Dolmar 7900w VS. (vid)

[Gambler]

Little hint: On a modified engine you are increasing the compression.

 

[Wet1]

P.S. Threads like this is why nobody that mods saws for a business lasts long here. Every video they post gets picked to pieces to the point that they get tired of it and find another home.

Just to be clear (and I think I can speak for Andy as well), I'm not throwing stones or doubting Slinger's ability to mod saws.

 

[Wet1]

What if I am not able to reach the sweet spot of my torque band, because it is peaked at a certain RPM which I can't reach because of the limited coil?

But in the cut it appears the coil is not limiting anything, so how would this inhibit you from reaching your sweet spot?

 

[Tree Sling'r]

Just to be clear (and I think I can speak for Andy as well), I'm not throwing stones or doubting Slinger's ability to mod saws.

I don't think that was ever an issue, shoot I am learning too.

 

[Wet1]

Gawd, I need a beer.

I'm drinking scotch tonight, maybe that's my major malfunction.

 

[Lakeside53]

What if I am not able to reach the sweet spot of my torque band, because it is peaked at a certain RPM which I can't reach because of the limited coil?

yes.. only if your peak Torgue is higher than that... but that's awfully high...


maybe racing.. but "work" saw? What is your rpm in the cut?? that's where peak torque matters..

 

[Tree Sling'r]

But in the cut it appears the coil is not limiting anything, so how would this inhibit you from reaching your sweet spot?

The sweet spot is above 13,500, rpm is rpm out of the wood or in the wood. In order for a saw to hit 13,500 in the cut it has to reach much more than that out of the cut right?

 

[Wet1]

The sweet spot is above 13,500, rpm is rpm out of the wood or in the wood. In order for a saw to hit 13,500 in the cut it has to reach much more than that out of the cut right?

But regardless of which coil is installed, you're not going to get the saw to spin to over 13,500 in the cut (as you stated earlier).

 

[Meadow Beaver]

That sounds right my 440 runs 13,800 out of the cut.

 

[Tree Sling'r]

yes.. only if your peak Torgue is higher than that... but that's awfully high...



maybe racing.. but "work" saw? What is your rpm in the cut??

I get my best torque on my 460s at about 13,800, get my happy medium of chain speed for limbing at around 14ish, out of the wood of course. But those saws are cutting in the high 11s in the wood.

 

[Tree Sling'r]

But regardless of which coil is installed, you're not going to get the saw to spin to over 13,500 in the cut (as you stated earlier).

Never, in the wood has never been a question, I think that is where we are seperated.

 

[Lakeside53]

Very funny, no I don't have a Dolmar coil. And it's limited and it rips.

It's not limited by the ignition. It's limited by the engine design. I can count on a couple of fingers the saws stihl makes that have limited ignitions.

 

[Lakeside53]

Never, in the wood has never been a question, I think that is where we are seperated.

yes.. but... WOT out of the cut has little to do with peak HP... you cut close to max torque.

Looks like we are going to have to agree to disagree

I'll tune in tomorrow (storm) permitting to see where this thread is..

 

[Wet1]

Never, in the wood has never been a question, I think that is where we are seperated.

So how would this effect your timed cuts then? Earlier you said for more gains (faster times) with this saw you'd need an unlimited coil...

:sips scotch:

 

[Jacob J.]

I guess I was hypothosizing all things being equal since timing hasn't been brought up until now.

I'm going to be swapping the limited coil on my 3120 soon. I don't know if the timing is any different with the 272 coil I'm going to stick in it, but I'm going to check it at the time. Regardless, I expect to see an improvement in the cut because I often run a small bar on this saw and the stock limited coil is limited to a low RPM and I occasionally hit it in the cut. But with the 7900, I never come close to hitting the limiter in the cut so I fail to see how swapping the coil would make a difference in itself.

You'll have to move your flywheel around quite a bit. The 272 coil has a timing circuit and it's not the same as any 3120 coil.

That sounds right my 440 runs 13,800 out of the cut.

Your 440 does not have a rev-limited ignition.

 

[Lakeside53]

I get my best torque on my 460s at about 13,800, get my happy medium of chain speed for limbing at around 14ish, out of the wood of course. But those saws are cutting in the high 11s in the wood.

Yes.. Limbing is chain speed, but get that with a sprocket change. In wood at 11... no limiter (if it had one) wouldn't affect it unless the timing was being retarded.

Now I really have to go.

later!

 

[Wet1]

You'll have to move your flywheel around quite a bit. The 272 coil has a timing circuit and it's not the same as any 3120 coil.

Let's take this to PM so we aren't treading on Slingr's thread...

 

[Gambler]

you guys are working the problem back asswards. You are all worried about the spark as it relates to the coil, with no basic understanding of how a two stroke engine works.

Who let all the remedial students in the room?

 

[Wet1]

Yes.. Limbing is chain speed, but get that with a sprocket change. In wood at 11... no limiter (if it had one) would NOT affect it unless the timing was being retarded.

Now I really have to go.

later!

Fixed.

 

[Wet1]

you guys are working the problem back asswards. You are all worried about the spark as it relates to the coil, with no basic understanding of how a two stroke engine works.

Who let all the remedial students in the room?

Like Lake, I have to get going. If you'd like to put your superior intellect to work, I'd love to come back to hear your thorough explanation as to how the limiter is holding the saw back in the cut if the timing and spark isn't being pulled since it's running at an rpm below it's limit.


Thanks in advance.