Stihl ms 460/660 Hybrid. 469e

[Mastermind]

So... But to summarize thus far. Yes it can be done... Should it? I ain't know. Not yet anyway. Even if it ever makes a sh*t ton of power (which is up to you guys, especially Doc), most would consider this a PITA. 82.45CC'S, well ported, should hang with a 500i and then some of it won't be worth it to most of ya. Myself, if I get it close, I'll enjoy the cool factor enough to justify it. But this should have been Doc's build, so any fruits will be butter sweet unless there's a bushel of them. I did learn one thing however. I bet any one of us would benefit from trying this slug in a 660. It would allow for squish to be cut without lowering cylinder. Transfer could be left tighter, and intake later. So that's on my mind. I bought 3 more of these slugs incase there's a famine View attachment 411133

The 288 piston seems to be the best.

 

[NateSaw]

The 288 piston seems to be the best.

The longer skirt? The weight?

 

[NateSaw]

Comic relief... The Goldberg choke linkage I abandoned. And my 7(teenth) cup of Joe.

 

[NateSaw]

 

[Mastermind]

The longer skirt? The weight?

And stuff

 

[Ketchup]

@NateSaw, did you look at fitting a 66 crank to dodge the height problems? Extra displacement too…

 

[NateSaw]

@NateSaw, did you look at fitting a 66 crank to dodge the height problems? Extra displacement too…

I glanced. I think it's above my pay grade right now. I'm not a real machinist. I only worked at that shop for a year and a half, so I and I was on a cnc mill. This is the most lathe work I've done. Without having measured, the visible differences in the cranks deterred me. However, it may be more possible than I gave it time to ponder.

 

[Ketchup]

I glanced. I think it's above my pay grade right now. I'm not a real machinist. I only worked at that shop for a year and a half, so I and I was on a cnc mill. This is the most lathe work I've done. Without having measured, the visible differences in the cranks deterred me. However, it may be more possible than I gave it time to ponder.

First questions are bearings, weight width, case wall thickness. Then shaft lengths and part fitment. If you have the bearings and the case wall then usually the shafts can be cut to fit.

Don’t sell yourself short. You’re already tackling stuff most people won’t touch. So much ingenuity and info in this thread! Don’t give up!

 

[NateSaw]

First questions are bearings, weight width, case wall thickness. Then shaft lengths and part fitment. If you have the bearings and the case wall then usually the shafts can be cut to fit.

Don’t sell yourself short. You’re already tackling stuff most people won’t touch. So much ingenuity and info in this thread! Don’t give up!

At any rate that I'm on some par, credit is due to ope and you, the crew. Hands down. That's what inspires me. I'm not worried about failing or setbacks. I just don't want to sit on my hands after all of you have shared trade secrets and experience. I've a long way to go before playin with me crank

 

[Ketchup]

At any rate that I'm on some par, credit is due to ope and you, the crew. Hands down. That's what inspires me. I'm not worried about failing or setbacks. I just don't want to sit on my hands after all of you have shared trade secrets and experience. I've a long way to go before playin with me crank

Um, that usually happens pretty early…

 

[NateSaw]

 

[NateSaw]

It shows promise. It feels /behaves to me, like it could take a longer gulp of air, and have less fuel in the ratio. Especially @wot. I plan to lower the intake to 78*. Still leaves it with 46* of case compression. I'd also like to widen and take advantage of these wide skirts. While in, I'm going to mill(drill) access to remove wrist pin clips, and cut the Dumbo ears off of them, square the ends. @Ketchup ,you have me obsessing over those things now,having confirmed my fears. Those Dumbo ear style clips are problematic in every piston I've ever seen. When the pin walks it pushes the ears out. Not to mention they probably don't need help as they are going for a centrifugal ride at 10k rpms. I doubt dumbos ears would stay on at 2kmph. At this point, I'd appreciate input on moving forward with port work. As much ch as I'd like to raise the transfers to 122* even, I know I need to run it after moving and widening the intake first.

 

[NateSaw]

Chamfering was over the top. It's interesting to me how each port requires it's own skillset. I've little experience in the intake. It shows.

 

[NateSaw]

Found a pair of oem pin clips. Measured @ 37thou, same as lrb units.

 

[Ketchup]

You’re in uncharted territory. Who knows what numbers will work? I would start by evening out your uppers and opening the squish to 0.022”.

And yeah. I agree you’re either under carbed or your throttle butterfly isn’t opening all the way.

Edit: Did you do any work to the lowers? A lot of jugs have a chrome lip at the bottom that should be removed for a smooth transition.

Second Edit: Definitely go with the Stihl clips if they fit. I think the problem with the aftermarket circlips is they aren’t spring hardened enough and they bend.

 

[NateSaw]

You’re in uncharted territory. Who knows what numbers will work? I would start by evening out your uppers and opening the squish to 0.022”.

And yeah. I agree you’re either under carbed or your throttle butterfly isn’t opening all the way.

Edit: Did you do any work to the lowers? A lot of jugs have a chrome lip at the bottom that should be removed for a smooth transition.

Second Edit: Definitely go with the Stihl clips if they fit. I think the problem with the aftermarket circlips is they aren’t spring hardened enough and they bend.

Butterfly opens nice and flat. I made sure of that with linkage mod. Didn't touch the lowers. Left uppers for now, as I want to see what the intake port change did. Oem stihl clips installed, and provision for removal drilled into pin boss.
I also lost another gram off the piston reducing the skirt struts, in the interest of increasing flow to lowers. However.... Pucker factor on the pistons strength.

 

[Mastermind]

Butterfly opens nice and flat. I made sure of that with linkage mod. Didn't touch the lowers. Left uppers for now, as I want to see what the intake port change did. Oem stihl clips installed, and provision for removal drilled into pin boss. View attachment 411235View attachment 411236
I also lost another gram off the piston reducing the skirt struts, in the interest of increasing flow to lowers. However.... Pucker factor on the pistons strength. View attachment 411237

That piston is gonna come apart....

 

[NateSaw]

That piston is gonna come apart....

Indeed... I should have bought a holzforma to try this.

 

[drf256]

Great work Nate.

Excellent craftsmanship and your ports look amazing.

That piston worries me a bit too.

Not sure why you are giving me any credit. I just said I always wanted to try it, you did it.

Great thread.

 

[NateSaw]

Great work Nate.

Excellent craftsmanship and your ports look amazing.

That piston worries me a bit too.

Not sure why you are giving me any credit. I just said I always wanted to try it, you did it.

Great thread.

Thanks Doc! Eh, you're too humble. The darn slug.... I don't know whether to try it, or bank on it grenading. I thinned it too far.