Tboost information
and installation,
from 2001

Zmax (1995 Vmax) projects, outdated pages are from the late 1990s>>early2000s.
This 2004+ page was uploaded again in 2023Dec, thus most links/addresses are void.
It is unknown if anyone presently is selling Tboost kits, as the only interest was reloading old Zmaxdata.

Iowaz Index Page
Iowaz Photo Hosting Site

Vmax Starter Clutch Fix

T-Boost Information and Installation
(historical information from about 2001)

....T-Boost moves the automatic operation of the V-Boost system from the stock 6-8k rpm range to the 3-4k rpm range of normal everyday riding. 
....The intent of this page is to supply basic T-Boost information to Vmax riders,
especially new VMax riders unaware of T-Boost.

1995 Vmax in 2000

What is V-Boost and what is T-Boost?
....A Yamaha ad in the 1985 Cycle World stated:  "V-Boost is Yamaha's latest powerband-widening trick.
....A servo motor opens a set of butterfly valves when the engine reaches 6000 rpm, effectively allowing two carburetors to feed each cylinder.  The system is simple and it works. 
....Each of the front cylinders on the V-Max engine is connected to its opposing rear cylinder at the intake manifold by the B-Boost passage.  This allows the four carbs essentially to do the work of eight at high rpm."
....TC (Terry Campbell) explains T-Boost:  "In a nutshell T-boost simply moves automatic V-boost opening to the 3-4K range instead of the stock 6-8K range by fooling the V-boost controller into thinking the engine is running twice as fast as it really is."

T-boost History
Terry Campbell (TC) can be given credit for developing the T-boost and making it available.  Terry was at one time offended I did not give him due credit for T-boost development and making T-boost available to all Max riders, however at the time, I had not been monitoring the T-boost or other V-Max posts throughly, as I was busy with other projects, thus I did not realize the process and time of development of the T-boost, only that Thomas Powell was making kits available for installation.  Thus Terry should be given due credit for T-boost in its present affordable form, while Thomas and Johan are making kits available.
T-boost originator Thomas Campbell's  info page

A little history of where T-boost came from....
....Terry Campbell can be and would like to be given credit for finalizing and getting the T-boost design and information out to the Vmax Tech List. Even though T-boost is being made and sold in kit form by others, Terry can be given the major credit for making the design available starting mid-year 2001---Terry noted:  I am flattered but generally embarrassed to get kudos for T-boost. As the overview states though ... it was the result of a lot of effort, sweat and input from several Tech List  members. T-Boost is public domain as stated when it was released in July of 2001 ...it is a product of the efforts of the Tech List.  Ken's was the first bike to have T-boost installed besides my own. He was the first to ever test it or know of it ... besides myself (when he test drove my '93). I originally made 35 of these things and distributed them for $5 each ... ($1 was postage) .. I made 10 more and distributed them for $10 each .. (as I was already losing money on overseas postage etc). Out of all of these I made about $40 ... which was long gone for gas money, getting supplies etc. I did this to get the concept out there. It was easier than answering all the "that won't work because" posts from the experts.  T-boost was something I also wanted to be available to everyone without some vendor sealing it in plastic and selling them for $150 each (and don't think I couldn't have made that deal ...). I was asked on the list about other people making the device and I stated clearly that I endorsed that. I never wanted to be a vendor anyhow. I appreciate the fact that Thomas and Johan are making and distributing them. I also realize that to do this on an ongoing basis they actually have to make some money ... fine ...However ... as embarrassed as I am about the kudos sometimes .. don't ever/go out of your way to edit my name out of association with tboost or/attempt to imply that it originated from anywhere other than from myself with the support of vmaxtech members.

....T-boost can take some getting used to. It can change riding style or low RPM throttle habits. The bike will feel like it wants to go faster as it passes by 3K ....even though you might be holding the throttle steady.  T-boost simply provides a means to take advantage of wide-open V-boost without all the shortcomings that come with full time V-boost for around town riding .. idling in traffic etc ...The concept of having the V-boost tubes open before 6K was not new, with many considering the concept as a good thing. The real challenge was to make wide-open V-boost disappear when we were sitting at a traffic light or cruising around town without having to flip a switch or spend a fortune to automate V-boost. . The T-boost circuit just ultimately popped out as a cheap and dirty way to do what we have been wanting to do for a long time.....Occasionally something pops out that does the job for us; like T-boost ...Stock V-boost just opens late .  T-boost originator Thomas Campbell's  info page  (working link, 2023)
Every rider does their own thing to the extent that interest, money, time and/or their modification "pain threshold" will allow ... Overwhelmingly though .. most are running pretty much stock carbs .... and T-boost is a tool/modification that adds a lot of enjoyment out of the box .. and if they choose to do so .. it also enhances their capability to tune their ride to a level far beyond what they had stock. 

