6401BB Build up.

[wendell]

Has anybody got a pic of the cases barrelless on these?

You mean like this?

 

[AUSSIE1]

You mean like this?

Thanks mate, your a champion

 

[Andyshine77]

What's exhaust timing stock? I raised a bit. This kit was at 105.5° its now at 99.5°

I've yet to put a wheel on a 7900, but 98 sounds too high to on a stock saw.

 

[gink595]

I've yet to put a wheel on a 7900, but 98 sounds too high to on a stock saw.

My 066 cylinder stock was at 95* on the exhaust, it's in the low 80's now.

 

[Andyshine77]

My 066 cylinder stock was at 95* on the exhaust, it's in the low 80's now.

Pipe?

 

[gink595]

Yes, but it seems to run pretty good on the muffler too. Pipe makes about .4 better in 8x8.

 

[Andyshine77]

Yes, but it seems to run pretty good on the muffler too. Pipe makes about .4 better in 8x8.

.4 in 8x8 is pretty good, I bet it sounds good with a muffler.

 

[parrisw]

I've yet to put a wheel on a 7900, but 98 sounds too high to on a stock saw.

Yep, my thoughts exactly.

 

[mtngun]

Really? I thought those were modded numbers. I find it hard to believe that it would be 98 on the ex stock.

That's what I thought, Will. I vaguely remember seeing much more conservative numbers posted somewhere ........ but those were the first numbers I found in a search, and they came from a respected builder.

TW would prolly know, if you PM him.

 

[parrisw]

That's what I thought, Will. I vaguely remember seeing much more conservative numbers posted somewhere ........ but those were the first numbers I found in a search, and they came from a respected builder.

TW would prolly know, if you PM him.

Ya, I know the thread your talking about, I've read it.

 

[blsnelling]

Here are the stock numbers I've measured

7900
Exhaust - 102°
Transfers - 130°
Intake - 75°
Squish - .025"

7900BB
Exhaust - 103°
Transfers - 127°
Intake - 81°

 

[parrisw]

Here are the stock numbers I've measured

7900
Exhaust - 102°
Transfers - 130°
Intake - 75°
Squish - .025"

7900BB
Exhaust - 103°
Transfers - 127°
Intake - 81°

Thanks brad, those BB#s are close to what I had.

 

[bsearcey]

Hey guys. Appreciate all the work you do figuring these saws out and posting your knowledge. I'm a newbie to chainsaw modding but have a HD Makita and some day (soon hopefully) will be putting on the BB kit. roninc's thread has been invaluable with the pics and helping me out with terminology, but he didn't go into the degrees. I can't figure out exactly what you guys are talking about. Can someone elaborate a little more, or if you know of some good online sources that explains (with good pictures) I really appreciate it. Again, awesome stuff and really like learning about it.

Another question is how do you determine the squish. I see that you use soldering wire, and assume that you somehow get a piece into the cylinder and crank it so that the piston "squishes" the wire against the top of the cylinder. Where do you fee the wire into the cylinder.

Also when you guys do the grinding on the ports, what kind of bit do you use on the dremel? There are several different shapes, and I didn't know if one was better then the others. I'm trying to get my x-mas list together. My family thinks I'm nuts for wanting all this stuff to mess around with my chainsaw, but I see it more as a learning process, that could one day come in handy.

 

[parrisw]

Hey guys. Appreciate all the work you do figuring these saws out and posting your knowledge. I'm a newbie to chainsaw modding but have a HD Makita and some day (soon hopefully) will be putting on the BB kit. roninc's thread has been invaluable with the pics and helping me out with terminology, but he didn't go into the degrees. I can't figure out exactly what you guys are talking about. Can someone elaborate a little more, or if you know of some good online sources that explains (with good pictures) I really appreciate it. Again, awesome stuff and really like learning about it.

Another question is how do you determine the squish. I see that you use soldering wire, and assume that you somehow get a piece into the cylinder and crank it so that the piston "squishes" the wire against the top of the cylinder. Where do you fee the wire into the cylinder.

Also when you guys do the grinding on the ports, what kind of bit do you use on the dremel? There are several different shapes, and I didn't know if one was better then the others. I'm trying to get my x-mas list together. My family thinks I'm nuts for wanting all this stuff to mess around with my chainsaw, but I see it more as a learning process, that could one day come in handy.

Here is a good place to start. http://www.arboristsite.com/showthread.php?t=108900&highlight=porting

ask some specific questions in there.

 

[bsearcey]

Will do.

 

[parrisw]

Ran a tank of gas through it today, I can't believe how much a difference 1 tank made in this thing. Got a vid up loading now, of the first few cuts with it, I wish I kept videoing it. It seemed to wake up allot. When I first tuned it, it seemed like it wouldn't even hit limiter, I never changed the tune at all, ran a tank a gas through it, now it just bangs off the limiter like crazy, it could probably do with a little more richer. Vid should be ready in a few minutes, the vid isn't the greatest, and doesn't really show what its capable of. My buddy really liked it, he's got a bone stock 7900.

 

[parrisw]

Here is the vid. At about 1.44 in you can hear the limiter briefly.

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[MCW]

Good work Will. Is that wood pretty hard and what is it?

 

[parrisw]

Good work Will. Is that wood pretty hard and what is it?

Yes, its hard as wood goes out here. Its Douglas Fir. Its considered a soft wood, but its much harder then you would think. Its about the hardest thing to cut around here. The bark is killer on chains, very dusty, full of **** usually. I've had a few arguments about it on here. Most people think its butter, but its far from it, its very tough wood, used mainly for lumber, and actually used allot for flooring too, that should tell you how tough it is.

 

[parrisw]

Here is a little info on Doug Fir, taken from a website.

Douglas Fir (Pseudotsuga menziesii) is not a true fir at all, nor a pine or spruce. It is a distinct species named after Archibald Menzies, a Scottish physician and naturalist who first discovered the tree on Vancouver Island in 1791, and David Douglas, the Scottish botanist who later identified the tree in the Pacific Northwest in 1826. The species is known by a number of common names including Oregon Pine, British Columbian Pine, Red Fir and even Douglastree; however, the U.S. Forest Service settled on Douglas Fir some years ago. Douglas Fir is North America's most plentiful softwood species, accounting for one fifth of the continent's total softwood reserves.

Western Larch (Larix occidentalis), sometimes called Mountain Larch or Western Tamarack, was discovered in 1806 in western Montana. However, it remained for the botanist Thomas Nuttall to recognize and describe the tree as a previously unclassified species in 1834. It is one of only three conifers that sheds its needles in the winter, with new needles developing in spring. Western Larch is native to eastern Oregon and Washington, Idaho, Montana, and southern interior British Columbia. Like Douglas Fir, it is among the strongest and hardest softwood species.