V-Boost Working But Not Working ?

[Jess Willhite]

Well I have looked through the forums under carb. tuning and other V-Boost related items but cannot find anyone having the same V-Boost issue as me. Most everything related to the V-Boost system is the actuator not working but mine works fine and always has. My dilemma is there is no V-Boost power like there used to be. I've got a Gen 1 98 V-Max and have owned it about 18 years. It's always been a great bike and love the power of this thing and loved it when the V-Boost would kick in and it was like opening the secondaries on a muscle car 4 barrel cab or power like a 2 stroke dirt bike. Well it doesn't do that any more When key is on actuator works like always but when riding and getting on the throttle in high RPM's where the V-Boost should kick in it stumbles and falls on it's face. I'm guessing it's a cabuerator issue but messing with carb. tuning and not being able to get it back where it was when I started moving things is a fear of mine. I did buy a good sync. tool and synced all the carbs following the instructions in the forum and surprisingly they weren't that far off. It runs fine and idles fine even has good power with no stumble till you get into the high RPM's or WOT. Sorry for the novel and any words of advice are greatly appreciated. It may just be time to send the carbs. to DannyMax and have them fully rebuilt then go from there. Thanks in advance.

 

[Penny Lee]

I just started to have issues with my vboost. Works fine in 2nd and 3rd gear but not fourth. Wants to cut out. 1986 with 71,000 miles. I have owned 15 years.

 

[Fire-medic]

Check your air filter and the fuel filter. Also check your fuel lines to ensure they don't have any pinholes or splits.

Drain your float bowls, leave the drain screws open, pressurize the fuel hose where it connects to the rigid gas feed on-top of the gas tank. Look along the gas hose for any leaking air. You don't need much pressure, you can hear and feel a leak.

 

[Jess Willhite]

Thank you I know the air cleaners are good. I will check all the fuel related items hopefully tonight.

 

[Pighuntingpuppy]

My 2007 just started having issues similar to yours. My bike starts, idles fine. Will go through the entire RPM range without a hiccup. Just lacking power on the top end and the Vboost does not appear to be functioning. One more thing I also noticed is that when I am at idle, the bike is idling around 900. Usually when warmed up, I was at 1000. What I am doing, is first I checked to make sure the air filter and Vboost servo are in visually good working order. I did a quick visual check of the slides in the carbs to make sure nothing appeared to be backing out. I then removed all my spark plugs to see if someone isnt playing nice. What I found is that the right front cylinder on my bike has a black fuel fouled spark plug. The rest are a very light golden tan color. So....now I know where to look.

I dont smell raw fuel on my bike at any time(unless I am filling up, but thats because I have the tank open to fill up). So...at this moment in time, I dont suspect my carbs to be the faulty party. I suspect weak spark. Since the front coils are in an amazingly fun spot, I started to remove the coil for that cylinder last night. I ran out of light, ambition and energy to get it out to test. So, before you start shotgunning parts at the bike, do the cheap easy stuff first. See if you can determine which cylinder is bringing you down. Fire Medic's advice is spot on as well. Do what he suggests as well.

 

[Jess Willhite]

My 2007 just started having issues similar to yours. My bike starts, idles fine. Will go through the entire RPM range without a hiccup. Just lacking power on the top end and the Vboost does not appear to be functioning. One more thing I also noticed is that when I am at idle, the bike is idling around 900. Usually when warmed up, I was at 1000. What I am doing, is first I checked to make sure the air filter and Vboost servo are in visually good working order. I did a quick visual check of the slides in the carbs to make sure nothing appeared to be backing out. I then removed all my spark plugs to see if someone isnt playing nice. What I found is that the right front cylinder on my bike has a black fuel fouled spark plug. The rest are a very light golden tan color. So....now I know where to look.

I dont smell raw fuel on my bike at any time(unless I am filling up, but thats because I have the tank open to fill up). So...at this moment in time, I dont suspect my carbs to be the faulty party. I suspect weak spark. Since the front coils are in an amazingly fun spot, I started to remove the coil for that cylinder last night. I ran out of light, ambition and energy to get it out to test. So, before you start shotgunning parts at the bike, do the cheap easy stuff first. See if you can determine which cylinder is bringing you down. Fire Medic's advice is spot on as well. Do what he suggests as well.

Thanks so much I will pull the plugs to see how they look also.

 

[MaxMidnight]

So, before you start shotgunning parts at the bike, do the cheap easy stuff first. See if you can determine which cylinder is bringing you down.

Good advice