Informational Clips from Vmax group posts give an understanding of the T-boost----

....A  Vmax generally runs better with the boost open all the time if tuned properly but that will rarely happen . The major problem with an open V-boost is the idle mix and the first 2500 rpm with the V-boost open. There is no advantage of delaying V-boost opening past 2500 rpm. Terry Campbell of the Tech List came up with his T-boost mod which starts engaging the V-boost at 3k rpm's.
....Nothing beats wide open Vboost if the bike is tuned for it. Even poorly tuned bikes will perform better from 6700 up if the tubes are completely open at that point, but with stock configuration V-boost is not fully open to about 8500 rpm. The problem has always been having the V-boost tubes open at idle and off-idle ... the manifold back pulsing causes the bike to go too rich. T-boost closes the tubes below 3K and has them completely open by 4K (about 500 RPM before the carb slides start ativating). T-boost simply doubles the RPM that the V-boost controller detects and is accomplished by two diodes and a resistor.  The 3-4k rpm range is about the best range for the V-boost to fully engage in order to not screw up pilot or main mixture tuning. 
....With T-boost, the V-boost is in a partial opening state from 3-4K.
....Running T-boost is the same as wide open V-boost past 4K. 
....Having the V-boost open makes the bike "richer" ... closing it makes the bike "leaner".... that is why a Max seems to run better with T-boost than with regular stock 6K V-boost configuration.
....T-boost is completely closed below 3K (as is the regular stock 6K V-boost)
....With T-boost, the V-boost fully opens as far as the servo can move it,  "around" 4000rpm instead of the stock 8500.
....Full time boost tends to run rich and goof up the idle mix and lug the low end.
....In stock form the V-boost system activated much too late to be of a real daily use.

ORDERING T-boost Kits 

1....Thomas Powell, VMOA#741,  makes up Terry Campbell's  famous T-Boost harnesses, but slightly modified and  ready to ship.  It has a toggle switch for switchable on 3k V-Boost operation, and off for stock 6k V-Boost operation. All electronics is fully potted, all wire and terminals marine grade. Easy to follow instructions with color pictures are included. No cutting, crimping, splicing or permanent mods to bike are necessary and the harness can be easily removed. The price is $40 + $4 shipping, email Thomas for availability and payment directions.  T-boost image page, Thomas Powell

2....T-boost kits by Johan, VMOA #1061, 17$, postage to US included, email for ordering information  http://home.hkr.se/staff/jk/www/stuff/index.htm
Note, 2023Dec:  Johan Kjellberg (jkvmax AT hotmail.com) responded to a check to see if his email is still functional and if he is still making kits ("I am sold out of the kits, but I make them from time to time.  Will let yu know when I have some ready to go.")  So if you are interested, contact Johan, bz/2023).

Kit from Thomas Powell (installation basics below)

T-Boost Installation, basic directions

Go to Thomas Powell's photo page and review----Many of his pictures have better close ups, and will compliment the info below.

….Remove the hood, left scoop and front portion of the seat to expose the two areas where you will be making connections.

….Wipe off the top of the fuel pump relay and mount the T-Boost Module with the Velcro supplied in the kit
….Locate the three wire connector going to the Servo Control Unit. 
….Unplug the Servo Control Connector.

….Release the six wires from the Servo Control Connector Plug (both sides). You can do this by sliding the flattened end of the provided copper wire into the front of the Connecter Plug and depressing the latch on each of the individual wire terminals.
....Slide the flattened wire from the front along the metal terminal and connector, depress the keeper latch and gently pull each wire out of the connector plug from the back.
....Do not pull excessively hard. If the wire does not come out with a gentle pull, the keeper on each wire end has not been depressed far enough. 

