Stihl 290

[Michael Golden]

I made a mistake today while starting my 290. After I cold started the saw I left the brake on with the throttle still wide open and walked away for a minute to grab my bar oil, and when I returned there was smoke a rolling. I hurried and shut the saw down and let it cool, but once I restarted it, if I was to put the brake on it would die immediately. I'm just wondering what I messed up, I ran the saw the for couple hours cutting up a maple. I am going to open it up tomorrow just not sure what I'm looking for, I'm hoping I didn't mess it up to much. Any opinions on what I may have messed up?

Thanks Mike

 

[cygnus]

I've never seen it happen, nor am I sure it's possible, but I'd say the clutch weights welded themselves to the outer drum. Can you move the chain by hand when it's off? If the piston cranks when you move the chain then you need a new clutch.

 

[Michael Golden]

Well I took the chain off immediately to cool thing off and it did pump the piston like you said, but I realized the break was on. I thought I weld it up in there, but after things were cooled down I put the chain on and it spun freely! The problem is though that when I would go the throw the break on to stop the chain while I moved around the saw would die? It really was a dumb screw up and I new better, but the saw was cold so I just left for a minute or two to grab the oil.

 

[welderboyjk]

Honestly not trying to start an argument but would you start your car cold and stand on the throttle? Why do it with your saw? Just seems wrong to me. Pistons can cold seize/scuff.
Now that that's out of the way when you pop the bar off you should be able to see what's not "right" I'd imagine.

 

[Michael Golden]

Took the bar off and nothing looks messed up. I was wondering though what would make the saw stall once the break is on? Thought maybe the break was plastic inside and melted or that someone may have experienced this and would know what I may have burnt up. Also, I appreciate your response, but that is not the advice I was looking because I already no I messed up.

Thanks Mike

 

[ScotO]

Sounds to me like possibly you have a bad clutch shoe spring, or something jamming between the clutch shoes and sprocket. You're gonna have to remove the clutch sprocket to even see it (that's an inboard sprocket).

 

[Michael Golden]

Thanks for weighing in Scotty, I was hoping for a little knowledge on it. I will open it up tomorrow and take a look. Saw ran good while I finished cutting, but I know something ain't right with it. Thanks

 

[ScotO]

Thanks for weighing in Scotty, I was hoping for a little knowledge on it. I will open it up tomorrow and take a look. Saw ran good while I finished cutting, but I know something ain't right with it. Thanks

Whatever it is (I'm thinking it's a clutch shoe), it's an easy fix. You'll get it figured out, get some pics and if you have questions there's lots of good guys on here that will help you out.

 

[Michael Golden]

I appreciate that, and if I get snagged I will look here for help.

 

[MasterMech]

Really common for the plastic housing around the brake to melt too with that kind of "failure" .

I'd count on replacing the clutch, drum, and needle bearing all in one shot. That much heat is bad juju.

Buy a clutch and rim sprocket kit for it. You'll get the drum and bearing in the rim sprocket kit plus wind up with a rim sprocket setup that will last much longer than a spur sprocket that the saw came with. New rims are 5-8 bucks instead of replacing the whole $30-40 drum/sprocket.

Don't bother replacing 1 or 2 clutch shoes either. That much heat has ruined the springs as well and you may as well just replace the clutch assembly.

Maybe snap a pic of the sprocket side of the saw (cleaned up if possible) and we can see better what may or may not have survived.

 

[Michael Golden]

I will see if I can get a picture today once I get it cleaned up and apart.

Thanks

 

[Michael Golden]

Really common for the plastic housing around the brake to melt too with that kind of "failure" .

I'd count on replacing the clutch, drum, and needle bearing all in one shot. That much heat is bad juju.

Buy a clutch and rim sprocket kit for it. You'll get the drum and bearing in the rim sprocket kit plus wind up with a rim sprocket setup that will last much longer than a spur sprocket that the saw came with. New rims are 5-8 bucks instead of replacing the whole $30-40 drum/sprocket.

