V-Boost Question

[mikemax04]

There are several on this list with knowledge of running boost full time wide open. The thought of the idle sounding like it has race cams installed appeals to me. I have several questions and all answers would be appreciated.
1) At what rpm will it idle satisfactorily?
2) Will the carbs have to be re-jetted and to what?
3) Will gas mileage suffer drastically?
4) Will there be a hesitation when leaving from a stop?
5) How will it behave through the whole rpm range while cruising?

Any additional information I should know before deciding on this mod or even if it's wise to go there for the simple pleasure of the race cam effect.

TIA

 

[maleko89]

Mike, I'm not sure how it will perform with stock headers and air box. Anything can be tuned but not sure how much work it would be. Vboost full open richens you up everywhere. You could try and unplug the vboost to the open position and run some tests. I'm betting you could get by on the same main jet but would probably need to go to DJ needles and set on one of the lower needle settings. A bigger PAJ1 might be necessary and you might need to turn the mixture screws in a bit. I included a jpeg picture of a sparkplug showing you how I test the carb circuits. The side electrode end is green and should be ashy colored. If it's sooty, drop the main jet size.The porelane just below the center electrode should be white. The porcelain located deeper into the plug should be black but not overly sooty. The bottom thread is your mixture screw. You should be able to use your finger nail to get a thin layer of carbon off. If it's poofy looking, rich. I don't look too much into the mixture screw part of the plug. I set each screw by slowly turning in until the cylinder stalls. Then, turn out until it recovers and then turn another 1/8 of a turn or so.

I have Morley's air box, stock jetting, DJ needles, air correctors, springs and drilled slides. With Vboost full open, I'm getting 35-38 in town and 39-44 on the highway. I get a good idle at 1000 rpm, just like stock.

You won't get a kick in the pants at 6000 anymore of course. But, I'd much rather have a kick in the pants starting at idle. You gain horsepower torque below 6000 rpm, which is where I am most of the time anyway. My carburation is just as smooth as stock, no problems. The only thing I do is raise the needle a 1/4 clip when the cold weather hits.

Hope this helps.

 

[Robbarrie]

Mike :

I would like to add a couple of questions to your list, please and thank-you.

1) How will it affect cold and hot starting ?
2) What now happens when you use the choke ? Is it now too much resulting in flooding.
3) If you did do it, and changed it back, why ?

 

[maleko89]

I use the same amount of choke. I never need to use full choke, just 1/2 if it's below 40. After 30-50 seconds I close choke to about 1/4 open. I then head out and once I have a couple of miles on the road I turn choke off.

I can see people going back if they'e running stock airbox and/or stock headers and stock exhaust or slip-ons. Some people shut it off in rain. I never understood why until riding with it full open and once I had sync'd my vboost.

 

[Rusty McNeil]

1) At what rpm will it idle satisfactorily?

Mine idles fine at around 1050-1100rpm, it does take a little longer to bring everything up to a temp to idle well with vboost open.

2) Will the carbs have to be re-jetted and to what?

I have my needles shimmed .023 and have cut two coils out of the slide springs. Idle mixture screw set at 3.25 turns. The stock exhaust is completely gutted on mine and I also have the airbox "Y" removed.
Cruising at steady speed it runs 14.4:1-14.7:1
It runs a nice even 13:1-13.5:1 all the way up the rpm's at medium throttle acceleration.
At WOT acceleration it runs a steady 12:1-12.5:1 all the way to redline.

3) Will gas mileage suffer drastically?

I get 34-37 on the highway at 75-80mph and around 30-31 city/higway if I stay out of the throttle..about 27-30 riding like I normally do which is pretty damn hard riding. I'm not very kind to this bike

4) Will there be a hesitation when leaving from a stop?

I don't get any hesitation or if I do I may be using more rpms to get it rolling than I used to; am not really sure since I'm used to it now.

5) How will it behave through the whole rpm range while cruising?

Kinda subjective? I would say that mine has no "bad" habits...it for sure doesn't have a "hole" in the power band anywhere...starting from any lower gear and holding it in that gear it pulls hard and steady all the way to redline without any kind of "wierdness"

1) How will it affect cold and hot starting ?

No affect at all for me.

2) What now happens when you use the choke ? Is it now too much resulting in flooding.

No affect on choke useage for me.

3) If you did do it, and changed it back, why ?
N/A


Before I removed it completely I had a switch installed on one of the wires to the servo allowing me to "trap" it wherever I wanted to while the servo motor cycles right after turning the key on......eventually I removed the whole assembly after I was sure I liked it this way..plus I needed the room for my airhorns.

