Aftermarket 7900 Coils

[jacob j.]

Plot thickens.

I'd like a 390XP top end with a lower exhaust port and six transfer ports while I'm banging this drum.

 

[Redfin]

Bang away J. When you type I read.

 

[Mastermind]

No JJ, nothing exotic.

I did use a little epoxy to get them right where I wanted them.

 

[Nitehawk55]

What type of epoxy do you suggest Randy , anything specific ?

 

[Mastermind]

These jugs I'm talking about were used to make molds. I could use epoxy wherever I wanted to and not worry about whether or not it would hold up.

In the MS660 jug I used epoxy to lower the exhaust port ceiling.

In the MS661, I raised the floor of the intake port.

Now, I do sometimes use epoxy in the intake, and sometimes on the transfers. I use aluminum impregnated Devcon putty.

I've yet to use any epoxy in the exhaust port of a running saw though.

 

[cgraham1]

When can I order one of the 7900 coils?

 

[Mastermind]

Soon I hope.....I need a bunch of em.

And so does Matt, and Mike, and...

 

[cgraham1]

I just need the one.

 

[cgraham1]

One will do for now, anyways.

 

[Mastermind]

Dang Clint. You've become a post hoe....

 

[cgraham1]

Dang Clint. You've become a post hoe....

Who, me??

 

[Mastermind]

I'm here now dot dot dot

 

[Adirondackstihl]

I'm here now dot dot dot

Go away troll

 

[Moparmyway]

We will also have the Masterminded 066 and MS661 cylinders.

What cylinder and port details can you share with us ?

 

[Mastermind]

What cylinder and port details can you share with us ?

What do you wanna know?

 

[Moparmyway]

It would be great to know if these are nikasil plated and are they stock replacements or performance replacements.
If they are performance oriented, it would be great to know the port timing numbers as well as base thickness and chamber modifications from stock.
Further;
- on the 066/660, if the squish band has been modified from stock, how much was removed and what shape is it in and will a 288 piston work with the new cylinder ?
- on the 661 and the 066, cutting the base to get exhaust closer to 100 yields huge intake duration on stock cylinders. Has this been overcome on the replacements if they are performance oriented cylinders, and is there room to do further modifications ?

 

[Mastermind]

Good questions.

I made the jugs that were sent to be cast from, so I might be able to answer some of those questions.

If the past jugs Bruce has had done are any indication, then yes, they will be nikasil plated.

They are performance replacements. They both use the stock type piston. I'm sure machine work would be needed to use any other piston.

Base thickness has not been compromised on either jug. They are plenty thick. I can tell you exact dimensions though, I just didn't check that.

I don't have my notes in front of me, but port timing numbers are mild rather than wild. I'll do my best from memory.

I cut .040" from the squish band on both jugs. On the 660 jug I used epoxy to lower the roof of the exhaust to 100° Transfers at 118° and intake at 81°. It should make a good runner without too much compression. I expect it to blow 200 - 210. It will use a factory base gasket.

On the 661, I used epoxy to raise the floor of the intake. After cutting .040 from the squish the ex is at 99 - 98. Transfers at 120°, and the intake at 80°

I didn't want these jugs to be over the top. I was looking for a good gain, with longevity in mind. Lots of room to go further......

 

[Redfin]

I would really like to see the process of using your jugs to cast new.

 

[Mastermind]

I would really like to see the process of using your jugs to cast new.

I would too. lol

The 661 jug is on hold while I do another one for them to cut apart.

 

[Moparmyway]

Good questions.

I made the jugs that were sent to be cast from, so I might be able to answer some of those questions.

If the past jugs Bruce has had done are any indication, then yes, they will be nikasil plated.

They are performance replacements. They both use the stock type piston. I'm sure machine work would be needed to use any other piston.

Base thickness has not been compromised on either jug. They are plenty thick. I can tell you exact dimensions though, I just didn't check that.

I don't have my notes in front of me, but port timing numbers are mild rather than wild. I'll do my best from memory.

I cut .040" from the squish band on both jugs. On the 660 jug I used epoxy to lower the roof of the exhaust to 100° Transfers at 118° and intake at 81°. It should make a good runner without too much compression. I expect it to blow 200 - 210. It will use a factory base gasket.

On the 661, I used epoxy to raise the floor of the intake. After cutting .040 from the squish the ex is at 99 - 98. Transfers at 120°, and the intake at 80°

I didn't want these jugs to be over the top. I was looking for a good gain, with longevity in mind. Lots of room to go further......

Thank you Randy !!