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MSF blacksheep
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721 Posts
Discussion Starter · #1 · (Edited)
I recently did a starter valve sync on my niner and found that there was a lot that the service manual left out. i also found that web searching yielded little in the way of good info. after doing it I'm probably gonna check it ever time i have the tank up because it doesn't take long and is beneficial. Here's my attempt at a decent write up that everyone can understand.

warning signs that sync is needed:

-rough idle
-a slight miss sound randomly while riding at a steady speed
-poor throttle response from idle
-uneven coloration on spark plugs when comparing all four

total time: 30-60 minutes

tools needed:

5mm allen wrench
10mm 1/4" drive wrench
10mm 1/4" drive socket
7mm 1/4" drive socket
1/4" drive ratchet
6" 1/4" drive extension
long 45 degree needle nose pliers
4 cylinder mercury or similar vacuum gauge i.e. carbtune , motionpro
large fan
something to prop up gas tank
laptop (for pc3)
5/8" vacuum caps (for pairs system)

prep:

-remove seat
-remove side covers <5mm>
-loosen bolt that is horizontal and keeps tank in place <10mm>
-slide tank bank and raise fully
-support tank with block of wood or something
-remove pairs hoses and cap the plates (skip is pairs system removed)
-remove vacuum hoses from throttle bodys 1 and 4
-remove the vacuum lines closest to center line of bike on 2 and 3 (the outer vacuum lines on 2 and 3 are tied to the fuel pressure regulator and should not be removed)
-remove the 5 way splitter that the aforementioned vacuum hoses are attached to, with the four hoses still hanging off of them
-remove the hoses from 5 way and attach to ends of the leads from the mercury gauge
-install the lead for cylinder 3 first using needle nose pliers
-install all leads from gauge left to right cylinders 1,2,3,4 for easy identification
-hook up laptop to pc3 to monitor idle speed
-set up fan in front of the bike to blow on the radiator

adjustment:

-turn on the fan
-start the motor and let the computer enter open loop. it will run like poo at first but don't worry
-observe levels for each cylinder on the gauge. they all should match cylinder 2 as this is the master starter valve
-allow motor to reach its normal operating temp
-adjust cylinders 1,3,4 as needed by turning the adjustment nuts just behind the mounting bracket for the starter valve linkage. <7mm> (cylinder 2 cannot be adjusted) these nuts will turn by hand with use of the extension. they have notches similar to a rebound damper knob. turn right to lower vacuum and left to raise vacuum. for cylinder 3 i suck the extension and socket between the umbilical cord of wires and the frame.
-make small adjustments and allow system to settle as changes aren't reflected instantly. adjustments also affect the other cylinders slightly so a couple rounds of adjustments may be needed. with some patience you can get all 4 cylinders dead on even with each other
-shut off the motor

reassembly:

-basically just reverse the prep steps to put everything back together (leave laptop hooked up)
-start the motor up again (i didn't need to reset the computer or anything but there may be a stored code that might need cleared at some point)
-adjust idle to 1200rpm +/- 100 rpm
-re-sync throttle position with pc3
-marvel at how smooth it idles
-disconnect laptop
-put on your riding gear
-take it out for a good flogging
-thank me later
 

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Le So Cal Troll
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5,766 Posts
Thanks!

and mods, we need a new banner *cough*my sig*cough* for the forum since g00gl3it has converted his carb source from rice to pasta ....:yes:
agreed.

And nice write up!!!!

question... does this need to be done on a 919 that doesnt have a pc3?

Mine idles pretty good (not perfectly smooth) and has a very minor miss at very low throttle openings while cruising (honestly not a big deal).... low speed throttle response is dang good though.
 

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MSF blacksheep
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721 Posts
Discussion Starter · #5 ·
agreed.

And nice write up!!!!

question... does this need to be done on a 919 that doesnt have a pc3?

Mine idles pretty good (not perfectly smooth) and has a very minor miss at very low throttle openings while cruising (honestly not a big deal).... low speed throttle response is dang good though.
yeah it should still be checked. i might not go out of my way to check it but plan on it the next time you have the tank up for coolant or plugs etc.

the reference to the pc3 was only because the rpm read out is clearer for idle speed setting and if you change your idle speed screw it could affect the tps sync for the pc3.
 

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Le So Cal Troll
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5,766 Posts
yeah it should still be checked. i might not go out of my way to check it but plan on it the next time you have the tank up for coolant or plugs etc.

the reference to the pc3 was only because the rpm read out is clearer for idle speed setting and if you change your idle speed screw it could affect the tps sync for the pc3.
gotcha.... hmm now where to get my dirty lil paws on some vacuum gauges.

EDIT - is it possible to do this with a single vacuum gauge, and caps on the other outputs?
 

