What's on your bench today?

[spudulike]

Sometimes the needle chrome plating starts bubbling and this makes their closure intermittent. You can sometimes get the rubber on the end of the needle having a little ridge allowing it to leak.....see how it goes and you can use a pressure gauge & pump or pop off tester to see if the needle valve is working OK.

[Stubby]

On 23/11/2018 at 21:47, bmp01 said:

Spud, 

No offence taken. My statement was bollox (I now realise). It needed correcting and any confusion clearing up. Not good to have doubt thrown into ones understanding of things, sorry about that. And thanks for taking the time to point out my error. 

 

Yes I'm from a racing back ground but that's not an excuse, I believed (incorrectly) all modern pistons were forged,  i was wrong, simple as. I'll go and adjust the grey matter now.

 

Forged pistons - yes the're hit with a punch but the process is a bit slower than you might imagine, there's the initial contact followed by the second stage where the punch is pressed into the material.  Even though the material is heated sufficiently to make it ductile the forge is a big bit of kit, close to 100 tonnes the one I experienced, maximum of 5 inch dameter forgings. The advantage of forging over cast (generally) is to get the material grain structure aligned to the shape of the piston, for strength and durability. Getting clear part numbers on a forged piston is relatively easy. Forgings were better than machined from solid but only marginally so in the game i was involved with. 

With a forging there's no way to get windows in the piston side panels nor the undercut below the g'pin boss, unless they're machined afterwards. So there you go chainsaw pistons often have both those features... must be cast. Fancy split tooling as well, to achieve that, split lines are the cause of the flash lines you see. 

 

 

There is of course  "pressure die casting "  Like a plastic molding machiene only with hot metal , as opposed to pouring  into a sand mold . . 

[billpierce]

Sometimes the needle chrome plating starts bubbling and this makes their closure intermittent. You can sometimes get the rubber on the end of the needle having a little ridge allowing it to leak.....see how it goes and you can use a pressure gauge & pump or pop off tester to see if the needle valve is working OK.

Cheers spud. Fairly sure this will come back to haunt me

[spudulike]

They always do when a fault "just disappears", been there and got the t shirt

[peatff]

The thread is disappearing down the list so I'll bring it back up. MS180 running but died in the cut and stalled. Fitted a carb kit, everything but the Welch plugs they were alright, put it back together and it was even worse if anything. Needle level looked ok but raised it a bit anyway and it's now pulling like a goodun. Why don't they have any adjustment on the carb ?

[Khriss]

On 23/11/2018 at 18:28, spudulike said:

......

No offence meant and don't intend any ridicule but this one just "niggled" at what I understood to be fact!

Now look up self-forging fragment rounds - fascinating ! K

[billpierce]

The thread is disappearing down the list so I'll bring it back up. MS180 running but died in the cut and stalled. Fitted a carb kit, everything but the Welch plugs they were alright, put it back together and it was even worse if anything. Needle level looked ok but raised it a bit anyway and it's now pulling like a goodun. Why don't they have any adjustment on the carb ?

You can buy them with carb adjust on. Replaced a few on ms170s a while back and made sure I had the ones with h and l jets. Prolly got a stash somewhere if you want me to post you one?

[peatff]

2 hours ago, billpierce said:

6 hours ago, peatff said:

The thread is disappearing down the list so I'll bring it back up. MS180 running but died in the cut and stalled. Fitted a carb kit, everything but the Welch plugs they were alright, put it back together and it was even worse if anything. Needle level looked ok but raised it a bit anyway and it's now pulling like a goodun. Why don't they have any adjustment on the carb ?

You can buy them with carb adjust on. Replaced a few on ms170s a while back and made sure I had the ones with h and l jets. Prolly got a stash somewhere if you want me to post you one?

Thanks for the offer Bill, it's fixed now and gone back down to the farm. I saw the adjustable carbs on ebay for about £7 so they can order one of those next time it conks.

[trigger_andy]

Well, had someone reverse over my 034 today.  The Saw was literally jammed under the chassis and we had to get a jack under it to lift it off the saw. Looks a bit bent out of shape but still runs. They offered to fix whatever was needed but as it runs whats the best option for me to do here?

[Ratman]

Well, had someone reverse over my 034 today. [emoji20] The Saw was literally jammed under the chassis and we had to get a jack under it to lift it off the saw. Looks a bit bent out of shape but still runs. They offered to fix whatever was needed but as it runs whats the best option for me to do here?

Whats bent? Just handle, bar, broken housing, trigger housing? Post some pics for us [emoji106]