Removing 95bhp restriction

[johnpclynch]

Removing the restriction on a 3UF VMax (95bhp > 145bhp)

The Japanese model of the Vmax is restricted in a number of ways
- VBoost, there is none so try to source a VBoost kit (expensive)
or do as I did and install VBoost elimination tubes first
- Carb diaphrams, get new diaphrams or carefully cut out the restriction
- Carb jets, get a jet kit - you should have tried this already
- Exhaust, simply replace with an aftermarket system, slip-on or full
- Speed restriction, don't go over 190kph, buy a Speed-Restriction Modification from Speed & Dyno Shop in Oslo
or modify the speedo to allow you to go over 190kph

Step 1: Getting Boost back!
A solid block of aluminium lives where the Vboost butterflys should be

You can replace them with identical but hollow tubes (similar to the stage 7 jet kit)

or with a manually operated VBoost

or (as I finally got around to) a FULL Vboost system! servo, controller & butterflys

Step 2: Removing the restriction on the carb diaphram
Because of the restriction on the diaphram the slides can only open 80% of the way.

The removal is a simple cut. If you are doing this with the restrictor still attached to the diaphram then beware of the rubber diaphram, do NOT touch it with the saw or the results will be disastrous!

Remember to clean the surface with a file or light sandpaper and do NOT allow any shavings or dust back into the carbs. Air jets could easily become blocked.

Step 3: Removing the speed restriction
On the back of the speedo-needle a disc with two different diameters is mounted.
On idle, one end of this disc is between the two legs of the switch.
Normal running, the disc is turned away from the switch until you reach 190kph.
Over 190kph, the other end of the disc reaches in between the switch, blocking the circuit. This activates the restriction (disables some of the cylinders)
1 - Take a pair of cutting nippers and remove 2/3 of the greater disc opposite the idle-position. Now the disc is still between the switch on idle but the rest is long gone = Full Throttle available! (Nothing's blocking the switch)
2 - or instead of removing 2/3 of the disc, simply bend one edge of the disc so that when it comes full circle it will hit the side of the switch and stop, your speed will keep increasing but the needle will remain at 190kph.

This is the circut in the speedo that restricts your speed.
Note the large (IR/magnetic?) switch in the center, this is what the disc slides between. I didn't want to modify the circut so I modified the disc instead

Step 4: Re-Jet the carbs, they will be all over the place
New spring vs. old spring

Old needle vs. new needle

Step 5? Inspect the cam timing
According to the book, when cylinder 1 is TDC (on the compression stroke) the small holes (A / GREEN) will align with the marks on the bearings (B / ORANGE)

And as you can see from the above pictures my exhaust cam was out by around 3 teeth on the sprocket !!!

Step 6,7,8,....
Get yourself a full exhaust system, with turbo, nitrous, supercharger, etc.. :biglaugh:

 

[KosRider]

WOW !!! What a way to de-tune a Vmax... should be considered a crime to do this to a Vmax !! :rofl_200:

 

[VMax-Mike]

I would sell it and buy a different one before i went through all that.

 

[KJShover]

Nice write-up, made it a sticky

 

[naughtyG]

Nice, and it makes me SO glad I do not have a Japanese/French etc shamefully emasculated bike!!

 

[thor_eyerdhal]

Your forgot the CDI swap!

The French ignition curve of the digital CDI (89=>) is very different from the US one.
More advance at 4000, less advance at top end, lot more vacuum advance.
Give smore torque at part throttle at 4000 but kills poneys at high end!

Solution : Buying an US CDI or a Dyna3000 one (no EU curves in it, only US shapes)


Regarding valve timing events mod, never heard of this on french ones and no speed limiter in France, but ours are 2EN, not 3UF...

 

[Dr.n2o]

Excellent observations and great write up....Glad I don't have a neutered one :biglaugh:

 

[johnpclynch]

Your forgot the CDI swap!

The French ignition curve of the digital CDI (89=>) is very different from the US one.
More advance at 4000, less advance at top end, lot more vacuum advance.
Give smore torque at part throttle at 4000 but kills poneys at high end!

Solution : Buying an US CDI or a Dyna3000 one (no EU curves in it, only US shapes)


Regarding valve timing events mod, never heard of this on french ones and no speed limiter in France, but ours are 2EN, not 3UF...

I did swap the CDI but I wasn't aware of any difference in the map - I only replaced it because it was newer and it came in the box of parts I bought with the Vboost servo & controller

1993 Restricted CDI

2000 Full Power CDI

 

[thor_eyerdhal]

I checked cam timing events of French motor :
-little hole for rear cylinders
-Big hole for front cylinders.

It seems to be the same as US one..

So timing for Japanese is different (Anyone has a japanese tech book?) or the timing of japanase is the same as others and your engine was badly overhauled by the previous owner.

 

[johnpclynch]

So timing for Japanese is different (Anyone has a japanese tech book?) or the timing of japanase is the same as others and your engine was badly overhauled by the previous owner.