....You can look into the plug from the front and see the keepers. If the flattened wire does not work to depress the keeper, try the flattened end of a small screwdriver.
....The wire tends to bend a lot, and may not work on one or more of the keepers.
....Be sure to save the connectors in case you want to uninstall this mod and go back to normal V-Boost operation at 6k.
....It is a good idea to label each connector half with a number, and perhaps even a description at to where it came from, then bag up all the parts in a Zip-lock and label the bag. Several years in the future it will be hard to remember just what these parts go too, without labels.

….Slide a piece of the provided heat shrink tubing over each of the short harness wires coming from the T-boost Module (one red, two black).

….Connect the red harness wire to the brown wire then connect the red with black stripe wire to the piggy back connection of the red wire.
….Connect the short black harness wire with the male end to the yellow wire and short black harness wire with the female end to the gray wire.

….Slide a piece of heat shrink tubing over one of the two black wires that were connected to each other before and hook them back together.

….Slide all the heat shrink pieces over their connections and carefully shrink them by heating with a heat gun or light. Be careful with a lighter, as you can burn the tubing, wire insulation, or other parts if too much flame/heat is used.

….Remove the three Phillips head screws that hold the plastic V-Boost controller mount (the electrical panel holding all the units). This will also release the fascia cover above it. Remove the turn signal relay (center black box) and route the module switch and long black wire through the hole and remount the turn signal relay.

…Decide where on the plastic fascia cover you want to mount the switch. Be sure you allow enough clearance behind the cover for the switch. Test it for room, as you may have located the switch where it will hit something behind it. Also be sure there is enough clearance in the front when the cover is re-installed. Drill a Ό" hole for the switch, or if you use another style of switch of your own, use the correct diameter of hole. Mount the switch with the slot on the threading facing in the down position, as this will ensure flipping the switch up, will turn the T-Boost on.

….Route the long black wire down the frame to the #1 coil (left back) and secure the wire with long black zip ties.

….The fascia removed above can now be re-installed using the three Phillips head screws. Securee the module wires using the small zip ties.

Summary of the wire connections at the coil side----
….Disconnect Yellow connector for #1 Coil.
….Hook Black to Orange Coil (bike harness side).
….Attach the coil side Orange to the piggyback terminal.
….Hook two Reds back together.

Make the Coil connection---

….Locate and disconnect the yellow connector for coil #1 and remove the four terminal wires from the connector using the flattened piece of copper wire or a small screwdriver, as before. Save this connector also.

….Slide a piece of heat shrink tubing on the red and orange coil wires. Attach the long black harness wire to the orange wire (bike harness side: and attach the coil side orange wire to the piggyback terminal. Reconnect the two red wires.

….Slide the heat shrink tubing over the connections and use a heat gun or lighter to shrink the tubing and stow the wires. Note: remember the gas tank on the Max is not far away so be very careful if using a lighter as gas fumes that may have built up in an enclosed area are very volatile and can flash in an instant.

….This complete the T-Boost installation. Reinstall the seat, the left induction cover and the hood.

Testing if the installation has been successful----

….Start the bike to see if the idle characteristics normal, as before the T-Boost installation.

….With the T-Boost switch in the off-position (Usually in a down orientation unless you installed the switch at a different angle.  (I use a forward for on, and back for off on both my manual fan switch and the T-boost, bz/2001), watch the V-Boost Servo and rev the engine past 3k rpm’s. You should see no movement in the servo with the switch in the off-position, thus on the road V-Boost would not go on until the normal 6k rpm’s before T-Boost installation.

….Place the T-Boost Switch in the on position (up or back)  and watch the V-Boost Servo while you rev the engine past 3k rpm’s. You should see the Servo Cycle open, indicating the T-Boost circuit has been installed correctly and is functioning.

….Take a test ride. You should notice the V-Boost starting to engage at 3k and not the normal 6k. Be careful until you get the feel of the new power curve.  Be careful in traffic, on bad roads, etc. 

T-Boost Reviews summarized from varies posts.


REVIEW Clips from the Vmaz list (2000+) which may help you with T-boost decisions==

Review----Installed T-Boost. If you have not,  you are denying yourself of some crazy acceleration off the line. T Boost was simple to install and is reversible if you wish. Keep mine switched on except on the interstates. Have yet to race anyone through the 1/4 mile but I have to believe the 1/4 mile time will be somewhat lower. To feel that boost every time twist the grip----it is priceless!  Best money ever spent. Thanks to Terry Campbell and Thomas Powell's user-friendly harness kit, easy to install, even for the electrically challenged.

