Thread: 3120 problem fix

the hard starting can be fixed with a spacer to move the carby away from teh head. teh spacer is avalable from husky.

teh spark arrestors shouold be teh first thing to go on any saw.

so they finely worked out there bugs.

yep spark arestors the first to go on all my saws

Originally Posted by swing mill

have read back through some old posts about 3120 huskys and see somepeople are having problems with hard starting when hot. The best way i have found to stop this is to stop the cs with the choke that way there is still fuel in the carby to re start

While it is worth knowing that one can stop a saw with the choke in emergencies when the kill switch fails, stopping any saw this way on a continuous basis is something I would be careful about doing. It is more of a problem if it is done from WOT, but continually stopping the saw using the choke places an unnecessary sudden strain on the carby, fuel lines lines and fuel tank vent valve and there is a small risk these will may kink or jam in a closed or semi-closed position which may prevent fuel getting thru to the saw and lean out the saw to the point where it will seize. The older the saw the more significant the problem becomes as lines become more brittle and dirty. The chance of this happening is small (and I know some people who do it for many years and get away with it) but why risk it. If the saw manufacturer thought stopping a saw this way could be done safely on a regular basis why would they bother to put a kill switches on saws?

also if you open up the nedle a bit in the carby i find that also helps and if you want it to go a bit harder when cutting take to the muffler with a 1/2'' drill and open up the baffel and increase the exit side of the muffler also flick the spark arestor this works well and i speak from experence as i have had this saw for over 4 years and made these mods from day 2 with full time cutting for over 2 years and occasional for the last 2 the saw has never let me down no matter the circumstances.

Removing the spark arrestor is one thing but diddling the carby and exhaust "a bit" on the newer model 3120s is also not something to take lightly, especially if the saw if going to be used as a milling saw. These 3120s do not have an adjustable H-screw and the max RPM is also coil limited. Opening up the main jet does generate more power but doesn't provide any more RPM as the coil limiter prevents the saw from generating any more than 9500 rpm. This means the saw ends up just bouncing off the rev limiter and even experienced tuners find it difficult to work out what is going on. Gutting the exhaust too far and not opening up the main jet sufficiently to compensate could also lead to running too lean and a saw seizure. I would not recommend these mods to owners of newer 3120 who are going to mill with these saws unless they have experience with tuning chainsaws.

you are corect bobl i should have explained it in more detail as i must have the older model as it revs out to 11000 rpm also i dont use the choke to stop it all the time only when i stop the saw for a few minits or so these mods where recomended to me from someone with over 40 years experence with sthil and many years as one of there toruble shooters

Originally Posted by swing mill

you are corect bobl i should have explained it in more detail as i must have the older model as it revs out to 11000 rpm also i dont use the choke to stop it all the time only when i stop the saw for a few minits or so these mods where recomended to me from someone with over 40 years experence with sthil and many years as one of there toruble shooters

Cheers SM. Just from the way you wrote your post I could tell you were an experienced CS user. We have a lot of newbies reading this forum and I just wanted to keep them from messing up their nice newer saws.

A small increase in the main jet size and no changes to the exhaust apart from just knocking out the spark arrestor is OK and will do no harm as it just richens up the saw (increases mix-air ratio) and this is a good thing for milling saws. I think the usual jet is 1.12 mm and I think it can take up to ~1.16 mm without a performance problem, ie too rich, but even at 1.16 mm the saw maybe just wasting mix and will eventually foul the plug.

Drilling holes in the muffler will require increasing the jet size for milling. This is where it can get tricky especially with the rev limiter. One way to accommodate a decent muffler mod is to fit a non rev limiting coil and to ream the main jet out to 1.18 mm. But please remember you are on your own with this and I would seek specific advice before going this far.

I have never modded a 3120 myself but I was going to do this to my mates 3120 and so I followed several threads about these and more detailed mods to 3120s on the arboriste site. In the end we decided the saw had plenty of grunt and we would use it as is. Tis indeed a fun saw to use on a mill.


Also, whether you believe in it or not, any of these mods will mean your saw is non-EPA approved.

never had to worry about going to that extent of reaming the saw is strong enough. was thinking of doing similar with the 088 magnum but i dont use it that much to worry about it (spare saw) 4 years old only done about 40 hours due to drama with bar oiler (MAJOR blow up with still dealer) 2 saws in 2 days and a weeks worth of lost production not happy) as for EPA just had to keep the saw away from view when cutting in state forest

Originally Posted by BobL

Cheers SM. Just from the way you wrote your post I could tell you were an experienced CS user. We have a lot of newbies reading this forum and I just wanted to keep them from messing up their nice newer saws.

