Mikuni VM 33 Carbs

I'll run it 100 miles then check the plugs. I may drop the pilots from 17.5 to 15.
Steve

Yep, looks like I need the 15's.
Steve

Not all bad to try something new for a positive change...



A couple weeks back I had 122.5 mains screwed in, and decided to try 120's. Then went to 15 pilots from 17.5 and she really came alive. Went from .6 to .5 air jets to rich up the idle a smidge and minimize the pops, then lowered the needles one slot.

Not sure what the inspiration was to go that lean, but I definitely had some old mental blockage blow out...which has been very refreshing!
Gotta open the throttle a bit more, but that is a very-good thing.

:woohoo:

I'll be going with the 15's too.
Steve

I have VM33 smoothies on an 83 GS1100ES, and they ran great (although refurbing them just now after the bike sat for almost 15 years)...but... this was a full-on drag bike, and develops enough airflow to make use of them. I briefly thought about putting them on my 99 ZRX1100, but it honestly might not be a good fit, as the rex only has minor mods. And they’d be complete overkill on my 78 KZ twin.

On the GS, the VM33 set idled OK, was controllable enough on the street, and ran like the proverbial scalded dog when you wanted it to. They are, like most race carbs, easy to work on, with access to the main jets from the drain plug, and the ability to sync them with the caps off. Yes, there are no vacuum nipples. I got used to tuning “by ear” listening to and feeling the relative airflow on each, and just going for the best lowest idle (first tried on an XKE I wasn’t smart enough to realize I couldn’t afford in my misguided youth). A good bench sync is often good enough, though.

Anyway, in the right application , I think they can run great.

Cheers,
fastfrank (I’m a newbie here)
(rapidly aging and not so fast anymore)
78 KZ750 Twin
83 GS1100ES
99 ZRX1100
13 GW250



It seems that these carbs are becoming pretty scarce now, and not many shops want to touch them. They fortunately share jets with other Mikuni carbs, at least.

Steve:

Very nice bike there - looks like you’re getting it dialed-in.

I need to check my VM jets and settings shortly, been too long to remember where they were left. I hope to have mine back on the road in a couple of weeks. I need to drop the oil pan and make sure it is de-sludged and the oil pickup / filter can actually still suck oil.

Just finished resurrecting my ZRX yesterday, now waiting for a battery. I’ve been out of commission for years with medical issues, just now trying to get back in the saddle... nothing like the smell of gasoline, strong solvents, and exhaust to help that along.

Cheers,
fastfrank (I’m a newbie here)
(rapidly aging and not so fast anymore)
78 KZ750 Twin
83 GS1100ES
99 ZRX1100
13 GW250

Hey, Steve:
Where you is in SoCal? I was trying to see signs, but you ride too darned fast.
Looks like you went East a bit?
Man, Escondido was just too hot for me.
I wanted 4 seasons and got em, but they didn’t warn me that Winter was 6 mos here.
I actually didn’t stop to think that you can’t ride all year here.
I used to take long lunches and hot laps up at Mt. Palomar in the Winter, when it wasn’t raining.
ff

SWest wrote: I'll be going with the 15's too.
Steve

Luv'n the 15's so far...

Back to the center needle slot, and .6 air jets. Also ripped the wrap off my Street baffle... :woohoo:

Replaced two old leaky carb manifolds...significant difference. Next will have a matched set of four brand new ones.

Should have mine next week. We'll see how it goes. How far out on the air screws?
Steve

SWest wrote: Should have mine next week. We'll see how it goes. How far out on the air screws?
Steve

1/4+/- turn out from lightly seated.
Mikuni RS34 specified range 1/8 to 1/2 max...pilot fuel screws.

I like them better. Mine are supposed to be 1/8- 1/2 turn. I'm at 1 or more.
Steve

No eBay APP ID and/or Cert ID defined in Kunena configuration

SWest wrote: I like them better. Mine are supposed to be 1/8- 1/2 turn. I'm at 1 or more.
Steve

Hi Steve!

What size are the air jets you have in those VM's, and are they the same little buggers the RS series has?

Like these: