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McTavish
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Inboard taps on the #'s 2 & 3 TBs are for the FPR.
Outboard taps on the #'s 2 & 3 TBs are for MAP.
Don't be fooled by the MAP tap on #1, which is in the Inboard position, meaning that only #1 has its MAP tap inboard.
DAMN!!!
I screwed it up!
OUTboard taps on the #'s 2 & 3 TBs are for the FPR.
INboard taps on the #'s 2 & 3 TBs are for MAP.
 

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Have you had a chance to see the latest posts and the Dropbox update?
Would appreciate any comments you may have accordingly.
I think we have it straight now.
I sure hope so!
It all makes sense to me! On top of that, looking at the coloured diagram had me realize that it is completely consistent with the port placement on the throttle body assembly. Just looking at the TB assembly in isolation, combined with the visible unused positions for additional ports, makes it look like they could have just drilled them at random at the factory (not completely crazy, if they were modifying some bikes off the assembly line to add the California equipment). But nope - Honda definitely had prescribed positions for those ports.

Still kinda odd they went through the trouble of making a diagram that is technically accurate for the manual, and then did a poor job of clearly labelling anything!
 

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McTavish
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6,524 Posts
It all makes sense to me! On top of that, looking at the coloured diagram had me realize that it is completely consistent with the port placement on the throttle body assembly. Just looking at the TB assembly in isolation, combined with the visible unused positions for additional ports, makes it look like they could have just drilled them at random at the factory (not completely crazy, if they were modifying some bikes off the assembly line to add the California equipment). But nope - Honda definitely had prescribed positions for those ports.

Still kinda odd they went through the trouble of making a diagram that is technically accurate for the manual, and then did a poor job of clearly labelling anything!
OK, so this now rests, corrected Dropbox documents included.

I had the same sense when looking at the TB's re the numerous piloted bosses and blank bosses.
Some of the piloted bosses had me wondering if they were related to the casting process as they sort of looked like cored holes and not drilled.
Whatever................

Thanks for your inputs.
 

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Left of Centre
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4,011 Posts
So I returned from my annual 1000 km round trip to the Boxing Day Street Races at Whanganui and started my bike after giving it a good wash and a change of oil and filter. I was expecting it to run as flawlessly as ever, but I got the most uneven blub-blub-blub idle I’ve ever heard from it.

Having done a starter valve sync for the first time in April of this year, it looked like I was on my way to another one. Still, it would give me a chance to use the Carbtune device I had picked up on-line during the lockdown. Sure enough, lots of difference in pressures to resolve (see pic). The Carbtune device worked great, BTW.

So - any thoughts as to why this should have happened? Anything inherent in hours of running at open road speeds that should affect the starter valves?

Not a biggie, more of an oddity.
 

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Valve clearance shouldn't have changed much since April, unless it was already out of spec at the time the first sync was done.

First thought would be a possible vacuum leak (I guess in this case it would be on #4, if that's what the problem is). Otherwise it would be anything else that would cause a slight imbalance - spark plug gap out of spec, dirty injector(s), wonky FPR(maybe?). If absolutely everything seems fine, maybe then just something freed up a little since April :p

The only other thing I can really say is that TB/starter valve syncs are at the bottom of maintenance list, because there's so many other things that can throw it off. So if you're paranoid like me, then it would mean checking pretty much everything lol
 

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McTavish
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6,524 Posts
So I returned from my annual 1000 km round trip to the Boxing Day Street Races at Whanganui and started my bike after giving it a good wash and a change of oil and filter. I was expecting it to run as flawlessly as ever, but I got the most uneven blub-blub-blub idle I’ve ever heard from it.

Having done a starter valve sync for the first time in April of this year, it looked like I was on my way to another one. Still, it would give me a chance to use the Carbtune device I had picked up on-line during the lockdown. Sure enough, lots of difference in pressures to resolve (see pic). The Carbtune device worked great, BTW.

So - any thoughts as to why this should have happened? Anything inherent in hours of running at open road speeds that should affect the starter valves?

Not a biggie, more of an oddity.
If one considers this:
D
If it’s a new problem that arises immediately upon, or soon after, your work completion, no matter how unrelated it may appear to be on the surface, revisit that work as part of the Assessment.


.......then I'd be starting with the bike just having been washed.
All this started right after washing post flawless operation.
I'd go as far to say it's extremely unlikely the cause is anything else.
The question then becomes, what could have been adversely affected by washing, to make the bike behave as it now is.

I get that you are dying to use your spiffy new Carbtune, but suggest you don't until the problem is sorted out, then have your fun with it.
 

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I get that you are dying to use your spiffy new Carbtune, but suggest you don't until the problem is sorted out, then have your fun with it.
Too late, mate, the spiffing is done...

All is back in order - the pressures have been realigned from pic 1 to pic 2. Scientific method will have to apply if it happens again, next time it gets a wash.
 

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McTavish
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Too late, mate, the spiffing is done...

All is back in order - the pressures have been realigned from pic 1 to pic 2. Scientific method will have to apply if it happens again, next time it gets a wash.
Hey, you got to use it, the bike's behaving again, so it's all good.
How much do you want to bet it won't happen again when you wash your bike the next time?
 

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McTavish
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6,524 Posts
Scientific method will have to apply if it happens again, next time it gets a wash.
More correctly, the Mr. Wilson Method.
High School Auto Shop Teacher Extraordinaire.
He switched to teaching after having been in the trade for years, having had a reputation for being an ace diagnostician.
One of the best teachers I ever had, the "best" being my Top 5.
 

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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
Dear All.

Is there any pictures, what I cal use next to this write up? I am from Hungary, I have a 2002 CB900F and unfortunately 2 weeks ago a mechanical tried to make a sync, but he was not an expert and create wrong setup on my bike. He also disassembled the TP sensor, but based on this forum, I was able to set it correctly.

Now I bought a Healtech e-sync tool, tomorrow I want to set it properly, so every tips/tricks/pics will be appreciated. :)

Have a great day!

Regards:
Gyula
 
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