Don't bother replacing 1 or 2 clutch shoes either. That much heat has ruined the springs as well and you may as well just replace the clutch assembly.

Maybe snap a pic of the sprocket side of the saw (cleaned up if possible) and we can see better what may or may not have survived.

I have the saw apart, and was wondering how to get the shoes off? When I popped the the top off the needles scattered, I was able to gather most of them but two went down under the shoes. Also, it did melt a little plastic, not bad though just kinda charred it. I don't really know all the official names for these parts, it there a replace where I can k
Find a exploded diagram on this kit you are saying to get?

 

[Michael Golden]

Just walked out and tried again to take the shoes off, I just don't want to force anything. I took off a cover, not sure what its called, but it allowed me to take off a stainless band. I thought maybe this was what was hold them shoes on, but it wasn't. When I put the saw break on I see how this all operates, but with the break on, the stainless band does not reach the shoes? I'm guess that it is suppose to squeeze them like a break? The center piece holding the shoes has nut head on like you should be able to unscrew it but it just spins freely? I will just wait for some advice before continuing.

Thanks, Mike

 

[Michael Golden]

Here's a picture:

 

[HittinSteel]

I haven't worked on an 290 in a long time, but I think you need to take the spark plug out and insert a piston stop. Then put a socket on the nut holding the clutch on. It should be reverse thread so turn the nut CLOCKWISE. Then you can take the whole clutch off and access the sprocket and needle bearing.

* I'd await a confirmation from a stihl guy before doing the above.

 

[Michael Golden]

I haven't worked on an 290 in a long time, but I think you need to take the spark plug out and insert a piston stop. Then put a socket on the nut holding the clutch on. It should be reverse thread so turn the nut CLOCKWISE. Then you can take the whole clutch off and access the sprocket and needle bearing.

* I'd await a confirmation from a stihl guy before doing the above.

Alright I will wait, thanks for the info. Where do I find a piston stop?

 

[Michael Golden]

Well I just watched a YouTube video, should have done that earlier. Looks pretty easy to take that all apart, but I don't see what I need to replace other than the bearing. The shoes show some sign of heat, but I still don't know why the saw would stall when applying the break?

 

[StihlHead]

Yah, that's the way to remove a Stihl clutch. Most saw shops will have piston stops. They come in the tool kits on some Stihl saws. They are an offset bar that you stick into the spark plug hole. That locks the piston in place so you can remove the flywheel and/or the clutch. You can also get them online, here is one on Ebay:

(broken link removed to http://www.ebay.com/itm/NEW-OEM-STIHL-CHAINSAW-PISTON-STOP-0000-895-5903-/160951461100?pt=LH_DefaultDomain_0&hash=item25797464ec)

BTW: Frying a clutch housing with the brake on is pretty common on the smaller Stihl 1123 series of saws (021-250). That is the most common way that I have seen them nuked after straight gassing. I bought several toasted that way to salvage the engines. The 1127 saws (029-390) are more tolerant of the heat but they can also melt. The oil lines can get damaged that way as well. When you pull the clutch check the oil feed line/galley is not melted through.

Needless to say, starting and leaving a saw running unattended at WOT with the brake set is a bad idea. Actually it is a collection of three bad ideas:
1) Do not leave a chainsaw running unattended.
2) Do not run a chainsaw at WOT (wide open throttle) out of the wood for anything longer than for brief testing with a tach to set the H screw on the carb, or revving just before a cut. You can overheat your saw engine really easy by running it WOT out of the wood.
3) Do not rev your chainsaw to WOT with the brake set, or you can damage the clutch/brake/housing assembly, as you have done. The clutch will not engage at low RPM and so the brake will not cause friction on the clutches. Above about 2500 RPM the centrifugal force will cause the clutches to fly out and engage the brake drum. At that point you want the chain to run free as it was designed to do, unless you are in a situation that you want the brake to activate, like in a kick-back situation.

