Getting to know my V-Boost

[Trondyne]

Just dumb noob questions here from a new owner...

I just took the bike on a 150 mile ride and had lots of chances to open her up here and there...

First thing I noticed is the speed limit is too low and the number of cars and trucks is too high... :biglaugh:

But I finally am getting in tune with the sounds and feel of the bike...

When I turn on the ignition there is normally no cycle of the v-boost servo that is plainly audible on other Max's that I have seen.... So I thought the V-Boost was not working especially since there once was a T-Boost kit installed...

But while riding today I realized the V-Boost *does* seem to be working -- she hits 5800, or around there and then the tone and feel changes.... It's not as dramatic as I had thought, which is why I didn't notice it before... But sure enough at just before 6K it seems like the boost is kicking in, it pulls harder and the exhaust note changes...

I also noticed, when, I assume the V-Boost kicks in, it seems to instantly vibrate, almost like a buzz feel in the bike.....almost reminded me of my other bike when the clutch is starting to go, it starts off with a vibration before it starts actually slipping as the clutch wears down...

So my question is: If the V-Boost is working why wouldn't the servo cycle when the ignition is turned on, and if it doesn't, is it still somehow working?

And is that buzzing vibration, if it is from the V-Boost, normal? Or is that a sign that either the clutch might be starting to slip or perhaps because of some imbalance in the carbs or something else?

It was fun grabbing a handful of throttle and I am seeing the oil light come on at times as well, which I see some others get but not all...

The engine and power is normally very smooth, but when revving it out with WOT there is a definite buzzing sensation....

Any thoughts are appreciated...

 

[jdeitz1979]

Just gonna throw an option out there quick. Look in the center of the carbs with a pen light or flashlight and turn the key to the on position. If the vboost is working, you’ll see the movement in towards the center of the cabs where the vboost cable goes in. Some of us cycle it open and unplug it to run it all the time.


Sent from my iPhone using Tapatalk

 

[RaWarrior]

You should hear the whirr-whirr of the servo cycling when you turn the key on and the kill switch is on RUN. If the kill switch is off I believe it will not cycle.

V-boost engaging does give a surge of torque, which could cause clutch slippage if it's worn out. Generally when a clutch slips it's smooth, but you get a surge of RPMs without a matching acceleration. I have had them chatter a bit, but it's distinct, not easily confused with normal engine vibration. That said, slipping clutches on the Max are not rare. The stock spring is marginal at best, and some synthetic oils are known to make the issue worse. I think the clutch on my '97 went around 40k. Replaced it with PCW's kit, which includes a slightly stiffer spring.

Pretty much any bike at WOT and higher rpm has a decent amount of vibration. You are sitting on a lump fueled by explosions, after all.

 

[1FK00]

They are both counter balanced and rubber mounted so they don't vibrate much even with a misfire. Could you have a driveline issue of some sort? As stated above, clutch slipping is usually smooth.

As to the V-Boost, I had marginal hearing and couldn't hear the power on self test unless I put an ear right down on the bike. (Sadly, I can't even hear "A dump truck driving through a nitroglycerin plant" now.)

Also since peak torque is right at 6,000rpm, they are going to pull harder there even if the V-Boost isn't working. A good test is to run it up in a lower gear with maybe one fourth to one third throttle - when it crosses 6k it will pull noticeably harder if the V-Boost is working.

 

[caseyjones955]

When I got my bike I could hear the Vboost cycle. It stopped cycling and working so I pulled the left scoop and jiggled wires on the vboost controller until it worked again. Its finicky, even after I did the solder iron fix on the vboost controller but if I pack it under the scoop right it cycles and I'm good to go.

Another thing I noticed when I first got the bike is it was fast and Vboost could be felt but it wasnt what I thought it would be, after lusting after a Vmax since 85/86 I had to concluded that I had overhyped it in my own warped brain, it was really no faster than my 955cc Triumph, which was actually still pretty decent... But still. Later on as I was trying to take care of a rich running condition (in this case courtesy of a ******* DJ jet kit installed by PO) and occasional whiff of raw fuel and a 4k rpm stumble. As I got the jetting sorted and floats adjusted properly I noticed increased performance and responsiveness. By the time the adjustments were ideal I could not only feel Vboost but it became everything I imagined a Vmax should be. In the first 3 gears I gotta watch my **** or that ****** metzler tire forgets its supposed to grip the road.

