MS261-C Smoky, Out of ideas.

[CFOD]

Got myself a 261-C the other day, heard they're very good saws and this was incredibly cheap, so thought it was worth a shot. Seems like the saw is all good, it just smokes quite heavily when under high load. I've done a bit of searching, I can rule out a chain/bar issue as it doesn't have one currently. The fuel is a good mixture, it's what I use in all my saws, the fuel filter is clean, and the air filter is clean. When I first got the saw it was idling EXTREMELY high, so I've managed to bring that back down to a 'normal' level, which makes me think it might just be a carb issue. The plan is to get a bar & chain (will be here in a few days), see what the saw is like and set the carb when that's on.

If you've got any ideas on what to check, please let me know. I've attached a YouTube vid of it running/idling, as well as pics of the smoke and fuel.
Thanks

 

[Andyshine77]

Try and get the carb tuned for proper idle. If you can't, the saw likely has an air leak. The smoke could just be from being too rich on the high side.



What ratio are you mixing the fuel at?

 

[DND 9000]

The idle mixture sounds to lean, you hear it coming down nen nen nen... As Andyshine77 already said it could be very rich on the H side or fuel with to much oil in it. It can also be possible that the saw has an air leak and got tuned for it to compensate. Check out what the matter is and don`t use it in that condition.

 

[CFOD]

The idle mixture sounds to lean, you hear it coming down nen nen nen... As Andyshine77 already said it could be very rich on the H side or fuel with to much oil in it. It can also be possible that the saw has an air leak and got tuned for it to compensate. Check out what the matter is and don`t use it in that condition.

The more idle I seem to push it, the more it seems to smoke. It's at the point where If I turn it any more, it will no longer idle without cutting out. The H screw is also at it's most counter-clockwise setting, and I cannot turn it any further. the fuel is mixed to a 50:1 ratio so I know that's okay. This is seeming more and more like it's an air leak, sadly.

 

[Gord404]

Probably need to vac- pressure test it, could be a seal or the boot etc

 

[user 122190]

The more idle I seem to push it, the more it seems to smoke. It's at the point where If I turn it any more, it will no longer idle without cutting out. The H screw is also at it's most counter-clockwise setting, and I cannot turn it any further. the fuel is mixed to a 50:1 ratio so I know that's okay. This is seeming more and more like it's an air leak, sadly.

Most counter clockwise is fully rich. You're being told to back off fully rich. IMO, testing for air leaks is not a simple thing. Start with the carb. Take it apart and clean it good, and make sure you remove the H/L adjustments and clean them good.

 

[PV Hiker]

It's a unknown history for the saw. Go to the basics to start.

Check cylinder compression
Pull muffler Look for condition
Vacuum test
Pressure test
Take carb apart check condition/ clean
Set jets to factory recommended turn outs
Check spark plug and gap
Fuel filter and hoses conditions
Check coil gap / adjust

If all ok then start it and see how it does. If anything needed to be corrected it should be a improvement.

 

[PV Hiker]

If you think it has a leak from the oil tank to the cylinder, you can drain the oil out and clean it . Do a vacuum and pressure test with oil cap off to check for possible leak.

Might smoke from oil seaping into the cylinder.

 

[Gord404]

If you think it has a leak from the oil tank to the cylinder, you can drain the oil out and clean it . Do a vacuum and pressure test with oil cap off to check for possible leak.

Might smoke from oil seaping into the cylinder.

Yes I have seen that before as well

 

[trains]

As its new to you, get the carb off, and have a good look at it, but from what others have said, and how it sounds in the video, it sounds very lean, and that could most likely be an air leak, but lets start with the basics first.
Take the muffler off and inspect the piston, need to find why it was so cheap.
Air leak run for too long will damage the piston.
Clean carb, but whilst you have the muffler and carb off, best to do a pressure and vac test as already mentioned.

Let us know what you find, and post up pics as you go.

as far as smoke is concerned, lets sort the running correctly first, then deal with the smoke, could just be loaded up in the muffler can burning off when its warmer, or the prior owner put loads of oil in the saw so it would run to sell it.

lets find out what it is.

 

[Captain Bruce]

If you think it has a leak from the oil tank to the cylinder, you can drain the oil out and clean it . Do a vacuum and pressure test with oil cap off to check for possible leak.

Might smoke from oil seaping into the cylinder.

This makes no sense to me. How the hell would bar oil, from a sealed and vented static tank, get into a sealed engine cylinder?

 

[Andyshine77]

This makes no sense to me. How the hell would bar oil, from a sealed and vented static tank, get into a sealed engine cylinder?

The crankcase seal can fail between the oil reservoir, and the crank housing, so the oil gets burned and creates lots of white smoke. Usually a lot more than what I saw in the video, but it's still a possibility.

 

[KASH]

Plugged muffler?
Kash

 

[pioneerguy600]

The crankcase seal can fail between the oil reservoir, and the crank housing, so the oil gets burned and creates lots of white smoke. Usually a lot more than what I saw in the video, but it's still a possibility.

I had an 044 do that, at first it was just a bit of smoke but after several more tanks of fuel the smoke got progressively worse, it did not make the saw run lean, I think the oil was thick enough to stop air from getting into the crankcase.

 

[Maintenance supervisor]

This makes no sense to me. How the hell would bar oil, from a sealed and vented static tank, get into a sealed engine cylinder?

Gasket fails here.

 

[huskihl]

I’d turn the idle screw out about 2 turns once you get a bar for it. It’s going to blow smoke until it gets some heat into it from cutting wood. Every saw will do that if it’s tuned rich with no bar and chain on it

 

[Del_]

Any chance that bar oil was put in the fuel tank by accident and this extra oil still has not cleared the saw?

I've seen it happen several times. Even if the fuel tank is poured out, refilled, shaken and poured out again, it still may smoke a lot for a while.

 

[huskihl]

There’s usually no mistaking the smell of burning bar oil. The saws I’ve seen that were sucking bar oil would blow white smoke and it smelled like burning gear oil

 

[speeco]

I’d turn the idle screw out about 2 turns once you get a bar for it. It’s going to blow smoke until it gets some heat into it from cutting wood. Every saw will do that if it’s tuned rich with no bar and chain on it

U will have a hard time tuning it with no bar or chain. And agree it will load up and smoke badly. I personally only run synthetic oil. Lot less smoke. I bet once it does some cutting, it will be fine. Just my two cents worth!

 

[cookies]

I have had saws land on my bench that were run super rich or way overloaded with cheap oil in their mix that took readjusting the carb, fresh fuel and 3 tanks of fuel run through them before all of the excess oil got blown out and burned out of the muffler.