Makita dcs6401 rebuild questions

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Joined
Dec 29, 2017
Messages
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Location
Greenwood CA
Hello,

Newly registered, long-time lurker. I’ve owned a Mikita dcs6401 for a couple seasons now, mostly clearing my property. This year it was hard to start and boggy. More than likely it’s just needing the carb cleaned, etc. I figured I’d rebuild the top end as long as I’m at it.

First question...what are the pros to sticking with the 64cc setup over going 79cc? Does the 64cc have a thicker cylinder wall? Is it more reliable?

If going 79cc is the way to go, does anyone supply the factory oem parts kit anymore? I always go oem on the bigger toys for reliability, and all I can seem to come up with on searches are the aftermarket big bore kits.

I’d really like to get oem, but if not possible, what are the better aftermarket kits for these engines? Also, any other suggestions to rebuilding one of these little guys is much appreciated.

Thanks!
 
Can you provide a link to a PS-7900 top end parts kit? When I search, it’s all 7910 or aftermarket. I don’t want the 7910 cylinder.

Sorry, I’m not great at computer searches...

if your top end is good i dont really see any need to rebuild it unless you really want/need more power? shouldnt have any problem getting OEM parts if you wanna upgrade @fordf150. most likely your carb needs a little adjustment, possibly diaphragm kit/fuel line? cheap and easy vs a top end swap.
 
The OEM 7900 top end is no longer available. By all accounts the 7910 is an equal replacement.

From what I have read, the parts don’t match up perfectly. Apparently, the muffler doesn’t quite match up as well nor does the new top cover with the right hand comp release(I never use the comp release, anyway). They were made with different mufflers and scavenge for air differently. People on here have said to go for the 7900 p/c over the 7910 for those reasons. Maybe this is complete bull-doodoo or maybe someone can chime in on this that knows better...

Found this for under $150:
https://sleequipment.com/makita-gen...l-dcs7901.html#product_tabs_additional_tabbed

Just need to make sure it’s a complete kit.
 
Benefits of staying 64cc:
- no need to purchase a 79cc P&C kit
- better fuel economics over the 79cc engine
- will pull a 20" B&C setup all day long without feeling under powered
- pairing up the 79cc engine with a short bar, lets say under 24", will leave a whole lot of power unused and vanish into thin air

Benefits of upgrading to 79cc:
- more power than You'll likely ever need, will handle up to 36" B&C
- a day long ear to ear grin on Your face whenever You use Your saw

The OEM PS-7910 conversion kit is a direct swap and should include everything You need, lest the cylinder base gasket (make sure You order one if You decide to upgrade).

For what it's worth I have been using exclusively my PS-6400 for the past three days to buck oak firewood logs - she didn't make me feel wanting my other girls once.
See my signature for my other saws. :)
 
After calling pretty much everyone I came across selling dolkita parts on the interwebs yesterday I was able to track down a 7900 p/c. I’m going to heed the advice of those who said to just tune it and run it, keeping the parts for when it wears out. Fuel economy is a great point. I have to put gas and bar oil in it a couple times an hour as is.

The only time I feel like I want the saw to work any faster is on bigger interior live oak...guess I could up my sharpening game. I only sharpen the full chisel every ten hours or so.
 
After calling pretty much everyone I came across selling dolkita parts on the interwebs yesterday I was able to track down a 7900 p/c. I’m going to heed the advice of those who said to just tune it and run it, keeping the parts for when it wears out. Fuel economy is a great point. I have to put gas and bar oil in it a couple times an hour as is.

The only time I feel like I want the saw to work any faster is on bigger interior live oak...guess I could up my sharpening game. I only sharpen the full chisel every ten hours or so.
Your saw is tuned too rich if You have to refuel "a couple times per hour", that's a couple times 0.75Liter of fuel!
I get about 30 minutes out of my PS-6400 bucking oak logs, cut after cut.
For comparison my PS-7900 gets 20 minutes on a tank full whilst being used in the same manner.
Both saws show extremely increased fuel consumption whenever I make excessive use of the dogs and force the saws through the wood.
My PS-6400 oiler is opened to its max and she spends almost a tank full of oil on a tank full of fuel.

You need to sharpen Your chains more often!
You can't go cutting wood "for ten hours or so" and expect Your saw to cut fast!
The only chain that I have encountered, and use, that will go hours on end without sharpening is a carbide tipped loop - and even it requires sharpening over time.

You need to tune Your saw properly, and sharpen Your chains more often.
A small touch up of the chain at least every other tank of fuel does wonders in regard of cutting speed.

Oem or aftermarket for the bbk?
"Big Bore" usually implies an after market 54mm P&C.

Only eBay sellers claim BB for their AM 52mm kits.

I have rarely seen OEM 52mm P&C kits to be referred to as Big Bore.
 
Not to be a smart ass, but a couple times per hour is every 30 minutes...which is about the frequency I refuel. Fuel efficiency is different in California than most places. We’ve so much extra crap added to our fuels for whatever reasons the liberals have here. I can’t get pump gas that isn’t at least 15% ethanol, which affects everything. Ethanol fuel destroys machines that weren’t intended to run on it so I run between 40-45:1. The saw was tuned properly for the last few seasons. The problem is ethanol attracts moisture and destroys anything it’s left in for more than a couple months. I pulled the carb and it looks like it had been sitting in water all summer. Lesson learned: run a tank of my VP race gas through it before long term storage. As for the oiler.. I have it adjusted so the oil tank barely outlasts the fuel tank. That way it’s never dry. As for chain sharpening, you’re right, I could sharpen more frequently. I admitted that in my previous post.

Not to mention my property is 90% live oak and tons of it. So the saw running at WOT for 30 straight minutes on one tank is about right. Live oak is a tough wood. The grain is in every direction but vertical.

As to the big bore kit, anytime you put a cylinder with a diameter larger than factory, it’s called a big bore kit...at least where I’m from. I’ve been around single cylinder ICEs my whole life riding motocross. There are only two terms describing an increase in displacement...big bore or stroker...or a combination of both.

Anyway it’s just semantics. Didn’t need a drawn out correction from you or to be told how to tune my saw. I have an owners manual and I’ve been tuning two strokes since I learned to read. I was merely curious if Wood Doctors bbk was in fact oem or aftermarket and if it is AM, how many hours he’s got on it. So if he’s inclined, maybe the person the question was directed towards could answer. Thanks
 
Oem or aftermarket for the bbk?
Not sure. I bought it from NorthwoodSaw supply about five years ago for about $100. I think it was made by NWP. I imagine I have 100 hours on it. The original owner straight gassed it before I rebuilt it. He practically gave me the saw because he figured it was worthless -- even the bar was beyond his repair.
 
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