The difference between 33.3 and 46.5bhp is there much

[Crumpets]

Hi,

Just a curious question about bikes and restrictions.

Whilst i'm busy searching for the right bike for me i've found many that have the old 33.3bhp restrictor which is fine but i was wondering if replacing it with a 46.5 bhp (which meets the A2 requirement) is worth it for the 100 or what ever it costs or should i just keep the 33.3bhp.

I can't seem to find any 46.5 throttle or epu kits for the honda 600 cbf sa from 05ish so i think i might be better off with the 33.

Any ideas?

[-]

Well it's about 40% more so you'll definitely notice it.

Has the A2 limit changed to 46bhp then? It used to be 33bhp the last time I looked.

[jeddy11]

Around 13.2 bhp difference
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[G]

In the 'real world', I'd say it seems fairly marginal.
This is from riding restricted 500 and same again unrestricted.

If you want to go faster, get on the throttle earlier .

Where it's just inlet restrictors, you could probably bore it out a bit, or better get some dyno time and get them setup perfectly.

While it may not feel much different, I wouldn't spend cash on the lower power if it's costing extra, just to save a bit.

[sabian92]

[-]

[Shaft]

I think it's about the same as the difference between my old Super Dream and my XL600 (27 v 40) and allowing for the fact that singles and twins perform differently, there's not much in it really.

What I will say is, although I've never ridden a restricted big bike, I've driven artificially restricted cars and vans and there's always a massive hole in the performance somewhere, so I imagine bikes must be the same; I would think the nearer you can get to the design limit, the smaller that hole is likely to be.
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[G]

An air intake restriction can feel pretty 'natural' - it's basically similar to restricting the throttle, but feels a bit nicer than halving the throttle movement.

I've had an SV restricted to one cylinder a couple of times and again similar - one time there was no spark, the second the slide was locked down. On that second time, I could tell something wasn't quite right, but it was trying to do a wheelie at the end of the race that really proved it. I wasn't much slower that race than my previous race, despite going from 67hp to 35hp (I got it dyoned after the race). When I sorted it, the next race I was lapping MUCH better, as I'd got my corner speeds and getting on the power early sorted niecly .

[positron]

Last week I de-restricted my bike (03 Fazer 600), and it went from 33 bhp to around 95 bhp, and ZO MY GOD, it's proper quick and I haven't even taken it past 8000 rpm yet!!

[barrkel]

It depends on how hard you ride. If you're on peak power often and used to the feel of it, you'll notice. Otherwise, it won't be big.

Torque curve will make more difference in feel for most riders. A wodge of low-down torque (or a down-geared bike) at 33bhp will probably feel more powerful than something that needs to scream to get 46, and the power will almost certainly be used more often.

The CVT on my scooter means its putting its max power (~27hp) out at fairly low speeds, and at London speeds (mostly 0-50-0 between lights) I'm faster off the line and to the next light than most guys on big bikes. There's the odd guy who pulls a wheelie off the line and gets ~10m ahead of me, but it's fairly rare on my commute.

You should also notice it in max speed, but be aware that power needed to increase to top speed grows with the square of the top speed, as wind resistance is the limiting factor and that's proportional to the square of the velocity. So 2x top speed needs 4x power. Gearing is also important for top speed, to match peak power with max speed.
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