That was always one of my worries, because the cam almost lines up with the big hole.
They may have forgotten what page in the book they were looking at and set it up like the front cylinders :confused2:

 

[bazwell]

That's some good info there John. Nice one!

If I were to take a guess, I'd say that the switch in the speedo is a infra-red switch. (Not that it makes any difference.) I'm thinking it probably works the same as the infra red beam they put across shop doors so that when someone walks in it sounds a bell.

THREE teeth out on a cam gear ... that's bat shit crazy! I'm surprised it didn't bend valves.

 

[johnpclynch]

That's some good info there John. Nice one!

If I were to take a guess, I'd say that the switch in the speedo is a infra-red switch. (Not that it makes any difference.) I'm thinking it probably works the same as the infra red beam they put across shop doors so that when someone walks in it sounds a bell.

That's a good point, it would make for much simpler electronics

THREE teeth out on a cam gear ... that's bat shit crazy! I'm surprised it didn't bend valves.

So am I, but it may have been a sloppy valve job/overhaul by the previous owner

 

[mista_max]

Manual VBOST . Think you need both hands on handle bards when bosts opened

 

[johnpclynch]

Manual VBOST . Think you need both hands on handle bards when bosts opened

Yeah, that was a bit crazy. I only used the Vboost on long rides and turned it off around town

but I did hear of someone using a bicycle grip-shift to operate Vboost while riding - throttle on both hands

 

[KDIMD]

Hi all. I have a Japanese spec model without vboost. Over the past month, bought all the parts listed above from ebay or sean morley. Also, to make it easier, changed the wiring bundle as the Jpn version didnt have the vboost wires, which then required changing my switches and ignition key wiring.

Can now see why everyone raves about the vboost. Just need to get used to riding at higher rpms.

 

[Diablotin]

Looks like somebody is enjoying the vboot in metro manila now you might forget that you have an harley lol

Sent from my SM-N9005 using Tapatalk

 

[The mongrel]

Hi chaps

Were all jap max's resticted?....i'm looking at a jap import that the seller assures me is full power

I'v not been to see it yet so what the easiest way to tell?

Thanks in advance....the mongrel

 

[sdt354]

When the key is turned on the V-boost will cycle twice. You'll hear it for sure, if its there and working.

 

[Fire-medic]

If the airbox is off, you can visualize the cable and linkage moving the VBoost mechanism, while it makes its noise.

 

[VEEMAX1998]

Removing the restriction on a 3UF VMax (95bhp > 145bhp)

The Japanese model of the Vmax is restricted in a number of ways
- VBoost, there is none so try to source a VBoost kit (expensive)
or do as I did and install VBoost elimination tubes first
- Carb diaphrams, get new diaphrams or carefully cut out the restriction
- Carb jets, get a jet kit - you should have tried this already
- Exhaust, simply replace with an aftermarket system, slip-on or full
- Speed restriction, don't go over 190kph, buy a Speed-Restriction Modification from Speed & Dyno Shop in Oslo
or modify the speedo to allow you to go over 190kph

Step 1: Getting Boost back!
A solid block of aluminium lives where the Vboost butterflys should be

You can replace them with identical but hollow tubes (similar to the stage 7 jet kit)

or with a manually operated VBoost

or (as I finally got around to) a FULL Vboost system! servo, controller & butterflys

Step 2: Removing the restriction on the carb diaphram
Because of the restriction on the diaphram the slides can only open 80% of the way.

The removal is a simple cut. If you are doing this with the restrictor still attached to the diaphram then beware of the rubber diaphram, do NOT touch it with the saw or the results will be disastrous!

Remember to clean the surface with a file or light sandpaper and do NOT allow any shavings or dust back into the carbs. Air jets could easily become blocked.

Step 3: Removing the speed restriction
On the back of the speedo-needle a disc with two different diameters is mounted.
On idle, one end of this disc is between the two legs of the switch.
Normal running, the disc is turned away from the switch until you reach 190kph.
Over 190kph, the other end of the disc reaches in between the switch, blocking the circuit. This activates the restriction (disables some of the cylinders)
1 - Take a pair of cutting nippers and remove 2/3 of the greater disc opposite the idle-position. Now the disc is still between the switch on idle but the rest is long gone = Full Throttle available! (Nothing's blocking the switch)
2 - or instead of removing 2/3 of the disc, simply bend one edge of the disc so that when it comes full circle it will hit the side of the switch and stop, your speed will keep increasing but the needle will remain at 190kph.

This is the circut in the speedo that restricts your speed.
Note the large (IR/magnetic?) switch in the center, this is what the disc slides between. I didn't want to modify the circut so I modified the disc instead

Step 4: Re-Jet the carbs, they will be all over the place
New spring vs. old spring

Old needle vs. new needle

Step 5? Inspect the cam timing
According to the book, when cylinder 1 is TDC (on the compression stroke) the small holes (A / GREEN) will align with the marks on the bearings (B / ORANGE)

And as you can see from the above pictures my exhaust cam was out by around 3 teeth on the sprocket !!!

Step 6,7,8,....
Get yourself a full exhaust system, with turbo, nitrous, supercharger, etc.. :biglaugh: