spudulike

Probably the clutch needle bearing - get some oil on it and see how it goes. It may also be the crank bearings but a lot less likely!

Interesing thread, my comments - I use "Simply Bearings" to source come bearings and seals, Chain brake - I only snap it on if I am walking with a running saw or repositioning myself on uneven ground with the saw running. I only snap it on at speed to test it during a service and start the saw with it off - I am an engineer so have some respect for the saw:thumbup: On the bearing wear - could this be down to the saws using less fuel oil mix? Less fuel consumption means less oil is covering the saw internals and during heavy use.......... Could the bearing wear be improved with adding a little more oil to the mix? Probably worth trying iMO. I am surprised the flywheel bearing is failing, it is usually the clutch one that gets more abuse from over tightning the chain and extr heat from the clutch. Interesting stuff - perhaps the autotune technology is too good at fuel control and bearing technology has to be looked at to catch up!

Yes but it worries me when you take a saw apart Matty, the hammer is rarely used by most saw technicians:001_rolleyes::lol Seriously, the cardboard method is something I used to use on motorike cylinders and crankcases. It is damn important to get the right length screws in to some holes as an over long bolt can puncture through in to oil tanks or crankcases on some machines!

Thats next on the list, it will be a good work out and judging by the way it pulls, should be good. This was some Walnut Marting dropped off. I know someone that works with wood so was milling it by eye for him - 2' length, no contest, far better than before and sounds glorious when idling, nothing quite like it:thumbup:

Excellent news, salvation at last. Just been out with this ported 181SE of mine, 24" bar, full length, goes like a train and pulls like one, it is bonkers:thumbup:

Procrastination is the thief of time:sneaky2:

Sounds encouraging, 026s are always a bit fussy on the carb, the older ones more so. If you need to hear fourstroking, put the H screw on 1.5 turns out and listen - it will thump and smoke a bit. The L screw on the older carbs does affect the H screw so 3/4 on the L screw may well lean down the H a bit but 3/4 doesn't sound to bad - if you do turn the L screw out, you will need to typically increase the idle speed and one check to ensure it isn't all over the place is to fire it up on the choke off fast idle setting and if it doesn't have a fast idle, you have probably gone out too far! The saw should be close to 1 turn on each, if it is out by a lot, it is showing up a fault!

Keep off the ported page, it is addictive:blushing: Most saws fail due to fuel issues, if the saw idles, the saw is getting enough fuel for it to do that. If the saw revs out when not cutting and then bogs in the cut then it sounds a bit like either lack of fuel or low compression. The 026 generally has a lot of compression, 170psi is very possible and must be over 150psi. Taking off the muffler and looking at the piston for scoring is well worth it - takes 5 minutes and gives you a good indication as to if the saw has seized or not. If the piston/compression looks OK then the issue is probably fuel related. Typical issues will be a holed impulse line, holed fuel line or a blocked carb internal gauze filter. It is also worth making sure that the H screw is 1 turn out from fully in as if it is running lean, this can stop peak power. The 026 is a better saw than the MS181 or Husky 135 etc, these are lightweight home owner saws although some pros use them for lighter cutting and hedge work! If you need a new piston, it is possible that the saw has an airleak and the cost of a decent aftermarket Meteor piston will be circa £25-30 It is also worth checking the wiring where it goes over the top AV mount between the cylinder and rear airbox plate - the wires can chafe and cause a short circuit and therefore a bad spark!

The muffler bolts can be a bit tricky to shift sometimes but once off, you will be able to see the piston and look at its condition. If it is OK, the running issue is probably fuel/carb related!

Yup, that's where my not liking of this device comes from, usually it kills the piston with time. It would be a good reason why the saw is only making 100 psi. You can pull the muffler off to take a look at the piston, any deeper scoring is bad.

If you take the cylinder off, support the von rod well as the big end rollers all fall out if you dont:thumbdown:

Thats a good point ADW has just made, I forgot the 338 had an auto decomp valve - bloody horrible things but he is right that it would drop the compression down. Don't know why you need one on a small saw like this but measuring compression on one of these saws is a PITA as the deomp needs blanking off before testing!

Enjoy fitting that - it is a clam engine so not that easy a job, you will need some liquid gasket for sealing the clam to the upper crankcase/cylinder plus if you remove the oil adjuster, when you screw it back in, push the oiler shaft well in so it doesn't bend the oiler shaft - common error!

I do a similar thing but am not fussed about wood. I have burnt Willow, Poplar, conifer and cedar and as long as it is seasoned, all is good. You are more likely to get this sort of wood FOC!

Possible tank vent, it is also possible that the compression is borderline and when hot, it is too low for combustion so the saw won't start. The coil may be failing when hot, worth checking the flywheel to coil gap as this can do it as well.

You have done a compression test and that is on secondary compression on the cylinder primary being the compression in the crankcase! A pressure test is putting around 10psi presure in to the crankcase and checking for leaks in seals and rubber parts etc sometimes called a leak down test. The 338 needs a new piston unless the ring has snapped, 100psi is very low, the others are OK

I was going to say the same as Stubby is correct. I think Wes is trying to say that the volume of oil going through the saw if the fuel saving is 25% represents the same amount that a mix of oil a 65:1 mix would give but he is American:001_rolleyes:

The issue is I will have no time to finish it when I am doing the cooking ironing & housework when she has kicked me out! Not a good idea. Did I tell you about the 066 crankcases I had sprayed up and put in the oven to bake when she came back home unexpectedly and wondered what the hell I was cooking as there was a strange aroma of paint oil and yesterdays meal:blushing: Just about survived that one!

Cheers:thumbup:

Are these prices inclusive of VAT end user prices?? doesn't seem too bad value. Just waiting for the day I get a buggered unit in so I can se if there is any way of stripping/repairing these units!

Started up on the 560XP, sorted the damage the disintegrating stuffer caused and have modified the transfer lowers and channel. From the standard image you can see the bulges where the exhaust bolt is supported and a casting flash nearer the upper transfer. I will clean and extend the uppers and also modify the lower skirt of the cylinder by the transfer where it pushes in to the crankcase but will wait for the bottom end to arrive as I don't have it yet. The support bulges have been reduced, the flashing smoothed and have smoothed and flowed all the angles in the lowers. Flow doesn't like angles as it caused turbulence and this slows flow! Next job is the exhaust port - this has a very flat lower edge so have to be careful it doesn't snag the ring so will be conservative with the port shape, may drop the lower edge and bevel it well!

Like my signature below says................

Blimey, you haven't even got off ground zero, guess it is good to have a dream:001_tt2:

I just hate working on clamshell saws and you have the added complication of having to seal the lower clam to upper clam as well on rebuilding the saw. For the average home owner without a scoobie on saw construction, the job may be a little complicated. You could put plenty of grease around the piston to catch any swarf that may get past the cloth. Perhaps use a piece of rolled up paper the shape of the bore to open when in the bore and direct the swarf out of the exhaust port. You could do the whole job with the saw upside down - perhaps that isn't as silly as it sounds and any swarf could be blown straight out the plug hole! V-tech do a nice pilot nose tap - expensive but does the job very well!