ea7900 rev limiter

[kiddpitt]

I have an ea7900 I want to port, but I dont know how to get around the rev limiter.

Any help/guidance in the right direction is much appreciated.

 

[JimmyT]

I have an ea7900 I want to port, but I dont know how to get around the rev limiter.

Any help/guidance in the right direction is much appreciated.

Howdy KP, Plan A---Modify a Husky 272XP non limited coil to fit your saw. Plan B--- I think you can switch coils and use a (038-143-042 Red Coil) and that would help a bit.You have a OEM 12,800 rpm coil and you would be bumping up to a 13,500 rpm coil then advance the timing a few degrees and possibly get it up to 14,000 before the limiter kicks in then you would have a real screamer.

 

[kiddpitt]

Thanks for the reply. I'd prefer to completely delete the rev limiter. I'll look into those coils you mentioned.

It's a work saw, I dont want to give up its torque...I added 2 degrees to the exhaust & intake on my 038 Mag & that thing is a pleasure to use.

 

[JimmyT]

I contacted Prufrex in Germany about 2 years ago and tried to get Info on which wire to cut to eliminate the limiter.They told me they were under contract with Makita and could not disclose any proprietary technical information.

 

[JimmyT]

KP, if you decide to go with the 13,500 Makita Red Coil 038-143-042 just don't wait to long
because that coil has been discontinued. Plus your horsepower will jump from 5.7 to 6.3 I bought an extra coil last March for $104.49 from DTL Equipment and he has 4 left. Here's his link. https://www.ebay.com/itm/334520743319?
P.S. Just got some info from Makita in Buford Georgia. They have 2 news coils available 181-143-214 for the 5105 and 038-143-043 for the 7900

 

[kiddpitt]

interesting your prufrex post was different in my email than what posted.

I appreciate your responses. stock, the 038 mag & ea7900 rev about the same, in hand the torque pulls about the same. i think another 500-1000 rpms would wake this saw up.

 

[JimmyT]

Yeah, sometimes I get off on a tangent so I go back and edit the post and try to streamline it to the subject at hand. I have been running chainsaws for over 60 years and haven't cut off any appendages yet.

 

[JimmyT]

Hey Kiddpitt, I snagged this posting from another forum and it might be something to look into

The speed limiter on the MS461 can be a nuisance at times.
#. Your old tach will not work for carb tune-ups
#. If you are used to setting your carb to any rpm above 13,500, its difficult.

In the MS461 the rpm sensing is done by the 3rd pole of the ignition module, which differentiates the 461(ignition module) from the 2 pole unit on the 460.

So, I just cut off the 3rd pole! Okay, not chopped off completely, but trimmed off enough so that this pole will not pick up any working magnetic impulses from the flywheel
And it works.

I held the pole compressed with a pair of pliers that had wet cotton waste on the jaws.This prevented the iron plates from transferring heat onto the coil inside while I used a hand held cutter.
Heat transfer will sometimes cause the copper winding to snap from expansion.