Pilot Mixture Screw Setting

[penningpd]

Evening all. Just a quick question. I have read the tech article on jetting the Mikuni carb and it states: For most purposes,
the baseline PMS setting is 3 ½ turns off the seat. So, while counting the revolutions of the screwdriver handle,
back it out that much. You’ll back it out more if the engine needs more fuel at idle and during deceleration or
you’ll turn it in for a leaner setting.

my question is this. How often do people have to back out the Pilot Mixture Screw more than 3.5 turns. Seems my bike runs better at 4.5 turns out.

thanks for the info!

[roadiemort]

That was old info, things have changed, what jet kit are you using? What year is your bike?

[penningpd]

Bike is a 2001 1600. Jet kit is a k& n kit should be all original size jets.

[roadiemort]

You're not going to find anyone here using that jet kit.

[Lug Nut]

What type of jets? K&N makes a jet kit? Mikuni jets?

What numbers are on the jets and is the needle adjustable with multiple grooves? Pics would be helpful. For Barons kit pms would be 2.5......never more than 3.5

At 4.5 out you would risk having it vibrate out honestly

[penningpd]

Ok. This is the jet kit I got from Dennis kirk

[roadiemort]

Lol.Carb rebuild kit is not a Jet kit.

[penningpd]

The needle is not adjustable. Just like a stock kit.

[penningpd]

I will buy this one if you think it will help

[roadiemort]

You will still need to buy the 37.5 pilot jet not supplied in the kit

[penningpd]

Why buy the 3.75 pilot jet?

[Shores]

If it hasn't already been said here, not all needles have the same taper though their number may be the same and not all needles match up with all jets. Wait for the gurus here to tell you specifically what you need.

[penningpd]

Waiting….

[Lug Nut]

Pennington...
year Modifications (exhaust, air cleaner/filter setup) etc?

[penningpd]

2001. No modifications that I can tell.

[davej]

If you have a 2001 with no mods to air filter or exhaust and you are at 4 1/2 turns out on the pms to make it run right then you need to check for an air leak at the intake manifold to head connection and check for possible air leak due to intake manifold cracking. The 37.5 pilot would still be of help to give more room for adjustment without having the pms out even close to that many turns and it will take care of low to 1/4 throttle response.

[penningpd]

Will someone please send me a link for the correct 37.5 pilot. Don’t wanna buy the wrong one.

[Lug Nut]

N224.103 For pilot jet (37.5 pilot jet)

[roadiemort]

https://jetsrus.com/a_jets_by_carburetor_type/jets_mikuni_N224-103_pilot.htm

[Horsehammerr]

JetsRus.com Mikuni 37.5 ( VM28/486)

[penningpd]

Thanks!

[penningpd]

While I am ordering the 37.5 pilot jet should I also get a different sized main jet? I am thinking no because I have a non adjustable needle.

[Lug Nut]

While I am ordering the 37.5 pilot jet should I also get a different sized main jet? I am thinking no because I have a non adjustable needle.

If your all stock leave main jet alone. A 37.5 pilot with everything stock is fine and your pms should be 2.5 out. However if your bike is all stock and you had stock jets in it why go to the trouble of drilling out the brass plug to access the PMS screw?? One thing I would be concerned about is that rebuild kit you bought is not super high quality IHad one before and the gaskets did not seem to fit very well. I'm wondering if the needle is actually the exact same as stock as well as the jets.You're always better ordering genuine Yamaha parts for the carburetor when rebuilding in terms of gaskets and needle valve etc. I would definitely not mess around with main jet setting if you have stock exhaust stock air filter assembly stock air filter etc.

[penningpd]

Lug nut. I did not drill out the PMS brass plug. It was done when I got the bike. That’s the real problem I am having. I don’t know what the previous owner did and am trying to fix it. That’s why I don’t really know what jets are in it. So far I know this: the secondary jet is basically a plug. I am going to order the 37.5 pilot jet and install that. After that if it doesn’t run correctly I will start another post. I guess. Not trying to be a pain. Just don’t know where to go after the 37.5 pilot jet. Plus - I am in no way an expert in carbs - learning as I go with this one…and it has taught me a lot!

[davej]

look for the air leak and fix it

[Pauli466]

That jet that looks like a plug actually is a plug it's in the starter enrichment circuit ( choke )

[Lug Nut]

No fun when previous owner did thing (that don't make sense)....COULD be that he had aftermarket air cleaner and pipes and had the carb set for that and before he sold bike took those parts off to sell and put stock pieces back on....?