 

[mikemax04]

Good info Mark and Rusty, thanks. Guess I'll have to try it out to see just what the pros and cons are for me. Thanks again.

And Robbarrie, any time.

 

[Robbarrie]

I read somewhere if you turn on the key and pull off the wire assy. for the servo as it is going through it's test cycle. You can catch the Vboost fully open. No, I never got to try it... I may try it next summer, just for the hell of it.

Thanks for the info on this guys.

 

[maleko89]

That's exactly what I did. I plug it back in when I sync the carbs.

 

[mikemax04]

Unplugged the boost today in the open position and that sucker sure idles like it's going to kick ass. One thing I noticed right off is that the throttle response has more umpf at the initial opening which made the tire break loose as I was turning right out of my driveway. Woo-hoo, what a surprise going sideways while the neighbors were watching, no doubt. Sure seems to have more initial power at most speeds (legal) and then there is a bigger flat spot in the middle. Jetting, no doubt. It was a good experience and I'm glad I tried it.

Mufflers sounded different with more of a growl to them. Went back to stock cause I really don't want to change anything on the engine for the short time I'll have the bike. The fat man didn't deliver the new Max this year but when I threatened him, he promised to have it here for next year. Seems like you just can't depend on anybody anymore......<he says with a smile>.

 

[Dreamster66]

Unplugged the boost today in the open position and that sucker sure idles like it's going to kick ass. One thing I noticed right off is that the throttle response has more umpf at the initial opening which made the tire break loose as I was turning right out of my driveway. Woo-hoo, what a surprise going sideways while the neighbors were watching, no doubt. Sure seems to have more initial power at most speeds (legal) and then there is a bigger flat spot in the middle. Jetting, no doubt. It was a good experience and I'm glad I tried it.

Mufflers sounded different with more of a growl to them. Went back to stock cause I really don't want to change anything on the engine for the short time I'll have the bike. The fat man didn't deliver the new Max this year but when I threatened him, he promised to have it here for next year. Seems like you just can't depend on anybody anymore......<he says with a smile>.

Mike....where do you unplug it?
I assume you wait til its at the top of its cycle, right?

 

[maleko89]

It's the round plug under the left scoop.

 

[mikemax04]

Mike....where do you unplug it?
I assume you wait til its at the top of its cycle, right?

On mine it was a small white connector where Mark already said. When you turn on the ignition, there are two sounds from the servo. When you hear the first sound ending, turn off the ignition instantly and disconnect the connector for the servo motor. I had to turn my idle up some but it's worth a try and easy to do.

 

[mikemax04]

Found a site where some dyno tests were held on the v-boost and t-boost of the Max. It pretty well shows what Rusty had experienced at the drag strip and I also noticed for the short time I tried full boost all the time. For those interested enough in finding out in black and white, PM me so there won't be a rush out of here.

 

[madmax94]

It's the round plug under the left scoop.

Having trouble finding the "round plug" under the left scoop. Do I have to remove the air scoop to find it or is it visible from the left side of the bike? A picture would be very helpful. thanks

 

[maleko89]

Take off the top cover, the left side scoop. It's the only round connector in there.

Mark
#1098

 

[4gasem]

I have the Sasy contoller on mine which is the best of all worlds...

I can set it for several different RPM openings, on all the time or off...

Mounted nice and doesn't look like total crap which I was affraid it would...

 

[madmax94]

Stupid question, I know....but there are lots of screws, which one is the screw to set the idle?

 

[maleko89]

It's on the left side. See the plastic chrome "H" cover? Look right there it's a vertical thumb screw.

Mark
#1098

 

[4gasem]

Since you don't know where the idle adj. knob is I would gather you haven't sync'd the carbs before...

If not, you will really want to do this at some point so all cylinders are running in sync which in many cases will help smooth the idle and allow v-boost to work better when on all the time...

If you sync them, make sure that you reconnect Vboost though so it is off when syncing!

 

[madmax94]

Nope, don't know how to sync the carbs, I've only had the Max for about 6 weeks.
Found the round plug and followed everybody's instructions.......Holy crapunk: A whole different beast and the torque is amazing. I'm lovin it, and the sound.......:thumbs up:

I've got Cobra's w/ the stock air filter. I'm not sure how the previous owner set up the carbs/jetting. But it runs perfect. Will it hurt the bike with v-boost on all the time if I do nothing else to the bike and keep running it like this?