Convert a 6401 to a 7900 or bigger...

My 6401 runs great, but a 24" bar is about max for it. Will building it up allow me to run a 28"- 32" bar"?
Remember, I live over 8K elevation, so there is a power drop off.
Thanks, JB
EDIT- Or, should I look for a 460/ 660? I found a decent 460 w/32" bar for $600 neg.

 

Yeah the big top will do the trick.

 

So maybe one of the Baileys 84cc NWP kits would work?
I recall some posts about them in the past but I can't find them. I'm going to pull the trigger on this by the end of April if not sooner.

 

Several saw builders have stated that the 84cc big bore top end is basically the same power wise as the oem 79cc slug and jug. It is cheaper though. Im not sure on the durability of them either. Maybe millermodsaws can chime in with some insight.

My 7910 pulls a 28" b&c very well and the balance is very good with that length too. I have no doubt it will run a 32 no problem too.

 

Good to know, thanks.
I want to mod. the 6401 to be a 90% single purpose saw, that being cutting bundles of Pine slab wood. 30"-32" bar would be ideal, longer bar length would be idealer!
Nose heavy is a plus for me, I'm going top/ down. When these bundles get set, they're around 60"+ ,so dropping a heavy bar on them and letting gravity work is a plus.

 

The 84cc kits runs good stock. About on parts with oem. At that elevation if you can tighten squish up on either one to get the most compression you can would help.

 

Those kits are decent, but I'd find a 79cc OEM kit for it. It'd be an easier to sell your saw down the road if you wanted something different too.
If you do get the 84cc kit, I'd really see if you can find a solid ring for it (like a caber). IIRC, the NWP kit I had came with a split ring (ductile) and they just don't make the same compression. Typically I would say that is splitting hairs, but at you elevation, I would get every bit I could out of it.

 

Have you done a muffler mod yet? If not you'll get gooder gains there too. Seems like I remember a jack-wheel member here posting a thread on the 7910/6401 muffler mod:

Gutting the Dolmar 7910 Muffler


Here's what it'll sound like when your done:

 

There pretty comparable stock for stock. I'd give the durability to the oem jug. And if ya ever decide to have it ported I'd definitely stick with the oem jug. On my 7910s. It wears a 28" reduced weight bar almost all the time. There is one down fall. If your wanting it to wear a 32" ya will want to modify the oiler. 28" is about all a stock oiler wants.

 

Not much to gain on a 7900 muffler. If it's the cat muffler then mod away.

 

A 6401 is the non cat muffler. From what I've heard, the non cat muffler isn't really restricting power. It looks to be a little pita to open mufflers up anyway. At least after buying a 6421 and looking at it. Simply buying a non cat muffler might be easier than gutting the cat from a muffler. When I was researching my purchase of a dolkita 6421, I found that most people that have tried the 84cc big bore vs the OEM 79cc kit found that the 84cc didn't really make any more power than the 0em 79cc top end. For the price, the 84cc kit is hard to beat. $100 is quite a deal. The OEM 79cc top end kit is $200-220. The $220 comes with new top cover and decompression valve. The factory kit from Bailey's didn't mention the cover or valve.

 

That's correct. There's dealers like Miller Mod saws that has a little better pricing than bailey's

 

Thanks for all the input. Sorry I haven't responded sooner, had a houseful of Montanawegians for the last few days.
So, OEM for durability. Modify the oiler for a bar longer than 28". No real need to mod. the muffler (non-cat).
Or should I look at that MS 460 and sell the 6401 as is?

 

I'd say try the $100 nwp aftermarket piston and cylinder kit. There's no replacement for displacement, especially at elevation. Well, until you can turbocharge that 6401..

I think I'll run a big block 84cc $100 top end kit on my 6421, just because.

From what I see, a 7900 runs a bit better than a ms460.

Durability wise, you don't hear any horror stories about the nwp 84cc, ductile ring or not.

It seems like guys have been running the 84cc big bore for years with no issues. I wouldn't have any qualms about running that big bore at all.

 

I agree my stock 7910 makes moar gooder power than any stock 460 I've run. Felt a little lighter too. Plus the AV is much gooder too. After running chainsaws (mostly stihl) all day every day for many years AV was important to me.

 

Works for me Horkn. NWP kits, Baileys or does someone else have better pricing?
EDIT- Never mind, just found one for $99.99 incl. S/H. On it's way.
I'm doing this, heck yeah !!

 

NWP Big Bore Piston & Cylinder Assembly (54mm) for Dolmar 7900, Makita 6401, Solo 681 Chainsaws | Po

$88

Unless a member here has better than Bailey's pricing.

Here's the nwp kit for 119 shipped NWP Big Bore Nikasil cylinder piston kit for Dolmar Makita DCS 6401 PS 6400 54mm | eBay

 

Thanks all !! I'll hit you up for install advise when I get ready to do this. Thanks again!! JB

 

Dolmar PS 7900, Makita DCS 6401, 6421 big bore cylinder kit 54mm

 

Thank you Sir! I already have one on it's way- $99.99 incl. S/H. ..should be here next Monday.

So let me throw a twist into this. Has anyone gone the Cryo route with these? I know a guy a few canyons over, who has a cryo freezer. I could hand these parts off to him and have them treated for about $25 or so. Has anyone tried that? I'm curious about this, for this application. I've had him treat rifle barrels and differentials for trucks in the past, always with good results. Don't know about a slug-n-jug, what do you think?