Alternative carbs

[petejw]

cont

after reading wat pggg put on his i was starting to head that way,
i raised the needles again by another 'washer' and raised the jets
to 120s, i took the bike out and wow this thing is starting to fly
pulling well in top three gears, but not quite rite,
mid range was pinging but pulling hard mains were flat,
i put another washer totalling 3 and upped the mains to 125,
my mixtures screws are pretty much all the way out at 4 turns,
the bigger the mains i went the richer i had 2 make the idle circuit.
thru out these stages ive had the vac adv disconnected,
and syncd the carbs occassionally and wen needed,
majority of tuning was done without airfilters, and only putting the pod filters on near the end when in was getting close.
u can really hear the difference with these carbs.
at the end of the day im with 35 pilots i need to go up in size,
125 mains, i need 2 go up at least 1 probably 2.
the mixture screws r set out as far as they will go at 4 hence the bigger pilots.
at this stage the bike is scary fast and will get better when finely tuned.
i havent worked out the vac adv at this stage, i have it restricted but wen connected bike doesnt idle or run well,
have a cpl of different ideas im goingt to suss out,
im so excited with these carbs that i took 2 days off from work 2get them running.
With pod filters and a fairly open exhaust the pull from idle 2 off idle is good beyond that its scary.
sorry 4 the drawn out post, its getn late. :-)

[audijunky]

I am lazy

I just read your last two posts, what bike did you get your new carbs off of?

[xschop]

choke

Does it look like you can remove that choke bar easily from the carbs?....I still haven't got ahold of a set yet! Have almost everything from a ZRX but engine frame and carbs....

[petejw]

sorry bout the long post last nite
i was so hyped up after getting back from a ride.

audi,
the first post had a link to pics,
not sure exactly,
there 36 kliehns
apparently off a kawa 1100/1200.
the stock jetting set up is way 2 lean,
chop,
not sure wat u mean?
the choke set up will come off in seconds.
if ur talking about the bar directly linking to the chokes
i think theyd come off by undoing the 4 screws.

pete

[xschop]

choke bar

yes, If the choke bar comes off easily. I would weld a thumb tab to it....would be cool to have a single carb, but still am looking for a set of zrx11-12 carbs....thanks for the info...

[showtime]

xschop I scored a couple sets of zrx carbs last fall in very nice shape. One set is on my bike but If you want to PM me we can talk about the other set.

[xschop]

PM

will do

[petejw]

hey showtime,
out of curiosity wat size jets r u running,
have u shimmed the needle?

thanx
pete

[Geezer]

I may have missed it but how did you guys get the vacuum port for the spark advance to work correctly?

Geezer

[Shuriken]

Originally posted by Geezer
I may have missed it but how did you guys get the vacuum port for the spark advance to work correctly?

Geezer

For my ZRX carbs, I had to insert a restrictor in the vacuum line. I ended up using a restrictor that was left over from a Morgan Carbtune tool...

[xschop]

Restrictor

Hey AE7F, That restictor goes between vac adv. (early motors) and where on the ZRX carbs? do you know the I.D. by chance....gracias.....I finished another airbox mod that I've got on my bike waiting on the ZRX carbs....ZRX airbox, looks cool with the rest of what I did and just drilled a few more holes in it to get it to flow better since it was running a little rich....chop

[Shuriken]

Chop, your mods are sick. I love them.

I don't know the ID.... it was really small, like maybe the same OD as a safety pin....

[Geezer]

Originally posted by ae7f
For my ZRX carbs, I had to insert a restrictor in the vacuum line. I ended up using a restrictor that was left over from a Morgan Carbtune tool...

Interesting. I always thought there was some significance to the place were the vacuum was drawn for vacuum advance.

Geezer

[Tdog]

Ported or manifold

Hi Geezer,
You're correct. But perhaps by using a restrictor at a direct manifold source, a happy medium can be achieved. Where-by the restriction is too great to allow vac. adv. at idle but would allow enough higher vac. thru at highway speeds when the vac. adv. mech. is supposed to be working. Could this mean a slightly over advanced low-midrange? My $.02
T dog

[3Phase]

Backwards

If you hook the vacuum advance to the manifold after the throttle butterfly valve the vacuum advancer will work backward.

Before the throttle plate, OEM ported vacuum, gives you low vacuum and little or no advance at idle and on deceleration; high vacuum and more advance on acceleration.

After of the throttle plate manifold vacuum gives you high vaccum and high to full advance at idle and on deceleration; low vacuum and little or no advance on acceleration.

It'll work, sort of, but you'd be better off not using the vacuum advance and recalibrating the static and dynamic timing.


For "People That Know What They Are Doing(tm)":

1) Drill through one carburator body ahead of the throttle plate to create a ported vacuum source, then press or tap a suitable tube for the vacuum advance line. This will involve very few physical changes (except for the hole in new the carb!) and minimal recalibration of the static and dynamic timing.

2) Reverse the vacuum advance connection at the ignition plate so it retards the ignition during high vacuum. As the throttle is opened, vacuum drops and advances the spark. This will involve major physical changes under the side cover and a different vacuum advance can along with recalibrating the static and dynamic timing.


Regards,

Scott