# Big bore kit dolmar7900



## Toddr (Sep 9, 2015)

Hi all new guy here so bare w/me ! I have a dolmar 7900 that needs a rebuild and have been wanting a little more umph ! Has anyone tried the big bore kits or should I just stay with the oem and find someone to port the saw ?


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## norman vandyke (Sep 10, 2015)

@jason stratton @Kevin


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## ripjack13 (Sep 10, 2015)

can't forget @woodtickgreg

Reactions: Agree 1


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## woodtickgreg (Sep 10, 2015)

I haven't used any of the big bore kits, but have used the aftermarket stock replacements. Just stay away from the chinese junk and you'll be ok. Meteor is an italian company that produces good quality replacement stuff. I am of the mindset of a well tuned and mildly modded saw is fine for me, they run well and are durable. @Kevin really likes his saws ported to change the timing. I wouldn't be afraid to try a big bore kit as long as I didn't have to permanently alter my saw in any way in case I wanted to go back to stock. I am also of the mindset that if I think I need a bigger saw I buy a bigger saw. I have small saws for limbing, bigger ones for felling and bucking, and a really big one for milling.

Reactions: Informative 1


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## jason stratton (Sep 24, 2015)

In general a big bore is a step in the wrong direction, I've tested many and have yet to find one that outperformed the oem. A 2 stroke is all about case compression and volume, if u add cc's your still feeding them with the same case volume and case compression wich in turn will slow velocity feeding the larger cylinder and hinder performance. A few saws can handle a larger cc cylinder, 064/066 044/046 are 2 that benefit, a 7900 lives and dies on case compression and the added cc's will kill it. Considerable modifications have to b made to get a big bore to perform with a stock oem. As he said the meteor is the best aftermarket I've used although quality is hit and miss, port shape and finish as well as timing will b Nothing like the oem. A 7900 is a hard saw to get gains from being a hotrod from the factory, muffler mod does little if anything. A small ignition advance and compression increase by cutting the squish band will net good gains but not like other saws. The only big bore I've cn that makes more power than a oem is a 660 I have, it's a cheap bailys kit that is heavily ported with finger ports and a 395xp husqvarna piston, it's a strong saw but a oem with the same treatment is stronger. Your oem cylinder with a new meteor piston and caber rings will far surpass the big bore. By the way the 044/046 064/066 i mentioned are all done with oem cylinders, only as a last resort would I use aftermarket cylinders and then I'd stick with the standard bore size. I'm not a cheap parts basher there are lots of them cylinders worked hard everyday but from a performance point of view they are lackluster to say the least.


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