Mikuni Air-Jet.... is this where it goes?

JDX-8 · Post by **JDX-8** » Fri Mar 28, 2008 10:48 am

This is where the Air-jet should be right?.... im looking in there but i dont see anything... just the needle jet in the very back... dont seem to have threads in there either????.... did some carbs not have them or somthing?.... im going from a parts diagram (thank you

) and im ordering all my stuff, i wanted to make sure of what size i do have in them... but dont see one in here!.....

Thanks guys, Kelly

JDX-8 · Post by **JDX-8** » Fri Mar 28, 2008 10:49 am

and a close up....

400brian · Post by **400brian** » Fri Mar 28, 2008 3:17 pm

If my memory is good, that's where it goes. Apparently they did not put them in all carbs. I'd bet it is threaded.

Joliet Jake · Post by **Joliet Jake** » Fri Mar 28, 2008 4:35 pm

Here is a pic to show where the pilot jet is ......you need a small straight screwdriver to unscrew the jet.

Pilot jet is not the pilot AIR jet that you adjust!

Jets are numbered and should correct to your sled.

Hope this helps .....if you need help picking adjusting the carb.......I can help.

400brian · Post by **400brian** » Fri Mar 28, 2008 4:48 pm

No Jake, I think he is talking about the tiny air jet that is in the hole there in the throat. This regulates the air flow to the orifice in the needle jet.

What you have identified as the pilot air jet, is simply refered to as the "air screw" in SM 2100. That adds air to the idle mixture in relation to the fuel flow the pilot is allowing

Mr. Deere · Post by **Mr. Deere** » Fri Mar 28, 2008 4:53 pm

Wait there is a jet in there. Maybe Im missing one and that is why it runs like crap. I have the Power Jet carbs. Does anyone have a pice of what that little piece is. BOB

JDX-8 · Post by **JDX-8** » Fri Mar 28, 2008 11:02 pm

Im about confused all to hell now!..... hahaha.....

So,... i dont see one in either of my two 34mm carbs.... i can put a small screwdriver all the way to the needle jet/thing the needle slides into... nothing in there!... and i have taken my camera and put it on macro so i can see in there real well... and i dont see any threads what so ever..... how is this going to effect tunning this carb????? <_< I have a set of 3.0 slides and a few sets of needles on the way now.... and ordering the main jets and such in the next day or two....

Just dont know what i need to know about a carb that dont have the Air-Jet????

400brian · Post by **400brian** » Sat Mar 29, 2008 12:38 am

Don't get in a sweat over it. Try it and see. If I remember correctly, the threads are in the very bottom of the bore, and would be hard to see.

It seems that some of the applications the carbs were used on just didn't use the air jets. I don't think it makes a huge difference.

The air jets aren't that expensive, you'll just have to try to install one.

Post by **ICCSF 108** » Sat Mar 29, 2008 1:29 am

More than likely your sled/carbs never had any in the first place, IF it did & IF they worked there way out YOU would know it, as they would now be stuck on top of the piston or embedded in the head..

You really need to purchase a fine tune manual ( the SP-509-H2 ) is the best, even if it isn't for your model sled it gives great coverage of the Mikuni carbs & the Comet & TR800 clutches, gearing, ski & suspension setups...

Kenny

JDX-8 · Post by **JDX-8** » Sat Mar 29, 2008 9:08 am

Carbs are all brand new.... never installed.... so that is what has me stumped

I got the carbs in a lot of 10 that i bought... and some parts were missing from a few of them.. and i was thinking that maybe someone stripped the Air-jets from them... but like you said... they are $2 each... i think i will just order 2 of them and see if they will thread down in there.... if not... i guess i will be rolling without them!... Looks like .7 was a sort of a standard on the sleds.... i will just order a pair of .8's and call it good!.... and just tune via needles.... as im getting a few sets in the mail soon... and main's are cheap as well!

Thanks for the info guys.... i will let you know how it turns out!

jdcat · Post by **jdcat** » Sat Mar 29, 2008 12:03 pm

Have the same problem with my 79 440 trailfire. Doesnt have an air jet. Service manual dont list one for this sled. Yet the JD parts site list a 1.5 & 2.0 air jet for this model sled. I assume the 2.0 would be for the 440. Carb is clean ,changed all fuel jets to the Deere specs [pip] . Engine wont idle unless air screw is turned all the way in, Acts like an air leak. JDX-8 ,Where do you get the air jets for 2 bucks? Im going to order a 1.8 an try that.

JDX-8 · Post by **JDX-8** » Sat Mar 29, 2008 2:24 pm

Hey there!.... i will get that info to you tonight... im not on my computer right now.. and that info is on there.. sorry... but will get that to you later..... if you read on the first page of this... "takeittothelimit" is using a .7 for a 440.... why would you want to use something with that big of a hole in it, like a 1.8????

My understanding is.... that jet allows a certain amount of air through to allow a metered amount of fuel to be sucked in around the needle and the pilot jet..... the more air it can suck through the front of the carb... the more fuel is able to be sucked in as well....... Am i even close on this guys????

So,... im thinking if my carbs were not made for the Air-Jet...... then a larger needle will be needed to control the fuel flow...... ... but i just dont know!.... <_< maybe it would need smaller needles to compensate for all the air???? hahaha... man.. i just dont know!

I really wish someone with rock solid info on this will ring in on this!

Mr. Deere · Post by **Mr. Deere** » Sat Mar 29, 2008 3:44 pm

Does an 80s series Liquifier Have one. BOB

Danzig · Post by **Danzig** » Sat Mar 29, 2008 3:53 pm

http://www.650motorcycles.com/CarbTuning2.html

Part#28 on this carb has this piece

JDX-8 · Post by **JDX-8** » Sat Mar 29, 2008 4:35 pm

hum... still scratching my head..... I had my girl take a look at it too..... i am 100% sure it does not have any threads in that hole... i can see all the way down and the light reflects back off of the long jet/thing that is in the bottom of that hole.... it shows that it is just as smooth and shiny as could be with no threads at all.....

How is this going to effect me tuning this carb????...... anyone???

Thanks guys!, - Kelly