YPVS Loses Position(?)

[2steve]

Dropped both needles 1/2 step more. Left will probably remain down 1/2 step lower than right. That's what the plugs, feel and ears tell me.

Still better, but a sputtering thickness as the throttle opens under load. Annoying.

Rode it further than usual and after a romp through the gears, apparently the bowls get too dry and it slows down to let them fill back up. I'm blaming that on the TZR125 fuel valve.

It was nice to wring it out in 1st, shift to 2nd and feel the front wheel lose contact.

[m in sc]

you're trying to tune out a fuel delivery issue?

[2steve]

Yes. Will have to get a higher volume petcock to make sure that there's no problem dropping enough fuel into the carbs. (Feeding fuel thru a "125" valve to a 350 might be a problem)

Then, drop both needles another 1/2 step. Trying to make small adjustments because there are only 250 miles on the rebuild which was running fine before these possible electrical issues.

[m in sc]

and restrictive petcock . I think a raptor one works. 

[Kawtriplefreak]

RD400 as stated earlier is cheaper and I think better.

[1976RD400C]

I finally settled on a 1978 IT175 valve for my RZ. It has a large outlet and the original 1 into 2 hose setup can be used but you can't turn it on/off with gloves on.

[2steve]

That one looks like is has better reach coming down from the tank 

Might not stick out through the hole in the side cover, but has a lever to grab.

I ordered a piece of crap from Amazon for $20 just to keep things moving but yours looks like a better move.

[SoCal250]

As Mark mentioned above a Raptor 660 petcock (5LP-24500-01-00) should work. You can even modify it to dual outlet if you want. Chuck (aka Supertune) did a write up about the mod many years ago on here.

[m in sc]

That's what I used on mine. 
never had a feed issue even with bigger flatslides  0.02

[2steve]

Thanks, all of you!

[2steve]

You can see which of these will NOT have a fuel feed problem.

[2steve]

The needles are getting lifted to the point that I am wondering if another emulsion tube is needed. Gonna go another step - step and a half up and then investigate going up from 375 O-8 needle jet to whatever is next up in flow.
That is not obvious by looking at Jets R Us under VM26 round slides. There is no 375 anything.

Hoping for success before I run out of needle jet.

Gratuitous photo included, featuring the higher flow Yamaha fuel valve that has been suggested.

[1976RD400C]

It seems the stock RZ carbs are one of a kind. I never found where you could get a 375 needle jet. They are a shorter length than a RD carb jet. Also the pilot jets are shorter length than other Mikuni pilot jets but you can find them.

[m in sc]

those stock carbs suck.

man if nothing else get a set of pwks from toomey and ebay the stock carbs, somebody will want em.

[2steve]

Just rode it with needles as high as they can go plus a washer.

Seems like a needle shape/emulsion tube issue.
Mark, I don't recall your above idle iggy curve number, but maybe the stock carbs and internals can't deal with it.

Idle is fine, opened up above 4k is fine.
Part throttle and lower rpm brings some unhappiness. That's where the YPVS is supposed to be helping and there's sputtering instead of some grunt.

I was at the other side of the needle adjustment too and it was a bit little worse. It's just not there with this hardware.

I'll drop back and punt, hoping for a growth bonus from work for January 15th. Those carbs have been off and back on at least 10 times. I got good at it. That will help me for the rest of my life