Let your saw warm up while idling. If it does not idle right after starting, clean the saw and retune the carb so that it does.

 

[Michael Golden]

Well I will check the oiler when I get it apart tomorrow. I saw immediately the roller bearing was toast, the bearing just fell out. I have never done that before with the throttle, it was a total brain fart just hope things can be fixed. I have it down to the clutch and I will get that off tomorrow and check for any melting around the oiler. I think the smoke was coming from the bearing. I saw there in a video a guy using a nylon rope to lock the piston, is this recommended?

 

[HittinSteel]

I've used rope before without a problem......just make sure none of the rope or fibers stay in the saw when you pull it out.

 

[fabsroman]

Well I will check the oiler when I get it apart tomorrow. I saw immediately the roller bearing was toast, the bearing just fell out. I have never done that before with the throttle, it was a total brain fart just hope things can be fixed. I have it down to the clutch and I will get that off tomorrow and check for any melting around the oiler. I think the smoke was coming from the bearing. I saw there in a video a guy using a nylon rope to lock the piston, is this recommended?

Things can almost always be fixed. Only a matter of how much it will cost in parts, and labor if you do not know how to do it yourself. I'm interested in hearing what the culprit part actually is.

 

[Michael Golden]

I've used rope before without a problem......just make sure none of the rope or fibers stay in the saw when you pull it out.

Ok thanks, I have found all the parts that were listed that I may need. It is amazing all knowledge online if you just look around!

 

[Michael Golden]

Things can almost always be fixed. Only a matter of how much it will cost in parts, and labor if you do not know how to do it yourself. I'm interested in hearing what the culprit part actually is.

Well the culprit was me! But, the problem with the stalling from everything I've read is coming from the clutch assembly and inexpensive from what I've seen. I figure if everything else checks out I will just get the clutch assembly and drum sprocket assembly. Just hoping the oiler checks out!

 

[fabsroman]

Well the culprit was me! But, the problem with the stalling from everything I've read is coming from the clutch assembly and inexpensive from what I've seen. I figure if everything else checks out I will just get the clutch assembly and drum sprocket assembly. Just hoping the oiler checks out!

Notice I said culprit part, not culprit person. I already know you screwed up, and you admitted it in your very first post. No need to beat a dead horse and lecture you about starting a saw and walking away from it while it is WOT. Think the others have beat you bad enough about it, and you are learning your lesson even moreso by having to spend money for the parts and time on the repair.

 

[StihlHead]

Well I will check the oiler when I get it apart tomorrow. I saw immediately the roller bearing was toast, the bearing just fell out. I have never done that before with the throttle, it was a total brain fart just hope things can be fixed. I have it down to the clutch and I will get that off tomorrow and check for any melting around the oiler. I think the smoke was coming from the bearing. I saw there in a video a guy using a nylon rope to lock the piston, is this recommended?

Rope works fine, as does some torn red rag in a jiffy. I used it for several jobs on several types of saws, including Stihl, Echo, Husky and Olympik. Just make sure not to use too much rope and keep the piston near TDC so that not much torque is applied to the piston rod. You can bend a rod pretty easy levering the clutch threads the wrong way (like normal threads). See, it is easy to get buried even deeper in your brain fart with more brain farts to come!

If the bearing is that toasted that was some amount of heat and wear that you applied. Clean the plastic around the area and look closely for melted leaks in the oiler galley and look at the bearings/seals on the crankshaft. You may have smoked the crank seals as well, though it is less likely. I have salvaged a lot of clamshell engines from some saws with clutches that were smoked and had completely melted through the oil galley and melted all the plastic around the clutch area.

All 2-stroke saws are only a brain fart away from being straight gassed and scored, or run with the brake on and smoked. You have to be carful when to say, "Here hold my beer while I try something" with a chainsaw in your hand.