How to make your 7900 or 681 NON rev-limited

[Andyshine77]

I've welded some pistons but not in that one! I had the oppurtunity to suit the 7900 with a 32" bar last weekend and cut some hard maple, it put my 880 to shame, it cut faster and had more balls. The bar was buried for the most part of several logs, sometimes I had to cut from the other side to finish it. That was the first time I've really had a chance to use it in big wood and I couldn't have been more pleased with it.

If you 7900 has more torque than an 880, I only have one word that come to mind and that is BOOM! I'm sorry but I simply can't see this saw lasting. But now for the real question, do I really give a hoot about what a so called wood ported saw can or can't do, my answer is no!

 

[tdi-rick]

BTW Andre, was talking to Matt the other day and he reckons that 7901 with the pop-up pulls some good revs in the cut, he was talking around 12,000 RPM in Blue Gum.
He said it's a much stronger runner than the other two 7900's. (that's if he can remember what the first one actually runs like, seeing as it's been on a holiday a few thousand km away )

 

[Andyshine77]

Revs in the cut is what matters, that saw runs well.

 

[gink595]

If you 7900 has more torque than an 880, I only have one word that come to mind and that is BOOM! I'm sorry but I simply can't see this saw lasting. But now for the real question, do I really give a hoot about what a so called wood ported saw can or can't do, my answer is no!

Well at least we know it isn't overheating, not sure about the big bang theory either, I figured if I were to have blown it, it would have happend last Sunday, hard wood, long cuts, long bar and a heavy handed operator, it never gave on clue on qutting. Time will tell though, I was told a year ago it would be to hot to run, I've cut some firewood since then and haven't had an issue, maybe the guy that built it knew what he was talking about

 

[CHEVYTOWN13]

Well at least we know it isn't overheating, not sure about the big bang theory either, I figured if I were to have blown it, it would have happend last Sunday, hard wood, long cuts, long bar and a heavy handed operator, it never gave on clue on qutting. Time will tell though, I was told a year ago it would be to hot to run, I've cut some firewood since then and haven't had an issue, maybe the guy that built it knew what he was talking about

:chainsawguy:

 

[FATGUY]

the 7900 IMHO is the greatest saw EVER made IMHO. However, beating an 880 (or a 3120, or an 084)?!!?!? not likely. Not saying you're not being truthfull, I'd just like to see for myself...

 

[CHEVYTOWN13]

It's been long rumoured but I can't recall a Husky piston actually being able to be used.

I'm pretty sure (but happy to be wrong) that the pin to crown height was wrong (and not easily corrected) or the pin diameter was wrong on any that were suggested as an alternative.

I do know we had a big discussion on this on RS a few years back and IIRC no one was able to come up with a viable alternative.

A rod change may change things, but the ol memory aint what it use to be :monkey:

Tocayo, you're getting waaaaaaaaarmerumpkin2:

 

[AUSSIE1]

Tocayo, you're getting waaaaaaaaarmerumpkin2:

681 spacer with Husky piston.

Edit: Actually they only use a spacer in the 681's when using the BB kit, so a spacer in the 7900 to allow the use of a Higher crowned piston.

 

[CHEVYTOWN13]

Info is over at the other, more rowdy saloon

Gink's EC 7900 shows what a stock piston can do.

Keep it in house:biggrinbounce2:

 

[tdi-rick]

681 spacer with Husky piston.

Edit: Actually they only use a spacer in the 681's when using the BB kit, so a spacer in the 7900 to allow the use of a Higher crowned piston.

Hmm.

Someone's getting some big bore kits in soon too that need testing.

I think I need another 7901.........

 

[gink595]

the 7900 IMHO is the greatest saw EVER made IMHO. However, beating an 880 (or a 3120, or an 084)?!!?!? not likely. Not saying you're not being truthfull, I'd just like to see for myself...

Sounds like your calling me a liar, that cool though. Another member stopped out where I was cutting Atlarge54 and watched, I don't think a 880 is that impressive by any margin, I ran a couple stock 3120 yesterday at Eric's that had alot more ass than my 880, my 066 has more ass then that saw too. I wouldn't tell ya stories Nik, the 7900 in big wood was more powerful than the 880. The 880 seems to bog out, you have to be a little lighter handed with it. I sent the 880 away, it is a pig

 

[AUSSIE1]

Hmm.

Someone's getting some big bore kits in soon too that need testing.

I think I need another 7901.........

Yeah, wish I had a chassis!

 

[04ultra]

Sounds like your calling me a liar, that cool though. Another member stopped out where I was cutting Atlarge54 and watched, I don't think a 880 is that impressive by any margin, I ran a couple stock 3120 yesterday at Eric's that had alot more ass than my 880, my 066 has more ass then that saw too. I wouldn't tell ya stories Nik, the 7900 in big wood was more powerful than the 880. The 880 seems to bog out, you have to be a little lighter handed with it. I sent the 880 away, it is a pig

Send that 880 out for porting......You can find people that port saws in OHIO...........




.

 

[gink595]

:hmm3grin2orange: Step ahead of ya!!!

 

[04ultra]

:hmm3grin2orange: Step ahead of ya!!!

I see that..........


.

 

[WoodChuck'r]

Ohio..... Bah.

I use a guy in Nebraska. Good ole Jimmy.


You Ohio guys need to get over yourselves.

 

[FATGUY]

Sounds like your calling me a liar, that cool though. Another member stopped out where I was cutting Atlarge54 and watched, I don't think a 880 is that impressive by any margin, I ran a couple stock 3120 yesterday at Eric's that had alot more ass than my 880, my 066 has more ass then that saw too. I wouldn't tell ya stories Nik, the 7900 in big wood was more powerful than the 880. The 880 seems to bog out, you have to be a little lighter handed with it. I sent the 880 away, it is a pig

Frank, in my first line I made it clear that I WAS NOT calling you a liar or even suggesting you weren't being truthfull. Of the limited experience I have, I really can't see a 7900 beating a 880 in anything larger than say 24". I ran Andyshines 084 just Friday night and couldn't believe how much torque it had in BIG wood. I'm not picking firghts here old man, I was just calling it like I see it.

 

[gink595]

Frank, in my first line I made it clear that I WAS NOT calling you a liar or even suggesting you weren't being truthfull. Of the limited experience I have, I really can't see a 7900 beating a 880 in anything larger than say 24". I ran Andyshines 084 just Friday night and couldn't believe how much torque it had in BIG wood. I'm not picking firghts here old man, I was just calling it like I see it.

Thats cool, Your calling it like ya see it, and I'm telling ya like it was

If you guys ever get to any other GTG's we'll suit em up and see!

 

[CHEVYTOWN13]

Yeah, wish I had a chassis!

Yeah, me too:greenchainsaw:

 

[blsnelling]

I ran Andyshines 084 just Friday night and couldn't believe how much torque it had in BIG wood.

I would not be at all surprised to see a 084 beat a MS880. Andre's 084 is not rev-limited. The MS880 is limited with both the carb, and the coil. Remember how Gink's 880 was constantly on the limiter that one time you ran it? Once you get rid of those, they'd probably be quite close.