Quantcast

95 hesitation/stalling when throttle cracked

Yamaha Star V-Max VMAX Motorcycle Discussion Forum

Help Support VMAX Forum:

Hijinx1812

Well-Known Member
Supporting Member
Joined
Jun 25, 2014
Messages
192
Reaction score
20
Location
Allen Park, MI
Hey guys... I sent my carbs out a few weeks ago to Danny for a rebuild with Sean’s jet kit. Quick turnaround and they look great!

The issue I’m having is that I can’t get the bike to run right with the carbs back on. It bogs down when I blip the throttle, makes a huge sucking sound from the front of the bike and almost dies. It will die if I hit the throttle too hard when it’s idling. Riding, it’s hesitating a little in lower rpm’s, is a little jerky with steady throttle, and the vboost isn’t kicking in. It almost sounds like a vacuum leak but I can’t find one - all the airbox boots are new, all the clamps are tight, and the carbs seem like they’re completely seated. The restrictors are all in place. I’m at a loss right now. Any advice as to what might be causing this? I’ve got an appointment with Damon Ferraiuolo after the first of the year to sort it out but I really want to get some riding in before it snows!

Again - Danny’s rebuild and Sean’s kit are top notch - I’m sure there’s something else that I’m missing!

I really wish I could post a vid of it running....
 

Fire-medic

Well-Known Member
Joined
Mar 25, 2011
Messages
10,190
Reaction score
608
Location
Miami Florida
Have you tried to use a can of ether/starting fluid to spray the airbox-to-carburetors, and then the carbs to VBoost, and finally the intake manifolds to cylinder head connections? Looking for a vacuum leak.
 

Parminio

Well-Known Member
Joined
Apr 22, 2016
Messages
185
Reaction score
59
Location
Atlanta
Did you sync the carbs? If so are you sure you put all the vacuum caps back on?

And if you didn't sync the carbs, I would start there.
 

Fire-medic

Well-Known Member
Joined
Mar 25, 2011
Messages
10,190
Reaction score
608
Location
Miami Florida
Dannymax I bet got the carbs very close on synchronization when he did them. Sounds like a vacuum leak somewhere.
 

Hijinx1812

Well-Known Member
Supporting Member
Joined
Jun 25, 2014
Messages
192
Reaction score
20
Location
Allen Park, MI
I’ve synced them & the caps are definitely on. The originals were starting to crack a little so I replaced them with new. I’m pretty sure it’s got a be a vacuum leak somewhere but I just can’t seem to narrow down where.

The carbs were doing awesome on Danny’s test motor so I’m sure it’s my bike 😡
 

Hijinx1812

Well-Known Member
Supporting Member
Joined
Jun 25, 2014
Messages
192
Reaction score
20
Location
Allen Park, MI
Have you tried to use a can of ether/starting fluid to spray the airbox-to-carburetors, and then the carbs to VBoost, and finally the intake manifolds to cylinder head connections? Looking for a vacuum leak.
I did and found a small leak in the boot between the carbs and manifold. I loosened them all, pushed the carbs down as far as I could, and it seemed to resolve the leak.

This is probably a really stupid question, but how can I tell if the carbs are COMPLETELY seated? I’ve got them pushed in all the way as far as I can tell, but is there a way to verify? Are there visual lines on the throats or something that line up? If it’s not too much trouble, would you mind posting pics of where your carbs meet the manifold so I can compare? Thanks!!
 

Parminio

Well-Known Member
Joined
Apr 22, 2016
Messages
185
Reaction score
59
Location
Atlanta
I can feel mine pop into place. It's an obvious pop.

The trick is to make sure the boots are seated to the manifold and tightened down before you put the carbs on.
 

dannymax

Well-Known Member
Joined
Jun 25, 2008
Messages
13,226
Reaction score
105
Location
columbia county new york
Glad to hear you got it! Ring the boots and outsides of the carb throats with WD 40 before pushing them down and as mentioned they will sort of pop into place. Then tighten the clamp screws. White lithium grease works well as a lube also.

Altho if it's running good...and all 4 carbs are at the same depth I wouldn't worry about it.
 

Hijinx1812

Well-Known Member
Supporting Member
Joined
Jun 25, 2014
Messages
192
Reaction score
20
Location
Allen Park, MI
Thanks! I’ll give it one last go tomorrow. I’ve got the day off so I’ll have a little extra time. I’ll give the white lithium grease a go, too. It should stop any minor leaks and make it easier to seat the carbs 👍🏻
 

Latest posts

Top