021 repair

[SJH]

Hi I'm after a bit of advice, My old 021 has been struggling for a while now and it hardly gets used but I fancy a project so...... I have taken it appart.

It was struggling through anything thicker than wrist thick, it just looses all power, so I thought that it might have been the pot piston. The pot looks ok appart from a large build up of carbon at the exhaust outlet and top, the top of the piston was black too, I have cleaned the piston top with wire wool and tomorrow I plan on getting the dremel to polish the pot and piston.

 

The questions that I have are.

 

Is the carbon build up the cause of it struggling?

 

If I polish up the pot and piston will this help it run better?

 

Whats the best way to port the inlet and how do I port the muffler?

 

I have to get a couple of new rings as I broke one and also a new seal.

I have never attempted anything like this before so this is all new to me.

 

Thanks.

 

Simon.

[elfinwood saws]

just fitting new rings may perk it up if the old ones are worn.

[spudulike]

You should have measured the compression before stripdown, anything over 145psi would be fine. Now it is apart, it is much more difficult to analyse if anything is wrong.

 

One thing you can do is check the ring ends and see if the ends are much thinner than the middle of the ring showing wear.

 

I would personally fit a quality new piston - Meteor are a favourite of mine.

 

Is there much carbon in the exhaust port - this would stifle the engine!

 

A muffler mod is relatively easy, 70% of the exhaust port area muffler opening will do.

 

Porting is another subject, if you have no experience, it is just as easy to mess it up in a very expensive way - do you know what you are doing?

 

The 21 has a clam engine and therefore you can't easily adjust the squish - not a great machine to tune!

 

Cleaning the carb and a decent tach tune should help.

[Daniël Bos]

I have an ms210 that was a bit "sooty in the exhaust department" not the port though.

Decided to rip it off during a tea-break, filled with petrol and set the blighter on fire. Runs much better now.

A friend had borrowed it and swilled the oil tank with some petrol as it was not oiling properly, then put the petrol back in the can! Result> oily, sooty exhaust:thumbdown:.

 

The most issues I've had with similar symptoms to those you describe have been with the tank breather though...

[GardenKit]

The main reasons for carbon build up, often with sticking rings, is the use of stale fuel, incorrect ratio of oil mix, or poor quality oil. (or all three)

 

As the other guys say, clean it up and whack on some new rings, or better still, while its down stick in a piston as Spud says. Probably best to forget grand ideas of porting this saw though.

[SJH]

Thanks for the responses.

 

I have cleaned out the exhaust and cleaned up the pot a bit with some very fine wire wool, heres a pic of whats left, its very tricky to remove, so I am tempted to get a new pot piston kit tbh.

 

 

I think I will leave the porting of the pot as I am not experienced at all in this area.

[spudulike]

If the pot is in good condition with no signs of wear/scoring and the plating has not worn through, just fit a new piston. The OEM cylinders are always far better than the vast majority of Chinese aftermarket cylinder kits and you will find the piston to cylinder clearance of a new QUALITY piston is far tighter and will generate better compression than using an aftermarket P&C.

 

Fitting a branded piston IMO is worth the extra £5-10.

 

Fit a new carb kit and making sure that the carb is tuned by someone who knows what they are doing should give the saw a bit more go. Don't forget checking the fuel piupe, filter and breather though.

[SJH]

Cheers for the advice everyone.

Well it works! I ported the exhaust and took out the spark arrester. The piston was a bit of a faff getting the piston in the pot but all up and working sort of, I think I need to fiddle with the carb though, it sounds like its ticking over a bit high and can build up rev and the drop back down, so it might need a carb kit. Again all new to me so I like to learn more.

This is what I have done so far I have set the H L screws to factory settings but the saw wont start, I then adjusted the L screw till it starts, Then back off the chain with the iddle screw. I then ran the saw at full throttle and adjusted the H screw till it sounded right.

Again I know I might be doing this wrong and I have been reading the other treads about tiny tachs, but I am trying to learn more about saws and tbh the 021 is old and guttless so its a practice saw for me.