Dolmar/Makita big bore kit

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MS460WOODCHUCK

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What is the best, most reliable big bore kit for the dolmar 6400 and makita 6421 other than the oem 79cc kit? How many cc does it make it? Looking for reviews on aftermarket.
 
I would think that in most instances, except possibly getting an older or junk saw running, OEM kit is the way to go.
 
The transfers are already tiny on the 7910.
I put an NWP kit on a saw and it ran about equal to an OEM 79cc top end. The worst part was the cheap split piston ring. If I did it again I would buy a Caber ring and install it instead. I sold the saw to @Poleman...

Thanks this is what I was looking for is info on the aftermarket kits. What size would the caber ring be and where would I find one?
 
I was told that the new Dolmar cylinders do not direct swap "cleanly" to the 6400 old platform because of the muffler change. Did not look horrible but I have not done any, also no longer own any 640o chainsaws. Cutoff saws are all running AM kits because of cost.

Also told that there were no more 79 or 73cc old OEM kits availible. New kits with additional bits was getting spendy. The AM kits are iffy, but cheap. Longevity wise the piston and rings are the weak point, literally.

They can be had in all three sizes in a few different "grades" or qualities from as little as $20.00 a whack depending on how many are purchased at once. Those were scary crappy to look at but apparently spin the disc. I would not want those myself, and would poke around until I found a better quality standard bore and up grade the piston. I have pulled quite a few big bore kits that have hung a ring or cracked a pin boss. Consider them to be iffy at best toys. The 395 big bore kits might be the sole exception, some of them seem to be useful. Have not heard of any typical 395 BB kit failures yet, quite a few 7900 BB kit failures.
 
It all depends on the price you pay for the BB kit and if you plan on swapping out to caber rings, some of the higher quality kits are approaching OEM prices once you add shipping and rings into the price. Personally I've seen enough piston failures on the BB kits they scare me. I did just buy a couple of Dave's cheap 046 kits to get a couple basket case Stihl patched together as backups for a tree service, we will see how they hold up
 
The 7300 kits "looked" better, do not know about power. Pistons still the weak link. When the kits are less than $50.00 a whack I understand the attraction especially for the cutoff saws. There was a batch of 6400s that again "looked" good but nobody gets excited about the 6400 or 7300 sets. The super cheapys are scary looking, no idea where they come from but they looked baaaaaaaaad.

AM Standard bore= check the bevels, check the bore and upgrade the piston. AM kits need to be less than half the price with the up graded piston for me to consider them an option as a person who would want to own the saw, unless it is truly just for kicks. Exceptions made for extinct OEMs sometimes, still would not want a BB kit with the piston/rings that usually comes with them.

Just took apart another Stihl 460 with an AM kit that shatter the piston after hanging a ring. Rings were worn before it destroyed the piston and cylinder. Rings wor unevenly and deporpotionally to the piston and cylinder. Get to split the case, way to many piston and "NiSil" fines to risk the rebuild. Supposedly a $100.00 eBay kit.

My opinion is unless it is truly for kicks, go OEM. BB kits and AM kits are in general toys not tools unless you can fit an OEM piston or at least a Meteor quality piston, even then it is better but not as good. Also not all of the AM standard bore cylinders are a good mix with better pistons. Buyer beware. They have their place just do not expect it to be anywhere near the same place as the extra money spent on the OEM.

Where you are at right now is why I no longer own any of those chainsaws. Not enough local used parts to feed my habit, no local new parts and the only good options were OEM. Nice saws though.
 
The saw with BB kit I got from c graham is still running strong. I did take the top off and install Cabers, and cut the base, and ported it and gave it a modded carb and unlimited coil and just just run it. I use it a lot to test carbs on and with the compression it has I've already shredded a starter. In normal work for it starts always on 3rd pull. It has a lot of torque and the saw never sees less than a 28 inch bar. It's tuned to 14,4k.
I got a BB top from fordf150 and changed the formula and that's on another saw. Same as the other just not unlimited like the other. Both have served me well and I would say they are my Big wood saws. No problems with either, both NWP'S. I have no experience with any other kits so I can't say anything about them just what I have.
I think there ok as I haven't had issues.
 
Was told by reputable source the "Greek" has a very good AM 7900 PC kit. He reports looks as good as OEM. He hasn't reported back so I assume they are good to go.
Shep
 

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