Chain loosening

[wildwes]

The nose sprocket shouldn't burred up like that should it? I don't think I have ever had a sprocket tip bar burr up that bad on the tip. On all of mine, the bottom of the chain links don't actually contact the bar rails, they ride on the sprocket itself around the end of the bar.

 

[barfer]

The nose sprocket shouldn't burred up like that should it? I don't think I have ever had a sprocket tip bar burr up that bad on the tip. On all of mine, the bottom of the chain links don't actually contact the bar rails, they ride on the sprocket itself around the end of the bar.

Agreed… (why I suggested the grease). That sprocket is either burned or it’s covered with like dark sap or something… but it needs some love for sure.

 

[Bludenz]

The nose sprocket shouldn't burred up like that should it? I don't think I have ever had a sprocket tip bar burr up that bad on the tip. On all of mine, the bottom of the chain links don't actually contact the bar rails, they ride on the sprocket itself around the end of the bar.

Will dress it and clean it with some petrol/diesel tomorrow. Any tips on how to get rid of the burs best? I'll usually hit it with a metal file "skating" across the bar.

 

[Bludenz]

Agreed… (why I suggested the grease). That sprocket is either burned or it’s covered with like dark sap or something… but it needs some love for sure.

Most likely would be covered in sap, if It is.

We've got a lot of gumtrees here, larger ones have sap "tunnels" that are absolutely huge. One of my smaller gums had a tunnel the size of my fist. Very thick and sticky sap. Impossible to get off your hands for a while. I assume can't do much good for a bar and chain if that stuff hardens up on it...

 

[barfer]

Most likely would be covered in sap, if It is.

We've got a lot of gumtrees here, larger ones have sap "tunnels" that are absolutely huge. One of my smaller gums had a tunnel the size of my fist. Very thick and sticky sap. Impossible to get off your hands for a while. I assume can't do much good for a bar and chain if that stuff hardens up on it...

Yeah you gotta get that off the bar/front sprocket. I’ve found degreaser to work very well for the sap in my area. Spray it on… let it sit… use a hard brush to scrub it off (but after the degreaser sits in it for a few minutes it comes off real easy). Then don’t forget to lube that baby up!

 

[Philbert]

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The nose sprocket can wear to a point where it rotates, but does not lift the chain off of the rails. So the bearings are turning, but not reducing friction.

So they can be ‘worn out’, even if looking good.

The illustration shows a minimum, recommended, clearance when replacing the bar nose, or bar, should be considered.

Philbert

 

[pioneerguy600]

When the nose sprocket teeth have worn down as much as the OP`s that the chain chassis is actually riding on the bar rails around the nose then the sprocket is worn out. Just look at the burr on the rails on the end of the nose, that shows the chain chassis itself is contacting the bar railson the nose and gouging them, time for a new bar for most folks.

 

[Mad Professor]

So in conclusion, the sprocket is the most likely cause of my chain loosening issues?

If it is, I'll most likely get a new sprocket and a new chain from my nearest stihl dealer. The bar still has some life left in it.

See if a clutch drum is available that takes rim sprockets. The rims are MUCH cheaper than the combination clutch drum/spur sprocket, AND much easier to change once installed.

While you have the bar off, clean out the whole groove to the bottom, and inspect the rail surfaces where the chain rides.

The rails should be even/not worn and perpendicular to the sides of the bar. Also look for a ridge that forms from wear on the rail edges. You can touch up the rails by draw filing with a flat file, or buying a tool made to do that.

When you have the bar off to clean the bar/under the chain cover, flip the bar when reinstalling so it the chain rides/wears on both rails evenly.

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That bars rails need to be dressed. Post some pictures of the rails.

Do you have vice and a large flat file to dress it?

You can make a groove cleaning tool with a LARGE long steel nail/spike. With a large hammer peen the tip flat enough to fit into the groove, then grind/file a hook into the flattened tip. Put the nail in a vice and put a bend a little above the flattened tip, in the same plane as the flattened tip. If this is not clear let me know and I can take a picture of the tool.

 

[coffeebrk]

Picked up a MS193T recently. Ordered up a new sprocket which came in yesterday

 

[Mad Professor]

Some people like to get the most out of their drive sprockets........

 

[Mad Professor]

Picked up a MS193T recently. Ordered up a new sprocket which came in yesterday
View attachment 1205823

New chain too?

 

[Mad Professor]

Will dress it and clean it with some petrol/diesel tomorrow. Any tips on how to get rid of the burs best? I'll usually hit it with a metal file "skating" across the bar.

The best way I've found, is using a vertical belt sander, that gets the rails perfectly square with the bar. I've saved some nastly bars that way. As I mentioned draw filing works too.

Also check the groove width, if that is worn the chain/drive links will wobble, and best to get a new bar.

PS. HF has cheapo vert belt sanders on sale now $45. What does a dressing tool cost?

 

[coffeebrk]

New chain too?

Yes, new chain too. New spark plug and new cord for the recoil starter.