Starter Valve Sync question

[Forden]

The factory manual is clear about the vacuum settings for cylinders #3 and #4 (-20mmHg and -10mmHg from #1 respectively), but says nothing about #2 (see pic).  Advice, please?  I'm sure I could split the difference and be fine but I'd like to know the real deal.

thanks

Mike

[Grum]

Hi Mike.

 

Sorry, but the manual is very clear for what cylinder 2 should be adjusted to!

It firstly states to "Adjust each intake vaccumm pressure with number 1", that implies cylinder 2 is matched to 1. Then there are the specific adjustments for 3 and 4.

 

Here's "the real deal" correct adjustment for a 5th gen. Service Manual is confusing for cylinders 3 and 4. See the link below for further info.

 

Cylinder 1 = Master, reference.

Cylinder 2 = Match to 1.

Cylinder 3 = 20mmHg MORE than 1. (NOT "dropped").

Cylinder 4 = 10mmHg  MORE than 1.

 

https://www.vfrdiscussion.com/index.php?/forums/topic/94504-5th-gen-starter-valves-sync-incorrect-for-last-22-years/

 

Here's some interesting Honda info I found specific to the 5th gen.........

 

"VFR800FI Idle Air Control - A starter enrichment valve controls airflow to each cylinder at idle speeds. The starter enrichment valves allow air to bypass the throttle valves at idle to keep the engine running and provide a fast idle for engine warm up. The VFR800FI is unique because the starter enrichment valves are adjusted to different vacuum readings to compensate for differences in exhaust length between cylinders."

[gropula]

I should do the starter valve sync soon because I adjusted the valve clearances. This got me thinking because I have a 6th gen with a 5th gen exhaust. The front pipes don't cross over anymore. Though, from the thread you linked, there should be a difference in fuel that is supplied at idle to each injector. I'll check in rapid bike app what are the injector opening times at idle for each injector at idle and go from there.

[Hingley]

I have a related question to this form

Has anyone ever synced the starter valves and found one valve to be very hard to get any movement on the balancing gauges, I came across this in the spring after 

I went through a 1999 VFR800 last winter and have wondered since what would cause it. The bike seems to run fine just not convinced the starter valve balance is 100%

 

[Skids]

I've always struggled to get the right vacuum levels and idle revs to be correct. Just get them as close as you can. 

[Mohawk]

Nope works great on mine. 

[Gaz66]

On 12/14/2023 at 4:40 PM, Hingley said:

I have a related question to this form

Has anyone ever synced the starter valves and found one valve to be very hard to get any movement on the balancing gauges, I came across this in the spring after 

I went through a 1999 VFR800 last winter and have wondered since what would cause it. The bike seems to run fine just not convinced the starter valve balance is 100%

 

Hi New member here.

My experience of starter valves being out of spec is rough low rpm running, snatchy throttle response & poor fuel economy.

You wouldn't think a simple adjustment would make much difference, but it really does transform the low rpm below 3,000rpm.

If you see no needle movement on you vac gauges from an adjustment, it's possible one or more of the starter valve plungers may be sticking within its bore.

What seems to not get discussed on this matter is that the old style vac gauges that most have must be synched to each other before any adjustments are attempted on the bike or any adjustments made are pretty much irrelevant.

It's simple process to adjust a 5th Gen, long nosed pliers are sufficient if a 7mm spanner isn't available, adjusters take little effort to flick them to the next index point, there's no fine adjustment as the valve heads use tiny tapered ramps to click to the next index point, so any adjustments are a compromise ...  "Pair" system needs to be blanked off prior to adjustment, may as well pull the whole system out as it does nothing for performance or fuel economy.

 

 

 

[Tirso]

1 hour ago, Gaz66 said:

1) it's possible one or more of the starter valve plungers may be sticking within its bore.

2) What seems to not get discussed on this matter is that the old style vac gauges that most have must be synched to each other before any adjustments are attempted on the bike or any adjustments made are pretty much irrelevant.

 

 

 

1) had this issue with my 5th Gen when I got it in late '18. It had only 18K miles and two of the plungers were sticking.

 

2) had similar issue last year with my Carbtune Pro 4 where the tubes needed cleaning.

 

and as mentioned by Grum above, read this

 

 

 

[Skids]

14 hours ago, Gaz66 said:

  "Pair" system needs to be blanked off prior to adjustment, may as well pull the whole system out as it does nothing for performance or fuel economy.

