HD Makita 6421 - Issue and Initial Thoughts

[nwroller]

I recently got a home depot Makita 6421. Backstory here and here.

It is a lot heavier than my Stihl MS241C and after 10-20 minutes I am looking to take a long break. The smaller saw is still seeing a lot of use do to this as I can use that for a complete tank of fuel without issue. I also got a Oregon 28" reduced weight bar and semi-chisel chain for it. I like the reach that it has with that. It cuts at almost the same speed as my Stihl with a 16" using that setup, though with more wood being cut.

Issue:

• The chain spins at idle. At home depot I didn't notice this when they ran it (I was not allowed - should have been a red flag). But it spins at a decent clip too, the chain becomes a blur but not enough to cut wood as the chain stops when touched to wood. When the chain brake is applied it will kill the saw immediately or after a few seconds. Obviously this is a issue I want to fix asap. From what I have read I am guessing this is a clutch issue? I don't know a ton about saws yet so some direction on what I need to look for and what part(s) I need to get would be helpful.

Thank you in advance for any help/direction you can give me.

 

[cuinrearview]

Probably just an idle speed adjustment needed

 

[cus_deluxe]

Is the saw running at a high rpm as well? If not, then you have either bad clutch springs or something up with clutchc drum bearing. If the engine itself is running at a higher rpm, then as tim suggested you should start by trying to adjust the idle. If that doesnt solve it you may have other issues.

 

[nwroller]

I’ll try the idle speed and let you know. I don’t know if it’s running at a high rpm or not as I’m not familiar enough to know for sure.

 

[nwroller]

I reduced the idle till it died, so that was not it. I opened up the clutch and one of the three springs was only half attached. I connected it and while it was better the chain still moved in a more pulsing way.

Do I replace the springs, the whole clutch? I was really hoping to use the saw tomorrow are the parts something a Makita dealer would carry or do I need to order online?

Continued thanks for all your information.

 

[nwroller]

Update for those interested. I ordered a clutch assembly and nylon air filter (old one was dirty so figured I’d do it now) $50ish for both. Also ordered the clutch removal tool from Baileys ($15) since I don’t have a grinder for a DIY.

Hopefully that takes care of the issues and I am good to go.

 

[nwroller]

Hi all

I got the old clutch assembly off and this is what it looks like underneath. Not sure what those two “blades” are but one looks chipped and the other slightly damaged perhaps. Is this the cause of my issue or is this something I should replace?

Thanks

Sent from my iPhone using Tapatalk

 

[team117]

Those tabs are attached to the worm gear that drives the oil pump. The clutch drum had slots that should match up with tabs. Replace it well its apart.

 

[nwroller]

Those tabs are attached to the worm gear that drives the oil pump. The clutch drum had slots that should match up with tabs. Replace it well its apart.

I’ll definitely replace it. Sounds like I need to make sure the clutch assembly is aligned to it when I do so?

Is it safe to run the saw with the worm gear as is? I really got to finish a job this weekend and I won’t have the part till end of next week.

 

[dougand3]

Is it safe to run the saw with the worm gear as is?

Put the clutch drum on and see if the metal tabs hit the worm gear wings when it spins. I doubt they will. You'll have no oiling.

 

[Poleman]

It could be the idle but I think the issue is more in the clutch. Bad springs (you can sub Stihl 039/390 springs) if no dealer is near by. Or not assembled correctly... it sounds like your posibbly missing a washer to isolate the two. The outer hub should turn free. #191 is what I’m referring too.

 

[nwroller]

View attachment 672038 It could be the idle but I think the issue is more in the clutch. Bad springs (you can sub Stihl 039/390 springs) if no dealer is near by. Or not assembled correctly... it sounds like your posibbly missing a washer to isolate the two. The outer hub should turn free. #191 is what I’m referring too.

I just got the whole 139 part so the clutch should be good now. I have part 191 though it’s not new. (Only 139 is). It did spin freely beforehand. I have not assembled the saw yet as I’m debating if I should run it with the worm gear (131) as is or leave it opened up till the part arrives Thur/Fri next week. Waiting won’t let me test the clutch till then to see if that fixes the original issue.




Sent from my iPhone using Tapatalk

 

[Mac&Homelite]

I'd stick on the clutch on and test it out to see if the new clutch solves the original problem, that way you can see if you need to fix anything else. You can always pop the clutch and drum off when you get the new oiler part, pretty quick to do. That said, I believe the new clutch should solve your problem. Good luck!

 

[nwroller]

I'd stick on the clutch on and test it out to see if the new clutch solves the original problem, that way you can see if you need to fix anything else. You can always pop the clutch and drum off when you get the new oiler part, pretty quick to do. That said, I believe the new clutch should solve your problem. Good luck!

Sounds good. I’ll do that tomorrow.


Does anyone know how much torque to set the clutch and spark plug to? Actually I don’t know how much to do the bar screws either I just make it tool tight.


Sent from my iPhone using Tapatalk

 

[dougand3]

The clutch is hand tighten against the stop of the recoil. Clutch will self tighten when running.
Plug and bar nuts - it's just feel. With a scrench, plug is whole hand and bar nuts are 2 fingers.

 

[nwroller]

The initial issue is fixed. New clutch assembly is working great.

The bar was getting some oil on the worn out worm gear but probably not as much as it should. Bigger issue is that it is leaking/dripping oil like crazy. Is that because of the bad worm gear?

You can see several drops of oil on the ground after about 30-60 seconds and the case is full too.

Sent from my iPhone using Tapatalk

 

[Deleted member 149229]

I have 4 Makita and to me they’re just like a shovel head Harley, they ain’t leaking oil, they’re marking their territory. There are a couple threads about replacing the oil line to stop the leak and @CJ Brown had a thread on fixing the leak.

 

[nwroller]

So that’s normal operation? It seems to just be dripping off constantly. My stihl seems dry in comparison.

Thanks for the response too much oil is better than too little.


Sent from my iPhone using Tapatalk

 

[Poleman]

There is an updated green oil line that runs from under the Oiler to the bar. If yours is already green take your Oiler out, lift up the oil line from the Oiler and put a washer that fits in the recess then put the line back. That will give added pressure against the oiler and usually seals it.

 

[nwroller]

There is an updated green oil line that runs from under the Oiler to the bar. If yours is already green take your Oiler out, lift up the oil line from the Oiler and put a washer that fits in the recess then put the line back. That will give added pressure against the oiler and usually seals it.

There is a green line in there. But I’m confused by what you’re saying. (This was the first time I took more than a bar off a chainsaw and still figuring out how it works).

Green line:

Sent from my iPhone using Tapatalk