Stihl 025 repair.

[KORNSTER]

Hi,

 

I bought a cheap stihl 025 from ebay recently. I wanted a cheap saw to lend out rather than lend my good saw, so I figured a cheapo fixer-upper would be the way forward.

 

The saw i bought for £25 looked like it had been set on fire and put out with a sledgehammer, but I like a challenge!

 

OK. So, I've replaced the bearings,seals, piston, rings, carb gasket and exhaust gasket. Everything has had a good clean, the carb has had a good flush through with carb cleaner. It has a new fuel line and filter. I've set the gap between the flywheel and coil to 0.5mm (which I think is right - happy to be corrected!).

I'm getting a spark. I've set the carb adjustment H and L to closed, then backed off a full turn. LA setting I'm not sure about, so I set it half way.

I've checked the rubber boot that connects the engine to the carb and its sound.

When I connected my compression tester to the exhaust port it was reading 120 after 4 or 5 pulls.

I managed to get it to start once, but it spluttered out. Now it wont start.

After a few good pulls I and seeing a light spray of fuel in front of the saw, presumably from the exhaust port - I've not seen any other leaks on the crank case.

 

I realise this sounds like a futile effort with little to gain, but I'd like to get it working. Any help would be appreciated.

[Ray1]

.5mm is too much, should be half that. Why did the piston need replacing? if it was due to a seizure was the cylinder cleaned up? Have you re connected the impulse line?

[farmer rod]

Im wrestling with an 028, I suspect the coil on mine, possibly a bit of damp when not used for a while, then break down when hot, but this is a guess at the moment.

[Ray1]

How are you testing compression through the exhaust port????

[spudulike]

I would like to see how the compression gauge was connected to the "exhaust port":001_rolleyes:

 

120PSI is low, too low IMO, these saws don't have loads but 140+ would be needed for it to run. As mentioned before, if the piston has been changed, why was it? Had the saw been seized, had all the aluminium transfer been cleaned off the cylinder? Is the top end aftermarket, is the plating in good condition - has someone had a go at it with a hone?

 

The compression needs to be sorted to get this baby to fire:thumbup:

[KORNSTER]

Well, there's a lot if information for me already.

Here's what I'm thinking. I replaced the cylinder with a cheap aftermarket piston and cylinder. The piston operation seemed to glide well in the cylinder when checked it.

The compression was checked by replacing the spark plug with my tester...didn't make that clear.

The impulse line is the original that looked to be in good condition.

 

I have the original cylinder which looks good. The kit I bought with piston and cylinder and a load of extras was cheaper than a new stihl engine pan and piston. Now I know why.

 

Probably best to get OEM piston , rings , pan and impulse line. Start again.

[KORNSTER]

How are you testing compression through the exhaust port????

 

By the power of magic !! Ha... My dumb ass. I was writing this on a nightshift. I get confused easily any time after bedtime.

 

I bought a tester from Halfords for the last few saws I fixed up. I'll go check the compression again....and I'll be sure to put it in the right hole.

[KORNSTER]

Just tested again. 125-130 psi.

After I tried to start it again as it's been left a while. As I pull on the starter it does sound like it's going to fire up , but it isn't quite getting there.

 

At least I didn't lose my rag and throw it against a wall. I see this as a positive.

[KORNSTER]

The stihl cylinder I have is scored. Didn't notice while I was cleaning it.

Balls.

[KORNSTER]

So, in nothing short of sheer desperation I tried to start it a few more times. It sounded like it was close to firing up. I wound in the LA screw on the carb had a turn at a time and each half turn gave a splutter that sounded more like it was going to go. Eventually it fired up.

 

It doesn't a exactly purr like my MS362 but it feels like I've got somewhere.

 

Here's the thing. I work as an electrical/mechanical engineer. I love making old dead stuff work again and I usually do well repairing things. I tried my hand at repairing saws. For me it's a black art. It's a load of ass and head scratching and swearing, but I'm learning and enjoying tinkering. What's obvious is how much I don't know.

 

Thanks for help and suggestions.

 

Just out of interest , are there any good quality after market spare part suppliers that people are happy to recommend or do most people go OEM every time?