cage to the left, the rod to the right and hold the rod in place and rotate the cage looking for cracks, missing cross sections etc. Repeat on the other side of the rod and then a final check - get the rod in the middle of the big end, push the small end hard to one side and see if the rod still rotates cleanly on the big end by moving the small end to and fro. If it feels notchy, something aint right. A bit subjective but it is my go to test.

I always think the lubrication isn't of great importance as most of the lube is thrown out during the first few minutes of work, I do however lube the needle bearing when in the workshop as most would. The 3120 is different as I am sure my friend ADW will tell you all.....we do get on, he is a good guy and mean no harm. Most of the damage is done by not bothering checking the bearing and drum to the point a little play becomes really terminal taking out the drum and then the crank. A yearly check or changing the bearing every rim and drum check/renewal is the answer.

It isn't always that obvious. As I said, the only way I found my first one was the cylinder would wobble when the machine was slowly rotated with the cylinder loose and being held down with a finger!

Ah...how about this, piston ring pin comes out, gets rammed between the piston crown and squish band, con rod gets bent......very possible, what does the squish band and piston crown look like? Any indentations?

That's a bit strange, no reason the rod should be like that as there is nothing to contact it. Perhaps someone has done something with it they shouldn't have....weird!

Possibly a bent rod, had that on a 630 once - the only way I realised was the way the cylinder rocked when held down lightly and the engine was turned over slowly! You tend to get scuffs on the sides of the piston.

Look me old mucker...In time they leak, and if they leak, I change them. The manual says about pressure testing only but cock all about vacuum testing. This is tosh as I have had saws with idles that are unacceptable but by the word of Husqvarna are fine on the stated pressure only check. They FAILED on MY vacuum check and guess what fixed them....A NEW SEAL!!!! You know how two strokes work, air should only enter through the carb and not leak pressure or vacuum from anywhere else on the engine. I have done enough 346s to know by now......and you know it

I measure the crank in three places and 0.25 of wear is well and truly fooked, 0.15 is on its way, 0.1mm with pitting is ....fit a new bearing, check the drum bearing surface for wear and see what it feels like.....it is not going to get better, that's for sure and is on its way. I don't know the nominal measurement of the crank - Husqvarna don't come up in nice round metric figures! Warning to others - a good regular service by someone half decent.....or a regular new bearing would have saved this happening.....expensive lesson! I can't be 100% sure it is the cause of the spring issue. Unlikely but something has been causing it.

They often get air leak issues on the inlet manifold through splitting or badly re-fitting and also on the clutch side crank seal!

The top pinion is a 346 one....part code 503 89 21-02 The lower one - I can't see the code on it.

Correct part code - 503 91 27-02

The hardened surface of the crank is breaking down so the bearing hasn't been changed often enough. I have scrapped 346s like this as a new crank is £££+ There is wear on the clutch cover where the clutch sits. This is due to the clutch spinning off when the saw de-accelerates. I find it happens on Husqvarnas more so than Stihl and usually take procedures to stop it happening. It is somewhat strange that the semi circular bit in the middle of the cover hasn't worn. It is possible that the damage was caused but the work crankshaft/broken clutch spring/worn clutch rather than the clutch spinning off. If it had spun loose they often re-tighten clamping the oiler pinion and not meshing with it causing damage. Lastly, measure with the ground end of the verniers!!