Right clutch for Stihl 050

[RomuloTDI]

Good morning, my name is Victor and I am new to the forum.

I explain my problem, looking for information I found this forum and I decided to register, I have a Stihl 050 chainsaw that I am restoring and I have put a new clutch on it but when the machine starts the chain rotates, I have seen that there are several sizes of clutches for this machine, mine is 84mm and I have seen that the bell used by my machine with .404 chain pass is 85mm so I wanted to ask you if you know which clutch is correct for my machine, I have seen that there are clutches for my machine 82mm but I'm afraid to buy it and then it's not the right one, can any of you guide me?

I have seen that there are also two bell sizes, 85mm for the .404 chain pass and 86mm for the 3/8 chain pass.

If you can help me I thank you.

A greeting from Spain.

[agg221]

Hello Victor,

 

When the saw is not running, can you pull the chain round easily without the engine turning over and feel or see if the clutch is actually rubbing on the drum? If it is quite easy to turn over like this then it is more likely that your idle speed needs turning down a bit on the carburettor. The clutch parts fly out at speed (centripetal acceleration) so if they are already going a bit fast then that can be the problem. Be aware that it is likely that you will always have the chain just moving occasionally (not really running because it will stop and start). This is because when the clutch pads are new, there is not much clearance and there is a compromise where if you set the engine too low it won't idle and just stalls, whereas if you run it that little bit faster it picks up on the clutch every now and again. If the saw had a chain brake (like a modern saw) then this would not happen and there is no load on the chain so just jerking round a bit from time to time may be the best setting you can achieve.

 

The instructions for setting up the carburettor are in the handbook which is easily found online if you don't have one - it can be set better with a tachometer but it won't damage the saw to use the stock settings. If you set high and low by the book and then adjust the idle as low as it will still run then that is probably about the best settings to go for.

 

If that isn't the problem, do post again and I am sure more answers will be forthcoming.

 

Welcome to the forum!

 

Alec

[RomuloTDI]

Hi Alec

Yes, the carburettor is well adjusted, I have lowered the idle to the minimum to the point where the engine shuts off and the chain continues to turn, it does not stop.

Yes, with the machine off, the chain can be easily moved by hand without rubbing against the clutch.

A greeting from Spain

Victor.

[spudulike]

If I am reading your post right, your clutch has an OD (outside diameter) 84mm and the clutch drum ID (Inside Diameter) is 85mm. If this is correct, you should have more clearance than 0.5mm around the clutch, more like 2-3mm.

The 404 clutch should be part code  1111 160 2003

The 404 7T drum should be 1111 640 2002

The IPL is on this post...it may help

Alec.....it is a centrifugal clutch as the force of the clutch shoes is outward, centripetal.....not heard that since A level physics...is inward force hope all is well with you BTW..long time.......

 

050 051 IPL.pdf

[spudulike]

BTW, were the clutch and springs new and OEM? If you are using old springs and they are worn or slack, it will let the clutch spin the drum at idle speed.

[RomuloTDI]

15 hours ago, spudulike said:

BTW, were the clutch and springs new and OEM? If you are using old springs and they are worn or slack, it will let the clutch spin the drum at idle speed.

Hello.

The clutch was totally new, and the springs too.

It is a non-OEM clutch but brand new.

A greeting from Spain

[RomuloTDI]

15 hours ago, spudulike said:

If I am reading your post right, your clutch has an OD (outside diameter) 84mm and the clutch drum ID (Inside Diameter) is 85mm. If this is correct, you should have more clearance than 0.5mm around the clutch, more like 2-3mm.

The 404 clutch should be part code  1111 160 2003

The 404 7T drum should be 1111 640 2002

The IPL is on this post...it may help

Alec.....it is a centrifugal clutch as the force of the clutch shoes is outward, centripetal.....not heard that since A level physics...is inward force hope all is well with you BTW..long time.......

Yes, exactly, the clutch is 84mm and the drum is a 404 chain pass

The gap between the clutch and the drum does not reach 2mm

All the best.

[spudulike]

OK, from what I am reading, your clutch is aftermarket and 84mm diameter, the clutch drum is 85mm giving only 0.5mm clearance clutch to drum - this is far to small with 2mm being more normal. This is most likely the issue.

You mention a 82mm clutch, this will give 1.5mm clearance between the clutch and drum which should work OK as long as the crank thread is the same.

Aftermarket parts can be a bit hit and miss but the clearance is far too small - a photo of your clutch may substantiate this.

 

 

[RomuloTDI]

16 hours ago, spudulike said:

If I am reading your post right, your clutch has an OD (outside diameter) 84mm and the clutch drum ID (Inside Diameter) is 85mm. If this is correct, you should have more clearance than 0.5mm around the clutch, more like 2-3mm.

The 404 clutch should be part code  1111 160 2003

The 404 7T drum should be 1111 640 2002

The IPL is on this post...it may help

Alec.....it is a centrifugal clutch as the force of the clutch shoes is outward, centripetal.....not heard that since A level physics...is inward force hope all is well with you BTW..long time.......

 

050 051 IPL.pdf 1.22 MB · 2 downloads

Hello, yes, exactly, according to the reference 1111 160 2003 the clutch that I have mounted on my machine is the correct one, 84mm, but then I don't know why the chain does not stop moving with the machine at idle

[RomuloTDI]

Hera a picture of muy clutch