Review----Have to more than second the opinion.  Have a big smile after nearly every ride with T-Boost installed. It is wonderful!!  Vowed no more mods to my Max so  had my head in the sand in regards to all the posts on T-Boost performance. Had not been paying close attention to posts regarding the development of bringing the V-boost "online" at normal street level rpm's. This mod brings into play the companionship of what the Max motor and V-boost design should have been from the start. T-boost gets Mr. Max with V-boost running at street rpm's.   Anyone with a stock Max needs to at least take a serious look at some basic suspension mods starting with new fork springs, a manual fan switch, sealed battery, etc, and of course T-Boost!!

Review-----Always on the look out for enhancements and compliments for the Vmax.  Only complaint in the Vmax was that in stock form the V-boost system activated much too late to be of a real daily use.

Review....The great thing about t-boost is that it is automatic.  At 3k instead of the factory 6k the V-boost butterflies start to open.  This is about the best place for this to happen.  Lower and the bike runs rich, loading up the plugs with a rough idle.  Above 3k and you are wasting allot of performance "feel" and throttle response. TC has done us a wonderful thing coming up with t-boost.  

Review....I am still smiling and wish the V-Boost would have been in operation at 3k long ago.  The Max literally jumps at the slightest throttle touch. Yamaha has missed the boat my not doing basic changes to make the Max a modern performer while keeping the looks and legend going.  After riding the FZ1 so much this past season....rarely wanted to just get back on the Max and ride it, as the FZ1 was so much more responsive. But the V-Boost coming on at street speeds has been just enough to make the Max fun again, and now am finding riding interest is about equal  for the two bikes.  The way both bikes are set up now, make them nice  compliments to each other.

Review....Been playing with my needles to cover a severe bog down when T-Boost is on and you hit about 4500 at say 1/3-1/2 throttle.  Replaced stock needles with some Venture needles. The ones that have a more aggressive taper than stock and 5 clip positions. With stock needles there were similar results but they were still displaying an ever so slight but obvious flat spot as rolling on the throttle at light openings. That's totally gone and T-Boost is perfect.

Review....T-boost or open V-boost does make you a lot richer in the middle. This is OK sometimes if you remove some intake restriction but it is nice to have adjustable needles.

Review....T-Boost is the single most "bang for the buck" mod you can put on your max!!!

Review....T-boost is  well worth it. Do it. You won't be sorry. If you have any doubts install it with an on/off switch as from TP's kit. This will give you the option to run with your normal V-Boost operation or T-Boosted! This is a fantastic, inexpensive mod. 

Review....Do it. Talk about value for money. Worth every penny.

Review....Put it on an 85 with the switch, the only time turn it off is to appreciate why it was installed in the first place. Do it, you won't be sorry unless you have weak arm sockets.

Review....Anyone that has not taken a serious look at T-Boost needs to do so.  Was playing "ostrich" when all the T-Boost chatter was going on but finally "saw the light".  Have installed three in the past couple of months; two stockers, one with headers. Easy to do and the biggest bang for the buck. All three work perfectly, I repeat perfectly, as in hold-on-tight perfectly.   Still smiling from the last ride.  Had placed the Vmax down to second fiddle on my ride list as the FZ1 has been such a "blast" to ride, but with T-Boost, "it makes you want to ride your Max even more."  If you have not looked into installing the T-Boost, you should.

Review....T-boost is installed with an on/off switch but the only time in the last 6 months or so it has been off was to test the difference on the
highway when it was first installed....since then it has never been off!

Review....Ken's  Max was the "first" bike to have T-boost besides TC's.  TC originally made 35 more T-boosts and sold them at cost, which was about $4 and shipping.  TC  also made the design and concept available to all Vmax Tech List subscribers so anyone could make their own
and no vendor could hide the design and sell them for $150 each. T-boost was a solution that TC was able to produce due to the input and effort of many Tech List subscribers.

Review....Not only will it give you the best bang for bucks but your fuel economy should get better. Averaging 20 miles more per tank.

Reivew....Never understood why such a great product never got wider recognition in the V-Max world, it is simple and works great. Have one on my bike with Stage 7 and can honestly say, it is one of the best products available, that actually delivers as promised.

