? On a Makita 7900

Okiefirewood

New member
Local time
5:25 PM
Joined
Sep 27, 2021
Reaction score
4
Location
Oklahoma
I have a Makita 7900 and it only has a L and a idle adjustment screw on the carb how do I adjust it so I can get my rpms up
 

Bob Hedgecutter

Moderator
Staff member
Local time
11:25 AM
Joined
Sep 12, 2021
Reaction score
516
Location
Way Down South New Zealand
Never owned one- but A: you are sure there is no H adjustment screw? and B: did Dolmar and Makita not have some problems with coil not advancing?
If your saw is running like half to 3/4 of what it used to be at full throttle, I would be suspecting the coil and it not advancing.

Having said that, I have never owned one, just repaired one that was way lean from the factory and the proud new owner cooked it up good and to be honest I cannot recall if it were a 7900 or 7910.
 

Okiefirewood

New member
Local time
5:25 PM
Joined
Sep 27, 2021
Reaction score
4
Location
Oklahoma
There is a screw for the high jet I didn't have a tool to adjust so I cut a line in to make it adjustable with a flathead ,but when I turn it either way my rpms don't go up or down
 

Attachments

  • IMG_20211210_180528.jpg
    IMG_20211210_180528.jpg
    1.9 MB · Views: 7
  • Like
Reactions: Tyy

Bob Hedgecutter

Moderator
Staff member
Local time
11:25 AM
Joined
Sep 12, 2021
Reaction score
516
Location
Way Down South New Zealand
There is a screw for the high jet I didn't have a tool to adjust so I cut a line in to make it adjustable with a flathead ,but when I turn it either way my rpms don't go up or down

Is that when you tune on the workbench- or with the chain in wood and cutting? Think these are meant to be tuned in the cut.
But I would still be suspecting the coil- can you post a video of the saw running?
 

Okiefirewood

New member
Local time
5:25 PM
Joined
Sep 27, 2021
Reaction score
4
Location
Oklahoma
I have only tuned on the work bench iam new at tunning so iam not to good
At hearing it yet , I been using a tachometer . But it stopped working on me to so I got another one on order. All my other saws are the Mtronics besides my Husqvarna but it's ain't as tricky as the Makita, I will make a vid tomorrow in the light.
 

Bob Hedgecutter

Moderator
Staff member
Local time
11:25 AM
Joined
Sep 12, 2021
Reaction score
516
Location
Way Down South New Zealand
I have only tuned on the work bench iam new at tunning so iam not to good
At hearing it yet , I been using a tachometer . But it stopped working on me to so I got another one on order. All my other saws are the Mtronics besides my Husqvarna but it's ain't as tricky as the Makita, I will make a vid tomorrow in the light.

Some Tach's do not work or give a true reading on the newer electronic controlled mtronic, autotune type saws.
All I am saying is, if the saw will not respond to carb tune adjusting and you cannot hear/see/feel a difference when you are turning the screws- odds are pretty good you have some other problem that is not carb related.
 

huskihl

Member
Local time
6:25 PM
Joined
Oct 25, 2021
Reaction score
81
Location
Northern Michigan
You’ll probably need to be about 2 1/2 turns out to get down below the limiter to where the RPMs will start dropping
 
Local time
3:25 PM
Joined
Jul 30, 2022
Reaction score
22
Location
14530 W Thorne LN SW, Lakewood, WA 98498
Hello, If your Makita EA7900 is not running fully and your photo is correct. Take the top of and take the sock type filter off of the regular filter. I sell the Makita EA7900 but reported to my rep that the extra filter on the heavy duty model was a failure. It should run better with that off.
 

Attachments

  • Mazkita7300b.JPG
    Mazkita7300b.JPG
    1.3 MB · Views: 5
Local time
3:25 PM
Joined
Jul 30, 2022
Reaction score
22
Location
14530 W Thorne LN SW, Lakewood, WA 98498
Before you break that carburetor adjustment seal I want to ask when did you purchase the chainsaw? Is it under a year? You might be able to send it to the Makita factory service center for free repair. Please contact your Makita dealer or if it was an online store please contact me. Makita would give you a shipping label and you could take it to a Fedex store (in the original box would be best) they would ship it for free and return it at no cost to you. You will just need to send the motor not the bar and chain. If you break the seal that is another story. You can contact me here https://schneiderschainsaw.com. I can help you coordinate this process. I have also had problems coils in some of my Echo CS7310 chainsaws. Once this was corrected they are fine machines.
 

Tyy

Member
Local time
6:25 PM
Joined
Aug 27, 2022
Reaction score
9
Location
North of Lake Superior
Tach use with the rev limited 7900 series can make tuning a little frustrating . In the wood tuning is the most precise . On the bench is just 1st or preliminary in the ball park session . If its 4 stroking & clears in the cut your spot on . Plug check after a few tanks will confirm . Sessional tuning is normal as barometric & atmospheric elevation conditions vary the tune as does saw wear & rear brother !
 

Tyy

Member
Local time
6:25 PM
Joined
Aug 27, 2022
Reaction score
9
Location
North of Lake Superior
Hello, If your Makita EA7900 is not running fully and your photo is correct. Take the top of and take the sock type filter off of the regular filter. I sell the Makita EA7900 but reported to my rep that the extra filter on the heavy duty model was a failure. It should run better with that off.
So do you remove the secondary sock or prefilter on all new HD saws or just advise new owners accordingly ?
 
Local time
3:25 PM
Joined
Jul 30, 2022
Reaction score
22
Location
14530 W Thorne LN SW, Lakewood, WA 98498
I converted a HD filter model to an EA7900 and sent it to Portland for carburetor calibration. That way the warranty was not effected. As for the sock. If it is one that I stock I will pull the sock off and leave it in the box. If it is one that I am direct shipping I recommend taking the sock off. I think that the sock makes air intake too restrictive and have read complaints about this model with the sock on. I also sent Makita my opinion about the sock and said that I was removing them when I received a HD EA7900 model. I got no negative feedback about this.
 
  • Like
Reactions: Tyy

Tyy

Member
Local time
6:25 PM
Joined
Aug 27, 2022
Reaction score
9
Location
North of Lake Superior
I converted a HD filter model to an EA7900 and sent it to Portland for carburetor calibration. That way the warranty was not effected. As for the sock. If it is one that I stock I will pull the sock off and leave it in the box. If it is one that I am direct shipping I recommend taking the sock off. I think that the sock makes air intake too restrictive and have read complaints about this model with the sock on. I also sent Makita my opinion about the sock and said that I was removing them when I received a HD EA7900 model. I got no negative feedback about this.
Well if your restricting that much air your enrichening the air to fuel , potentially leaning out oil to fuel mixture under load . Should also tweak the carb to fatten it up accordingly ?
 
Last edited:
Local time
3:25 PM
Joined
Jul 30, 2022
Reaction score
22
Location
14530 W Thorne LN SW, Lakewood, WA 98498
Happy customers mean repeat business. I am a new Makita dealer but have had an stereo and tube radio repair shop since 2015. The only way to stay in business is to have fair prices, good work and be straight with customers on whether I can fix something. Sometimes I have sent Stihl and Husqvarna owners back to their dealers because I cannot get the required parts in a timely manner or for a fair price. Once their warranty periods are over then I can help them.
 
  • Love
Reactions: Tyy
Top