When I got mine it was stock save for a Kerker pipe, because I had the pipe it made sense to use Morleys Muscle Jet Kit, which came with his excellent guidance on jet selection. Its such a kick to ride now that I decided this project is complete.

I know other things can cause the Sx your describing, but this was my experience after feeling the same initial disappointment with performance not matching the hype. There is greater detail on this in the carb and tuning section. Its snappy, responsive and vboost requires a firm grip on the bars. Its what I wanted in a Vmax. Now I can go dump some money into my A4 and wait for spring.

 

[Zeus36]

You pointed out the bike had a T-boost installed. That may be a source of improper operation of your V-boost. I would check the T-boost instructions and then work backwards to make sure everything is back to stock once it was uninstalled. Check the manual for V-boost operation/adjustment and testing.

 

[Trondyne]

Thanks for the replies... I've been busy with work and away....

The servo from what I have seen on other bikes is loud and clear to me at least with my limited experience ... I have noticed the servo cycle when turning the ignition on only a few times, when it was very cold out.... or at least what I think sounded very much like it, but other than that not a peep...

When I did my last 150 mile ride over the weekend I had lots of time to play around with power... I did realize that just at the right time, 5800 the bike would get a moderate kick in the ass.... It seemed pretty clear that the v-boost was kicking in but still no cycling sound when turning her on.... The Cobra pipes I assume are eating some of the power in the midrange and I am used to the power she is making now, it's quite manageable, but as with any other used bike I really have no way to know how close she is to putting out max performance....

I don't have a lot of time or place to work on the bike, and I am not super comfortable messing around with things that I can mess up... I don't want a lot of down time because I ride the bike everyday or as often as possible...

I wouldn't be surprised if the T-Boost installation, which was done long ago, was undone also long ago... This bike came with a giant, and I mean giant binder, containing all the work the first owner did to it....up until the second owner, who dropped the ball... and he did a TON of stuff to the bike, both repairs and mods...

I have yet to have the chance to tune or get the bike tuned ... I just did the fork seals, which was pretty critical as she was bleeding oil badly from the forks...

There was a severe wobble if I took my hands off the bars at speed which is thankfully now gone....and the front suspension seems much more stable... I just happened to have 30 weight oil around, which is what I used for better or worse, but it seems pretty good...

There is a distinct gas smell at random times...not sure what that means and the instrument cluster on the cover sometimes needs a slap to work... I want to have the fuel system checked out and tuned, I am going to replace the rear shocks and I would like to put the stock exhaust back on....

The bike came with an aftermarket headlight which is loose but there isn't any easy way to tighten it since the headlight stay doesn't grab the mount in any way other than holding it, it moves up and down as I go over bumps...

She is tough to shift with the gear teeth making themselves known especially at high RPMs.... I'm hoping there is no case splitting in the near future... and the damn shifter is still too far away from my foot although I did get it a little closer...

If I can get her to make more power I'm thinking of putting on a Venture rear gear or if a case split happens possibly a taller 5th gear... Too bad these didn't come with 6 gears, it would have made the bike perfect...

And that's about it... I love the ride and I am hoping that not too many problems are in the near future.. Looks like the original owner had his fair share of problems, not sure why but he dropped thousands of dollars into this girl...plus all the addons..

Thanks for all the support on the forum... It's nice to hear from other owners...

 

[sdt354]

When I bought mine with 12k miles on it, the vboost didn't cycle. The first work I did was to check voltage to the servo, all go. Then take the servo apart and inspect it. I gave it the "Chopper fix" whacked it a couple of times and it started working, and has worked ever since for over 14 years. The bike sat a lot and the v-boost was seldom ever used. Sitting stagnant is mechanical abuse, sometimes.

 

[caseyjones955]

If your going to farm out the tuning see if you can find someome that has some Vmax tuning under their belt. I had that random fuel smell too and when I found no external leaks around tbe tank, lines and carb rack I figured I was going in. The second time I pulled the rack it only took 15 minutes. Got pretty good at it while trying different main jets.

