Boost or boosts? Chop that garbage out test

I have 2 cyls right now that are amazing.

Both started shitty.

Stock Hobbit and zuma cyl.

Both have a single big open boost port each.

I looked at my DR and Wizard kit, and I'm just not buying the idea that those bridged or double bridged boosts actually help much. All that garbage just restricts flow. So I'm gonna cut that shit out.

I'll keep the angle, and make sure there's still ring gap support,

But 2 small 3/16 in holes can never flow as much as an almost 7/8 inch port.

Kinda psyched to see what happens.

My hypothesis is that it's gonna fucking blast

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Re: Boost or boosts? Chop that garbage out test

Their is some correlation between performance and Swiss cheese.

Re: Boost or boosts? Chop that garbage out test

I'd love to port a swiss cheese block.

I'd eat those shavings so hard

Re: Boost or boosts? Chop that garbage out test

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Both of these cyls are the fastest I've ever ridden.

Re: Boost or boosts? Chop that garbage out test

Overpriced Parts /

Damn good R&D

You're making me want to get a PAII

Re: Boost or boosts? Chop that garbage out test

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This is going to be awesome.

Soooooomuch more flow.

Even if it doesn't work it's fucking awesome

Re: Boost or boosts? Chop that garbage out test

Haha. Better have some good brakes if you try this.

That was the most fun ride I've ever had on this hobbit.

Chop em out bro

Re: Boost or boosts? Chop that garbage out test

Every time I see one of your thread it makes me want to blow all my money on stock cylinders and just go nuts on them, wish I had the money to do so lol. Keep it up man, I'm more than likely going to use some of the shit that worked for you when I port next!

Re: Boost or boosts? Chop that garbage out test

Stock cyls are basically free. ????

You don't have nothing?

All I use is a drill, dremel, files, sandpaper, and sometimes a torch.

And a chopstick

Re: Boost or boosts? Chop that garbage out test

Hey JBOT, so, from what i understand, all you did was remove the material within the port itself as well as the section of the cylinder lining to convert it from 2 (or 3) intake windows to one large one, as long as its wouldn't be too wide afterwards to allow the ring to bulge or snag.

Correct, yet?

I assume this would transfer over to an av10 cylinder as well, yes?

Re: Boost or boosts? Chop that garbage out test

Yes. It worked for me.

On a single variated it might do the same.

The power is stronger across the rpm range it seems.

Idk the physics reason it works, but it just does.

Maybe because moped transfers aren't so great?

Re: Boost or boosts? Chop that garbage out test

Just in case anyone actually reads these posts I do,

Get these bits to cut cyls or something similar.

Then make curves really easy.

I love them. So cheap on eBay.

Carbide China cutters, like $10 or so.

I use the 2 in the bottom left corner most.

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Re: Boost or boosts? Chop that garbage out test

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I'm committed to this mod.

Re: Boost or boosts? Chop that garbage out test

I need a new dremel unit. Cast iron kits lasts longer that the tools that make them

Re: Boost or boosts? Chop that garbage out test

I got a foredom, just haven't started using it yet.

I guess I'm used to this dremel

Re: Boost or boosts? Chop that garbage out test

Anonymous User /
scootertrash

Right oN monkEy FeatHer, I'm gittin sum

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Check out thw wedge case stuffer

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pUMP uP the jAmmmm

Re: Boost or boosts? Chop that garbage out test

Nicceee. More posts scoot!

Re: Boost or boosts? Chop that garbage out test

This is where i get my dremel bits. They are inexpensive (relatively) but still quality and have held up for many bouts of case matching and porting with no noticeable decrease in sharpness.

Re: Boost or boosts? Chop that garbage out test

thats hardly cheap enough.

These bits I posted are awesome.

You cannot beat the price

They are too sharp when you get them.

Gotta dull em down on some steel first.

Re: Boost or boosts? Chop that garbage out test

I have those same bits, jbot. They are great nice and big and cut real well if you keep em oiled

Re: Boost or boosts? Chop that garbage out test

I'll have to check it out when I'm not at work - ebay is blocked here :(

Re: Boost or boosts? Chop that garbage out test

Overpriced Parts /

I use the same bits too on a lot of stuff, the bits are sharp but the shafts bend easy so I use other bits too that have hard shanks

Re: Boost or boosts? Chop that garbage out test

With cast you don't have to oil much at all.

They cut dry really well.

I still lube a lil bit though.

Yes, cast is harder to port....but it's so muc more satisfying.

Re: Boost or boosts? Chop that garbage out test

The big barrel cutters are shitty on these.

Best to only use the biggest at slower speeds

Re: Boost or boosts? Chop that garbage out test

There is a very interesting sound that a big boost port creates.

It's mostly heard when you get into the power.

It's like a frantic sound, like nothing can drop the rpm once you hit,

Just doesn't give a shit. "BAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH'!!!"

I love it, just have to be more responsible with throttle.

Re: Boost or boosts? Chop that garbage out test

Overpriced Parts /

JBOT, Bro Wrote:

-------------------------------------------------------

> There is a very interesting sound that a big boost

> port creates.

> It's mostly heard when you get into the power.

> It's like a frantic sound, like nothing can drop

> the rpm once you hit,

> Just doesn't give a shit.

> "BAHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH'!!!"

> I love it, just have to be more responsible with

> throttle.

Ya reed induction/case induction with big multiports is a whole different animal compared to piston port kits/cylinders, love the sound and power especially with a big carburetor and a k&n filter

Re: Boost or boosts? Chop that garbage out test

Too loud with just a foam filter.

Deafening.

That's why I run airboxes with all my bikes.

They still make the same power, but the intake brutality is cut by more than 1/2

Re: Boost or boosts? Chop that garbage out test

my guess would be that on setups with less agressive pipes or no pipes at all, the people designing the kit were going for higher velocity to scavenge. when you have a lot more blowdown and a big pipe not only does it scavenge itself better, its going to suck a lot more through the transfers, especially the top one, when the pipe is drawing.

maybe ring life, but i'm just not buying that, i think they are going for velocity.

Re: Boost or boosts? Chop that garbage out test

But if you look at a stock Zums cyl,

It's got the same open boost.

And they definitely didn't come with a tuned pipe.

Looking at some fast cyls,

It seems like some go for a single large boost,

While others run a multi boost.

Seems very random

Re: Boost or boosts? Chop that garbage out test

yeah there might be different dynamics on a stock zuma because they are more of a cup-handle transfer arrangement.

some of the CFD stuff i've seen shows that you can get wierd scavenging with too much boost, especially without a pipe, it can short circuit and leave a dead zone at the top of the head.

the other issue could be core complexity, if the zumas were counting on being made with a less accurate casting technology, they might have forgone a more delicate core mold?

i dunno man, its crazy town. looking at late model 2 strokes, TZR's and shit like that, its obvious that the transfer size to bore proportion is just not even close on even kitted moped cylinders.

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