Makita DSC34 chainsaw hot start issues?

[Lehobbit]

Hello all. I live in deepest rural France, in Limousin. Earlier this year I purchased a secondhand Makita DCS 34 chainsaw in very good, hardly used condition. I had read very good reviews of the slightly larger model the DCS4610 and apparently the old Makitas are based on the Dolmar saws.

For most of the year the saw has been working fine and it's a great little saw, but I didn't use it for a few months and went to use it last week.

 

Now it will start easily but after the first start or two it will just not start? I have the manual but it states that any carb adjustment must be done by a specialist? Compared to my old Husqvarna it is really not clear how to adjust the carb. Our property is a high altitude (810 metres to 840 metres) and I have read the saws are set up at factory for sea level. Would this make a difference. On the exhaust muffler the spark gauze has been removed so that is not an issue. Also I have noticed some oil being expelled from the muffler.

The saw runs well, idles perfectly but WILL NOT start once it is warm, no matter how many times I try?

Any thoughts please. How do I adjust the carb? Maybe it is running too rich?

 

Edited September 14 by Lehobbit
extra detail

[spudulike]

On the oil from the muffler, are you running a 50:1 mix? 

Usual hot start issues can be operator error using full choke rather than just the fast idle setting, the saw being lean, blocked fuel vent, low compression, coil to flywheel gap too big, coil beginning to fail, carb needing a rebuild/ clean, dodgy plug/HT and probably many others.

If you start the saw and shut it off within seconds, does it start OK or is it not starting after running it hard?

Have you pulled the muffler off and looked down the exhaust port for scoring on the piston? 

When a saw runs, compression drops. If the piston is worn or has been lightly seized, it may have enough cold compression to start it but this will drop when the saw is hot causing starting issues.

[adw]

Poor quality, or stale fuel, if the saw has a purge bulb, does it help if you pump it 10 or 12 times to pull cooler fuel through the carb?