MS290 sprocket & oiler questions

[ihatesaws]

Hi

do I need a new sprocket?  Is an aftermarket one for £5 from China okay or do I need an oem one for £20?

 

Had arbor biooil or some such stuff in the saw and it clogged it up.  After doing a bit of cutting the chain wouldn't move anymore.  I cleaned all of the gunk out and even put in a new worm gear although I think the old one wasn't too bad.  When I run the saw and take off the bar the new oil trickles out and down the saw but when the bar is on the flow seems to be slow.  I don't  see a great amount of oil in the groove on the bar and when I go through a tank of petrol then maybe only 1/4 or 1/3 of the oil tank has been used.  I thought they should both empty at the same rate.  Since I cleaned the whole thing out the chain doesn't seize anymore but it does look a bit dry and feel hot.  Is this model of saw a poor oiler?  I don't see what could be stopping the oil flowing in the bar as i cleaned out the groove and the small inlet hole thoroughly.  Does the oil pump wear out and not pump as strongly with time?

 

Thanks

[Rough Hewn]

Yes you need a new sprocket.
0.5 mm of wear is the recommended limit.
Get a "rim sprocket conversion kit" For about £30. (Oem)
Spur sprockets like yours are more expensive to replace regularly.
Rim sprockets are about £10 (oem)

Oiling: have a look at your bar, are the tiny holes to let the oil through in to the bar blocked?
Clean the bar.
Good luck.
[emoji106]

[EricBradley]

Nothing wrong with that sprocket IMO, its obviously warn but there is a lot of life left in it.

[NFG]

As per Rough Hewn & perhaps replace the needle bearing while you're at it.

 

LS Engineers do kits & are a good supplier

 

N

[spudulike]

The sprocket is worn and should be replaced. If you put the sprocket up against the light, you will be able to see two indentations in the very top of the gear/lobe and at this point, it needs to be replaced. Sure, it isn't as bad as this one as the chain was actually slipping round the spur drum!

[ihatesaws]

I won't be using the saw enough to replace the sprocket regularly so I'm not going to get a conversion kit.  The one on it is probably the original one.  What are the consequences of continuing to use a worn sprocket?  If I replace with an aftermarket one will it just wear more quickly than oem or could it damage other parts of saw?

 

As regards oiling I did write that I cleaned out the bar groove and the inlet hole on the bar so that can't be it.  Is it the case with every saw that the oil tank empties at the same rate as the fuel tank? Is there a vent in the oil tank to prevent a vacuum and if so where?

[Stubby]

Oil tank should empty slower thank fuel tan by design . Should be a breather somewhere .

Edited December 20, 2017 by Stubby

[spudulike]

I would fit a new sprocket as using a worn one will wear the drivers of the chain, the tension changes as the chain moves from worn to less worn parts of the sprocket and will stretch the chain unevenly. The sprocket is a consumable part and should be changed if worn - when else would you consider changing it - another chain or two and it would resemble a farmers saw!

 

The breather is a small aluminium valve pushed in to the bar mount to the right of the rightmost  bar stud. If it is blocked, oil will flow les and less as the saw is used rather than ceasing immediately.

 

Typical oiler issues are the worm stripped or damaged, the oil pump inlet plugged, the tank pickup filter plugged, gloop in the bottom of the tank or wear between the oiler shaft and the oiler body - this usually means oil is slowed rather than not working altogether. Also check the oil channel in the bar mount but is a pretty obvious fault.

 

You can thin the oil with a bit of petrol to flush the system but usually find it quicker to strip out the parts and get them clean and fixed than cocking around the issue for weeks!

[spudulike]

Oh - and a reasonably manufactured aftermarket is better than a badly worn OEM. The Hyway stuff is better than most.

[Khriss]

Old trick I used to use , especially in winter was a pint of deisel in a gallon of chain oil, it thins it enuff an the soapy nature of the fuel cleans the pump of any dried oil from previous long-stands in the shed , K