4cycle and 2cycle Mikunis?

wsemajb /

May 12, 2009 12:34PM

I’d like to get a VM16 Mikuni to replace my 12mm Bing. For some reason they are 20USD more than the VM18. But going from a 12mm carb to 16mm just seems more sensible than anything bigger. The intake port on the block is no more than 14mm anyway.

So I find an "overstock special" (fraud alarms are screaming in my head, but WTF) for 26.99 on a 16mm "four stroke" Mikuni carburator.

Here’s the link. http://www.videogameaccessories.com/product.php?productid=1370

I’ll have to telephone them to find out for sure, but it looks like it’s not available for a couple of weeks if I’m reading the "RESTOCK ETA….... MAY 31, 2009" correctly on that page.

Anyhoo,,,,, now I’m wondering…. is there really a difference between four cycle and two cycle Mikunis? None of the other sources of VM16 Mikunis for about 100USD refer to them specifically as two cycle carbs. Boost pump or no boost pump? Less vacuum at idle for the four cycle? What the hell? Who knows for sure? I'm, at the moment, reading PDF files on tuning VM series carbs right off the Mikuni site

http://www.mikuni.com/pdf/vmmanual.pdf

and so far there has not even been any mention of either engine style. Weird.

If there actually IS a difference, then where’s the best place to get a 16mm Mikuni 2cycle online for my Puch? (I"m just going to tig weld together a new 16mm intake manifold for it.)

Re: 4cycle and 2cycle Mikunis?

Rick /

routabit

May 12, 2009 12:46PM

YES! The 4-stroke Mikkis use a different needle jet called a "bleed" type, as opposed to a "primary" type needle jet on 2-stroke versions. I'm not talking about the "jet needle", but the needle jet it drops into for metering.

Re: 4cycle and 2cycle Mikunis?

jake /

mopedjunky

Jun 01, 2009 02:19AM

shit, can anyone shed some light on this subject? I am having a hell of a time getting my stock qt50 to run with the vm18 on it- i am wondering if i got a 4 stroke? how would I know?

Re: 4cycle and 2cycle Mikunis?

King Drunky JCams /

jcams

Jun 01, 2009 02:57AM

Not sure about the VM16 carbs. I have noticed before that they cost more for some reason???

My friend Jamie (small engine mechanic) says that the VM18 is a 4 stroke carb. I'm not positive on it. I mean, my pinto got 64mph out of a VM18 and idled fine...

But, I've recently discovered the VM20 and oooooooohhh it's the cat's ass.

One of it's main uses is on Banshees which are 2 strokes.

Let me tell you the VM20 absolutely rips! Super duper easy to change the main jet too. No removal of the float bowl. Just pop out the main jet thingy with a 10mm wrench and change the jet in like 20 seconds.

Here's the VM20...

Here's a side by side pic of a VM18 and a VM20...

Good luck! Mikunis are the shit!

Re: 4cycle and 2cycle Mikunis?

timmay /

tjb8022

Jun 01, 2009 11:04AM

So are u even able to replace the needle jet because it looks like they are pressed in and also i heard that another difference between the 2 is the jet needle has a more intense tapper than a 4 stroke needle. I am looking to try to convert a 4stroke carb to a 2 stroke but trying to find the right needle jet and jet needle is turning out to be a lot harder than it seams especially for the smaller 16 and 18mm carbs.

MOPED ARMY

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