A small increase in the main jet size and no changes to the exhaust apart from just knocking out the spark arrestor is OK and will do no harm as it just richens up the saw (increases mix-air ratio) and this is a good thing for milling saws. I think the usual jet is 1.12 mm and I think it can take up to ~1.16 mm without a performance problem, ie too rich, but even at 1.16 mm the saw maybe just wasting mix and will eventually foul the plug.

Drilling holes in the muffler will require increasing the jet size for milling. This is where it can get tricky especially with the rev limiter. One way to accommodate a decent muffler mod is to fit a non rev limiting coil and to ream the main jet out to 1.18 mm. But please remember you are on your own with this and I would seek specific advice before going this far.

I have never modded a 3120 myself but I was going to do this to my mates 3120 and so I followed several threads about these and more detailed mods to 3120s on the arboriste site. In the end we decided the saw had plenty of grunt and we would use it as is. Tis indeed a fun saw to use on a mill.


Also, whether you believe in it or not, any of these mods will mean your saw is non-EPA approved.

watch that python there Bob!!

Pete

I'm one of the blokes that has a 3120 with the odd starting hassle, more so when the weather is stinking hot, one thing I will do is let it idle for a bit after a slab then sit it in the shade while I setup for another slab, I think it helps, I don't do a lot of milling so hasn't been a major issue for me, but is a PITA when it don't wanna go,

The spark arrestor, not sure if mine is there or not, the general opinion is take it out, yes?
by its name it stops sparks, I would think if sparks are shooting forth it won't be long before its gonna stop, or is it to stop cabon deposits getting burnt up and coming out as sparks? and setting the bush alight?
By removing it what could I expect from the saw? improved power?


Pete

Originally Posted by pjt

I'm one of the blokes that has a 3120 with the odd starting hassle, more so when the weather is stinking hot, one thing I will do is let it idle for a bit after a slab then sit it in the shade while I setup for another slab, I think it helps, I don't do a lot of milling so hasn't been a major issue for me, but is a PITA when it don't wanna go,

I used to let my saws idle for 30 seconds after a long cut but since I got a temperature gauge on the 880 I now let it idle for 2 minutes.

I guess I have used Huds 3120 on and for about 4 weeks - Never had any trouble starting it hot. In fact ir reminds me of my 076 - 1-2 pull starts when warmed. the 880 is a 1-4 pull start most times.

The spark arrestor, not sure if mine is there or not, the general opinion is take it out, yes?
by its name it stops sparks, I would think if sparks are shooting forth it won't be long before its gonna stop, or is it to stop cabon deposits getting burnt up and coming out as sparks? and setting the bush alight?

Yep - to stop glowing soot from coming out and starting fires.

By removing it what could I expect from the saw? improved power?

Yes a little when new and a lot once they gunk up with soot - that's why there is always some info provided in CS user manuals on cleaning the spark arrestor..

To meet EPA emission requirements all recent saws have had their exhaust sizes cut right down. But this also drops their performance so opening up their exhaust even just a little improves performance by allowing more air to flow through the engine. This decreases the mix-air ratio (ie makes the saw run leaner) and makes the saw run hotter and increases the WOT RPM. Maybe hot enough even to seize the saw. To get around this the H-screw is adjusted to add more fuel so the mix-air ratio is restored (and for milling saws richening the saw up a little more is advisable), this makes the saw run cooler and decreases the WOT RPM. A well executed muffler mod that includes a proper retune will make a significant improvement to a saws performance. Since the saw runs slightly cooler compared to the unmodified saw and increase the longevity of the saw. Of course this makes it non-EPA approved. One danger with muffler mods is that on some saws it is possible to open them up so much that the H-screw runs out of adjustment and cannot be richened up enough to compensate. It's not rocket science but it's also possible to make a small adjustment and then seize your saw so you just need to be aware of this especially of you are going to mill with it.

teh starting issue with the 3120 is due to the carby being to close to the head and the heat vaporising the fuel in teh carby.

that is why its more prominent in hot weather.

putting a bigger exaust on just about any motor improves performance. i put a 2.5" exhaust on my rodeo and it improved the power incredibly.

removing teh spark arrestor makes a big difference to teh way an old saw mill run.

once my saws have done 400 hours o so i take the exhaust off and put it on teh ground chuck a cup full of petrol in it and light it up. burns all the old carbon off and opens her back up.

little trick we picked up from the old 2/bikes.

Thanks for the input, when I next am about to do some milling I shall have to have a look at the muffler at least, mine is a 1998 model, will that have a rev limited coil?

Pete

Originally Posted by pjt

Thanks for the input, when I next am about to do some milling I shall have to have a look at the muffler at least, mine is a 1998 model, will that have a rev limited coil?

Sorry I don't know, but if it is limited it will be 11,000 or 11500 rpm which give you a bit more to play with than the more recent ones.

It's not a carpert python, it must be a sawdust python

Originally Posted by comgreserv

It's not a carpert python, it must be a sawdust python

It's a Serpentes Elastica.