I just got done completey disasembling a stihl 031av that I bought off ebay to install all new gaskets and seals. The saw had this problem before I took it apart. The saw will only rev up to 11,200 rpm before it gets so lean it begins to bog down. THis is without the bar. THe spec is 12,000 rpm. When the bar is installed i set the saw by ear. When it starts to 4 stroke its running about 10,000, well below the 12,000 spec. shouldn't the saw be able to rev well about 12,000 when its set to the full lean setting. The only thing I haven't checked is my fuel filter. It starts and idles and runs good. Compressiom is at 150psi. I havn't used it to cut anywood because I wanted to set the carb with a tach before I used it. Im using a wirelss digital tach that is accurate. The saw is the electronic model and carb was rebuilt by the guy I bought it from. any ideas.
stihl 031 low max rpm when tached
- Thread starter mike031
- Start date
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Grande Dog
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Could be a ignition / timing problem.
something is wrong with the ignition module itself
I guess put it together and try cutting something, if you have fuel problems they should show up real quick. Spark shouldn't be affected by the load
Grande Dog
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The electronics on the 031 AVE are 2 piece systems. They were built with some degrees play in the flywheel key. There was a pointer ( special tool ) that mounted on the bar studs and pointed toward the clutch. I don't remember the specs. but, you had to set the piston X amount of mm before or after TDC. Then you put a timing mark on the clutch hub, hook up your timing light, and away you go. I don't remember those saws turning that high of RPM's no load. I do remember that they ran about 6000 to 9000 under load and max. HP was at the low end of that range.
dozerdan
Addicted to ArboristSite
Hi
I have seen the 031s with three different ignition systems. The first design was with points. They used two different designs of electronic ignitions, some had the two piece ignition and some has the standard one piece design. I have only had two of the 031s with the two piece design in my hands. Most of them I run across are the one piece, they could have been changed over at some point in their life.
Here is what Keystone Stihl Inc. printed in 1996.
031 idle rpm 2400-2600, Max rpm 11500-12000
If someone else was inside the carb, I would look there first.
Later
I have seen the 031s with three different ignition systems. The first design was with points. They used two different designs of electronic ignitions, some had the two piece ignition and some has the standard one piece design. I have only had two of the 031s with the two piece design in my hands. Most of them I run across are the one piece, they could have been changed over at some point in their life.
Here is what Keystone Stihl Inc. printed in 1996.
031 idle rpm 2400-2600, Max rpm 11500-12000
If someone else was inside the carb, I would look there first.
Later
I pulled off the fllywheel, then set it on the shaft to see how much back and forth play there was. Practically nothing. I also tried to see how much play was in the bolts of the coil to see if i could move it forward or backward, hardly any in them either. So Im confused. thanks
Grande Dog
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Does your saw have a module under the flywheel?
Justin Garrison
ArboristSite Operative
Are there any fins broken off the flywheel?
dozerdan
Addicted to ArboristSite
Mike
OK . Now we are getting someplace with your saw. I think what you have is and old 031 that originally had points in it. Someone over the years removed the points, condenser and used the points coil and then added the replacement module. This works fine most of the time but I have seen a few that wont run correctly. I assume that your saw still has the original points flywheel. The points flywheel will have two small plastic inserts with a screw in the center of them. They can be removed and it will give you a window for setting your points.
Take your saw back apart. Its only a 5 minute job on an 031. LOL
Remove the flywheel key, set the flywheel back on the crank, line up your keyway, now turn the flywheel in the same direction that the engine runs and align the opposite edges of the key cut outs. Mark this position for reference, tighten the flywheel, put it back together and tell me what happens.
Later
Dan
OK . Now we are getting someplace with your saw. I think what you have is and old 031 that originally had points in it. Someone over the years removed the points, condenser and used the points coil and then added the replacement module. This works fine most of the time but I have seen a few that wont run correctly. I assume that your saw still has the original points flywheel. The points flywheel will have two small plastic inserts with a screw in the center of them. They can be removed and it will give you a window for setting your points.
Take your saw back apart. Its only a 5 minute job on an 031. LOL
Remove the flywheel key, set the flywheel back on the crank, line up your keyway, now turn the flywheel in the same direction that the engine runs and align the opposite edges of the key cut outs. Mark this position for reference, tighten the flywheel, put it back together and tell me what happens.
Later
Dan
so basically your advancing the flywheel the width of the key.
I can run it without the key installed, the flywheel wont move.
Have you had this problem before?
How did you figure out how much to advance it?
I need to borrow the tach again but if this works should I just leave the keyway out completely? THanks for your help
I can run it without the key installed, the flywheel wont move.
Have you had this problem before?
How did you figure out how much to advance it?
I need to borrow the tach again but if this works should I just leave the keyway out completely? THanks for your help
dozerdan
Addicted to ArboristSite
Mike
Yes you can run the saw without the key in it. As long as you have the flywheel tight, it will not move.
I have seen this happen a few times when you change the 031s over and use the old flywheel.
Yes just move it the width of the key and you should be fine. If you get the timing to far ahead, it will pull the rope out of you hand.
Later
Dan
Yes you can run the saw without the key in it. As long as you have the flywheel tight, it will not move.
I have seen this happen a few times when you change the 031s over and use the old flywheel.
Yes just move it the width of the key and you should be fine. If you get the timing to far ahead, it will pull the rope out of you hand.
Later
Dan
flywheel
See if there is a transistor symbol on the flywheel somewhere. This will tell you if it was electronic or not.
I am not a big fan of the Stihl replacement module, I won't use the for points. The after market modules work much better. But don't forget to reverse the polarity of the primary coil wires when installing the module. It will make a HUGE difference in top end performance.
See if there is a transistor symbol on the flywheel somewhere. This will tell you if it was electronic or not.
I am not a big fan of the Stihl replacement module, I won't use the for points. The after market modules work much better. But don't forget to reverse the polarity of the primary coil wires when installing the module. It will make a HUGE difference in top end performance.
Sounds good, thanks for all your guys help.
Im actually building up 3 stihl 031s I have 4 total flywheels. I only have one done, which is the one Im having problems getting the rpm out of. Ill give some of your ideas a try. thanks a lot mike
Im actually building up 3 stihl 031s I have 4 total flywheels. I only have one done, which is the one Im having problems getting the rpm out of. Ill give some of your ideas a try. thanks a lot mike
Guys a though of another question.
My manual says rpm setting should be around 12,000. so 12,000 should be a fuel mixture thats not going to damage the engine and give optimum performance. What Im wondering is, if I turn it as lean as it will go to give max rpm how much higher will they usually rev above there max rpm setting. thanks.
My manual says rpm setting should be around 12,000. so 12,000 should be a fuel mixture thats not going to damage the engine and give optimum performance. What Im wondering is, if I turn it as lean as it will go to give max rpm how much higher will they usually rev above there max rpm setting. thanks.
