Fast Moby Cylinder

I have 6 cylinders, 4 of which have come off A speed bikes, and none of them have oval transfer ports. I know that two of them at 35mph bikes completely stock so I am wondering if there is a different stock cylinder that is even faster. These look as the wiki fast cylinders except for the transfers. Anyone have a good clear pic of the oval window so I can compare. The pic attached is the transfer off of my 35mph stock 50vlc.

1193888558_dsc00098.jpg

Re: Fast Moby Cylinder

To be honest, the information that one of the Creatures compiled is misleading. I have read many, many post just like this were people have a cylinder that goes well over 35mph stock and does not look like the ones he posted.

It is not all about transfer port shapes but rather timing. I have almost no technical knowledge about how it all relates together but its obvious there are plenty of different cylinders made for the AV88.

Re: Fast Moby Cylinder

Correction, AV7, the motobecane motor.

Re: Fast Moby Cylinder

its ALL about timing and port size - then just match an intake, carb and expansion chamber to what you have, then mess wif the gearing and ZOOM ZOOM ZOOM

Re: Fast Moby Cylinder

the shapes of the ports change on the fast bikes they are not always oval i have learned, ist really where they are (timing) vertically in the cylinder that makes the difference, also the fast cylinders have different transfer ramps for the most part.

theinfo i posted about fast cylinders a while back is only from a collective of i think 7 cylinders, so i have not seen them all.

i belive that is a fast cylinder and there might have in fact been a "super fast" cylinder 35mph or so, i had a stock bike with a cylinder that just broke all my rules about them, it was bone stock went 35 with the gurtner.

the post of fast and slow cylinders should be remade with port maps, i will get on it as soon as i have some time, as i have many more cylinders now, but many are ported so hopefully i have enough to make a better classification guide.

Re: Fast Moby Cylinder

lol elliot must be like mine well managed stock orange moby engine

Re: Fast Moby Cylinder

I can work on the port mapping here soon, I have a couple of those 35 mph stock cylinders sitting around.

Re: Fast Moby Cylinder

I don't know if he has any stock engines on his anymore. Not all Motobecanes have the same piston either, most have port windows but I have one that is a slipper type, no idea which engine it came from. I have three cylinders in may possession, none are the rumored slow type judging by the cooling fins. I have a depth gage that I could use to measure the ports.

One of my cylinders also has a vertical groove up the side, and by all accounts it looks like factory as it is straight and cut, not scored ot gouged. The engine also had good compression when I took it apart. This is the cylinder from my 40 by the way. I should also take a note of the casting numbers on all three, see if they mean anything.

Re: Fast Moby Cylinder

We need to figure this out.

I'll be recording all of the mobys I work on.

Re: Fast Moby Cylinder

looking at that picture really makes me want to get a dremel out.

Re: Fast Moby Cylinder

So stupid question maybe, but how can I tell what cylinder my 1980 50V has? It's got an A stamped in the top of it, but I thought that was just for matching it up to a piston size, at least that's what the repair manual says?

I'd measure the ports if I had a caliper set...

Re: Fast Moby Cylinder

Umm......did anyone notice the Wari post with the Canadian IP? What the FUCK!!! And doing it on Eliot's login is so wrong.

Stop messin' with the stock cylinders Jesse.

Re: Fast Moby Cylinder

yeah its weird.

whats wrong with messing with stock cylinders?

Re: Fast Moby Cylinder

eh, there's only so far you can go. but i think everyone should work on modifying their stock cylinder to see what they can get out of it before upgrading to a kit. it makes a whole lot more sense to experiment with cheap stock stuff than it does a 250 dollar kit.

Re: Fast Moby Cylinder

What happened is when a user account is deleted the post stays but it assumes the username of the post above it because the original user no longer exists. If that makes any sense. Its not a hack or anything, it just has to do with the forum software.

Re: Fast Moby Cylinder

what do u mean on my login allen???

yeah mod ur stock shit, i got my moby to 42mph on the slow 20mph cylinder with a pipe.

jesse has gotten even faster.

Re: Fast Moby Cylinder

i just wanna say that i think there must be a shitload of stock cylinders. I have personally port mapped at least 5, and read port maps of oh probably 5 more. i havent seen any two that were identical. some were close, but never right on.

of course there is the variable that since i didnt map _all_ of the ones ive seen, then that pits my margin of error against someone else's. so technically two port maps that arent identical _could_ be from the "same" cylinder. i wont discount that, but from what ive seen it seems very hard to believe that would produce so many "extra" cylinders.

rant

Re: Fast Moby Cylinder

I've thought about the cylinder thing a bit now and what I've pretty much come up with is that since every bike used the same engine but weighed different amount, had different gearing and clutches, and different speed ranges that there is lots of different cylinders that all go the same speed on different bikes. A 30mph 7 doesn't need the larger mapped cylinder like a full 50LVC would so it has a more powerful engine on it to make it go 30. And a slow cylinder has a small intake, carb,and sometimes a different pipe, gearing,non variated. Where if you just put the larger stock parts on a slow cylinder it will go faster than it's supposed to. Just putting a variator on a 30mph single speed 40 makes it go faster unless you regear it. It's a thought.

Oh and just so you know I have moved on to different cylinders. Should be fun. But as Shay said, there is a lot to be learned on stock parts that will make kits much easier.

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