Vboost problems

[Daniel]

Hello, I purchased a second Vmax ('97) and I?m having problems with the Vboost on my second max. When riding I don?t feel the boost at 6K rpm. When turning the key the servo motor is doing his normal reset. When I turn the throttle to 6K rpm I see the Vboost cable opening the valves. So mechanically everything is working OK but riding I can?t feel the boost. As I still had my first Vmax I swapped a few part (CDI unit, carb?s, advance ignition unit, ?..) to diagnose the problem but with no results.
The sparks are OK on the 4 cylinders. The valves are opening normally.
Now my fist Vmax is sold and I don?t have any parts to swap anymore.

Do someone have an idea?

Thanks a lot.

 

[maleko89]

I would take the carbs off and sync the vboost as per service manual. Turn key on, and shut off before vboost valves close again during the self test. Stick your fingers on each side and make sure valves are open all the way. If not, there's an adjustment screw at the cable junction.

Mark

 

[Daniel]

This was checked. Vales are all open.

 

[maleko89]

Are they open all the way though? Valve should be parallel to vboost tube.

Mark

 

[shawn kloker]

Hello, I purchased a second Vmax ('97) and I’m having problems with the Vboost on my second max. When riding I don’t feel the boost at 6K rpm. When turning the key the servo motor is doing his normal reset. When I turn the throttle to 6K rpm I see the Vboost cable opening the valves. So mechanically everything is working OK but riding I can’t feel the boost. As I still had my first Vmax I swapped a few part (CDI unit, carb’s, advance ignition unit, …..) to diagnose the problem but with no results.
The sparks are OK on the 4 cylinders. The valves are opening normally.
Now my fist Vmax is sold and I don’t have any parts to swap anymore.

Do someone have an idea?

Thanks a lot.

My vboost was working correctly when I took it off and sold it.I never felt it open and shut ever.I guess if I was going to haul ass,full throttle, it flew right up past 6k pretty quick.Maybe it you roll it on real slow?

You should adjust the slack up in the cable so it is fully opening.

 

[Daniel]

All mechanical adjustmenst are done like described in the service manual (Haynes).
Can it be a ignition problem? Or "broken" wiring problem?

Daniel

 

[4gasem]

Did you replace the unit that controls the Vboost servo?

My buddy's '86 did this exact same thing. Would work great sitting there but never opened or opened every once in a while on the street. He swapped it out and bang it took off...:clapping:

 

[shawn kloker]

I have opened them up and resoldered the wire connections for other people and they worked fine then.They seem to get loose and corroded.

 

[Daniel]

Yep, Vboost controller has been swapped with a good working one, unfortunately without any positive result.

I'm really out of idea's........:confused2:

Daniel

 

[Robbarrie]

I was thinking that the carbs weren't jetted right or badly out of sync. However you said switched carbs so now I'm thinking now of some kind of obstruction - is this possible ? It just doesn't make sense, when you think about how the boost works in the first place.
On the cycle test unplug the controller it at the point it is opened fully and take the bike for a rip - just to see how it responds.

 

[Daniel]

I tried also this test of disconnecting the connector during the reset at the point when it?s fully open. When riding I still don?t feel the boost. The only thing I notice is when running stationary or in neutral position (I don?t know if this is the good word in English) he is not running as smoothly as when the valves are closed but I think this is normal.
It is also a proof that the valves do open when the vboost cable is pulling it up.

Pfff.... loosing all the hope..........

Daniel

 

[Daniel]

I tried also this test of disconnecting the connector during the reset at the point when it?s fully open. When riding I still don?t feel the boost. The only thing I notice is when running stationary or in neutral position (I don?t know if this is the good word in English) he is not running as smoothly as when the valves are closed but I think this is normal.
It is also a proof that the valves do open when the vboost cable is pulling it up.

Pfff.... loosing all the hope..........

Daniel