 

 

 

PAIR system needs to be removed. 

[Gaz66]

On 12/15/2023 at 10:14 PM, Tirso said:

 

 

1) had this issue with my 5th Gen when I got it in late '18. It had only 18K miles and two of the plungers were sticking.

 

2) had similar issue last year with my Carbtune Pro 4 where the tubes needed cleaning.

 

and as mentioned by Grum above, read this

 

 

 

Hi Tirso.

 

Agreed, it's a pain in the ass when starter valve plungers get stuck, if the bike is new to you, it pays to drop the throttle body off for a good wash out, it's not uncommon for starter valve plungers to be gummed up with dirt, it's surprising how much crap gets past the air filter, as you'll see when cleaning out the throttle butterflies & bores, also a good time to pull the injectors & blast em thru with some Holts EGR cleaner in a spray can, far more aggressive than any carb cleaner, it's nasty smelly stuff, I've yet to find anything more effective to blast thru injectors, most won't have the applicable injector pulsing tool, so just use a 9V (PP3) torch battery, 2 lengths of wire with crimps fitted rig a tight fitting hose over injector inlet, & squirt EGR solvent thru while pulsing On/Off on the 9v battery, if spray pattern won't come good, after a few squirts, leave em vertical & soaking with EGR cleaner inside for half hr & try again, never failed using this method, avoid EGR cleaner on skin/eyes/clothes/paint etc.

Talking of Carbtune vac balance tool, I don't rate them personally ... can't see how you can synch one tube with another, they're a rough adjustment at best, old style dial vac gauges are cheap nowadays & actually more than up to the job of synching carbs/throttle bodies etc, Carb-tunes are silly money IMHO, you can spend whole lotta cash on higher spec oil filled dial units too, they're no more accurate than the cheaper dry gauges for this job, just synch all 4 gauges on the same vac port & you're good to go, used this type for the last 40+ yrs on my own & customers bikes, never had any issue.

Electronic versions are now readily available at not silly money, they were crazy money up until a few yrs ago as the tool was aimed at the pro-mechanics market, electronics are the way forward, but like I've stated above, old Skool is all that's required for this synch job.

[Grum]

2 hours ago, Gaz66 said:

Agreed, it's a pain in the ass when starter valve plungers get stuck, if the bike is new to you, it pays to drop the throttle body off for a good wash out, it's not uncommon for starter valve plungers to be gummed up with dirt, it's surprising how much crap gets past the air filter, as you'll see when cleaning out the throttle butterflies & bores, also a good time to pull the injectors & blast em thru with some Holts EGR cleaner in a spray can, far more aggressive than any carb cleaner,

WARNING - Be very careful when cleaning the Throttle Body not to damage the Molybdenum seal coating for the butterflies do that and you'll end up high rough idle, you could end up needing a replacement throttle body assembly!.

 

[Forden]

On 12/13/2023 at 8:10 PM, Grum said:

Hi Mike.

 

Sorry, but the manual is very clear for what cylinder 2 should be adjusted to!

It firstly states to "Adjust each intake vaccumm pressure with number 1", that implies cylinder 2 is matched to 1. Then there are the specific adjustments for 3 and 4.

 

Here's "the real deal" correct adjustment for a 5th gen. Service Manual is confusing for cylinders 3 and 4. See the link below for further info.

 

Cylinder 1 = Master, reference.

Cylinder 2 = Match to 1.

Cylinder 3 = 20mmHg MORE than 1. (NOT "dropped").

Cylinder 4 = 10mmHg  MORE than 1.

 

https://www.vfrdiscussion.com/index.php?/forums/topic/94504-5th-gen-starter-valves-sync-incorrect-for-last-22-years/

 

Here's some interesting Honda info I found specific to the 5th gen.........

 

"VFR800FI Idle Air Control - A starter enrichment valve controls airflow to each cylinder at idle speeds. The starter enrichment valves allow air to bypass the throttle valves at idle to keep the engine running and provide a fast idle for engine warm up. The VFR800FI is unique because the starter enrichment valves are adjusted to different vacuum readings to compensate for differences in exhaust length between cylinders."

Ah, thank you, I was reading that as "in reference to" #1, and didn't catch the implication that #2 just match.  Thanks for that other thread also, I will be giving that a shot.

Cheers