Mastermind Meets The Husqvarna 3120

[Hedgerow]

Yes I did. I just couldn't remember who needed em.

Shouldn't you be posting a vid or something???
opcorn:

 

[timmcat]

Let me get this right, you have a customer who bought a 3120 and didn't think it had enough power?:jawdrop:

Nice job otherwise, Is the end user going to stick with 3/8 or go for the .404 to harness the power?

 

[Warped5]

Sure it's a nice saw, but without the vid we have no real evidence that anything was done ....

opcorn:

 

[blsnelling]

Let me get this right, you have a customer who bought a 3120 and didn't think it had enough power?:jawdrop:

Nice job otherwise, Is the end user going to stick with 3/8 or go for the .404 to harness the power?

I don't find a stock MS880 at all impressive either. .404 is not required on this kind of saw. I run a 3/8 9-pin on my ported 084.

 

[Mastermind]

Sure it's a nice saw, but without the vid we have no real evidence that anything was done ....

opcorn:

Welp I have been on the phone trying to stop a package that left here heading to.....you.

It seems my son-in-law packaged the wrong saw.

 

[3000 FPS]

A saw is a saw is a saw........... :msp_wink:

To answer your question Graham. I check squish without a base gasket, then determine how much additional squish clearance I would need to lower the cylinder enough to allow me to get the intake timing where I want it.

On this engine the squish was at zero without a base gasket and I wanted to lower the intake floor about .080"/2mm.

I didn't want to take quite that much from the cylinder base (too much compression) so I cut the squish band to achieve a squish clearance of .085"/2.16mm and then removed .060"/1.52mm from the base. I then had to lower the intake floor a bit further to get the number I was looking for on the intake timing.

Clear as mud?

So I understand your methode of lowering the intake floor, but what I do not know is what effect does this have on the performance of the engine. The intake is obviously open longer but why lower it?

 

[blsnelling]

Welp I have been on the phone trying to stop a package that left here heading to.....you.

It seems my son-in-law packaged the wrong saw.

That's something I've always been scared of doing!

 

[Warped5]

That's something I've always been scared of doing!

How could Randy's SIL be packaging saws for you? :msp_confused:

 

[timmcat]

So I understand your methode of lowering the intake floor, but what I do not know is what effect does this have on the performance of the engine. The intake is obviously open longer but why lower it?

You could raise it but you would also have to cut the piston to have it make any difference. The intake works by opening from the bottom first so if you want more duration or need to maintain duration after a change in the cylinder position then lowering the floor is the way to accomplish it.

 

[morgaj1]

I didn't make a video of the saw totally stock. By the time I got this big chunk of maple the carb was in Canada. So...here it is wearing a 32" bar, 3/8 LGX and an 8 pin. The engine and muffler are stock at this point but the coil is unlimited and the carb had been modded.

Tuned to 12,200...

[video=youtube;nzSsnYT9st8]http://www.youtube.com/watch?v=nzSsnYT9st8[/video]

Randy, you could sue those legs for non-support :hmm3grin2orange:

 

[Mastermind]

Randy, you could sue those legs for non-support :hmm3grin2orange:

LOL I've been waiting for a comment on on my bird legs.

They look like two toothpicks stuck in a tater. :msp_sad:

I've got the muffler done........we've been working on a Poulan 4000 that will not stop starving for fuel.

I'm thinking the intake block gasket is fubar. We shall see.....it's not leaving till it's right.

 

[Majorpayne]

LOL I've been waiting for a comment on on my bird legs.

They look like two toothpicks stuck in a tater. :msp_sad:

I've got the muffler done........we've been working on a Poulan 4000 that will not stop starving for fuel.

I'm thinking the intake block gasket is fubar. We shall see.....it's not leaving till it's right.

I thought you were riding a chicken.

 

[Zombiechopper]

I thought you were riding a chicken.

I thought he hired an ostrich to do the testing

 

[Hedgerow]

I don't find a stock MS880 at all impressive either. .404 is not required on this kind of saw. I run a 3/8 9-pin on my ported 084.

I'm probably the odd guy out here, but I always liked .404 on the BIG saws... As in over 6 cube... Just seems more appropriate...And forgiving in the field...

 

[promac850]

I'm probably the odd guy out here, but I always liked .404 on the BIG saws... As in over 6 cube... Just seems more appropriate...And forgiving in the field...

My McCulloch 250 (80cc) wears .404 on a 24" from the factory. (well, I'll admit it is currently wearing a 18" bar with .404 since I should get a new chain for the 24")

Obviously, it has more low end balls than a 372 or the like. Top end rpm balls, no... but gobs and gobs of torque balls.

 

[Scooterbum]

I'm probably the odd guy out here, but I always liked .404 on the BIG saws... As in over 6 cube... Just seems more appropriate...And forgiving in the field...

Don't have to sharpen as often either..........ummmm............ less to sharpen also.
Your not the odd man out.

 

[mweba]

Randy, you could sue those legs for non-support :hmm3grin2orange:

Looks to me as if he shaves :taped:

 

[Mastermind]

Still sorting out the carb tune....it's tough to get lean enough.

 

[Graham99]

A saw is a saw is a saw........... :msp_wink:



The cross slide is at the end of the jug so I just have to clear the mandrel at that point. Also the lathe has been modified to allow the cross slide to back up further from the lathe centerline....that helps with setup as well.

To answer your question Graham. I check squish without a base gasket, then determine how much additional squish clearance I would need to lower the cylinder enough to allow me to get the intake timing where I want it.

On this engine the squish was at zero without a base gasket and I wanted to lower the intake floor about .080"/2mm.

I didn't want to take quite that much from the cylinder base (too much compression) so I cut the squish band to achieve a squish clearance of .085"/2.16mm and then removed .060"/1.52mm from the base. I then had to lower the intake floor a bit further to get the number I was looking for on the intake timing.

Clear as mud?

The machining part is actually quite simple, and I understood why you did what you did. You wanted to lower the intake port, but couldnt take it all off the base or the piston would hit the top of the cylinder (which is was already doing). Therefore you compromised on the base, machined the desired clearance into the squish, and adjusted the port to achieve the final result.

Is that correct?

What was the driving reasons behind lowering the intake port? Does this increase the charge air by opening the port sooner for a longer duration? I am guessing it is years of experience that gave you the .080" adjustment in the port.

I think one day I'll grab a cheapie chainsaw and hook into it. I have my 4620 Mac at home, it may become the test bed.

Thanks for the help Randy

Graham

 

[TK]

Obviously, it has more low end balls than a 372 or the like. Top end rpm balls, no... but gobs and gobs of torque balls.

You sure know your balls :hmm3grin2orange: