Dolmar 510 inconsistent idle

Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
There is something else that helps these saws. You need to delete the crappy carb compensation Dolmar used. They have a solid foam disk instead of the doughnut, it covers the hole you see in the top of the carb, that's the metering side of the carb. This improves idle stability greatly. Also make sure the fuel line where it enters the tank hasn't rotated, this will cause the line to pinch bestrewn the carb box and the tank handle. I've had that issue several times.
Does the donut cause it to lean out on the idle? I'll check the fuel line, but I wouldn't think it would have the power at top end. It runs flawless at top end.
 
There is something else that helps these saws. You need to delete the crappy carb compensation Dolmar used. They have a solid foam disk instead of the doughnut, it covers the hole you see in the top of the carb, that's the metering side of the carb. This improves idle stability greatly. Also make sure the fuel line where it enters the tank hasn't rotated, this will cause the line to pinch bestrewn the carb box and the tank handle. I've had that issue several times.
Thanks Andy that is good to know. The disk is on the out side of the carb right?
 
Correct, the black foam disk. At one point new filters came with a solid replacement disk, not sure if they still do or not. I mad my own and glued it on. Make sure you don't get anything in the hole, that could prevent the diaphragm from moving.
 
Will the insert from the Husky 346

I just made a small window where my pictures were located. Then, I drug and dropped them where you normally type a message. After you drop the ones you want, it gives the option of full size or thumbnail. This time I picked thumbnail and let's see what that does. This is what the 510 did to the original chain today, of course right after I sharpened it and knocked the rakers down.View attachment 322276 View attachment 322277
Dang that is crazy! What does the rim sprocket look like? Was the chain skipping?
 
Interesting! So the style on dsell's saw is ok to use right?
How is this foam doughnut suppose to work?

It's fine to use, but it can cause idling issues. If you look at the bottom of the filter you will see it has a hole in it, the foam is simply a seal. The idea was, as the filter plugs up it will create more and more vacuum, this vacuum will prevent the metering diaphragm from traveling as far, which means less fuel will be supplied to the carb jets. In theory this should keep the saw in tune as the filter gets dirty. It's the same principle as Stihl's IntelliCarb, but not executed very well on the Dolmar's part.
 
I understand what your saying now. So you mentioned making your own. How do you do that and what improves it from stock?
Or would you just recommend removing the foam piece and use silicone to plug the hole in the filter?
 
Dang that is crazy! What does the rim sprocket look like? Was the chain skipping?
The chain was tight and I was making a cut in the trunk end of a hedge tree about 14 in diameter. There was a loose strand of hedge on my side from when the tree fell. The strand got hold of the chain and stopped it against the saw instantly. The spur (not rim) sprocket still looks close to new. I've never had this happen before other than throwing a chain and nicking a few drive links.
 
Correct, the black foam disk. At one point new filters came with a solid replacement disk, not sure if they still do or not. I mad my own and glued it on. Make sure you don't get anything in the hole, that could prevent the diaphragm from moving.
Andy, I don't have one of these but am just interested in carbs. How does that work if they put a solid foam disk over the diaphragm vent? Doesn't that block it, or is the foam porous?
 
It's fine to use, but it can cause idling issues. If you look at the bottom of the filter you will see it has a hole in it, the foam is simply a seal. The idea was, as the filter plugs up it will create more and more vacuum, this vacuum will prevent the metering diaphragm from traveling as far, which means less fuel will be supplied to the carb jets. In theory this should keep the saw in tune as the filter gets dirty. It's the same principle as Stihl's IntelliCarb, but not executed very well on the Dolmar's part.
This would make sense with my problem. The longer it idles, the leaner it gets until it dies. Wouldn't it be better to plug the filter hole and just remove the foam?
 
I put a foam ear plug in the air cleaner hole. Next, I cut the nipple off the air cleaner where it connects to the donut. I removed the donut from the carb. Put a brass insert from a 346XP in the intake tube. Filled it with gas and oil from the same can as yesterday. Didn't touch the carb settings from yesterday. I cut 62 maple cookies out of logs and let the saw idle between getting another log and putting up the cookies. The saw started and idled perfect after 3 pulls and never died until I hit the kill switch when I was done cutting. No hesitation off idle. The saw never hinted any signs of sickness. Thanks for the great advice, you guys fixed this one.
 
Glad to hear it's fixed.:clap:

Chris. The hole is so the carb reacts to pressure. If you block it off with foam it simply keeps the pressure constant, which in turn keeps the tune the same. Covering the hole also prevents dust from getting in which could lead to other issues.
 
I have the same setup (the foam under the filter with a hole in the midle)at my dolmar 5000.The intake boot have a metal insertion.
No problem at idle speed, but after the filter gets dirty(3 tanks of fuel) the saw at WOT hits the rev limiter.(H 3turns out 12500rpm mix 45:1).
 
I have the same setup (the foam under the filter with a hole in the midle)at my dolmar 5000.The intake boot have a metal insertion.
No problem at idle speed, but after the filter gets dirty(3 tanks of fuel) the saw at WOT hits the rev limiter.(H 3turns out 12500rpm mix 45:1).

Some 5100's didn't have any issues, others did and almost always at idle.:)
 
Thanks!
Other problem: If I keep the saw at WOT More then 10 secons the rpm increase from 12500rpm to 130000 rpm and then hit the rev limiter, tach goes crazy.Its that ok?
 
Back
Top