MS880 problem

[Blackbriarwoods]

Have done a search but found nothing, so apologise in advance if this has been asked before.

 

Was using the 880 yesterday, it started ok and ran fine until it warmed up, power started to drop off noticably, so turned it off.

As I'm a mechanical numpty, I'd like to ask what the likely problem is? Is it worth sorting out or is it terminal?

The saw is about three years old, was bought used, from a bloke that milled with it, about a year ago. Worked ok for a couple of jobs, this occured after about 15 minutes discing up a pine trunk.

Thanks

[treequip]

Lets start with the basics, is the air cleaner blocked?

[spudulike]

Personally I would pull the muffler off and look at the piston to make sure it isn't fried - the 880 is an expensive bitof kit and will have a good residual price whether it is good or broken.

 

If the piston has vertical scoring then it will need a bit of work to see if the cylinder is salvageable. Let us know if the piston looks clean and in good condition.

 

If you want it gone over then let me know.

[Blackbriarwoods]

No, it's all clean, replaced spark plug and fuel filter when I first bought it, took it to bits as much as I dared and checked for worn bits, not confident enough yet to dive into the engine without advice or assistance

[Blackbriarwoods]

Spudulike, I'll try and do that asap and let you know, is it an easy job to remove the muffler, or any tricks I should know about? Thanks

Edited August 14, 2011 by Blackbriarwoods

[spudulike]

Spudulike, I'll try and do that asap and let you know, is it an easy job to remove the muffler, or any tricks I should know about? Thanks

 

Not done an 880 but from this - Plance éclatées MS 880 : Smaf-Touseau.com

 

There appears to be a couple of clamps held in place with a spring, not seen anything like this before but would think the exhaust should come off reasonably easy:001_rolleyes:

 

Generally this is the first check I do on most saws as it gives a good indication of how well the engine is. If you have a compression gauge then that would also give good info.

 

If the piston is good then that is very good as the problem is probably fuel related - is the compression good, if you pull it over with the decomp out, does it feel all springy and spongey at the top end as the piston goes over tdc?

[Paul Jenks]

Ours packed up earlier this year. It hadn't done a huge amount of work but had certainly earn't it's money.

Had to get the engine rebuilt or something like that. Cost about £300 or so. Worth it on a big saw.

The air filters are not great on most stihls, IMO, as there is always crap around the carb inlet caused by gaps in the seating.

I can understand the fine stuff getting through. To stop it you'd need a paper filter that wouldn't last five minutes in the field and would require so much energy to pull the air through the small saws wouldn't run.

[blazer]

Ok it's at the other end of the scale but my little MS170 lost power, did the normal stuff; plug, air filter, fuel filter, strip & clean carb, compression OK

 

Noticed the muffler outlet part blocked, stripped- wire brushed innner/outer parts - runs a treat plenty of power again:thumbup1:

 

I only missed it because I had never had this problem before:blushing:

 

Bit like my ignition prob on a MS 280 - I believed 'it can't be the coil assy thay don't ever go wrong'?

[TREE-SURGEON-ESSEX]

Had this problem was scored piston and pot i think it was old fuel not sure tbh, but the pot is 300-400 and the piston is 80-100 ouch no patent parts so im sticking with a 660

[Acle Garden Machinery]

take the exhaust off and check