1996 VT1100 throttle hesitation

[Poundingsand]

I've had the bike for about a year now, given to me as a gift. It had sat in an in-laws garage for a long time, and the carbs seemed to be dirty. After several carb cleanings AND an idle screw adjust, the symptoms have gotten milder, but are still there.

Once the bike is warm, it has a stumble on initial throttle application, but seems to rev well through the rest of the range. In experimenting, I removed the seat and placed my hand over most of the air intake. As a result the hesitation went away, and midrange was fine, but the bike choked out at the top end.

My GUESS is it's lean on the bottom end (go one size larger in slow jet?) and fine through the rest of the range.

It also has a mild pop on decelleration and a decent backfire through the pipe a wide open throttle in it's normal state (no hand over the intake).

Any other (even differing hahaha) opinions are most appreciated!!

[gdb069]

Has there been any modification to the carb ie. jet kit or air intake or exhaust?

G.

[John Hopkins]

several questions..

Twin carbs?

both pilot screws adjusted in until they gently touch the rubber o'ring then opened 2.5 turns?

carbs balanced after cleaning?

both carb diaphragms gently stretched to check for splits or pinholes?

Air cutoff valves stripped and cleaned when carbs cleaned?

Fuel filter replaced?

Taken for a long run to clear out old and fill with fresh gas?

[Poundingsand]

Twin carbs, diaghrams checked (would this only affect low range or all ranges of throttle?)

Fuel filter - wouldn't this affect all ranges of throttle, or be more likely to affect full throttle settings?

Stock carbs, stock exhaust. Stock jets as far as I know.

[Scrapdog2grand]

Originally Posted by John Hopkins

several questions..

Twin carbs?

both pilot screws adjusted in until they gently touch the rubber o'ring then opened 2.5 turns?

carbs balanced after cleaning?

both carb diaphragms gently stretched to check for splits or pinholes?

Air cutoff valves stripped and cleaned when carbs cleaned?

Fuel filter replaced?

Taken for a long run to clear out old and fill with fresh gas?

any mods to the exhaust or intake as asked?
make sure the transfer holes behind and under the throttle plates are clear.
Once you do all that ^^ one up on the pilot jet may be what you need.
That answers all that, Thanks

[Poundingsand]

ALso, nit sure which the air cut-off valves are, but I cleaned everything I saw and/or was able to disassemble.

Carbs were not balanced, but were also not seperated.

Unfortunately I have no way of determining if anything else on the bike was changed, or if the running slowly degraded, or it was a sudden change, as the previous owner passed away.

Pilot screws are at about 3 1/4 turns at this point to try to fix the lean situation at just above idle.


Also, all old gas was removed and replaced when I cleaned the carbs.
I may need to check the diaphragms again...

[JRega]

Sticky situation. The problem is a bit beyond my knowledge, but I do have a word of caution. I've posted on my own carb issues and I was warned that if you bring your screw out that far that they tend to fall out while riding. If you are going to ride with them out that far I was told that you should put some tape over the hole to make sure you don't end up having a worse day.

[Scrapdog2grand]

Originally Posted by Poundingsand

ALso, nit sure which the air cut-off valves are, but I cleaned everything I saw and/or was able to disassemble.

Carbs were not balanced, but were also not seperated.

Unfortunately I have no way of determining if anything else on the bike was changed, or if the running slowly degraded, or it was a sudden change, as the previous owner passed away.

Pilot screws are at about 3 1/4 turns at this point to try to fix the lean situation at just above idle.


Also, all old gas was removed and replaced when I cleaned the carbs.
I may need to check the diaphragms again...

Not all carbs have air-cut valves, look at the parts diagram or service manual.

Originally Posted by JRega

Sticky situation. The problem is a bit beyond my knowledge, but I do have a word of caution. I've posted on my own carb issues and I was warned that if you bring your screw out that far that they tend to fall out while riding. If you are going to ride with them out that far I was told that you should put some tape over the hole to make sure you don't end up having a worse day.

I use touch up paint for this, works pretty good.

[Poundingsand]

any mods to the exhaust or intake as asked?
make sure the transfer holes behind and under the throttle plates are clear.
Once you do all that ^^ one up on the pilot jet may be what you need.
That answers all that, Thanks
______________________________________

I doubt there were any mods. The previous owner was a rider, not so much a modifier...

Transfer holes were blown through. One side sent a nice mist of solvent when blown through, and the other side needed several blasts with air and cleanerd until it also would stream through, although not with the same consistent mist...

[Pothole]

Set your air/fuel screws at 2.5 turns, dump half a can of seafoam in a full tank of fuel and run the piss outta it.