zrx carb update

[yamahansolo]

well ijust tried to get my zrx carbs to work while i fixed my bs34's. the po broke 2 of the idle mixture screw's off in the holes....

anyway the stock zrx jets must be way to lean... idle was easy but above 4 grand it would bog. the plugs looked greyish white. the carbs have 92 mains on the outside carbs and 95 on the inner two. also with the vacuum advance hooked up with no restriction the advancer slapped open and closed. if i slightly pinched the hose it didn't. i had the side cover off so i could watch. any ideas on how high to go on the mains. mods are in sig. i just don't want to order 20 sets of jets.

also anyone know where i can get the stock idle mix screws for the bs34's? i need 2. the pic on mikesxs does not math my screws. mine are th external ones.

[red bandit]

I have 130 mains and 38 pilots with good results. Stock exhaust, moded air box. My ZRX are off a 2000 something. CRS

[DiverRay]

georgefix on ebay has carb sets with the correct screws. He may be able to help you get just the screws if you send him an email. I also thought the EARLY 650 carbs used the same screws, so they may be on the mikes650 site. HTH

[gareth]

Currently using 38 pilots and 130 mains per the prevailing wisdom. Dropped the needles to the second slot from the tapered end, snipped 1/2" off the springs. I just ordered a set of 135 main jets to see if I can open up the top end further and perhaps richen the entire range. I am running Mikes XS oval pods and supertrapp mufflers on a jardine spaghetti 4-2 header system. The plugs look OK right now, maybe a little lean. I am getting a lot of popping on decell, and the power kicks in hard and sudden after 5000rpm. The bike feels a bit stuffy in the midrange, but I am hoping to play with the disc system on the Supertrapps to see if I can make it perform a bit more evenly across the RPM range. With the intake noise and the fairly open exhaust system, the bike sounds like a serious powermaker, but the butt dyno jury is still out..
I have been reading a lot about back pressure in exhaust systems and was planning on tapping the exhaust system in both mufflers with some carb sync adapters to see if I could actually measure and balance the back pressure for both headers. Sort of like an "exhaust sync".. Most of the decel popping is from the 2-3 header. Could be an exhaust leak, might just need to be richened up a fraction on 2-3..
Its a schizophrenic bike right now...OK off the line, tentative and a bit stuffy from 3-4500k, a manic lunatic after 5k...
I have also been reading about airbox design, especially in regards to CV carbs. I am wondering if I might have been a bit hasty fitting the pods, no matter how cool they look. Since I have a few jets for the ZRX carbs, I thought I might just put the original airbox back and do a few runs to do some sort of comparison.
When I get to it, I will report back..

[yamahansolo]

the ones on mikes don't match. i have bs34's they show a different screw. and i didn't see a kit on ebay. what is the name this george uses? thanks

[CatatonicBug]

what is the name this george uses? thanks

He uses "georgefix". One of the better places on ebay to find carb parts for the XS11. He really seems to go out of his way to get you what you need, and knows his stuff too.

[bikerphil]

http://stores.ebay.com/GEORGEFIXS-MO...E-PARTS?_rdc=1

[yamahansolo]

thanks for the info.....

now my next thought is since the po drilled out 1 and 4 screw holes must be why he put in 210 airjets. with my mods i am thinking going bigger on the mains. po gave me a brand new set of 145 and 150 mains. i am using 140's now, with 45 pilots. i am thinking th145's should work. any thoughts???

[yamahansolo]

wow i just did a search on jetting... here is something i found.

A little research at the Yamaha OEM Parts site reveals:78, 79 and 82 employed Air Pilot Jets.80 and 81 did not. I'm sure there was a port that sucked air but no removeable jet. Why?Also...in general....as time progressed the jets got smaller...WHY? Was it emissions? And also...did 78, 79 , and 82 have same carbs while 80 and 81 had different carbs?1978main - showed three diff sizes (130, 137.5 & 140)Pilot - (45)Air pilot - (210)1979main - (137.5)pilot - (42.5)air pilot - (180)1980main - (125) #2&3 (120) #1&4pilot - (42.5)1981main - (110)pilot - (52.5)1982main - (112.5)pilot - (47.5)air pilot - (170) .

this was posted years ago... my 79f is no. 491 built in april 78. clymer doesn't show this extra info it says 78 and 79 have same jets... 137.5, 42.5, 180 air. mine look like genuine mikuni's but they are 140, 45, 210 .... something is weird right??? these are the origional carbs as well. so i think i may go to the 150's.

anyone else have 210 air jets??? this bike is really really fast. it will accelerate faster than my yzf600r did easily.

[yamahansolo]

ok i just installed the 150 mains. runs great. now if i can get 2 mixture scews i'll be in business.