Mastermind Meets The MS661 Again

[LegDeLimber]

Any of you guys work with the Devcon stuff, enough to know IF they have anything
that you could use to build a brush holder for a "12-volt" automotive alternator?
I'm talking about as an equal to the factory part in longevity, temperature tolerances etc...
Reason for asking? I want to run a more properly sized set of brushes in one.

 

[KG441c]

Any of you guys work with the Devcon stuff, enough to know IF they have anything
that you could use to build a brush holder for a "12-volt" automotive alternator?
I'm talking about as an equal to the factory part in longevity, temperature tolerances etc...
Reason for asking? I want to run a more properly sized set of brushes in one.

Belzona 1121

 

[jsmith40004]

Randy I'm glad you keep posting the new info that you learn.

If it wasn't posted some other porters would just buy one of your saws and copy the numbers and work.

It's happened before on this sight

Would a full circle crank help these saws as much as raising the port floor?

James

 

[KG441c]

Any of you guys work with the Devcon stuff, enough to know IF they have anything
that you could use to build a brush holder for a "12-volt" automotive alternator?
I'm talking about as an equal to the factory part in longevity, temperature tolerances etc...
Reason for asking? I want to run a more properly sized set of brushes in one.

http://www.belzona.com/en/products/1000/1111.aspx

 

[Yukon Stihl]

Hi Randy
I used some of the metal version of that epoxy on some bushings on the air ride of one of my Macks.So far there hasn't been any sign of it breaking down in that environment.
Is there a spot that you could drill and tap through the jugs intake and the epoxy from the outside and locktite in a small bolt to anchor the epoxy in place should it decide to come loose.Or maybe a roll pin or two from the outside.
Thomas

 

[Stihl working hard]

I never did get a real good "looking" cut today......I ran a little fuel through the saw noodling a few big nasties. Then filed the chain.

Just about rolled the round over on me but here's that vid.



I'm really anxious to see how the jug with the epoxied intake does. I prolly need to find a better way to hold them rounds though.

Randy what % gains do you think you have achieved on this 661

 

[drf255]

Changing the mix ratio to 40 or 32 to 1 will also increase the octane because oil will not burn as fast as gas.

Can someone confirm this?

My understanding, at least in 4 strokes, was just the opposite. Excessive connecting rod side clearance in a 4 stroke sprays the cylinder with more oil which causes a mixture with gas and causes MORE detonation. Oil burns slower, but does that mean it's more detonation resistant?

Perhaps I was taught wrong.

Also, Randy, please don't stop posting pics of your work. A lot of us find it very interesting.

 

[LegDeLimber]

It's early and I'm not coffeed up yet, so this is just some wild speculation of my own.

I can imagine if an excessive amount of oil, was making it's way into the combustion chamber,
That you'd be getting some carbon build up.
Now the the carbon will occupy some of the chamber space and thus raise the effective
compression ratio. That much I'm confidant of.
Now when the carbon gets pretty thick, it has been known to have some places
that catch enough of the (normal) combustion cycle heat for these places to begin igniting
your incoming fuel/air charge.
This would give you a knocking noise. depending on when it occurs, perhaps a little before the spark plug is fired (pre-igniton) or a bit later, say after the plug has lit the mix,
Then it can cause an extra pressure wave to race out fron it's hot spot and when that crashes into
the pressure wave from the normaly intended, spark igniton,
You can get such a sharp pressure rise from the two waves combined, that it hits the cylinder walls and head so hard that it sounds like something metallic is hitting them.
Either way that this second or unwanted ignition of the fuel is bad for the motor.
That clattering is as hard on things as whacking them with a hammer, if let happen enough.

Now hopefully someone with a better education and its accompanying vocabulary
will provide us all with a proper, scientific explanation.

 

[weedkilla]

Can someone confirm this?

My understanding, at least in 4 strokes, was just the opposite. Excessive connecting rod side clearance in a 4 stroke sprays the cylinder with more oil which causes a mixture with gas and causes MORE detonation. Oil burns slower, but does that mean it's more detonation resistant?

Perhaps I was taught wrong.

Also, Randy, please don't stop posting pics of your work. A lot of us find it very interesting.

You are right and wrong. Oil in fuel increases octane rating, but there is more than octane rating that determines knock resistance in fuel.
One of the reasons oil in the combustion chamber of a 4 stroke makes detonation worse is excess carbon build up, creating hotspots where detonation begins.
The other reason is it's not all of the components of engine oil that get into the combustion chamber, it's the fumes that have been whipped out of the oil by the crank. This can be pretty nasty combustible mix when mixed with petrol and air.
The list goes on, but you probably get the point.

Then think about how many dollars go into developing a reasonable budget race car engine, then imagine paying 100k for a chainsaw engine.....
This isn't knife edge tuning.

 

[Mastermind]

Randy I'm glad you keep posting the new info that you learn.

If it wasn't posted some other porters would just buy one of your saws and copy the numbers and work.

It's happened before on this sight

Would a full circle crank help these saws as much as raising the port floor?

James

I don't think it would James. I do believe that we need the case volume to support this 90cc saw.

Also, although that would decrease case volume, I don't think case compression would be increased like it would by closing the intake sooner.

Hi Randy
I used some of the metal version of that epoxy on some bushings on the air ride of one of my Macks.So far there hasn't been any sign of it breaking down in that environment.
Is there a spot that you could drill and tap through the jugs intake and the epoxy from the outside and locktite in a small bolt to anchor the epoxy in place should it decide to come loose.Or maybe a roll pin or two from the outside.
Thomas

I drilled some divots to anchor the epoxy. I think it will be ok.

I'd rather keep it in one large piece.......if I drill thru it, could it crack apart possibly?

Randy what % gains do you think you have achieved on this 661

I have no idea.

 

[old-cat]

I drilled some divots to anchor the epoxy. I think it will be ok.

I bet that is the right approach but I'm thinking the divots need to be deeper?

 

[Mike from Maine]

Is there a video comparing a stock vs ported 661?

 

[Mastermind]

I bet that is the right approach but I'm thinking the divots need to be deeper?

I'll do just that on the next one Lynn.

 

[bryanr2]

"In Mastermind we Trust"

 

[thomas1]

Randy I'm glad you keep posting the new info that you learn.

If it wasn't posted some other porters would just buy one of your saws and copy the numbers and work.

It's happened before on this sight

Would a full circle crank help these saws as much as raising the port floor?

James

Randy has given a step by step tutorial on more than one occasion. I think on the ms261 one of the other porters tried it Randy's way, found Randy's way to be significantly better, then went back to his old way because he just "knew" that his way was better.

Is that thread still around?

 

[DSS]

Randy has given a step by step tutorial on more than one occasion. I think on the ms261 one of the other porters tried it Randy's way, found Randy's way to be significantly better, then went back to his old way because he just "knew" that his way was better.

Is that thread still around?

I'm quite sure you'll find it.

 

[thomas1]

I'm quite sure you'll find it.

I ain't got that kinda time, what with herding rifraf all day and whatnots.

 

[DSS]

I ain't got that kinda time, what with herding rifraf all day and whatnots.

Plus you're uneducated to start with, like the rest of us.

 

[jsmith40004]

I was thinking 7-8 years ago when he was starting

 

[Mastermind]

Randy has given a step by step tutorial on more than one occasion. I think on the ms261 one of the other porters tried it Randy's way, found Randy's way to be significantly better, then went back to his old way because he just "knew" that his way was better.

Is that thread still around?

http://www.arboristsite.com/community/threads/ms261-vs-ms261-c-m-comparison.243686/