bmp01

I understand England are playing at the weekend, Covid is available most places if you look. Let us know when you're done comparing....😨

If chain sharpness / condition is in doubt just get a new chain ... Its a small outlay before admitting defeat. Just coz someone else can push harder on a bar and get it to cut that doesn't mean it's the right way to go about it. Are you getting nice 'chips' of wood or saw 'dust' out the back ?

Collection only from Ryde, Isle of Wight. 80 pounds. Just incase that saves 2 mins of internet time. Ah-ha "Wightbay", I should be awake after lunch... maybe....

I agree, the heat pattern says the crank bearing was the hot bit. Gets cooler as you travel away from big end bearing ie up the connecting rod (and along the crank). Ouch ! Edit - Maybe some of the previously mentioned crap got in the bearing at the first rebuild....

Nice one, thanks for posting your result. Did you repeat compression test, number?

Youtube channel afleetcommand has been playing with a g888 recently. Cant say its much of a review or the saws caoability and there's a lot of talk but the guy has run a few saws and he's pretty happy with it. Sounds pretty rough though, bag of nails rough.

Wouldn't have thought of that one, counter intuitive to me .... 👍 I suppose you're releasing any positive pressure (due to heat build up) and getting rid of most of the air (the springy bit). Maybe cooler, more viscous, oil plays a part as well.

Re. chinese clips- yep, its a true story, only safe place for them is in the bin. But its still accurate to say that any extra material (ears) attached to the useful bit of circlip effectively derates the useful bit - cant be any other way. The full circlip is more effort to fit, yes, but in all other respects its a better solution.

Circlips with tails are a personal hate of mine. No good can come from a bit of unsupported wire exposed to the accelerations of the piston. Sure, easier to fit but thats no concillation right now is it. The 357xp I stripped recently had an after market piston in it, same story, every thing is still assembled but tail missing from circlip, cylinder and piston written off. Remaining 'good' circlip was cracked from root of tail.

Well, in amoungst grass cutting and shower dodging here's a piccy or 2. It is a 170 2 mix cylinder, think the brg and seal arrangement is the same... Conclusion, seal will pass though the housing but will not pass the oil pump (another thing to remove then ).

I agree with you, once engine is out of saw just pull the pan off. I've got a 170 2-Mix in bits in the garage, I'm going to mock it up to a look at removing the seal behind the clutch. Picture in due course...

Ha, that's useful info. I wondered if that was the difference between the 2 types of seal listed. And why do they have the lip in the housing anyway ? Its not a feature that exists in many other split bearing designs. Think I'd be tempted to dremel the lip away 😈 😨 What about access behind the clutch though ? If you have to take the engine out that's still 90% of the effort / time / money...

Err, yeah sorry, we're talking different things ..... I think. I was on about the inner race - the hardened steel 'tube' bit, like this....

Needs to be a chuffing hard layer for it to last more than 2 minutes, the sort of thing that you're obliged to grind.... Edit: I've come across shaft repairs where the shaft is machined to accept a needle roller inner race of an appropriate size. Suspect there's not enough meat on a chainsaw crank though.

That's sounding hopeful ! Re carb - I've done the same thing with the metering diaphragm before now, round and round in circles trying to sort that one. The pictures all suggest piston, rings and cylinder are happy. If it now runs properly I'd be looking for an excuse to dismiss the low compression number. Might be the compression tester isn't really the right one for a small 2 stroke engine. ... Might be the decomp valve, blanking it off with a bolt and sealing washer is the cheap solution, common practice. Leave the rest of it assembled, less cleaning and less chance of getting crap inside the engine. Thanks for update btw.

Nice pictures - pictures always good for adding info. Extra saw history helpful too. As you say age isnt a big concern, pictures suggest the insides are in decent condition. The light scuffing above top ring I've seen once before - it was on a saw i did porting on, assumed I'd left grinding grit in there. Probably fine brick / concrete grit in your case, suspect its just a visual tell-tale. Worth noting: sometimes the top few mm of the cylinder increases in diameter a smidge (it's a manufacturing thing, honing to top of a closed cylinder is difficult) - its a good place for crap to get trapped. Compression numbers, thats low at 115psi but depends on your tester. Compare your numbers to what you get on another 'good' 2 stroke with same tester... Two stroke mix down plug hole or flooding the engine will give higher numbers through partial ring sealing - like your picture through ex port which looks shiney / oily. Personally, I'd keep going with carb cleaning / fuel investigations before anything more drastic, because that picture says the piston is happy. But keep in mind that compression number is low. Fingers crossed for you.

How old is it ? How much use has it had? Have you checked cylinder health with compression test ? Can hear any piston slap noise when running ? You could pop the exhaust off to see the exhaust side of piston - might give you a clue as to general piston health. But really you want to see the inlet side. I'm wondering if you've got a worn piston which is no longer closing the inlet port, that might lead to your soggy filter. A bit more saw history would be useful. ...

T27 Torx bolt head, might get a hex driver to work but it aint right.

Only buy in 5L qtys. Was surprised to find Screwfix sell 5L Oregon bar oil at 15 quid a go - about as cheap as online prices.....

I have limited knowledge regarding cutting angles but if you do some digging I'm sure you'll find info on here.

My advice would be to do a proper health check on saw before you start milling - paying attention to fuel system and check for air leaks around crankcase seals, intake boots, gaskets etc. As you're probably aware milling is harsh, it'll find any mechanical niggles in short order. Might be best to do some cross cutting first too, make sure it behaves itself. I'd set the saw up to run a little rich which will keep piston temps a tad cooler. Depends what value you put on the saw. And can it be rebuilt if it seizes a piston? I did all the above with a seconhand 390XP and it still shat itself in a 12" milling cut. Later I learnt it had an aftermarket piston and repaired cylinder in it..... thats the lottery of secondhand saws.

Think I'd put the breather at the top of the oil tank ....

Well that's different ! Clearly it's a filter. The location is good for the oil pick up so I'd say that's what it is. How does it work though? Given the height of filter and the fact you can't leave the top part exposed to air (coz then the pump will then only stuck air) - I imagine the filter goes into sealed a plastic tube, top of the tube connects to pump inlet, bottom of tube should connect to oil tank.... Have a look in the hole the filter came out of and see if there is a connection to the tank down low. If there is a "cross drilling" I bet its blocked. You might also see something useful through the filler plug hole ....

Never seen such a thing (sump plug), are you sure that's what it is ? As you've fitted a new pump you'll know which drilling or hose feeds the pump, clean that line out and check the oil filter for 'blockedness'.

There's a lesson for the design team - all failures straight down the centre of the rib I bet. I suppose the rib was put in to relieve the stress associated with expansion 'n contraction but they've concentrated all the load on a very tight inside radius, so it work hardens and cracks. Clever and daft in equal measure.