spudulike

Bugger, it is the second ice age

I have used Haynes manuals but chainsaws are relatively simple in construction compared to a car. About all I need are max revs, possibly the carb settings on the weirder ones and the odd torque setting but the rest of it is pretty intuitive to work on and the manual doesn't give me too much I need. The four stroke KMs have been an anomaly to this and seems the Stihl dealer also who attempted to fix the last one I looked at - valve timing all akimbo!!!! Very dangerous on a 4T!

Mmmm, I seem to have picked it up without reading too many manuals, is that bad?

I always think that if you need a manual, you shouldn't be taking the item apart in the first place.....is it just me

Well that is what I thought but some say it will lean the engine and cause seizure - Personally I think it is misguided and stems from thinking that more oil means less petrol and therefore the engine will run hotter due to less fuel but in reality, the oil is part of the fuel so there is no leaning effect and like you, I see many machines, mostly home owner and farmers machines, with "Cherryade" in the tank which struggle to make any revs at all! Not sure I am going to go on with this as it is a bit like arguing religion!!!!!!!!!!!!!!

Clean the cylinder up and fit a new piston, the quality of the OEM part will always be better than a £15 Chinese one off Ebay. Stick with Meteor, Hyway or a branded piston manufacturer and all should work out. Make sure the seals and fuel line are OK as these older saws often need a bit of TLC to bring them back again.

Just work out how much work will be done by the machine once working and how much money you will make on each outing and £40 will not seem so big a price after all. It isn't the cost of the part but the value of having a working machine that you can make money with!

Echos trials on 40:1 will be interesting to hear but would really need to get comparisons on cylinder temperature and max rpm to get a true comparison.

Stubbys comment is what I am getting at. You put oil and petrol in the fuel tank, both burn in the combustion process so it is reasonable to suggest that two stroke fuel is a mix of petrol and oil not just petrol. The two trains of thought are that petrol is the fuel content on a two stroke fuel or the oil and petrol are the fuel. On conventional saws, it is easy to lower the H screw to drop the high speed revs thus controlling the engine RPMs reducing the risk of overheating and seizure....but what happens if the manufacturers bolt on an Autotune module and the control of over revving is down to electronics. Say these saws started having issues with knocking out their bottom ends due to the lower consumption of what I call "Fuel" (OIL and PETROL). Personally I would stick a dollop of extra oil in the fuel mix to help the bearings get a bit more lube on them....oh, and use a higher spec 2T oil like the synth ones that the manufacturers tell us to use on their lean burn strato engines. Having seen some low hour autotune engines take out their main bearings, you can see why I think this!

The air always remains the same as it goes through the carb, sucked in by the piston going up in the cylinder producing a vacuum in the crankcase. All these are constants, set by the bore of the carb, crankcase volume, bore volume, RPM etc etc. The carb dispenses the fuel in to the engine so if the ratios of oil to petrol change, unless the viscosity of the fuel changes radically, the same amount of fuel is dispensed in to the engine as dictated by the setting of the carb screws. So......if you are changing the ratio of petrol, air and oil by changing from 50:1 to say 40:1, the ratio between fuel and air remains the same so my comment is that "leaning" in two stroke terms means reducing the amount of fuel let in by the carb or a mechanical issue letting air in to the engine where it shouldn't and doesn't relate to the air to oil or air to petrol ratios. The prime effect of a lean mix is an increase in engine RPMs, this produces more heat and eventually fries the piston through the piston material melting. If you stick more oil in your fuel, it is more likely to foul the plug more readily lowering revs rather than raising them! Lean = too much air or too little fuel

I think we have to be careful about saying it "LEANS" the saw as "LEAN" is used in two strokes to describe the relationship between AIR and FUEL with FUEL being the liquid we pour in to the tank and not the components of the fuel - oil and petrol. All we are leaning when we add more oil to the fuel is the PETROL content in relationship to the air content and are replacing the petrol with oil. Unless the extra oil changes the atomisation of the fuel vapour to the extent it doesn't flow through engine in the same way or the oil heavy fuel doesn't flow through the carb in the same manner, the amount of fuel delivered will stay the same so the air to FUEL ratio will stay the same so no leaning.

Sounds like you have an air leak on the seals or the inlet manifold would be my guess. Worth getting it pressure and vacuum tested to make sure. You can check the easy things like gauze strainer, diaphragms and fuel line/filter and if OK, do the bigger job.

Most of the couriers are pretty good, Hermes are generally the worst and DHL, Parcelforce, DPD, APC etc pretty good. In a situation like this it is best to get hold of the actual delivery driver that made the original delivery. If it went to a neighbour you have an issue with, it is likely he has it but has been slow to come forward. They usually leave a docket saying where the parcel is - DPD take photos which is a good idea but the rest usually deliver to another location and use the docket to say where it is and post it through your box. In the couriers defence, I have had some right old shyte saws posted to me in crisp boxes, saws stinking of fuel and the contents breaking out of the box due to no packing material or crap box. Our DHL guy is often out until 8-9PM so it cuts both ways. Hope you get hold of the goods, the law is that the lack of delivery is with the supplier however fair that is in this case!

Sounds like WYK and I agree on the oil rich mix leaning a saw theory lauded by some. I have never seen a saw heavy with oil having seized. Most are poor carb adjustments, air leaks, fuel delivery issues or old/straight fuel. None have been oily and seized.....never have got that statement used by some. Stating "Fuel" with two strokes means OIL & Petrol not just Petrol! that is key!

Well try a 25:1 mix in your saw and let me know when this happens, has anyone seen it actually be the route cause of a seize, what about WYKs millers, surely his 16:1 man must get through a saw per week!!! I know what you are saying but the heat is caused by too much air and not oil, both will have different effects on combustion!

But as we all know, running an oil rich mix means the saw will overheat as it will be running lean Does any one really get this????????? Sorry Wes, been around the houses on this damn subject and you are backing up what I believe!

Do mine with nylon rods and a small boss soft nylon brush. The main rule is to keep turning the rods clockwise so the joints don't come apart. It works for me although only the first few feet of out flue is lined, the rest is brick chimney.

The OP has been in touch, prices swapped and is in his hands. Will see what falls out but the issues are the main bearings - may have debris in them, the crank - has it suffered any damage, what caused the original failure - has the bore suffered. Not an easy one to call without inspection but up to the OP to decide.

Oh dear........

Nice blocked gauze strainer! Had an MS200 with the wrong diaphragm fitted once, stumped me for a while!

It was more a comment about the general state of the saws I get in rather than this model in particular but can't say they come up as an all time great on my list!

Just to clarify, none of this "modified" exhaust outlet is mine, I would have preferred doing the job right in the first place! What you see is a bad job being modified further....badly!

Try leaving the side cover screws slightly loose otherwise you have completely lost me with what is going on! And......it is easy.......always got all these mechanisms working fine!

Even my Mrs could see something wasn't right....some of the stuff I get in....shocking!

The only bit I have done is to modify the baffle plate and spray it black, the rest of it is someone else's work!!!!! I am calling it "up Periscope"!