Skip to content

General An interesting situation General

You are in... Forums > General > General > An interesting situation

Got something to say?

Got something to say?

Go to most recent reply



May 12

Posts: 29

scott111193 says:

An interesting situation

Ok guys, here it is. 

I have a 1988 Honda XBR500 in black, all ready for its mot. I am on an a2 licence, so the 44bhp XBR needs to be restricted to 33bhp. 

Went down to the mot place to ask if they would restrict it, the guy in charge said he is confident the bike won't even exceed 33bhp on the dyno test, mostly because of its age. 

The dyno test is going to cost £20, and if the bike does produce over 33bhp even if its just over, I will need a restriction kit put in... £200 including vat. The dyno test comes with a certificate. 

If the bike does produce less than 33bhp, do I need to prove it to the insurance company or can I just ride it? 

In the event of a claim, they will see that the bike is 44bhp, so they will want to make sure it's restricted. I have asked the insurance company if in the event of a claim, they will accept the certificate as proof or not, still waiting to find out. 

Has anyone ever been in a situation like this? Or have any advice? 


Reply to this Topic  
  • Posted 2 years ago (06 January 2013 18:22)

Post a message in General

Fields marked with an asterisk * are required


Please note. You cannot submit more than 4000 characters as a message.

Upload image(s) from your computer (up to 3 images)


Terms of use

Use of our community areas and forums is subject to important terms of use. By joining our community and using the features you agree to be bound by these terms. See terms of use below. 



Aug 09

Posts: 2721

MarcusMarsh says:


Manufactrers in those days were often over-enthusiastic about the BHP figures quoted for their bikes.  Even when new, I doubt that an XBR would have produced the full 44 BHP quoted.  Run it on the dyno and see what you get. 

From experience with a couple of mates that have recently passed their tests, their insurance companies did not ask for any proof of power output of restrctions but you can pretty much guarantee it will become an issue if you have an accident.  Better safe than sorry should be the approach.     

Reply to this Topic


Feb 11

Posts: 2633

gungerdin8 says:

take the

right handed bit off the plug itul run like shit but b right down on the dino ?

well worth a shot ?:blink:

oh im lashed up x

Reply to this Topic


Dec 10

Posts: 12021

preunit says:

Has been posted before

 here i still think you'll be find with a dyno read out of 33 bhp or less, or they'll have to remove the engine and test it on a bench, which in the real world ain't gonna happen.

[This Reply has been modified by the Author]

Reply to this Topic


Aug 07

Posts: 6169

stevebaldy says:

i would have thought

if the dyno says 33bhp or less, that is a binding document.........just don't lose it !!  A drop off of 25%(:unsure:) from original manufactures figures does seem quite a lot though.......fingers crossed though! 

Reply to this Topic


Mar 12

Posts: 1286

Good old classic bikes

When they aren't wrecking their starters:upset:

Doesn't the dyno measure at the back wheel?

That 44bhp (measured at the crank) figure quoted for this 4 valve head 500cc may be a bit optimistic.

My guess would be 36bhp.

A diy slide stop might do the job.

Reply to this Topic
52 Black Shadow


Apr 03

Posts: 716

Not sure about this??????

I don't have the regulations in front of me at the moment, but seem to remember the phrase "Designed power output" or something similar.  This would mean that if the manufacturer designed your bike to have 44 BHP then that is the figure used to determine whether you can legally ride it.  If you have a kit fitted, then the design of the bike with the kit will be 33 BHP, but saying "it's not running too well today so it's OK to ride it" would be a bit like taking a sppark plug out of a Honda Superdream and saying "it's now only a 125, so I can ride it as a learner".


Don't mean to piss on your candle, but you could let yourself in for a lot of trouble if you aren't very careful.


Ride safe,



Reply to this Topic


Mar 12

Posts: 1286

With modern bikes....

I would guess you'd have to use a manufacturer approved restriction kit. For the warranty if nothing else.

But! would they be available for older bikes?

If not, then what are the rules?

Reply to this Topic


Aug 02

Posts: 1002

ANichol says:

Telling your Ins co

Do you have to do this? I didn't when I had my GPX250R - limited it to 33bhp from its claimed 39, but I don't recall the ins co giving a rats arse if I had the right licence or not. The authorities on the other hand....but if you can prove your bike can't / won't exceed the limitations applied to your licence then you should be ok.

Reply to this Topic


Jun 12

Posts: 342

Meatbingo says:


Apparently, a certificate from a dyno test or from a restriction kit means nothing in law. In the event of the police or insurance getting involved it is up to them to prove you are in the wrong by testing your bikes output after the fact. I don't think this can happen very often as there is very little anecdotal stuff online about it.

Reply to this Topic


Aug 02

Posts: 2751

spondonste says:

Power restictions

Manufacturers BHP figures are best conditions, best engine tolerances at the crank. Every real world power test however is at the wheel.

The absolute power that an engine produces will be dependent on ambient conditions, engine tolerance, humidity, engine wear etc so will vary day to day. The only way the police can check if a bike is within the limits is to put it on a rolling road dyno and test it so that would be a power test at the wheel.


If I was in your situation I would simply get the bike dyno tested and if its below 33BHP then that would be sufficient to show due diligence to complying with the law. If the power is slightly over then a limit on the throttle slide would be the cheap way to go but you would need to get the bike rechecked on the dyno to confirm.

The reality is that the only time the police will stop someone and check is if they're going too fast for the power limit of the vehicle.


I think the comments about original power relate to the new legislation just coming in to force this year. You can restrict a bike to 33BHP but only if the original unrestricted model did not produce more than 66BHP (96BHP for 47BHP restriction limit ie you can restricted it by up to half its original power but no more).

Reply to this Topic


Compare Insurance

Save money by comparing quotes. It's quick and easy

Motorcycles for sale


It's only £13.99 to advertise your motorcycle on MCN

Sell your Motorcycle

Motorcycle pricing tool

New! Find used bike prices