Makita 6401

[Andyshine77]

i haven't seen any hard data supporting a high failure rate but it is my perception. these saws are rare compared to stihls or huskies but there seems to be a lot of interest in their ignition modules. someone said earlier that it was only because guys were looking for an unlimited coil but i think most makita/dolmar owners "don't mess with it if it ain't broke." that certainly describes me. that's what got me curious. i have two 6401's one had symptoms of a failing module, wouldn't run after it got hot, wouldn't restart until half an hour after it cooled down. i balked at the cost of a new module, $130. when checking to see if it was red or black i encountered the oil/chips impacted module. i cleaned it up as well as i could without removing it and it started running when hot, though it felt like the rpm limiter wasn't working. it would rev to 13.5k, maybe more. so i took the module off and cleaned the back side and the cavity where it rests. now it runs correctly. so my conversion to 272 mode has been put on hold.

Some modules were set to different rpm's than others, Husqvarna and Stilh both play around with rpm numbers as well.

 

[fordf150]

i haven't seen any hard data supporting a high failure rate but it is my perception. these saws are rare compared to stihls or huskies but there seems to be a lot of interest in their ignition modules. someone said earlier that it was only because guys were looking for an unlimited coil but i think most makita/dolmar owners "don't mess with it if it ain't broke." that certainly describes me. that's what got me curious. i have two 6401's one had symptoms of a failing module, wouldn't run after it got hot, wouldn't restart until half an hour after it cooled down. i balked at the cost of a new module, $130. when checking to see if it was red or black i encountered the oil/chips impacted module. i cleaned it up as well as i could without removing it and it started running when hot, though it felt like the rpm limiter wasn't working. it would rev to 13.5k, maybe more. so i took the module off and cleaned the back side and the cavity where it rests. now it runs correctly. so my conversion to 272 mode has been put on hold.

another likely culprit in your problem may have been the oil soaked chips providing a ground path for the coil and killing spark. There is a service bulletin pertaining to just this problem although i beleive it was issued for the 5105. i havent encountered many failures of these or any other dolmar coils.

If you were seeing prices of $130 you were looking in the wrong place.

DOL, 038143200
IGNITION COIL, PS-7910 $103.64

DOL, 038143041
IGNITION COIL CPL., PS-7900H $103.64

 

[Paragon Builder]

[QUOTE="heyduke, post: 5428133, member: 34832" i have two 6401's one had symptoms of a failing module, wouldn't run after it got hot, wouldn't restart until half an hour after it cooled down. [/QUOTE]
Did it shut down when running? Or just wouldn't restart?

 

[heyduke]

par

[QUOTE="heyduke, post: 5428133, member: 34832" i have two 6401's one had symptoms of a failing module, wouldn't run after it got hot, wouldn't restart until half an hour after it cooled down.

Did it shut down when running? Or just wouldn't restart?[/QUOTE]

it would die after the throttle was released, but it was running at reduced power before that. bear in mind that after cleaning the module and the cavity around it, it now seems to run well. idon't want to start a click & clack moment.

 

[Paragon Builder]

[ QUOTE="heyduke, post: 5428366, member: 34832"]par

Did it shut down when running? Or just wouldn't restart?[/QUOTE]

it would die after the throttle was released, but it was running at reduced power before that. bear in mind that after cleaning the module and the cavity around it, it now seems to run well. idon't want to start a click & clack moment.[/QUOTE]
Something to think about... I'll have to check mine and see how dirty it is.

 

[heyduke]

Some modules were set to different rpm's than others, Husqvarna and Stilh both play around with rpm numbers as well.

andy-

it wan't just the apparent non-limiting condition. the 84cc saw just didn't have the juevos. the saw seems to be running ok now after cleaning the module and the cavity that it is mounted in.

 

[heyduke]

another likely culprit in your problem may have been the oil soaked chips providing a ground path for the coil and killing spark. There is a service bulletin pertaining to just this problem although i beleive it was issued for the 5105. i havent encountered many failures of these or any other dolmar coils.

If you were seeing prices of $130 you were looking in the wrong place.

DOL, 038143200
IGNITION COIL, PS-7910 $103.64

DOL, 038143041
IGNITION COIL CPL., PS-7900H $103.64

thanks for the info. i'll look at these.

 

[Poleman]

For anyone interested, I just installed a 272 coil on a stock 7910 with success tonight. Timing was set the same as the 7900. Only think I noticed was the flywheel seemed to be advanced 3 or so degrees ahead of tdc on the crank using the locator tab on the fly wheel. I could be off on this but sure looked like the tab was canted ahead of tdc.
Any way you 7910 owners can unlimit your saw the same as the 7900 and get it outta the 12,8 basement.

 

[Paragon Builder]

That's awesome!
Locator tab?

 

[Paragon Builder]

That's awesome!
Locator tab?

 

[Poleman]

Locator tab is the key molded into the fw that indexes it on the crank, usually the tab/key is in the crank. It gets ground off anyway so you can advance the fw 30 degrees.

Sent from my HP Slate 7 using Tapatalk

 

[Paragon Builder]

Locator tab is the key molded into the fw that indexes it on the crank, usually the tab/key is in the crank. It gets ground off anyway so you can advance the fw 30 degrees.

Sent from my HP Slate 7 using Tapatalk

Oh ok I thought there was something else I was missing. So how could you tell it was advanced? Was the key filed and the flywheel rotated?

 

[Paragon Builder]

Locator tab is the key molded into the fw that indexes it on the crank, usually the tab/key is in the crank. It gets ground off anyway so you can advance the fw 30 degrees.

Sent from my HP Slate 7 using Tapatalk

Oh ok I thought there was something else I was missing. So how could you tell it was advanced? Was the key filed and the flywheel rotated?

 

[Paragon Builder]

Weird I'm getting all double posts this morning...

 

[Paragon Builder]

Weird I'm getting all double posts this morning...

 

[Poleman]

When I set the crank to tdc the key was on the advanced side compared to it. It was a visual thing comparing the two. I used my tdc mark to set timing and all was well!!??

Sent from my HP Slate 7 using Tapatalk

 

[Paragon Builder]

When I set the crank to tdc the key was on the advanced side compared to it. It was a visual thing comparing the two. I used my tdc mark to set timing and all was well!!??

Sent from my HP Slate 7 using Tapatalk

Awesome!

 

[Poleman]

Just another way around using the 12,8 limited factory coil in the 7910 and 13,5 in the 7900.

Wanted to put it out there.....

 

[Paragon Builder]

I'll be doing this to my 6400 at some point...

 

[artwood]

This is a great thread! I have a stock 7900 & 6400bb that have both been down for awhile because I didn't want to pay the $120 my dealer wants for a coil.

And yes, I believe this a problem with these models. Has to be more than coincidence for this to happen on both saws.