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MSF blacksheep
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721 Posts
Discussion Starter · #8 ·
nd4spdbh said:
gotcha.... hmm now where to get my dirty lil paws on some vacuum gauges.

EDIT - is it possible to do this with a single vacuum gauge, and caps on the other outputs?
I would imagine that it would be possible but way more time consuming and possibly not as accurate
 

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Hippie Tinkerer
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492 Posts
Gotta say guys, this sync proceedure made a noticeable difference in my bike. It sounds totally different than it used to, purrrrrs like a kitten, idle is smoooooth, and clutchless shifting has never been easier....

I borrowed my bros motion pro gauge set and had at it, start to finish about 50 min, easily worth the time....:yes:
 

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Le So Cal Troll
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5,766 Posts
Gotta say guys, this sync proceedure made a noticeable difference in my bike. It sounds totally different than it used to, purrrrrs like a kitten, idle is smoooooth, and clutchless shifting has never been easier....

I borrowed my bros motion pro gauge set and had at it, start to finish about 50 min, easily worth the time....:yes:
did you think your bike was idiling bad before hand... or was it kind of an ignorance is bliss deal?

OH and to add to the op.

IF your doing this on a california bike. you will have an extra vacuum line coming off EACH THROTTLE BODY for the evap system.. personally i recommend to get rid of everything involving the evap system... its easy, just unbolt everything, and put 4 small vacuum caps on the throttle bodies.

That said, the 4 vacuum connections you need to use for the sync of the tboddies are the ones that connect together to the MAP sensor in the attached pic.
 

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Hippie Tinkerer
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492 Posts
did you think your bike was idiling bad before hand... or was it kind of an ignorance is bliss deal?
Honestly, mine was just the usual 919 idle burble....same as all my friends bikes, same as all the idle sound files posted here over the years. Now mine sounds different, much smoother. When I burp the throttle now the reaction is immediate and perfect, whereas before there was a bit of a hesitation, again, just like all my friends bikes. Please understand that I am being picky, but still, if you have any mechanical inclination and the tool to do it with, it's worth the time

Oh, and Thx for posting that vacuum hose diagram, that'll be a time saver for sure...
 

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The chill Moderator
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3,304 Posts
This is a great write up! I wouldn't mind doing this my self as the idle does have the burble, it was more noticable when I put on the Delkvics. I remember haveing to bench sync and vacume sync the carbs on my 81 GPz550 now that was a PITA!

Only other thing is I am a visual person so some photos would have been cool.
 

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Hippie Tinkerer
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492 Posts
I've got my bros gauges still, prolly for another week or two anyway. Swing up if ya got time, I'm in Littleton, only takes about 45 min or so to sync the 9'er.
 

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The chill Moderator
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3,304 Posts
Thanks for the offer!!! I'll send you a text, but first I have to find a day I can wake up early and ride up. I am on mids so i spend my days sleeping my night working or playing video games.
 

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Le So Cal Troll
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5,766 Posts
Honestly, mine was just the usual 919 idle burble....same as all my friends bikes, same as all the idle sound files posted here over the years. Now mine sounds different, much smoother. When I burp the throttle now the reaction is immediate and perfect, whereas before there was a bit of a hesitation, again, just like all my friends bikes. Please understand that I am being picky, but still, if you have any mechanical inclination and the tool to do it with, it's worth the time

Oh, and Thx for posting that vacuum hose diagram, that'll be a time saver for sure...
hmm... cus my 919 has the classic burble as well... never had any issues with it but if there is room for improvement im all for it.

Now how to do this as cheaply as possible as far as tools.
 

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Registered
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134 Posts
Thanks bro!
I tried to do it in July, and then I thought that my FPR died because there was a failure to 3k RPM.
But yesterday, I repeated the operation, in your guide and I have achieved a good result) I love my 919.
A thousand devils!))
 

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Registered
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2 Posts
Thanks for the writeup! I did this today using a carbtune i bought for my old gpx. I tried this a few months back but got stuck at the sync bit. The owners manual just mentioned adjusting the throttle and thats all i did last time. It didnt seem quite right... But now that u pointed out the 7mm nuts, i've adjusted it properly and the bike idles much nicer now. Sweet!

Cant ride the 919 as earlier in the day, i used the chain press tool to push in the rivet link.. Except i pushed in a working link instead and overtightened and now its stuck :banghead:
 

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Le So Cal Troll
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5,766 Posts
quick question. OP.

What was the max vacuum reading you were seeing. Going to buy a gauge but need to kno if its going to be able to show the vacuum properly.

also, when you removed the vacuum tubes and 5 way splitter, this obviously left the map sensor open with no vacuum source correct?
 
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