Help with a 460

[Tothemax]

Hello,

I have a stihl 460 that is giving me an odd issue. It was rebuilt approx 4 years ago with a new aftermarket topend, seals, and a carb kit. The saw starts and runs well until it warms up. Then the idle starts to bounce around a bit. Normally I would think a vacuum leak but when I did a leak-down test it passed. The needle on the vacuum gauge doesn't move.

The exhaust exit on the cylinder has been opened up a little. It looks like the casting marks were smoothed out, maybe a little extra material was removed but nothing crazy.
Slight scoring inside the cylinder on both the intake and exhaust. 125 compression.

Ideas?

 

[Bob Hedgecutter]

Who made the aftermarket top end?
Aftermarket seals and carb kit as well?
If you/they got 4 years out of that- they possibly did well considering.

125lb per inch is down at the very nitty gritty end of not running.
Static pressure and vacuum tests on a cold saw may not show what s happening when its hot and being flexed on- many an oil seal or manifold will shows its failures when put in to compromising positions- its a good excuse to replace AV buffers when you rebuild saws.

 

[ballisticdoughnut]

125 psi is low. That saw should be in the 165+ range. You got four years out of an aftermarket top end. I’d call that a win. Time for another rebuild. Do yourself and the saw a solid, use OEM parts this time.

 

[Bob Hedgecutter]

125 psi is low. That saw should be in the 165+ range. You got four years out of an aftermarket top end. I’d call that a win. Time for another rebuild. Do yourself and the saw a solid, use OEM parts this time.

Now come on- play nice- Meteor make aftermarket top ends- they are better than most and come with Caber rings as standard.

 

[ballisticdoughnut]

Now come on- play nice- Meteor make aftermarket top ends- they are better than most and come with Caber rings as standard.

The Meteor stuff looks pretty good, if I had to go aftermarket that would be my first choice. The old Tecomec stuff was pretty good from what I hear. Don’t think they make saw parts anymore though.

 

[Tothemax]

No clue as who made the cylinder. I started the saw, ran it until it warmed up and started causing the issue. Probably 3-5 mins then I tore it down for the pressure test.

Where is the best place to buy oem cylinders kits?

 

[Dean-O]

No clue as who made the cylinder. I started the saw, ran it until it warmed up and started causing the issue. Probably 3-5 mins then I tore it down for the pressure test.

Where is the best place to buy oem cylinders kits?

Any Stihl dealer. If they don’t stock it they can order it. My shop stocks 046/460 cylinder and piston because in Northern California there are 1000’s of those saws out there and we rebuild them all the time.

 

[Tothemax]

Any Stihl dealer. If they don’t stock it they can order it. My shop stocks 046/460 cylinder and piston because in Northern California there are 1000’s of those saws out there and we rebuild them all the time.

The one I have close to me is a hot mess of a shop. It took them 45 mins to find a rim sprocket for a 044 and that was with me finally helping.

 

[Dean-O]

The one I have close to me is a hot mess of a shop. It took them 45 mins to find a rim sprocket for a 044 and that was with me finally helping.

That’s sucks. No other shops that you could call with in driving distance to see if they could help? My shop has no shipping department or I would offer some help. Good luck

 

[Tothemax]

I have another option its just planning a trip to get there.

 

[Tothemax]

The Meteor stuff looks pretty good, if I had to go aftermarket that would be my first choice. The old Tecomec stuff was pretty good from what I hear. Don’t think they make saw parts anymore though.

I did see a Meteor kit on ebay for 160. I have never has issues with their stuff in the past.

 

[stihltech]

#1-throw away the compression gauge. It only gives false readings on a 2 stroke. Do not use them in the shop.
2 Now the visual inspection. You said slight scoring? You need to tear the cylinder off. BUT FIRST- Vacuum and pressure test in that order. Part of diagnosis. Find the issue before the teardown.
Not a fan of aftermarket but the diagnosis is the same. Did the piston fail on it's own after 4 years? Doubtful.
Finding the cause is key. Don't focus on the piston. Focus on the reason for the scoring. AND if it has never had a carburetor, get one if all other tests and visual pass.
Always work from the outside in. Visual and testing along the way is what repairs issues.

 

[huskihl]

Used oem 046/460 cylinders pop up on eBay from time to time for $100. A saw like that deserves good oem parts. Meteors might look nice, but you’ll still run into port bevel issues, flaking plating, and port area/timing issues. They just don’t run nearly as well as an OEM cylinder.

 

[muddy42]

I've just overhauled a stihl MS460. As others have said, inspect and test the thing as much and as thoroughly as you can. I use a mityvac, but I even submerge saws in a bucket of water to find the really stubborn or minor air leaks (once the ignition if off and fuel lines plugged). rotate the crank during tests. Make sure you dry everything out using towels and a radiator.

This saw passed, so I can only assume this saw was used with straight petrol/gas. The cylinder too badly damaged to save, deep scoring so I fitted a meteor cylinder and piston kit. I am pretty impressed with it - ports look clean, piston clearance is tight, the piston moves up and down well. The saw is powerful to use, admittedly I only have 10 tank through it yet, but I have inspected the piston again and it looks as good as new.

 

[lone wolf]

I've just overhauled a stihl MS460. As others have said, inspect and test the thing as much and as thoroughly as you can. I use a mityvac, but I even submerge saws in a bucket of water to find the really stubborn or minor air leaks (once the ignition if off and fuel lines plugged). rotate the crank during tests. Make sure you dry everything out using towels and a radiator.

This saw passed, so I can only assume this saw was used with straight petrol/gas. The cylinder too badly damaged to save, deep scoring so I fitted a meteor cylinder and piston kit. I am pretty impressed with it - ports look clean, piston clearance is tight, the piston moves up and down well. The saw is powerful to use, admittedly I only have 10 tank through it yet, but I have inspected the piston again and it looks as good as new.

The ignition don't need to come off to dip the saw in water.

 

[muddy42]

The ignition don't need to come off to dip the saw in water.

Yes I suppose so, but Id rather not risk it, ignition modules are expensive!

 

[lone wolf]

Yes I suppose so, but Id rather not risk it, ignition modules are expensive!

Don't worry about it, I have dunked plenty of them and washed many, never a problem. Blow the spark plug boot dry with air after.

 

[stihltech]

A good ignition will not be affected by dunking. A marginal one might. Best to remove it. And replace the plug wire. Just because it is a wear part.

 

[muddy42]

When overhauling a saw, I remove as much as possible. If nothing else to clean and check everything. Why not? having the wires waving around is also not ideal. Actually I do leave the flywheel and clutch on, unless they or the crank seals need replacing, simply because I don't have all the specific tools for this.

 

[stihltech]

I usually remove coils (modules) before washing simply to clean the area where they are mounted. Blow the coil off separate. Coils don't like a lot of build up on or around them. Just makes sense.