zrx carb update 2.0 41mpg!

[petejw]

as long as its not pinging,
you wont go blowing anything up,

by pinching the vac hose,its a good
indication that the vac adv is operating correctly
in that it will hold vacuum.

instead of pinching the hose, disconnect it
and plug the vac hose then the vac adv
will return to its stationary position.

[petejw]

another thing came to mind when i was
reading your thread, u can bleed the fuel line,
attach one fuel line to the petcock and turn it on, let the fuel flow
till u see it just starting to come out the other hose, turn the tap off
and connect the other hose to the petcock
this will bleed the fuel line from air, i do this every time
i reconect my carbs.

[cywelchjr]

Well I am happy but I don't want to
blow something up...

The only real problem I had was trying to crank it but that was before I realized that the fuel filter was almost empty when I tried to crank. I have to prime it first every time. I never used prime with the stock carbs unless I let it sit for a week.

My other concern is when I pinch the hose closed it doesn't. Move the advance. It stays all the way to the left.
I'll check it again tomorrow... thanks for the input.

What Pete said. In order for it to drop back if the advance unit is good it MUST be open to air. I'll be working on mine this weekend, if I get into the timing cover, I'll try to shoot some video of how the system works, mine is pretty much completely stock so I can show what it should do that way.

Actually I just looked at Pete's video and that is normal operation there.

[xsroadrunner]

hi xsroadrunner,
alanb from the uk site is running the slingshot
carbs on his bike from memory with really good
results, try doing a search not sure if he did a write up on,
but he has on the uk site.

welcome to the forum btw.

Thankyou petejw. I am not familiar with the uk site but will look for it. Thanks for the welcome too.

[bikerphil]

Link to the UK site...

http://www.benefiscal.co.uk/forum/index.php

[xsroadrunner]

Link to the UK site...

http://www.benefiscal.co.uk/forum/index.php

Thanks bikerphil

[yamahansolo]

Ok just ran a tank of 87 and I only got 38 mpg...
I wonder if I get the vac advance working right if it will yield more power?

[petejw]

try running it disconnected
and see how u go.

[yamahansolo]

I don't know if you remember the earlier posts I made on this thread but I did run it a week unplugged before I got an airjet to plug up the hole. I didn't notice any difference but I was also running a tank full of sea foam and I got 35 mpg or so.
What was it someone said about hooking up the carbs togethher? Where they talking about the ports on the carbs or the little vents on the front side?

[petejw]

pull the timing cover off on the left side,
while u have it hooked up,
before u start the engine, look at the location of the vac adv
if the vac advances fully while its at idle, disconnect it and block
off the intake that it was attached to.

what size main jet are u running?

i was at 130 but that was a bit lean
drilled it out to a 140, now thats a bit on the rich side,
im about to run 135 when they get here from nz.

im also running 40 pilots, but might drop them down
to 38's the nxt time i take em off.

[81xsproject]

Ok just ran a tank of 87 and I only got 38 mpg...
I wonder if I get the vac advance working right if it will yield more power?

Probably not, but you might get better economy. When you're deep in the throttle there isn't much vacuum or related advance.

[petejw]

like 81 said, the vac adv wont give u more power
as such, its more for economy at cruise.

what ive done with mine atm, is disconnect the vac adv unit
altogether and adv the initial timing.



the red marks are for initial timing,
i havent put a timing lite on it yet or ridden it,
but want to adv the initial timing around a further 5 degrees
or until it wont ping under load.

also took a video of the vac adv with it connected to a restricted
line on the inlet barb, as can be seen, it advances slowly but stays
fully advanced at idle, when the engine is killed u can see the vac adv
slowly returning to its initial position where it should be at idle.
the vac guage is connected to the carb barb that i put in previously
and unfortunately doesnt do to much but flutter.