spudulike

Check your gauge with a known good saw that is run in and working well - if it pulls the same then all is well and your gauge is reading low. Standard test is to test a cold saw (a hot saw lowers compression), it should have been run if possible so normal levels of fuel/oil cover the piston/cylinder, the saw should be put on the fast idle setting and the choke taken off, the first pull should give around 100psi and then around 4-5 more pulls should maximise the compression reading which should be as originally specified in my earlier posting. 120 psi is low and you may have damaged the ring on assembly, does the saw run - 120 psi and it would be touch and go as to whether it runs. Does the 51 have a number of piston options - perhaps you have fitted the wrong one? I think they came in 44 and 45mm versions!

Oh - I gather you salvaged that comp gauge off the Ark Royal - think you may need a new one - the Gunson one usually does the job - much read about Schrader valves and the like but mine works just fine.

Think you had better read my last post my friend - compression testing is NOTHING to do with pressure checking. FYI - compression in a decent running saw with a flat crown should be 150PSI - 180PSI, a saw will run with as low as 130PSI but usually badly. Maximum PSI I have recorded was 240PSI with a vintage Jonsered with a domed crown. Exceptions to this rule are vintage Poulan Countervibes where they are renowned for 135psi being normal and good. Generally, good compression = good power

Right -No 1 - Thanks Matt for the good rep - your 372 is coming along nicely - found some interesting stuff wrong with it....... Pressure checking, firstly absolutely NOTHING to do with compression or the performance of the top end of the engine. A two stroke engine pulls fuel oil mix from the carb, into the crankcase and then pushes it up through transfer ports in to the compustion chamber, this action also expells the exhaust and then once the piston clears the exhaust port, we are all ready for a good bang and lots of smoke. The air is controlled by the carb and the integrity or the seal of the engine is critical to its correct running, if the crankcase seals, impulse line or carb boot are leaking, you will pull air in to the engine in varying and unwanted amounts and this then can cause a very weak mixture. If you are lucky, the dodgy idle will warn you about the problem, but if you just adjust it out and carry on then the next thing that happens is the exhaust side of the piston melts on to the cylinder wall - a full or partial engine seizure. So - if an engine has seized, new parts are fitted and a pressure check ensures that it wont happen again as long as this is followed by the correct adjustment of the "H" carb screw - tach tune or tune by ear! The early signs of air leaks are poor idle, an idle that has increased unexpectedly - like when your saw runs out of fuel - that increase in speed just before it dies - you may also get the saw hitting higher revs and sounding like a demented wasp you could also get that flat spot between 3,000 - 6,000 revs - like the 345, 350, 346, 357 Huskys when they are fully cold but it will not clear after 30 seconds running - thet wohh wohh sound in the midrange! So - a pressure check = an important bit of the saws health and not engineering sphericals - this single check has saved the 066 Magnum and 048 on my bench further damage after repair.

Oh - and invariably I do a lot more on top and don't charge - like give the saw a good clean and check the carb over including a rebuild - but you know the score, it is rare where you do one particular job without doing three more!

Around £25 - £30, I have just done a couple of saws recently - one had a dealer fitted seal that was turned inside out when the cases were split and a new P&C were fitted and had then seized and the other a split impulse line that took out the piston. Many people can throw a P&C on a saw but few make sure the saw is set up right and the route cause is found and resolved. What would you charge for similar?

With the Stihl 181/171 you get what you pay for - a home owner saw that will do a bit of pro work at a push. The bar and chain are lightweight using 1.1mm drive links, the engine is a bit lethargic and they don't allow you any "H" adjustment on the carb. I have done a few up and now don't do them unless really pushed - secondhand cost £100 - £120. My favourite rear handle saw is my Husqvarna 345 - yes, a 345......nice and light, well made, powerful and works even better now I have opened up the exhaust. If you get a good one off the bay, it will cost you £150 - £175 and would recommend a 15" bar. I know it isn't an MS260 or 346XP but we are looking at keeping the costs down here! If you can wait a few weeks, I have a Tanaka top handle and a Husky 345 to do up - I don't do cheap but I do get saws up to excellent working order - a few of the guys on this site can back this up! I believe Hitachi bought up Tanaka and there products are green versions of Tanaka products - small Japanese reasonably well made saws!

I have given up working on these low cost saws, you put the same hours in as working on MS200, MS260 etc but make £50 for hours of work - not really worth it IMO, there are plenty of people on ebay that will give you £30 for it though - just clean it up first and make sure it is not missing major parts! Will have to get another MS200 ready for sale for you - not enough hours in a day - perhaps I could make a tardis!

