Whats Up? Don't ask me!

[TCHILDERS]

You may remember me, I posted last week about my new purchase- a 2002 with Walker's stage 1 and 4-2 exhaust. I was unsure about how it was running. I finally ran a tank of gas through it and got 24.5 mpg. Whats up? Don't ask me! I'm taking it to a guy I know to tune the carbs/ make sure they're synched, etc. I was doing some reading and saw that some people either wire around the Vboost, jumper it on all the time, throw in a key switch for the former and on and on. If something like this has possibly been done, what should I look for. Just looking for more input. Thanks!

Travis

 

[maleko89]

When you turn the key do you hear the vboost open, close? It sounds like a motor whine.

 

[TCHILDERS]

I do hear something. I 'm at work now and I don't have my bike with me (I'm not wanting to ride it until I get this resolved). I was told by the previous owner that it was the fuel pump, however it sounds like two separate things happening. I'm definately needing to check it better tonight. What exactly would i hear? Can I physically see the valve shift if this is the case?

 

[maleko89]

If you look past the plastic "H" cover on the side you can see the valve cycle open and closed. Check this thread, there are a couple of links illustrating the sound of vboost.

If you hear a clicking noise, that's he fuel pump.

http://www.vmaxforum.net/showthread.php?t=3249&highlight=vboost

 

[RVAVMAX]

If you look past the plastic "H" cover on the side you can see the valve cycle open and closed. Check this thread, there are a couple of links illustrating the sound of vboost.

If you hear a clicking noise, that's he fuel pump.

http://www.vmaxforum.net/showthread.php?t=3249&highlight=vboost

I'll have to give mine a listen tonight... I dont recall hearing that.

 

[TCHILDERS]

I listened to the youtube clip of the valve opening. I'm almost 100% sure I here this when I turn the key. This would definately explain the odd power and bad mileage, especially if it wasn't tuned for it in the first place (whether or not that would be needed, I don't know) what should I check first to try to get it working back at the stock 6000 rpm range?

 

[maleko89]

Travis, it's normal for vboost to cycle when you turn the key. It opens, closes and then removes slack in the cable. To see if it opens at 6K just slowly accelerate to 6K in 1st gear and you should feel a small increase in acceleration.

For mileage problems, check your carb sync. With Cobras, your mileage will go way down unless you decrease main jet size. Make sure your floats are all 17 mm and make sure you are using stock needles.

 

[TCHILDERS]

Thanks Mark! you're quite the pool of knowledge!

 

[maleko89]

Not a problem. One more thing to check is your mixture screws and make sure you air filter is clean.