What exhaust do you have, what jet kit do you have? If its reflected in the magical tome of knowledge compiled by the first owner. I love me a good service history! There may be some clues there. An exhaust would usually require jetting down and not up which lies contrary to instinct. Max likes to be a tad lean. When I got mine the PO had it to a local reputable powersports shop to install the Kerker and a Dyna Jet kit, they followed the instructions and it was disgustingly rich, turns out this is a pretty common issue and the directions leave it drowning in raw fuel. I ended up leaning it out step by step and it got snappier with each step down. That raw fuel smell disappeared too. If I dont ride like a ******* maniac I can get 120 ish before fuel light or switchinf to reserve. Often more than 130 on country scenic roads. Less on the highway.

If the 30wt feels a little harsh in the forsk you can use synthetic import ATF/PS fluid which lands closer to 7-10 wt. I found some Valvoline synth import ATF at Orilies and its just about right. Morley has a youtube vid I used as a guide, its what he suggested and its spot on. That guy and so many others really know their ****. This place saved me untold headaches and money.

For the notchy shifting, what kind of oil are you using? A popular choice here is Rotella 15-40 conventional oil. Using synthetics in older vehicles has been enough of a mixed bag for me that I just dont do it anymore. Some guys like it but my shifting quality seems best with the non-synthetic version of Rotella (T6 is synthetic, I use the other version). I do the same in my Venture with the same result. Its the same story with the Venture community (same-ish engine and gearbox different state of tune and ratios).

I live in the hills and wide open roads, and I know exactly what you mean about needing a 6th gear. I considered tbe Venture final gear too but I didnt want to neuter its snap for schooling Harleys. I love to tour and hit the open road, avoiding cities, I find the Vmax a bit high strung for more than a weekend or day ride that includes highway speeds, which is many places here in the Dakotas, MT and WY. My solutuin was to buy an 89 1300 Venture, one picks up where the other leaves off, its perfect and I think the Venture cost less than a case split/5th gear/pumpkin swap. I love my Venture as much as my max but for pretty different reasons.

 

[ga_max]

As another maxxer with Cobra's, I noticed a BIG difference in the feel of the VBoost when I added the Cobras. While I love the look and the sound of the Cobras the vboost went from "Yee-ha" to "ok that was fun". I'm thinking about switch to something different down the road to get the "Yee-ha" feeling back but for now I'm OK with it. Just my 2 cents.

Doug

 

[Trondyne]

If your going to farm out the tuning see if you can find someome that has some Vmax tuning under their belt. I had that random fuel smell too and when I found no external leaks around tbe tank, lines and carb rack I figured I was going in. The second time I pulled the rack it only took 15 minutes. Got pretty good at it while trying different main jets.

I found a new shop that actually has reasonable prices and does a decent job... I'm not equipped to do a teardown so we'll see how these guys do.. The head mechanic is supposed to be very experienced...

What exhaust do you have, what jet kit do you have? If its reflected in the magical tome of knowledge compiled by the first owner. I love me a good service history! There may be some clues there.

I have the dreaded 4 into 4 Cobras.... Sound good, I like the crackling roar revving from idle but it's too loud and robs power... I'd rather have the power and quite ride of the stock plus I like the looks of the stock exhaust...

The insides of the Cobra pipes have a thick coat of carbon, not sure if that's just the nature of the beast running those...

I haven't seen anything in the book regarding jets, but there is a ton of sheets in there and I haven't seen them all.. I'll have to spend some time looking them over...

An exhaust would usually require jetting down and not up which lies contrary to instinct. Max likes to be a tad lean.

Yeah, so I'm thinking all the black soot might mean it's a bit rich...possibly it has the stock jets....

When I got mine the PO had it to a local reputable powersports shop to install the Kerker and a Dyna Jet kit, they followed the instructions and it was disgustingly rich, turns out this is a pretty common issue and the directions leave it drowning in raw fuel. I ended up leaning it out step by step and it got snappier with each step down. That raw fuel smell disappeared too. If I dont ride like a ******* maniac I can get 120 ish before fuel light or switchinf to reserve. Often more than 130 on country scenic roads. Less on the highway.