I use a gunson one, gives sensible readings that work for me i.e. new saw - 175psi, older saw - 150psi and fubared saw - 100 - 130psi:thumbup: Poor mans compression check, raise the saw and let it drop holding on to the start handle - 10 - 15 seconds fall is good - 3 seconds and you have a buggered saw:thumbdown:

It is a simple one - if your saw has 150 psi compression or over then it is good. If it is under that then a new piston will probably bring it back in to order, inspection of the plating will decide if the cylinder/jug needs replacing. The only exception I have found to this has been an old vintage Poulan Countervibe that ran at 130PSI and this is generally where a normally running saw of this manufacture sits - many owners on Arboristsite.com verified this. 175psi on a newish saw is normal

Any big bore kit has to be purchased complete - the original bores on saws built mid 70s onwards have plated bores with Chrome being on the older saws and Nikasil on the newer ones - only cast iron liners can be bored out. Some of the US guys do big bore kits - Baileys are one of the companys but they charge $$$$$ for delivery to the UK! Cost of fitting a P&C kit (customer supplied) - around £75 and will include a pressure check and tach tune to the carb.

I thought ash trays but I don't smoke......only when I put too much oil in the mix:thumbup:

I have commented a few times on the importance of fuel/oil mix, not using old mix, pressure checking the engine and carb adjustment - here is a collection of pistons from saws whose owners didn't share my views thought it may be of interest: -

Shame you are not closer - Id have it off you - they are worth £100 - £120 in working condition but you should be able to get £30 - 40 as a non runner. To do it up may not be worth it but the spares will have value - guys are to quick to bin stuff - IMHO, one mans junk is another mans gold!

I had heard that Oregon made the bars for Husqvarna:confused1:

I've had stuff ship from the US within 7 days - some take two weeks but generally one week - pretty good really!

Most decent oils mix at a ratio of 50:1, this is dictated by the oil and not by the equipment as many think. Oil has progressed since the 1970s leading to less oil being needed. One oil called Amasoil mixes at 100:1! I use Stihl oil in a 40:1 mix, I add the extra oil to add a further degree of protection, I know the damage an air leak or lean mix can cause and a little more oil would help in this situation. A couple of other facts - only mix enough fuel for a day to a weeks cutting as the oil is degraded byt he petrol and also never mix in the tank, always use an external container and mix well. Always drain the tank if the saw is left for a long time - the fuel has a tendency to destroy fuel lines in time.

Don't know about the Stihl but the 346XP in its 50cc "Silverside" guise is one fine saw - a best of breed.

Mixing the oil and fuel in the tank is a big NO NO - firstly at best the oil will gloop up the fuel filter and then be sucked in to the carb, at worst, it won't mix properly and will kill the piston as soon as the saw hits high revs for a minute or two. Mix the oil and fuel in a separate container and enough for a day to one weeks cutting as the oil is degraded in time if it is in mix with fuel..........I must post my collection of fried pistons - not my saws I hasten to add!!

Got a C Scope for £45 off the bay - it was a TR950 - only something I could dream of 25 years ago but it is a fine bit of kit without breaking the bank - found a few quid on the beach last year.

In the 70s/80s, the two stroke oil was not as good as it is now, in those days a 25:1 mix would have been the done thing, with modern oils they specify 50:1 but personally use 40:1 to ensure that an air leak or weak mixture at the top end will not mess the engine up too much. That piston on the Madisen link looks like heat seizure to me - I would have thought detonation would have damaged the crown of the piston - I have around 15 pistons from refurbed saws that look like that!

I have a 345 - the perfect bar on this saw is 15" as it gives excellent balance and handles it fine with a semi chisel chain. Mine is muffler modded to give it a bit more kick and will go through 12" oak easy. It is my favourite saw for a bit of logging - I know it isn't a true "pro" saw but is worlds apart from your 136! 13" bar is more of a top handled bar but if you must have one - Husqvarna 531 00 38-13 Bar and Chain Kit - 13 325 I believe these guys are good on price - 13 inch Chainsaw Bars | Clark Forest : Chainsaw And I also believe that Oregon make the bars for Husky!

All saws are for right handed use, I have never heard of a left handed saw although an aquaintance said that saws were for right or left handed use but he was misguided:confused1: In your post, the best advice I could see was to buy a pole cutter - this should be ideal for your olives, especiallly if you get one with a spare extension piece. Stihl do such a piece of kit, fine for left or right handed use and the dangerous sharp bit will be well away from your pinkies! Just don't stand underneath a big branch when you are cutting it off!

Two hours use - my backside! more like 200 hours use - the side cover looks well scraped as is the handle. I would bid on it expecting to get it serviced with a new sprocket to be fitted. I would like to see inside the covers:thumbup1: