Makita 7900 or 6400

[KarlD]

Morning guys
I’m replacing my ms362c with a makita (would love a Dolmar but that won’t happen) and I’ve pretty much decided I want a 7900 running a 22” bar. I will also get the HD filter set up. Before I pull the trigger, am i right in saying the chassis of the smaller cc saw is exactly the same as the 7900...ie there is zero point buying the smaller saw and fitting the bits to take it up to 78cc? There’s no weight saving implications etc? I think I’ve seen mention of an 84cc 7900 esque saw; I’ll look into that whilst I’m waiting for your feedback.
Thanks in advance

 

[computeruser]

Same chassis, same weight, same parts. Might be different coil still - 12.8k limit on 79, 13.5k on 64.

The 84cc cylinders make less power and are Chinese AM crap.

 

[KarlD]

Same chassis, same weight, same parts. Might be different coil still - 12.8k limit on 79, 13.5k on 64.

The 84cc cylinders make less power and are Chinese AM crap.

Ah, so the 84cc version is just achieved by fitting shite AM rubbish. I won’t be doing that then!
Thanks

 

[cuinrearview]

If all you want to run is a 22, you could save some $$ and get a 64 or 73cc. With a smaller bar the 79cc isn't going to be much faster.

 

[KarlD]

I didn’t even know about the 7300! You definitely have a point but I think I’ll just go big, never regretted such a decision. My latest research has told me that Husqvarna flippy caps are a straight swap; HD filter, flippy caps, a lightweight 22” bar (yet to pin that one down) and I will have scratched all of my itches...for now! Thanks for the feedback

 

[CentaurG2]

I own both of these machines a Makita 6400 and a dolmar 7900. There is no difference other that the piston, cylinder and color. Stock air filter works fine as long as you are not cutting under extremely dry conditions. The saws are built like a tank but they are an older bulky design. If you are only going to run a 22” bar, husky 562, 372 or 572 would be a better choice. If you do end up with the Makita/keep an eye on your bar oil output. My Makita had a problem with an oil line and like to oil your boots instead of the bar. Not a big fix but something to keep an eye on.

 

[KarlD]

I own both of these machines a Makita 6400 and a dolmar 7900. There is no difference other that the piston, cylinder and color. Stock air filter works fine as long as you are not cutting under extremely dry conditions. The saws are built like a tank but they are an older bulky design. If you are only going to run a 22” bar, husky 562, 372 or 572 would be a better choice. If you do end up with the Makita/keep an eye on your bar oil output. My Makita had a problem with an oil line and like to oil your boots instead of the bar. Not a big fix but something to keep an eye on.

Thank you, I will keep an eye on that. Dolmar are my favourite brand of chainsaw so regardless of there being better Husqvarna alternatives out there, 7900 it will be Having the cc’s on hand should I want to increase the bar size is no bad thing. You never know this might end up as my one saw plan when I sell the 500i, 066, 084 and 1201

 

[CentaurG2]

The 7900 is a very strong saw. It can pull a 32” bar but its oil output is better suited to a 28”. My 6400 is an x-pat home depot saw. I think a paid like $200 for it. It is one of the only saws I will loan out. I use it more for demolition than tree cutting. It has cut asphalt roofs, chain link fence, even gave a t-post growing inside a tree a run for its money. Built tough.

 

[Slotracer577]

Just converted a 6400 to 7900 this week. Easy swap, just bolt on the new top end. The muffler and coil are different. Buying a HD rental can be a cheap way to get a 7900.

 

[livemusic]

Just converted a 6400 to 7900 this week. Easy swap, just bolt on the new top end. The muffler and coil are different. Buying a HD rental can be a cheap way to get a 7900.

So, you need to also buy a muffler and coil? After buying a used 6400, how much do you think total cost is to convert to 7900 size? And what do you think max size bar is a 7900 could reasonably handle? (Saw would be used for the occasional felling/bucking large DBH hardwoods.)

 

[4CornersPuddle]

10 years ago I set up a 6421 for a local wood carver. He bought it along with a big bore top end (84cc) from Baileys. At the time, we ran it side by side against my 371, 20" chisel on both. The 371 had the slightest edge at the time. For these ten years I've been bugging him to let me to to at least gut the muffler, and preferably, install the NWP top. "No thanks," he repeated time and again, always with some version of "warranty; it might develop a problem; yada yada, blah, blah, blah."

Well, this summer he offered to trade me the whole works for one of my many 372s. The switcheroo happened before he could even blink his eyes. Lots of smiles on both of our faces indicated our mutual satisfaction.

Immediately I pulled the cat from the muffler and opened up the exhaust outlet. Big difference! A month or so later I swapped the top ends. Old piston looked fine, no questionable marks on it or cylinder. NWP cylinder came with 2 spacer plates of different thicknesses. With no base gasket, I was able to achieve about .020" squish by using the thicker plate. I'd have to review my notes. It may be that squish is .021. When I first tried the thinner plate, I found that at TDC the piston was contacting the top of the combustion chamber.

Saw is running perfectly, is much stronger than when 64cc, pulls a 28" skip tooth .375 just fine. In fact I compare all saws to my hopped up 288s that I used for years when felling timber up in Idaho and Oregon.

Recently I packed the Makita (it's lighter) for felling 48 aspens around a million dollar home up the hill towards Purg from Durango. These trees were 16" to 28" DBH, mostly 100' tall, on a slippery, steep slope, often leaning towards the house, and with some rot in many. A springboard to climb up above the rot at the bases of some of them would have certainly been helpful. We put the winch line in some of them to get them to initiate in the desired direction.

The homeowners (from Texas) were so enamored of the project that they were baking 2! batches of fresh cookies for us each day. I avoided the bathroom scale throughout the project.

My only criticism of the saw is that is does not have a full wrap handle bar on it yet. Each day when I made my first cut, I'd have a big grin on my face, second only to the burst of laughter that comes from the first time in a day that I dawg my 288 into a cut.

 

[Deleted member 117362]

Just converted a 6400 to 7900 this week. Easy swap, just bolt on the new top end. The muffler and coil are different. Buying a HD rental can be a cheap way to get a 7900.

OEM parts or AM?

 

[Slotracer577]

OEM parts or AM?

Oem. It wears a non cat 7900 muffler. So it’s the best of both, 13k coil, open muffler, oem 7900 cylinder. Put a 28” sugi bar on it.

 

[Slotracer577]

So, you need to also buy a muffler and coil? After buying a used 6400, how much do you think total cost is to convert to 7900 size? And what do you think max size bar is a 7900 could reasonably handle? (Saw would be used for the occasional felling/bucking large DBH hardwoods.)

I wasn't clear. The 7910 coil is 12k, the 6400 is 13k. by converting a 6400 get the higher rpm coil. when I bought it, it came with a non cat 7900 muffler which is better than the 6400 muffler. I did gut the 6400 muffler to try as its stainless Vs plain steel on the 7900.

from all I have read the oiling limit is about 28” bar. It’s about $200 for an oem cylinder and that’s all that’s needed to convert.

 

[cuinrearview]

SLE Equipment had 79cc OEM tops for $165 last I looked. Unless you know someone that can mod these to cut above 12k the coil shouldn't matter.

 

[CentaurG2]

So, you need to also buy a muffler and coil? After buying a used 6400, how much do you think total cost is to convert to 7900 size? And what do you think max size bar is a 7900 could reasonably handle? (Saw would be used for the occasional felling/bucking large DBH hardwoods.)

I am getting the same part numbers for both the muffler and coil on both of these saws so I don’t think you need either to do the conversion. I have run a 36” bar on the 7900 but only to finish a cut. You can probably go 30” but I would recommend a 28” bar. Husky large mount pattern so if you run huskys, you can switch bars with other saws. You should be able to find a 7900 OEM cylinder and piston for under $200.

 

[wde_1978]

I got most of the "modern" Dolmars, see my signature.
Most wear 20" 3/8" main B&C setups.
The PS-6400/7300/7310/7900 will oil and handle a 36" 3/8" chisel full complement B&C fully buried in oak and beech well, logically the 73's and the 79'er are more capable of doing so than the 64.

The HD air filter ads to the look of these saws, but it has been proven that it will rob some power.
I'd keep the stock AF cover and utilize the white fine nylon mesh AF.
Do a simple muffler mod, it is fairly easy on these units.

Running a 22" B&C setup on a EA7900/PS-7910 should place an ear to ear grin on Your face!
Have fun.

 

[Fatherwheels]

I had the 7900 Makita, I would buy the 7300 if going again, just because I did not need the power,
the 7900 can also drink fuel, economy is important to me, didn't realize this until I had the 7900.
I would also forget the big filter, the standard filter flows better, the big one somehow doesn't
flow any better, maybe its velocity drops.

If you need a big saw, there is no point in buying the smaller version and adding parts, waste of time.
The 84cc big bore, no point, when you add a bar long enough to use the extra power, it wont oil enough,
and the springs / av wont take the extra either, unless you don't mind replacing springs often, they
will still feel soft though.

You get two filters with the saw, a nylon and a tighter flocked type, use as required.
They are a good saw.

 

[KarlD]

Ok guys, good info and I’ll forget about the HD filter. I simply want to make a reliable beast that is as optimised as possible without the hassle of porting etc. I will happily do a MM though.
Thanks again

 

[Fatherwheels]

Ok guys, good info and I’ll forget about the HD filter. I simply want to make a reliable beast that is as optimised as possible without the hassle of porting etc. I will happily do a MM though.
Thanks again

Yep, I had a non cat muffler on mine, but it had a cage inside with holes, I drilled the holes larger
and opened the outlet under the spark screen a bit, not big enough so the original spark screen no longer works,
its all you need to waken them saws up, getting one ported is another story, but you can only go so far without
requiring a bigger carb, some can run the 7300 carb on a 7900 cylinder, so that makes a cheap upgrade from 73 to 79,
the 6400 carb really is no good on a 7900, nor a 7300, so that adds a carb to the equation if you want to get it spot on.