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Removing 95bhp restriction
  #1  
Old 01-14-2013, 11:25 AM
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johnpclynch johnpclynch is offline
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Default Removing 95bhp restriction

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..

Last edited by johnpclynch; 01-30-2013 at 03:49 AM..
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Re: Removing 95bhp restriction
  #2  
Old 01-14-2013, 12:07 PM
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KosRider KosRider is offline
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Default Re: Removing 95bhp restriction

WOW !!! What a way to de-tune a Vmax... should be considered a crime to do this to a Vmax !!
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Re: Removing 95bhp restriction
  #3  
Old 01-14-2013, 12:14 PM
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VMax-Mike VMax-Mike is offline
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Default Re: Removing 95bhp restriction

I would sell it and buy a different one before i went through all that.
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Re: Removing 95bhp restriction
  #4  
Old 01-14-2013, 04:21 PM
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Default Re: Removing 95bhp restriction

Nice write-up, made it a sticky
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Re: Removing 95bhp restriction
  #5  
Old 01-15-2013, 05:55 AM
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Default Re: Removing 95bhp restriction

Nice, and it makes me SO glad I do not have a Japanese/French etc shamefully emasculated bike!!
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Re: Removing 95bhp restriction
  #6  
Old 01-15-2013, 10:43 AM
thor_eyerdhal thor_eyerdhal is offline
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Default Re: Removing 95bhp restriction

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...
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Re: Removing 95bhp restriction
  #7  
Old 01-16-2013, 04:11 AM
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Dr.n2o Dr.n2o is offline
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Default Re: Removing 95bhp restriction

Excellent observations and great write up....Glad I don't have a neutered one
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Re: Removing 95bhp restriction
  #8  
Old 01-16-2013, 04:12 AM
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johnpclynch johnpclynch is offline
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Default Re: Removing 95bhp restriction

Quote:
Originally Posted by thor_eyerdhal View Post
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
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Re: Removing 95bhp restriction
  #9  
Old 01-16-2013, 09:42 AM
thor_eyerdhal thor_eyerdhal is offline
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Default Re: Removing 95bhp restriction

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.
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Re: Removing 95bhp restriction
  #10  
Old 01-16-2013, 11:35 AM
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johnpclynch johnpclynch is offline
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Default Re: Removing 95bhp restriction

Quote:
Originally Posted by thor_eyerdhal View Post
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
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