Review...Go four it; T-boost...totally...you will never regret it...you do not need a switch...you will never want to be without it again... :)))

Review....Thomas Powell's T-boost harness is switchable so you can activate the T-boost to on position anytime you choose.  The switch is good mainly for times when there is limited traction, i.e. wet, sandy etc, and generally around town....The switch is often in the off position when going up and down  past the 3k point in a single gear or shifting in slower traffic.  Why cycle the v-boost when it was not necessary?

Review....A dyno test V-boost vs. T-boost: T-Boost yielded 1.1 more hp, and 2.5lbs less torque in back to back runs. Whatever the dyno says it feels faster and is more fun

Review....It really is not the slight hp gain, but the throttle response gain that gives the improved "seat of the pants" feel of more power/acceleration. 

Review....T-boost is closest to a real free lunch any of us have ever seen. Only use T-Boost sometimes, as like the stock power curve, but when you are on the highway and want that part throttle instant viscous response you can't beat that T-Boost.  

Review...Will have a kick in the pants earlier with the T-boost compared to normal V-boost.. Hence, the improved throttle response. It is already been established that T-Boost does not add significant real Horse Power.

....Hp gain is small in the area where t-boost works and most of the fun comes from the throttle  response.  Just with the plug and play grins everyone gets it is more of a seat of the pants feeling than actual hp gains. The throttle response is what I like.

Review....There are HP gains to be had by opening the tubes below 6K .. and having them fully open before 6700 .... the mid-range "dip" may be eliminated by opening the V-boost tubes. T-boost allows us to have those tubes open while eliminating all of the bad things that comes with it below 3k. . After 4K we are the same as someone who has their tubes open full time. 3-4K is of course the super responsive partially open area ... that is a blast as we spend a lot of time there around town.

Thomas Campbell originator of the T-boost says it nicely:  "In a nutshell T-boost moves automatic V-boost opening to the 3-4K range instead of the stock 6-8K range by fooling the V-boost controller into thinking the engine is running twice as fast as it really is. T-boost simply provides a means to take advantage of wide-open V-boost without all the shortcomings that come with full time V-boost for around town riding.


Site/page chonology None of the iowaz pages contain Vmax info/ideas after 2006.
...1996+...Most of the Zmax pages were originally uploaded to Angelfire.com from about 1996>2002, at a time when digital photo size was small and web page space limited.  There were very few, if any, helpful Vmax pages at the time, so the major objective of the pages was to share with other non-mechanics various processes learned the hard way.
...2006...About 2006, a web host with unlimited storage and a better interface available and future web work was uploaded to iowaz.com.  Cycle pages were not transfers but instead left on the free version of Angelfire.  About this time more people with much better mechanical knowledge and experience were building better pages.
....2007...By 2007, there were too many complaints and opinions coming in on some of the Vmax pages, and especially the orange oring project that originally started with the Zmax material, so the Vmax pages were taken offline about this time.
...2023...Due to a requests for information a few of the old Zmax pages have been transformed the old Angelfire material to the iowaz host.  None of the pages contain new information after the 2006 timeframe.  Zmax has been gifted to another rider.

Vmax turned into Zmax:  With fork brace, head set "fixed", frame brace, manual fan switch, Galfer green brake pads, braided stainless steel brake and clutch lines, Speedbleeders, National Cycle Plexistar II shield, case guards, factory sissy bar and tail piece, a few other accessory odds and ends.  Hindle 4-1 Stainless Steel Headers with a 16" Carbon Fiber Stealth Can, K & N air filter, four 1/2" holes drilled in the air box "Y" (later taped over), carbs left stock but needles shimmed 0.025" with five coils tied off on the slide springs, center stand removed,  Work's shocks with dual rate springs and adjustable rider system, Works dual rate fork springs, reinstalled Bridgestone V rated Excedra tires, T-Boost installed.  PCW racing starter clutch fix, orange-oring issue reseaches/fixed. The dyno run stock was 107+, with mods 111+ and the curve exactly follows the stock run, no hesitations, no weak spots.  The net weight loss from center stand and stock shocks removal was about 50lbs, which produced another net of about 6 hp, for a total gain of 10 useful hp on a massively improved handling package.  Vmax was good stock, but the frame mods, loss of weight and efficient exhaust  Zmax produced the third best bike I had owned, behind the more modern 2001FZ1 amd 2002R6.  Yamaha should have completed the basic mods needed on their stock Vmax.   Zmax is running GREAT!!   bz/2006

In 2023, Iowaz' Zmax was gifted to another rider.

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Barry Zbornik
Hannibal, MO