Stihl Ms460 piston scoring

[sixty]

I picked up a used Ms460 saw on CL for $120 that was missing the muffler, airfilter and housing and chain. The saw was in great shape and not much signs of use but one thing the seller didn't mention in his ad was the piston scoring (@ the bar side of the exhaust port) and bad compression (about 50psi). I caught it while inspecting the saw so I bought it knowing it was going to atleast need a new piston and cylinder hone.

I saw the write-up for rebuilding the 1127 saw here and I was wondering if the tear down of the 460 is the same. Also, how much scoring can be taken out of the cylinder? to it looks like it could probably be honed out as the most of the scoring is from the aluminum piston, not the rings so it is hopefully superficial. Would it be recomended to get as big bore kit on ebay like this? What other parts would be needed?

Also where is the best source for the missing parts with all related hardware? (see attached pics, sorry for the crappy iphone pics, it looks better in person)

Hopefully I can get this thing running like new for an additional $150 or so and a few hours behind a wrench. Any additional info on this saw would be helpful!

 

[sixty]

last pic

 

[D'Animal]

I thought Mace was going to buy it.

 

[D'Animal]

First, forget about putting it back together and getting it running for $150. Not going to happen.

If it cost $150 to get it in top shape, the PO would not have sold it for dirt cheap.

Before you tear it apart, you need to find out why the piston scored. Lack of enough lubrication is no brainer. Pistons and bearings sieze because of the friction.

You will need to find out if the crankcase seals are leaking under pressure as well as the neg pressure. The only way to check that is to pressure and vaccum test the cylinder and piston assy as well as the crankcase.

 

[D'Animal]

Here is an example.

Scored/Melted main bearing on a 2F. Most would not even think about putting a new bearing in there and reassembling the engine. First thing they would do is find out why it failed.

That is were you are right now.

Many shops would stick a new cylinder and piston on there and hand it back to you. They do not even find out what caused the failure.

 

[D'Animal]

The cylinder is Chrome Impregnated. You can clean a lot of Aluminum off of it using muratic acid applied with a q-tip. Once all of the aluminum is cleaned off, you may ahve to clean it up with a barrel hone.

 

[sixty]

I didn't even know Jason was looking at it. I check CL about 20x a day so I sent the guy an email about 15 min. after he posted it. Stihls don't come up often here so they are snatched up pretty quickly. I've been looking for something to replace my Mcculloch EB 3.7 for awhile.

I figured $150 might be fantasy land, but if the cylinder could be salvaged with just cleaning (wasn't sure if the muratic would harm the cyl.) and possibly honing then I figured I might be in that range. i've rebuilt a few dirt bike, jetski and outboards and if you don't add up your costs then you can trick yourself into believing you did it on the cheap

Thanks for the advice on the crank case pressure/ vacuum, I have a vacuum pump and tester that I used on OB's so hopefully it will be in the correct range. Does the Stihl service manual cover the procedure? I'll drain the gas and see if it looks mixed lean, but I doubt if I'll be able to tell anything from that, especially since the gas mixture may have been swapped out by the PO. I figured I'd have to go thru the carb as well.

Thanks for the reply, hopefully I'll be getting a service manual soon.

 

[Mace]

Fawker!!!!


That was MINE!!!


lol

Now I know who to borrow a bigger chainsaw than I need from

BTW, listen to Dan. He might know what he is talking about

 

[sixty]

Hahahahaha! This was you paying it forward for when I found you your welder on CL. ..... nevermind the drill press you found me, but I did send you that killer deal on the lathe you passed up! Besides I'll probably have over $1000 and 500 hours to get it running so maybe I saved you
If I do get it running you can borrow it anytime... You know I owe you that much for all the stuff you've lent me in the past.

I did find this excellent post on pressure testing the crankcase. I think I'll need a new pump as mine has appeard to have died!

 

[Mace]

Hahahahaha! This was you paying it forward for when I found you your welder on CL. ..... nevermind the drill press you found me, but I did send you that killer deal on the lathe you passed up! Besides I'll probably have over $1000 and 500 hours to get it running so maybe I saved you
If I do get it running you can borrow it anytime... You know I owe you that much for all the stuff you've lent me in the past.

I did find this excellent post on pressure testing the crankcase. I think I'll need a new pump as mine has appeard to have died!

Go buy me a shop for that lathe then

 

[D'Animal]

Hahahahaha! Besides I'll probably have over $1000 and 500 hours to get it running so maybe I saved you
If I do get it running you can borrow it anytime... You know I owe you that much for all the stuff you've lent me in the past.

It would not have cost him that much to get running. I have been carrying his spare tire around for a week or so, incase he comes to the central valley and gets a flat.

Go to a Napa and get a Miti Vac one man brake bleeder. Get the one that does pressure and vacuum. They are about $38.00 at Sears.

I did find this excellent post on pressure testing the crankcase. I think I'll need a new pump as mine has appeard to have died!

That thread has a lot of pictures that really don't make sense when you read the text. It is overly complicating the process.

 

[Mace]

It would not have cost him that much to get running. I have been carrying his spare tire around for a week or so, incase he comes to the central valley and gets a flat.

Go to a Napa and get a Miti Vac one man brake bleeder. Get the one that does pressure and vacuum. They are about $38.00 at Sears.

LOL that tire will not work on anything I own right now


I think I have one of those brake bleeders sitting around somewhere. I just have to find the right one that has both Vac and press.

 

[sixty]

Go buy me a shop for that lathe then

If you would have said yes when I asked you to marry me we would have a badass "Love Shop" right now!

 

[sixty]

It would not have cost him that much to get running. I have been carrying his spare tire around for a week or so, incase he comes to the central valley and gets a flat.

Go to a Napa and get a Miti Vac one man brake bleeder. Get the one that does pressure and vacuum. They are about $38.00 at Sears.



That thread has a lot of pictures that really don't make sense when you read the text. It is overly complicating the process.

Looks like Jason is going to loan me the the pump.. I doubt he misses the spare tire since he must have a hundred or so old tires and rims lying around his mom's house...

He does seem to overcomplicate the process but I get the overall idea. I had to do a similar test when rebuiling my lower unit on my outboard. This is pretty much the same but I need to build blockoff plates for the intake and exhaust and plug the decompression hole (not sure on how to do this).