Carb sync question, ST1100A model

[vinny]

The Synchrometer is what I use...it's so easy and works.

 

[mtnpat]

The Synchrometer is what I use...it's so easy and works.

I had no problem getting the carbs synced using my Carb Stix and making the bike run marvelously (night and day difference), the problem is it not staying that way.

 

[Brant]

Likely won't stay unless the sync was done with airbox/filter in place, or if cooling fan comes on during process, or if you didn't shut it off and blip throttle several times to seat the screws stable, re-start and check again...........a few time process to get all stabilized.......a ten minute sync ain't gonna cut it......for any length of time anyway. Use an external cooling fan on the floor of the man-cave to stave off that cooling fan coming on......helps speed up the process a bit.

 

[mtnpat]

Likely won't stay unless the sync was done with airbox/filter in place, or if cooling fan comes on during process, or if you didn't shut it off and blip throttle several times to seat the screws stable, re-start and check again...........a few time process to get all stabilized.......a ten minute sync ain't gonna cut it......for any length of time anyway. Use an external cooling fan on the floor of the man-cave to stave off that cooling fan coming on......helps speed up the process a bit.

This makes sense to me too. Thanks

 

[Uncle Phil]

Likely won't stay unless the sync was done with airbox/filter in place, or if cooling fan comes on during process, or if you didn't shut it off and blip throttle several times to seat the screws stable, re-start and check again...........a few time process to get all stabilized.......a ten minute sync ain't gonna cut it......for any length of time anyway. Use an external cooling fan on the floor of the man-cave to stave off that cooling fan coming on......helps speed up the process a bit.

Hmm, I must be pretty lucky then. The 5 or so ST1100s I've synced with the Flowmeter (3 of which are mine), seem to stay synced without all the fuss.

 

[mtnpat]

Brant,

I have friends in Whitewater, CO. I visit every chance I get!

 

[Bigmak96]

Hmm, I must be pretty lucky then. The 5 or so ST1100s I've synced with the Flowmeter (3 of which are mine), seem to stay synced without all the fuss.

+1
I'm sure the more involved steps are needed to do a lot of applications and I applaud your attention to detail. The 1100 does seam to be fine with the Synchometer in my case too. I have to think something is making the screw move after the fact. Mine have always stayed put.

 

[Uncle Phil]

If you think about the mechanical part of it, they are springloaded screws. If they are indeed moving after the fact, then the springs could be weak - not impossible, but unusual or the stops are worn awful funny or the linkage is messed up. It could be stripped threads that the screws are going into or worn threads on the screws themselves. I'd still check for torn carb diaphrams, fuel pump problems, vacuum hoses loose or cracked, or carb boots cracked. Unusual problem to say the least as usually a sync lasts a pretty good while in my limited experience. With a Flowmeter it would be real easy to spot which carb or carbs got back 'out of sync' and chase the problem from there, since you are not 'disturbing' any linkage or hoses or screws in the process of checking.

 

[Bigmak96]

Maybe those carbs were taken apart at some point and the spring is just not there. If everything is there, it seams really odd that it would not stay put. A person would have to really mess up to strip the threads I would think.

 

[Brant]

Another factor to consider is, even though shutting off and blipping the throttle to seat the screw threads, I guarentee I could come to ANY muti carb scoot after a known good sync and it was ridden five minutes the sync would be off a little again. In saying that, it also depends on what you are calling 'being off'. In reality, the idle mix to be set first, sync, re-check/ set idle mix and again re-sync. Don't know if this procedure is TOTALLY necessary unless carbs were apart. BTW mtnpat, Give me a shout when your this direction, # in on the RAN list.

 

[George]

Just for reference, did my synch with the snail thing a few weeks ago, had the carbs off for fix the enricheners and check for a coolant leak. Put it back together and rode it yesterday, all good. Didn't bother to check the balance.

I do the synch with the air box open, all 4 carbs get the same treatment in the same atmosphere so not a problem doing it that way. 48 MPG and smooooooth.

Waiting to hear the results of the second check from OP.

 

[Ross Smith]

Hmm, I must be pretty lucky then. The 5 or so ST1100s I've synced with the Flowmeter (3 of which are mine), seem to stay synced without all the fuss.

Agree with Uncle Phil. I've only needed to do mine once since 2007 and I started by first thoroughly cleaning then mechanically synchronizing the 4-pack. Then I used the vaccuum method as specified by Honda. Maybe you should clean things up and check your linkages first, too.

Once synced you should stay that way for quite a while. Loss of performance can be from other sources. Verify you're still synced first, then start looking elsewhere. If not, I'd bite the bullet and remove then check out your carbs. Comments about "slipping" or "missing spring" screws posted earlier is where I'd start looking first, too. Dirt and oil from a previous owner lubricating the screws or damaged seats can also create problems.

Ross

 

[jfheath]

Exhaust leaks can interfere with the balance of the engine.

I sometimes managed to get the balance right straight away. Then on other occasions it seemed to take ages, and gave different readings every time I blipped the throttle. I mentioned this to the local Honda Service chap. He said - 'The engine needs to be warmed up, but if you don't get it right in the first few minutes, the engine gets too hot. Walk away from it and let it cool down a bit and go back a bit later.

 

[mtnpat]

Update.

Synced the carbs for the second time and all is well again. I have about 500 miles on it since and smoothness and power is back where it should be. So they were out, no other problems found.

A lot of wisdom on this forum, thanks everyone for chiming in.

I think next steps if I have another problem (or just because I probably should anyway) are to clean and inspect linkages, remove adjuster screws and springs, clean, re-install. I think also I might take a file to the bottom of each adjuster screw and make sure they are all flat and smooth, this I hope will help keep them from drifting.

Thanks again

-mtnpat

 

[George]

Pat, simple question here: has anyone ever removed those screws 'n springs? I'll be surprised if we get an affirmative answer.

 

[Ross Smith]

has anyone ever removed those screws 'n springs? I'll be surprised if we get an affirmative answer.

Yes, I have. I completely dismantled my carbs back in /07 when I had just bought the bike. Wanted to clean up everything in there before synching them mechanically. Followed that by the standard Honda vaccuum synch as shown in the shop manual.

Ross

 

[GitSum]

Pat, simple question here: has anyone ever removed those screws 'n springs? I'll be surprised if we get an affirmative answer.

Yep

 

[John OoSTerhuis]

Not yet, but I will eventually, and plan to replace the screws with stainless steel 5mm hex-socket-head screws to make it easier to do a carb sync.

John