9 pin 3/8 rim

[cdog]

I am thinking about buying a 681 solo.
I would like to know if there is a manufacturer that makes a 9 pin 3/8 rim for this saw?
If I understand correctly the only 9 pin rim oregon offers is for .325 chain?
Any info or "enlightenment" would be greatly appreciated,
Cdog.

 

[Dibbs]

Danzco Inc.

or

Madsen's

 

[cdog]

Sounds good, I appreciate it.
Cdog.

 

[drmiller100]

i've got a couple of pretty hopped up 7900's, that so far seem to cut as fast as the 681's they have run into.

maybe one of the saws is a little faster then the 681's.

in my mind, big question whether they cut faster with 7 tooth or 8 tooth. day in and day out, i like the 8 tooth, but if i had to spend money on a bet, i'd probably throw the 7 tooth in.

no way would the 9 tooth keep up unless i went to the next step on the engines.

which is nitro.

 

[motoroilmccall]

My 044 will pull 3/8th with an 8 pin and cut faster than the 7 tooth. As long as you don't lean on it, and you're not cutting super hard wood, I'd think the 9 tooth could handle it pretty well, just gotta let the chain do the cutting, not weight. Of course, weight and the speed could win with an 8 tooth, I don't know the 7900's all that well. No way in hell would I put a 9 tooth on my 044.

 

[redprospector]

I've got a 681 that's been ported, trust me, you don't want a 9 pin on a stock 681.
Use a stop watch and try a 7 (write down your times). Then try an 8 (again write down your times). Then try a 9, I think that most will be very surprised at the results, especially with a stock saw.
BTW, I run a 7 on my 681.

Andy

 

[drmiller100]

also, fwiw, i cut firewood, with 28 inch bars.

because i'm mostly lazy, i tend to run skip tooth chains. my logic is a sharp chain cuts a lot faster then a dull chain, and when i do hit rocks, it is a lot quicker to sharpen a skip tooth then a full comp.

so, with my skip tooth chain, cutting firewood on my 7900's, i think the 8 tooth is a little faster.

again. If i had to cut green wood with full comp on a bet, i'd probably swap the 7 tooth back in.

 

[timberwolf]

A stock 066 will cut well with a 9 pin gear and shorter bar, yet even a ported 80 cc saw will struggle depite having greater HP numbers. The difference in torque is why IMHO. Porting a saw there can be gains made in peek torque, but the biggest part of the gain is just carying the same torque at higher RPM to produce higher HP and chain speed. So a ported saw may be no better or even worse than stock at pulling a bigger gear depending on how it was ported.

example, an 066 would have about 4 ftlb of torque @ 10,000 rpm to produce 7.6 hp but a ported 80cc saw producing 8 hp @12000 RPM would have only 3.5 ft/lb. Torque is what dictates what gearing can be used. Also the 066 may have a peek torque over 6ftlb @ 7500 rpm vs say 3.7 ftlb @ 9000 rpm for the ported 80 cc saw.

On pipe or alchohol power is made by burning more fuel either as a result of the charging effect of the pipe or extra O2 in the alcohol. Burning more fule in the same space produces more heat and higher cylinder pressure which transfers more torque to the crank and this is why more gear can be used on alky/piped racers.

 

[cdog]

I was going to run a 16" er 18" bar, does that change the opinions???
Cdog.

 

[timberwolf]

No, answer is still 8.

 

[Crofter]

On small wood with a square filed race chain and a modified saw you might get the odd faster time with a nine than an eight tooth sprocket but it would take far too much concentration to do on a regular basis.

Add to that a nine pin is a specialized pin type sprocket that does not wear well and that you usually have to modify the tail of your bar to install. you may also have to install bar, chain and sprocket together(providing you dont have an outboard clutch. No you dont want a nine pin sprocket!

 

[Wet1]

I have a new 7900 that's currently stock (will do a muffler mod this winter). Are you guys saying it's probably faster with the 7 pin on a 20" bar than it would be with an 8? I suspect the 7 would be faster with a 24"+ bar, but I would have thought the 8 would be faster on the 20". I ask because I haven't had the chance to try this.

 

[timberwolf]

20 inch bar and 8 pin likely about the cut off point, but it's going to depend on what you are cutting and how you sharpen the chain. Over 20 then 7 is likely the better on an 80cc saw. Though maybe 8 would work ok with skip chain and a bit longer bar.

 

[Wet1]

Thanks TW!

 

[redprospector]

Here is a stock 7900 running an 8 in 17" dead Ponderosa Pine.



Andy

 

[redprospector]

Here's the same saw, same log, same chain & bar with a 7.
Get out your stopwatches.



Andy

 

[Wet1]

Wow, I didn't expect the 7 to be that much faster in 17" wood (pine no less)! I guess I'll just leave the 7 on after all...

Thanks for the info guys!

 

[redprospector]

Wow, I didn't expect the 7 to be that much faster in 17" wood (pine no less)! I guess I'll just leave the 7 on after all...

Thanks for the info guys!

Hahaha. Dead Ponderosa Pine is a little tougher cutting than most of you guys give it credit for. Not hard, just tougher cutting.

Andy