Carb Indentification?

pj sportfire · Post by **pj sportfire** » Wed Jan 28, 2009 9:28 am

Thank you!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Cheers!
PJ

pj sportfire · Post by **pj sportfire** » Wed Jan 28, 2009 11:39 am

Thanks Rich, I'll look into it.

pj sportfire · Post by **pj sportfire** » Wed Feb 04, 2009 7:14 pm

Well folks, I finally located me an original VM34/231 SF 440 Power Jet Carb and ditched the "whatever-it-is" Mikuni VM34 carb that I've been fiddling with to get it jetted right for this machine. I cleaned the new carb out well, set the static adjustments and factory jetting to factory specs and installed the thing.

WOW! Is all I can say.... WOWWWW! :suprised: I had the old carb dialed in pretty good, which made it run a ton better that what it did when I first got the sled, but now....just WOWWWW! This thing pulls *HARD* through the low to mid-range now; even more than before after the finer adjustments to the old carb did. Plus it *WILL* pull the skis about 2"-3" EVERYTIME I stab the throttle from a dig when on hardpack snow!!!! It starts hot much easier too, which is a bonus and it hits 50 MPH at the flick switch!

Geeez, I thought the sled was fun before... Thans for all the help everyone.

pj

wycrumb · Post by **wycrumb** » Wed Feb 04, 2009 7:39 pm

PJ,
I have a sportfire and my powerjet carb is toast, I am putting in a standard VM34 like you did and I am wondering what jet you used in it? I am sad mine was stuck and broken but at least it will roll.
Thanks,

pj sportfire · Post by **pj sportfire** » Thu Feb 05, 2009 12:02 am

What's wrong w/ your SF carb? It's not cleanable?? Heck, I'll trade you the carb I just took off my sled for the SF carb you got there if it can be fixed. The standard VM34 carb I was using looks like virgin aluminum inside and out it's so clean... Let me know and I'll help you out where I can.

pj

oscar89 · Post by **oscar89** » Thu Feb 05, 2009 1:41 am

Hey Pj you said you verified that the needle & jets were of the correct size. How did you do that? Is a micro number stamped on them?
Sounds like I have the same deal w/ my '80 SF as you w/ a apparently brand-new- everything-is-shiney Mikuni. But as w/ yours mine is missing the power jet also the main is part of the needle jet rather mounting underneath it in the bowl as the SF Service Manual says it should. My problem is that the carb is metering way way too much fuel out w/ a small pool of fuel left in the rubber carb mount & wet plugs after several attempts too start. The needle is set to the 3rd notch. Just talked to a "Mikuni carb expert" at the local cafe & he thot I should add an extra notch of depth to the needle at a time til I get the desired A/F mix. The problem being the 3rd notch is what is specified. Leaves me to wonder if the main jet is oversized & will cause bogging at WOT but how do you tell the size of the jet?

pj sportfire · Post by **pj sportfire** » Thu Feb 05, 2009 7:56 am

I can't remember what main I have in that carb without taking it back apart again and looking, but it has a Primary Type needle jet, a 6F27 needle set at the 2nd notch from the top, a Model C main jet (can't remember the size, but I believe it's a 200) and a 25 pilot jet. The float level is set to stock specs, the pilot needle is set at 1 1/4 turns out from fully seated and the throttle slide height is set to just clear the main bore of the carb on the engine-side of the slide when at WOT. The choke cable is also set to have about 3/16" of slack, to allow for cable movement when the dash panel is in the closed position.

These settings make the carb just a ***tad*** rich, but easy to operate on this engine both cold and hot. It pulls HARD at WOT and I've got about 250 miles on this configuration with excellent results, tan plugs and pretty good fuel economy @ about 35+ miles to the half-tank full. Plus, since it's a bit rich, it covers those days when the ambient temps are very cold and the baro pressures are high. (+30.00)

Hope that helps.

pj

pj sportfire · Post by **pj sportfire** » Thu Feb 05, 2009 8:02 am

wycrumb wrote:PJ,
I have a sportfire and my powerjet carb is toast, I am putting in a standard VM34 like you did and I am wondering what jet you used in it? I am sad mine was stuck and broken but at least it will roll.
Thanks,

You know what, nix my last reply to you.....

In the spirit of the "Pay It Forward" thread that's circulating around and because so many on this board have helped me here, I'll just send you my old carb for FREE if you want it and if it will help you get back on the trail sooner!

I have about 250 miles on this configuration and I know it works well, so you can have it if you want it, just email your address and I'll ship it to you.

pj

wycrumb · Post by **wycrumb** » Thu Feb 05, 2009 11:52 am

E-mailed you!

pj sportfire · Post by **pj sportfire** » Thu Feb 05, 2009 12:00 pm

A quick note~ I managed to finally identify this "whatever-it-is" Mikuni carb I've been running and it's a Mikuni VM34/389 snowmobile carb, but I don't know what sled it originally came on. At least I know what the heck these are now...

pj

pj sportfire · Post by **pj sportfire** » Thu Feb 05, 2009 12:26 pm

It's on the way to you now and I've attached a photo of the thing, just so you can see what it looks like. This carb should get you pretty close and if you want to tweak it more to suit your specific sled, altitude, etc., you easily can do that. At least now you'll be in the ballpark.

Enjoy!

PJ

Attachments:

pj sportfire · Post by **pj sportfire** » Thu Feb 05, 2009 12:27 pm

As a side note, this thing doesn't look "vintage" to me, as it's too new looking and if I had to guess, I'd think it was an new Mikuni- or at least relatively new. The inside is as clean as the outside.

pj

Attachments:

wycrumb · Post by **wycrumb** » Thu Feb 05, 2009 12:58 pm

WOW, I don't think I have ever seen one so clean! Can you tell I work on vintage?

oscar89 · Post by **oscar89** » Thu Feb 05, 2009 3:12 pm

Wonder why I have the same deal, a new looking carb on a SF?

oscar89 · Post by **oscar89** » Thu Feb 05, 2009 3:19 pm

pj sportfire wrote:I can't remember what main I have in that carb without taking it back apart again and looking, but it has a Primary Type needle jet, a 6F27 needle set at the 2nd notch from the top, a Model C main jet (can't remember the size, but I believe it's a 200) and a 25 pilot jet. The float level is set to stock specs, the pilot needle is set at 1 1/4 turns out from fully seated and the throttle slide height is set to just clear the main bore of the carb on the engine-side of the slide when at WOT. The choke cable is also set to have about 3/16" of slack, to allow for cable movement when the dash panel is in the closed position.

These settings make the carb just a ***tad*** rich, but easy to operate on this engine both cold and hot. It pulls HARD at WOT and I've got about 250 miles on this configuration with excellent results, tan plugs and pretty good fuel economy @ about 35+ miles to the half-tank full. Plus, since it's a bit rich, it covers those days when the ambient temps are very cold and the baro pressures are high. (+30.00)

Hope that helps.

pj

Curious "pilot needle is set at 1 1/4 turns..." are you referring to the air screw?