How hard is it to fit restrictors to a vfr 400

Rich1988

Rich1988

Rich1988

Soldato
Joined
8 Jan 2005
Posts
6,453
Location
wiltshire
As title really there is a kit going cheap friend has one and needs to restrict , is it something you could do easily? (there are a set of washers on the bay)
thanks
 
If its for insurance purposes they will require a certificate usually, but sometimes they include them with the restrictor kit ;)
If so search google im sure there will be a dedicated forums to the VFR showing how to do it, but im sure the washers go on the carbs, well they did on my old SV.
 
ok so its actually me, the reason I didnt say it was is that no doubt i would get lots of jip for changing my mind every five seconds about what I want, i wont try and lie to people, its never pretty ;) although in hindsight im probably going to get more jup now :p
 
It's not that hard to get at the carbs of a VF/VFR Honda, I've had a couple of 750's and it was no more of a struggle than any other bike really. Nevertheless, you will have to get them fitted by a garage with a Dyno who will certify that it's producing 33bhp or less for you to take to your insurers, it might take more fiddling to get exactly 33 bhp than you might be able to do at home.
The VFR400's often don't produce much more than 50-55 at the wheel and restricted German ones are down at 45bhp anyway (though you don't see a lot of them TBH) so I have heard of them being restricted by merely installing a throttle stop.
Beautiful bikes though, like little jewels, a well tuned one can give 70-75hp at the crank for nearly 140 mph with scalpel like handling.
A 33hp one will get up to about 105mph they are so little.
 
Guzzidom said:
It's not that hard to get at the carbs of a VF/VFR Honda, I've had a couple of 750's and it was no more of a struggle than any other bike really. Nevertheless, you will have to get them fitted by a garage with a Dyno who will certify that it's producing 33bhp or less for you to take to your insurers, it might take more fiddling to get exactly 33 bhp than you might be able to do at home.
The VFR400's often don't produce much more than 50-55 at the wheel and restricted German ones are down at 45bhp anyway (though you don't see a lot of them TBH) so I have heard of them being restricted by merely installing a throttle stop.
Beautiful bikes though, like little jewels, a well tuned one can give 70-75hp at the crank for nearly 140 mph with scalpel like handling.
A 33hp one will get up to about 105mph they are so little.
Click to expand...

surely I can just fit the restrictors and buy one of those 'replacement' certificates ? I know its not technically ok but its not like i dont have them fitted
 
There's not a lot that can go wrong when you're putting them in. You should get it dyno'd though otherwise there's no point putting them in. The way you're doing it is a cheap way round to being legal. A fake certificate will shaft you just the same as not fitting restrictors. You will limit your choice of insurers by not having FI International paperwork and restrictors if you do it yourself though.
 
my friend (my actual friend this time!) had insurance on his zxr400 with restrictors he put in him self and no certificate and they never asked him for it either the policy is up and he is goign with carol nash so Ill found out if they ask him for it or not
 
Not sure about the technicalities with insurance and the certificates, but if the washers go between the carbs and the heads then it's a bit of a fiddly job but not too hard.

Need to take the seat unit off first, to get at the tank bolt and get the fuel tank off. Then there is are two clamps per carb rubber, undo the screw on each of the top clamps (so the rubbers stay on the engine), remove the idle adjust and choke from the side of the bike and pull up on the carbs (and/or use a claw hammer to get some leverage :p) and off they come, to get them off completely you need to take the throttle cables off which is a bit fiddly but fine.

Putting them back on is the most awkward bit though, the trick is to put the front bank carbs into the rubbers first, and then using a tiny screwdriver get the rubbers for the rear banks to sit properly before pushing down hard, do up the clamps (then remember you forgot the throttle cables and take the carbs back off again, you'll only do that the once though :p) and reassemble it, nice and easy :)

I race a VFR400 now, seems I've pretty much done everything to mine now other than rebuild the engine (which is planned over the winter, need more power :p), the Haynes manual is (obviously) very useful, also the best forums I've found are the 400 grey bike ones (http://www.400greybike.info/newforum/index.php)
 
Last edited:
Your bike must be 33bhp though, how will you know if it's 33bhp once you've fitted the washers?, what if you've managed to get yourself 25bhp?...or worse.
You don't need a cert as such, but in event of a claim, having a Dyno printout sheet that proves it is 33bhp or less, would be...to say the least..handy.
It is solely incumbent upon you to regulate the power, an accident where speed is an issue will result in the bike being tested, if it's 33.1bhp, you are not insured for it, you are not licenced for it etc etc.
If you are happy to take those risks then so be it, but why spend a fortune on lessons/tests/insurance if you are happy for it all to stand for nothing?.
A Dyno test, even if you fit the kit yourself, is between £30-£40, gives you the evidence you may need and will also tell you if you've cocked up the power.
An advantage also with spending an extra £100 or so for a Dyno setup with a reputable installer is also the fact that they will not just poke the washers in and be done, but actually jet it for it's new 33bhp airflow, resulting in an engine with a better torque / power spread, in effect giving you more of your 33bhp for more of the rev range.
A properly set up 33bhp conversion is a speck in the distance of a chasing home bodge.
 
i agree Guzzidom i would go and get a dyno done just for peice of mind !!
my point is that a restriction cert and a dyno cert are two different things , most if not all of the places that do the restrictor kits DONT do a dyno test , they just charge you nearly £200 pound for a couple of washers and a bit of paper that means nothing !! ie FI International

as said i would get a dyno test done just to make sure
but even then the dyno print out also means nothing in the eyes of the law its more for peice of mind
it takes 5 mins to remove the washers and keep the paper

in the event of a claim or getting done for speeding the police or insurance peeps will dyno the bike weather you have either bits of paper

sorry if my first post was a bit harsh just pointing out that a restriction cert is a worthless bit of paper
 
I had to send a cert to my insurance company within 14 days of starting the policy. The 'cert' could have been knocked up on a pc in two mins, though. I guess the insurance company just wanted to cover their backs in case of a claim.
 
You must log in or register to reply here.
Back
Top Bottom