I'm getting around 96 miles now before reserve on the highway but I'm not riding too conservatively either... I have seen the oil light come on a few times and it makes me pause....

If the 30wt feels a little harsh in the forsk you can use synthetic import ATF/PS fluid which lands closer to 7-10 wt. I found some Valvoline synth import ATF at Orilies and its just about right. Morley has a youtube vid I used as a guide, its what he suggested and its spot on. That guy and so many others really know their ****. This place saved me untold headaches and money.

Thanks, the ride is a little harsh and some of the roads here are horrible.... But the stability is way better than it was...and it feels great on the highway... But I'll try that out at some point...I hate the bumps...

For the notchy shifting, what kind of oil are you using? A popular choice here is Rotella 15-40 conventional oil. Using synthetics in older vehicles has been enough of a mixed bag for me that I just dont do it anymore. Some guys like it but my shifting quality seems best with the non-synthetic version of Rotella (T6 is synthetic, I use the other version). I do the same in my Venture with the same result. Its the same story with the Venture community (same-ish engine and gearbox different state of tune and ratios).

I made the PO have the oil changed before buying it because I had to ride it home...and I'm not 100% sure what he used... I am about to change the oil now and I usually use a lighter weight mixed 10w and 5w for the Winter, a non-additive conventional oil for bikes with wet clutches... I forget the name of the other oils, that have that super efficient energy saving something additive... It was always a no no for bikes with wet clutches...

I'll have to see what everyone seems to like here and see what works best.. Missed shifts are a PITA....I need to check the segment to see if that's part of the problem...

I live in the hills and wide open roads, and I know exactly what you mean about needing a 6th gear. I considered tbe Venture final gear too but I didnt want to neuter its snap for schooling Harleys.

Lucky you!

I don't know, this bike just seems like it should have a taller final gear with all that midrange torque..... The ratios seem very close together... Funny thing is that the actual RPMs @60Mph are close to my CB900C in "HI" .... which was considered pretty conservative, back then...with a redline @ 9500...

Not sure if the 18" rear changed that much but the Cobras get loud after a while on the highway......

I wonder what the difference in top gears would be with a Venture rear.... The Max would still pull just as hard once up to speed....and whisper down the road at 70...

I love to tour and hit the open road, avoiding cities, I find the Vmax a bit high strung for more than a weekend or day ride that includes highway speeds, which is many places here in the Dakotas, MT and WY. My solutuin was to buy an 89 1300 Venture, one picks up where the other leaves off, its perfect and I think the Venture cost less than a case split/5th gear/pumpkin swap. I love my Venture as much as my max but for pretty different reasons.

With the cobras I think it seems to be working harder than it is.... I would guess that with the stock exhaust she'd sound like more of a purr...and even moreso with a Venture rear...

 

[Trondyne]

When I bought mine with 12k miles on it, the vboost didn't cycle. The first work I did was to check voltage to the servo, all go. Then take the servo apart and inspect it. I gave it the "Chopper fix" whacked it a couple of times and it started working, and has worked ever since for over 14 years. The bike sat a lot and the v-boost was seldom ever used. Sitting stagnant is mechanical abuse, sometimes.

Thanks for the ideas...

I might take a look next time I'm working on the bike... The Boost does seem to work but I know there is a really good chance that little switch means someone did some strange wiring job on the bike... I don't know why it doesn't seem to cycle yet the boost does seem to work the same regardless of the T-Boost switch position...

 

[Trondyne]

As another maxxer with Cobra's, I noticed a BIG difference in the feel of the VBoost when I added the Cobras. While I love the look and the sound of the Cobras the vboost went from "Yee-ha" to "ok that was fun". I'm thinking about switch to something different down the road to get the "Yee-ha" feeling back but for now I'm OK with it. Just my 2 cents.

Doug

Yeah, the Boost is there but honestly I didn't notice it when I first started riding her because it just wasn't as dramatic as I had imagined, like a rocket booster coming on... LOL....

I would rather have more power, quieter ride and the stock look....myself..