bmp01

How about a turned (lathe) insert epoxied in ? Could have a rim on it .... so a "top hat" insert, put in from exhaust side. Benefits are, it won't come out, top hat rim is thinner than a nut, can have the location nose on it, can take a proper thread most likely a size down on the self tapper cack. Concerns: is there enough meat to centralise the hole and can you then file / drill a reasonable hole (doesnt need to be perfect if the insert is glued in).

Here we go again.... Think OP is going to find Spuds answer slightly more useful. For entertainment value we'll give you 9/10 for effort Stubby. I'm in agreement btw.

Ok, as simple as.

How did you go about doing that ? Seems like a plan if you've got a half used can kicking around.

3 spare plugs for one saw sounds a bit excessive. 3 spare plugs for your collection of saws doesnt sound enough 😆

In terms of overhang from crank bearings its a few mm in a handful of mm - big percentage for the engineer's sums. With you on the rest of it.

First part: No, brake band is a wibbly wobbly thing. And gets hot if rubbed too much....oo-er-misses. Second part: Lets exagerate things a bit and imagine a top handle saw with the bar and chain half a meter away from the engine; top handle above the engine. Apart from being horribly cumbersome, I think you can see it would be almost imposible to react the chain pulling force in a cut, single handed. So again, its an advantage to have chain as close as possible to engine centreline. As you say, the manufacturers seem to agree.

That. It doesnt matter the route the forces take, clutch or cltuch bearing route.

Exactly. It did seem to work surprisingly well without brg. Lucky the brake band held the clutch approximately in the right place I suppose. The transition from from idle to chain runnning though .... horrible ! I should say I didn't cut with it like that, took it apart because it didnt feel quite right. I know the MS261 story. But even the substandard cranks were hardened steel , I still think it's a valid statement to say bearing works hard. Ok, sensible. But I have an issue with the clutch not running as true as one would hope. They're not that accurately made, carrier is held on with a thread, obviously play between the components for the weights to move. My guess is the bearing clearance is tight enough to do a job of keeping the clutch assembly concentric while clutch is driving the chain. So its carrying a force - I think. How much, dunno.

Emmm... dunno. The 390xp i bought s/h started and ran ok'ish, slightly strange behaviour as clutch engaged. Turned out the clutch bearing had been pinched out of the saw 😲 On t'other hand the early ms261 fiasco says the clutch bearing/crank has to be up to spec to survive - it clearly works for a living, that says its not just a spacer IMHO.

Yep. Space for chain end float same for both too. I was thinking about the forces on the crank. Forces ought to be smaller with chain closer to crank bearings. Then I got stuck, considering the load path from crank to chain. I suspect theres a better case for the outboard clutch, chain forces supported through clutch bearing which is closer to engine centreline. But when the clutch is engaged does the bearing take all the chain force .... or does the clutch ?

Which one puts the chain closest to the centreline of the saw ? Does that mean the crank dimensions can be smaller (ie lighter) ?

I know. But its skirt trimming on inlet side as you said and crown trimming on exhaust / transfer sides (not crown trimming on inlet side, which is what needs editing...). STICKY..... STICKY..... STICKY..... 😀

This ought to be a Sticky at the start of the thread. Quick edit of '...crown inlet side of the piston...' maybe ?

Aw crap did it happen again.....

The same, cheapest of the cheap. So turns out it was piston trouble with mine, not a lean seizure but heading that way ....

I price checked Meteor and Hyway top ends before buying, need to check rod width as its '04 model then time to order.... Needs the inlet clamp update and carb rebuild.

Weird timing... picked up a 357xp yesterday, non runner - described as having low compression. Expected piston trouble but its free enough, cylinder 😩 looks like this:

Sorry frammo, lost me there matey, dont have a scoobie do what that means....

Well, I don't know the guy or have any experience of his saws so this could be total bollox .... but at least he has detailed his work in the listing description, quite comprehensively. I guess he could have said "exhaust ported" rather than "ported" not a huge sin though. Feedback looks ok, I've not bothered to view the video of the saw...

Yep. Low speed fuel circuit will affect fuel mixture at high engine speed, to a small degree. High speed fuel circuit shouId not affect idle speed mixture. Both low and high speed circuits are in play at part throttle so both affect engine pick up. I tend to go around the loop (low speed jet, idle speed, high speed jet) a couple of times if I have to do much adjustment on the first go round, just to be sure.

Nice one, glad you got a result.

Awkward situation, been there a few times, never found a satisfactory way out of it. Looks like it will end up with ebay making a ruling if you pursue it. The seller's stance is clearly that youve messed with it (taken it apart) and its a valid point. Exhaust off isnt anything out of he ordinary to us but its ebay we're talking about... I dont think there is any merit pursuing a knackered piston approach. Aside from obvious compression issue, its relatively high tune of engine - timings need to be accurate for this saw to run well and inlet timing (controlled by piston skirt) will be out of wack with that level of damage. The cylinder is most likely gone too (scored rings) but you never know, you might get lucky. The part refund thing might work but could just as easily backfire - its like you're accepting you are keeping the saw (to seller and to ebay). I dont have a real answer to the situation, sorry.

Or as it 'peters out' at idle then a fuel issue. Most likely fuel residue left behind as last fuel droplets evaporated out of the recesses and crevaces of the carb. Alternatively, it could be the rubber parts inside the carb have just got to the point they need a refresh. Worth winding the low speed screw all the way in (gently) and back out to the same point as a quick and dirty test to see if it improves plus you get to know how far off std settings you are. If it runs ok at speed give it a tentative run, might clear cobwebs out. But be wary of fuelling issues at high speed for fear of seizing it if fueling is wrong. How fresh was the fuel before it went in the can?

Spiders built multiple cobwebs over the air filter and blocked it.