Bike restriction to 33bhp

Not too sure where to put this, but i was just wondering if anyone could clear this up for me.

A lad's just told me that restricting a bike to 33bhp means that it is 250cc, well assuming i've not misunderstood him

getting more training dosn't make you safer there are other people on the roads that are dangerous , and i only stated 250cc because thats what they restrict your engine down to eg 33bhp is the same as a 250cc.

I would have said this isn't true, can anyone tell me if i'm just showing my lack of knowledge, or if he's making things up.

If it is true how does it work

Thankyou

Does he not mean that its about the same power as a 250cc puts out. The new ninja 250 puts out about 33bhp. A restricted SV650 is still classed as a 650cc

Thats what i'm unsure about, and he's just being rude to me as i'm a girl and obviously know nothing.

An earlier post was him saying you could only ride a 250cc bike. By restricting a bike to 33bhp you make it a 250cc engine.

So what i think he's saying to by restricting it you make your engine 250cc, rather than it's similar to a 250. But it definitely doesn't affect the cc of a bike does it?

sorry, not very good at explaining what i mean.

[andrewsmith]

its ********!!!

The power is restricted to the equivalent of a 250cc 4 stroke motorcycle. The bike is still a 650cc twin with top end power restricted (with washers or electronics).

A bike that is learner legal and A/ A2 pass legal is an RS125 or Derbi GPR125 both produce 15 brake with the restrictors (almost all 125 strokers are sold restricted) or between 24 and 32 brake with it off.

[timwilky]

As others have said a restricted 650 is still a 650. the restriction is placed on the power output not the cubic capacity of the engine.

The learner spec machine of my youth (LC) produced about 38bhp. so if the guy is saying you are restricted to the power output of a 250. Whilst confusing he is sort of correct. If he is saying you are restricted to 250 as a maximum bore displacement he is talking out of his backside.

[Geodude]

Ignore the 'lad' and tell him to shush as has been said already its still a 650cc twin with top end power restricted.

Originally Posted by bathwiggle

Thats what i'm unsure about, and he's just being rude to me as i'm a girl and obviously know nothing.

..and he seems to be a **** and obviously knows nothing! Don't worry Wiggle, as all before have said, it's only the power output that is restricted. A little knowledge is a dangerous thing and it sounds like he sums that up quite nicely.

[yorkie_chris]

Originally Posted by bathwiggle

Not too sure where to put this, but i was just wondering if anyone could clear this up for me.

A lad's just told me that restricting a bike to 33bhp means that it is 250cc, well assuming i've not misunderstood him



I would have said this isn't true, can anyone tell me if i'm just showing my lack of knowledge, or if he's making things up.

If it is true how does it work

Thankyou

Tell your mate there to be quiet as the grown ups are talking.


He's right and wrong, you restrict it to 33bhp, it's got nothing to do with the capacity, just power output. Only thing he is "right" about is a passing resemblance of 33bhp to the power output of some 250s.
Look at americans, they manage to make 12l muscle cars make under 100bhp, it's a miracle of engineering. Or those crafty japs who can wring 50+bhp out of some of those 250ccs.

Your bike is 645cc, that's fixed by the size of the pistons and how far they go up and down. Restricting the engine doesn't change that.


The way the restrictor works is by limiting the amount of air which can go into the engine. Exactly the same as the throttle.

[yorkie_chris]

Originally Posted by andrewsmith

A bike that is learner legal and A1 pass legal is an RS125 or Derbi GPR125 both produce 15 brake with the restrictors (almost all 125 strokers are sold restricted) or between 24 and 32 brake with it off.

Bit confusing that, please sort out your knowledge of the licence categories. If you have an A1 licence you're not allowed to derestrict them, you're limited to 14.5bhp just like on CBT.

She's talking SV650s, so probably has or is aiming to get an A2 licence.

[yorkie_chris]

getting more training dosn't make you safer there are other people on the roads that are dangerous ,

You shouldn't need us to tell you that's a load of bull either.

Who is this f***ing mong?