Stihl 025 diagnosis

[link]

So I have a 025 on my bench, not mine. I have pulled it completely apart, cleaned all parts with a dish and tooth brush and put it back together again.
All rubber parts including crank seals are replaced, I have used plenty of gasket silicone when I mounted the engine together. New gasket/membrane kit in the OEM carb.

As I understand it - it has the classical symtoms of an air leak, it won't hold a reasonable low idle and it needs exessive + rounds on the low rpm blend adjustment.
At high it goes smooth up to about 11500 rpm, but from there it goes straight to 14k+, nothing in between.

The only thing I can think of is pulling the carb booth off and add some gasket silicone to the cylinder end of it.
I do not have a pressure/vacuum tester. Any suggestions what else might be the problem?

 

[link]

Now that chainsaw looked like it had been dragged by a tractor trough the mud for the past 15 years, but the cylinder and piston looked like barely run in.
You dont get that light weight at that hp these days so I think it's worth another go at it, what you say?

 

[Bob Hedgecutter]

Gasket silicone- what exact product did you use?
You say "plenty of it" was used- if it was perhaps not what might be a deemed correct product, it may be too much was applied and is holding something apart, rather than together if some of it blew out at initial start up.
Were all the rubber parts replaced- OEM rubber parts?
Manifold to cylinder joint should not require silicone adhesive to complete a seal.

 

[link]

Gasket silicone- what exact product did you use?

A good enough product for cars and motorcycle engines. Plenty of time from build to start up - weeks.

 

[link]

Were all the rubber parts replaced- OEM rubber parts?

All rubber parts is made in china, with the same rubber as OEM, and dont throw that on me now - I'm just not in the mood for it.

 

[Bob Hedgecutter]

A good enough product for cars and motorcycle engines. Plenty of time from build to start up - weeks.

Okay, I'm out- good luck with the adventures.

 

[link]

Okay, I'm out- good luck with the adventures.

You think that Chineese made rubber (EPDM) with the same formula will somehow leak air and gas through it by default=?

 

[link]

Okay, I'm out- good luck with the adventures.

Put your finger in the rearth mate, if all those parts where OEM - it would be better to just buy a new saw. Thats you're suggeston?

 

[Automender]

I inspected the rubber boots on a chop saw I totally rebuilt and felt good about them. Started the saw and it had an air leak. Here the bottom intake boot had a crack in it maybe from the effort to get it on the cylinder.. I also noticed that the older OEM boots really didn't have enough thickness to get a good squish between the carb plate and the carb. Installed aftermarket boot and it fixed the issue. I also noticed the boot clamps didn't have the range to tighten to what I would want. Removed the spacers on the clamp screw and the tightened the boots up fine. Really should do a pressure test. I pressure tested the crankcase and cylinder but not the impulse line and boots. So I knew where the leak could be.
By the way, not that it is your problem, RTV silicone is not used on a gas contact application. Found that out 40 years ago on a carb.
Spray the area with carb cleaner and it should change your idle speed if it is an air leak.

 

[Okie]

Pressure test of the block can save a lot of GUESS work. Them 025's calm shells are just little bit tricky keeping the sealer in place while going back together. If you find it's a block leak and you have to go back take a look at the crank bearing and if they have the plastic bearing separator, upgrade to the all steel steel type bearings @ less than $15 for both. The plastic type will break-up and easily ruin the engine.
If you are going to try to repair your own eq or chainsaws you need to knuckle down and think about at least a blood pressure bulb pressure tester rig ($15) and maybe later get a mity vac dual pressure/Vac tester @ $60.

 

[HarleyT]

Is the impulse line still connected to the orange nipple? gasket/plate below carb correct?

 

[a. palmer jr.]

If you're gonna take on the task of rebuilding saws you need to figure out a way to vac/pressure test the crankcase. It'll save you a lot of re-rebuilding later. And no, not all chainsaw rubber products are the same even if Stihl does make some of their stuff in China, they are closely supervised on both materials and labor practices compared to the AM manufacturers.

 

[Vintage Engine Repairs]

Link your attitude sucks.

Don’t come and ask for help and then scorn at every bit of advice given.

If you aren’t prepared to get the tools necessary to do the repair, like a pressure & vacuum tester or the right adhesives, give it to someone who will. Especially
as it’s not even your saw..

 

[Captain Bruce]

Link your attitude sucks.

Don’t come and ask for help and then scorn at every bit of advice given.

If you aren’t prepared to get the tools necessary to do the repair, like a pressure & vacuum tester or the right adhesives, give it to someone who will. Especially
as it’s not even your saw..

Ditto. This lonely person lacks a life away from the keyboard. Everything chinesium is poor quality, always unreliable, routinely returned, and a waste of other peoples time, when the use of that crap, stimulates another posting like this.....some guys just don't have, "you're right", and "thank you" on their work bench.

 

[Oletrapper]

Is the impulse line still connected to the orange nipple? gasket/plate below carb correct?

You beat me to it Harley! lol OT

 

[Oletrapper]

Put your finger in the rearth mate, if all those parts where OEM - it would be better to just buy a new saw. Thats you're suggeston?

I think you need to chill. Get another cup of coffee. You ask for help then jump on someone when they quiz your approach? Just saying. jmho OT