2005 Makita 6401 meets 2014 Dolmar 7900 Piston and Cyl: Very big grin factor :)

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zzr7ky

zzr7ky

Minister of Fire
Hearth Supporter
Jun 12, 2006
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After reading a lot of encouraging posts at AS, and encouragement here over the years I bit the bullet and sprung for a Dolmar 7900 piston and cylinder. It's the first time I've cracked open a 2 cycle engine and expected it to run again.

Going slow and double checking the instructions it took me about 2 hours. I found a poor looking clutch drum bearing so I had to wait a couple days to tune and try. I had not tuned one before either. Several you tube visits and the new Dolkita 7900 is running great. Plenty of power. Nice quick work of some 24" willow I had laying here, so I headed out and cleaned up some 18 inch dead standing Elm. I am very pleased. Thanks to those who helped me scratch this blossoming CAD rash ;)

Mike
 
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Good deal!
 
I'm trying to force myself to wait until this winter to convert mine to a 79ccer. I've got too many important projects that need my time and attention first. So please don't post a vid of that beast cutting through wood!
 
The cylinder on the 6401 I picked up a few days ago is usable, but the piston is toast so I'm debating whether to upsize it or just replace the piston. If this project has left you with an unneeded OEM piston, I might have a use for it...
 
Jon1270 said:
the piston is toast so I'm debating whether to upsize it or just replace the piston.
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I'd go for the 79cc jug and piston. If you only put piston in, you may say "Man! I coulda had 79cc!!!!" I really want a 79cc Dolkita but surely don't NEED it.
 
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Hi -

Since I have a pair of these and a 17year old son, I'm thinking I better keep a piston and cyl on th shelf ;).

Also - I think I'd spend the extra cash and get the bigbore kit. PM me if you like.

Enjoy!!
Mike
 
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When I bought the 79cc kit, my dealer couldn't find any prices for 64cc parts. Part numbers, but no prices. I guess there isn't a big market for them when you can bolt on a horsepower and a half ==c
 
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jeff_t said:
When I bought the 79cc kit, my dealer couldn't find any prices for 64cc parts. Part numbers, but no prices. I guess there isn't a big market for them when you can bolt on a horsepower and a half ==c
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Yep, the 6401 OEM piston is NLA except as part of an entire P&C kit. In my case keeping in a 6401 with original cylinder and AM piston would get it working very cheaply, but I'm leaning towards getting a 7900 kit.
 
+1

I vote for the 79cc kit. If you go that route, you will possibly add a few tools (long torx bit, t-handles, compression/vac tester, etc.) and experience that you can use to diagnose/repair/mod future saws yourself.
 
TreePointer said:
+1

I vote for the 79cc kit. If you go that route, you will possibly add a few tools (long torx bit, t-handles, compression/vac tester, etc.) and experience that you can use to diagnose/repair/mod future saws yourself.
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I already have the toolkit, and have repaired/rebuilt several saws over the last year or so. Just deciding what to do with this one.
 
I just needed a piston, too, though it looked nothing like yours. I thought about trying to locate one, but just briefly.

The saw really is a pleasure to run. I have run a 440, a 460, and a 372, and they all cut similarly by my SOP meter, but I just like the way the Dolmar feels. Maybe just 'cause it's mine.
 
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I'd like to have a 79 cc saw, but what would I do with it? I guess I'd have to cut bigger wood, but that sounds like a lot of work :rolleyes: Looking forward to a video of it running
 
D8Chumley said:
I'd like to have a 79 cc saw, but what would I do with it? I guess I'd have to cut bigger wood, but that sounds like a lot of work :rolleyes: Looking forward to a video of it running
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I have no practical need for a saw in that class, either. Such a saw works just fine on smaller trees, and it's fun to buzz through wood in a fraction of the time it takes otherwise, but I only burn 2 - 2.5 cords a year; it's not as if I'm actually cutting often enough that I need to save time. I could do fine with just a 50-60cc saw, but the big ones are fun. Bought used, they hold their value well so it doesn't really cost that much to have one for a while and then re-sell it.
 
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That's a good idea. I have 5 saws at the moment, if she found that out I'd be selling one or two haha
 
D8Chumley said:
That's a good idea. I have 5 saws at the moment, if she found that out I'd be selling one or two haha
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For me the dynamic is different because I only buy saws if I think I can sell them at a decent profit. That usually means they need work, which is fine because I really enjoy working on them. It also means my saw hobby produces a little income, rather than being pure indulgence, so my wife doesn't mind a bit.
 
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Right, I could sell one or two if I got in a bind. I have the 025 now, the 170 might just take a back seat or get delegated to the jobsite wood cutting machine. I wasn't looking for this last saw but I couldn't turn it down either
 
I could also get by fine with the Dolmar 5100. But then I got by better, with a little more power with the 6401... Then I saw You Tube video of Dolkita 7900 vs Stihl 460... and now I have a project for it. A 60" diameter Ash is on the roster of jobs :). No rest for the wicked;)
 
Jon1270 said:
I already have the toolkit, and have repaired/rebuilt several saws over the last year or so. Just deciding what to do with this one.
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I just realized that I confused a couple different discussions. The idea of rebuilding the engine and getting tools and experience was for the "RIP 036" thread. Sorry about that.
 
TreePointer said:
I just realized that I confused a couple different discussions. The idea of rebuilding the engine and getting tools and experience was for the "RIP 036" thread. Sorry about that.
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No problem at all.
 
zzr7ky said:
... and now I have a project for it. A 60" diameter Ash is on the roster of jobs :). No rest for the wicked;)
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I whacked a solid 5' silver maple trunk a couple of years ago. Ran out of gas about a third of the way thru the second round :eek: It was fun, though. Had to kick piles of chips out of the way so I could keep cutting.
 
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I went to a get together yesterday, and a guy had a ported 7900 that repeatedly went through a 12" square poplar cant in just over 3 seconds. The trouble with that sort of fun is that it's over so quickly.
 
Yesterday I weighed the 7900. It is 1# less than the 372XPG and has substantially more grunt.
 
If one of my 6421's goes down, I'm going with an aftermarket 84cc P/C kit.
 
Is this a difficult project to do? Does it require any specialized tools? Does someone who is mechanically inclined but has never taken apart a small engine have a chance to do this swap successfully?
 
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