What's on your bench today?

[spudulike]

Been playing with a 200t a little bit. Not noticing much in the way of gain post porting the exhaust. Guess Stihl did not leave much on the table when the produced them

Hope you took it easy on the inlet port, the ring ends are very close to the inlet port. The exhaust can be fattened up, squish can be lowered and a muffler mod brings the saw to life.

[geoff]

Hope you took it easy on the inlet port, the ring ends are very close to the inlet port. The exhaust can be fattened up, squish can be lowered and a muffler mod brings the saw to life.

 

Looking forward to getting mine over to you Spud.

[pleasant]

Right- the replacement piston kit arrived for my 2010 MS181 yesterday and went to fit it yesterday afternoon. Everything was fitted and going well- however before I re-fitted the engine into the cradle I (always do) turned the engine over by hand to ensure it was free. After 3/4 of a revolution it locked up on the downward stroke. Had another try and same thing, so removed the barrel end cap and left the crank and piston in situ whilst turning engine over so I could see what was going on. It would appear on the down stroke the two crank balance weights come up and foul the underside of the new piston. I removed the lot as a whole and placed it beside the old original piston and it seems there is more meat on the inside of the replacement piston around where the gudgeon pin slides through compared to gthe original- thus causing this problem. I have emailed the seller, but in the meantime was wondering if anyone else has had an experience of this?

[spudulike]

If the kit is an aftermarket kit then there is your problems, typical issues I have had have been piston crown arrows pointing the wrong way, ring ends badly formed so the piston wont fit, piston rings breaking in use, ports beveled too much causing ring ends to pop in to the port and jam in them (ouch), small end of the con rod not fitting in to the piston, pitting on the bore, squish being far too much and poor compression.

 

My advice is to reclaim the OEM cylinder where possible and fit a quality piston where possible - the Meteor ones from Danikrop and Tesgol on the bay are very good and Tesgol has proven to be a decent seller - I don't know him!!

If the piston is aftermarket then you may need to machine off some of the bottom of the piston but guess you have probably come to that conclusion yourself.

This sort of problem separates the men from the boys:lol:

[pleasant]

Yup it's an aftermarket GOLF one. It's only a light under oiling and out of the two rings on the old piston one is unharmed and only the lower one is slightly compressed due to the light smearing. If i don't get the Dremel out with the grinder attachment to fettle the underside of the piston, I was thinking of cleaning up the old piston and re-fit using the two new aftermarket rings that came with the GOLF piston kit. The barrel is fine- gently removed the light ridging with a bit of oil and emery cloth.

 

It's not a customers' job, but one I was going to keep for me to play around with, but I may sell it on the bay once repaired as a few bills new paying.

[GardenKit]

Will aftermarket rings really fit a genuine piston???? I have never tried, but did not think they would be manufactured to match.

[pleasant]

Dunno- probably going to find out tomorrow.

[spudulike]

Will aftermarket rings really fit a genuine piston???? I have never tried, but did not think they would be manufactured to match.

 

In a word - YES...rings ae generally 1.5mm or 1.2mm thick, 1,5mm is very common but have found 1.2mm on the 441 that I am working on.

 

If the piston can be cleaned up then it is an option, slight scoring is OK as long as ALL aluminium transfer is taken off the bore.

 

Golf pistons are generally not too bad but have had to do work on a few of them in the past, to make one fit.

[Rich2484]

A ht 131 pole saw.

 

Running very bad, had to 'play' with the choke to get it to run and it would only run full wack.

 

Cleaned carb air filter and fuel lines, no cracks to be seen and impulse line ok. Good compression aswell.

 

After refit runs better as it can be controlled on throttle on a stop start and run but still only works on half choke?

 

Any ideas as to what it could be? Did spot air leaking from a metal pipe from carb that connects to the fuel line return to tank?

 

Have been looking for a new engine but customer wants the ht 131 as it is bigger than the others and he likes to have some grunt behind the saw to cut without it getting stuck? Go figure.

 

He is happy as it is running better but I'm not and I like things to run as they should.

[GardenKit]

Rich2484, the HT131 is a 4 mix engine, equipped with valves, so valve clearances are critical.

I have yet to have one in for service that does not need adjustment, and they cannot be tuned until the valves are correct.

 

You mention that it has good compression, but how do you know?