YPVS Loses Position(?)

[2steve]

Stock RZ carbs are maybe sensitive?
Raised needles 1 step because it was lean there, and turned in air screws from 1.5 to 1 turn out.
Kid rode it and I listened. Told him to pull enrichener when it got messy.
Report is that it's actually a little rich in the needle range now, so back down 1/2 step is where I go next. Sounds kinda picky, but maybe that's a thing.
Should be going like stink all over the rpm range.
I'll work it out, but if anyone knows about those 26mm carbs being finicky on settings, let me know.

[Kawtriplefreak]

Thats why I put VM30s on mine and never looked back. I have both kinds of 26s. The infernal 48H EPA bridged style and a set of conventional 26s the rest of the civilized world got. I have very little experience with the individual non EPA 26s, but I assume they are like any other VM. The bridged carbs are a compromise at best on anything but a completely stock engine. Just my opinion. Your mileage may vary,  etc. If I were building another stock or mildly mofified motor it would be flat slides, probably TM32 since I have one brand new one and a shit load of Mikuni brass. My 421 build has Keihin PWK35s on it and they are a whole different animal.
And I digress. Yes in my limited experience the bridged carbs are quite difficult to tune and after 1 time spending an hour trying to access the needles that was enough for me. I gave mine away to a dear friend.

[1976RD400C]

I installed those UFO inserts on my stock carb slides and finally it runs great after spending hours trying to fuss with the needles. They said they fit an RZ but I had to open up the ID of the bottom of the slide to fit them in there. I have them in my VM34 carbs on my 400 and love these things. They make a world of difference, 0-1/2 throttle response is so clean and strong.

[m in sc]

make sure the airjet is clear.

[2steve]

Thanks guys. I can formulate a plan now.
Mine are annoying because they seem to have a different slide stroke length. One has a larger gap at idle, but that same one is the last to completely arrive at wide open, slightly.

I have not checked the airjets yet, so there's that.

I have UFOs that should work, too.
They do work very well in the 400, though a little too small in diameter for those carbs.

At least it's down to carb tuning - except it's carb tuning on an RZ.

[m in sc]

they are a huge pain in the ass. you might want to consider the pre jetted setup from toomey w the pwks.

[2steve]

they are a huge pain in the ass. you might want to consider the pre jetted setup from toomey w the pwks.

Shew, Mark. I can only do free stuff right now. Just had a little go at the hospital last week. We were at about the halfway point when a guy rolled up with his PC that showed $25k. Blew past the deductible well before that.

I'm gonna lay low and put in some serious garage time. I'll know how to pull, tweak and reinstall those stock carbs in my sleep. Went much smoother last time when I discovered that moving that electronics panel under the tank made the carb cables/adjustment a LOT easier.

[m in sc]

oh I get it. trust me

[2steve]

Finally got jetted as good as it will go, dropping the needles 1/2 step from before.
Apparently the left cylinder is still not producing joy until it feels like it at higher rpm/main jet. Otherwise better than at the beginning of all of this, but certainly not right.

Last time apart, I did not "check the air jet".
Is there an embedded air jet behind a brass "ball" plug in the carb mouth of these unique-to-RZ VM26's?

Mark - I saw you mention to take the emulsion tubes out and put a carb cleaner straw in the air jet passageway and flush it out. Where does that come out the other side?
Can I remove a brass plug?

There are 3 holes in the carb mouth, one is open where the pilot air screws control flow, the other two holes are brass plugged.

Coil and 5k ohm caps are new. BE8S plugs are not, but presumed fresh and ok. They ohm out ok.

The only thing left is that the left carb must need help. The RZ seemingly bogs a lot on one cylinder trying to start off from a stop
Both needle jet tubes are clean - even the little mixing holes on both sides of the brass tubes.

Last desperate attempt will be to hope something is in the left carb air jet - wherever that is. Would love to actually get to get it out to inspect. This has been a major part of the problem all along, and never ironed out.

[m in sc]

yup. carbs need a proper cleaning

[2steve]

How can I do surgery on that air jet and passageway, though?

[m in sc]

theres a thread on removing the brass ball here somewhere in the tech section or chucks area

[2steve]

I thought that was only an RD400 thing and have done that to drill out the air jet for the much-needed Dave F mod.

Will do some research.

[m in sc]

nope same thing.  you can tap the housing and plug it back to keep the tune exactly the same after cleaning

[2steve]

nope same thing.  you can tap the housing and plug it back to keep the tune exactly the same after cleaning

Good news! Thanks much.
I have a couple extra carb bodies that I can experiment with