RS 125 Power Figures and A2 Licence

[HD]

Hey,

I am planning on taking my A2 in December. At first I was considering getting a Bandit 600 as it seemed the best, cheapest and most sensible option of getting a bigger bike.

However, money has gotten a bit tight and the insurance has gone up since my last quote. I will do quotes up towards the time but if it does remain high I have another option.

My mate is selling an RS 125 but is planning on keeping it for a bit if I want it. I know a lot what has happened to it in the last 12 months and have made some conclusions as to the reliability, ride comfort, practicality etc.

One of the things holding me back is the power/weight ratio for the A2 licence. For it to meet the 0.16kw/kg figure, it must be making no more than 27bhp as it ways 126kg (apparently).

I know it is derestricted but the power valve is either not working or disconnected. Someone the guy knows recommended he disconnects it as it can reduce reliability of the bike. I'm not saying whether or not he is right or wrong but I would like to know some figures, if possible.

I am aware in restricted form it makes 14.6bhp. So how much would it make with the powervalve connected, and without? Some places say 33bhp or there abouts but it must be at least a little bit lower than that? If it would keep it below 27bhp, how much would it be to for a new powervalve system?

Any info would be appreciated!

Ta
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Rusty '02 Vito Camper + CBR600F3

[WannaBeDude]

A2s 33 bhp afaik, fuck 27 .. RS will be 25/26 and drink fuel !
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Jogging on, destination living.

[Kickstart]

Hi

Depends on the model of RS125. Older ones Aprilia didn't quote a power figure (bit of a storm in around 1989 when Gilera launched the SP01 and a magazine got 107mph from it in a road test - to stop the backlash against 16 year olds riding them they stopped quoting power figures and a load of the Italian magazines stopped performance testing them). UK road test for the early RS125 was 28.5hp at the back wheel (but the 25kW / 33hp is meant to be a crank figure) but later ones are less powerful (latest are only a bit over 20).

Weight wise, it depends on which weight is counted. Early ones have a frame plate for 115kg, but that is dry weight (and probably a bit hopeful). Rules for the 25kW limit are here:-

https://www.opsi.gov.uk/si/si1999/uksi_19992864_en.pdf

Page 7 of that states the weight used for the power to weight ratio is:-

“power to weight ratio”, in relation to a motor bicycle, means the ratio of the maximum net power output of the engine of the vehicle to its weight (including the weight of any side- car) with—
(a) a full supply of fuel in the tank, (b) an adequate supply of other liquids needed for its propulsion, and
(c) no load other than its normal equipment, including loose tools;

So with a full tank of petrol, etc, there is probably at extra 20kg on top of the weight on the frame plate.

As to the power valve, leaving it disconnected it will probably cause more problems. They are a pig to unstick it left closed for too long.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[HD]

Was hoping you'd be along Keith

It is a 54 plate so the bigger/curvy model. I believe they are the fastest? and IMO the best looking. Custom paintjob too that is quite tasteful.

So I am looking around the 125kg weight mark then?

I have ridden it like it is and there is a jump in power at around 8k as it hits the powerband so is that just the engine or is that the powervalve kicking in so is it really disconnected? How much of a difference does the power valve make? What issues/gains are there in the real world?

Any idea what power I am looking at with/without the pv?

Sorry about all of the questions, just don't want to make the wrong choice
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Rusty '02 Vito Camper + CBR600F3

[Kickstart]

Hi

At that age it will have the smaller carb and also probably a pretty poor exhaust. The original shape ones should be quite a bit quicker.

At a guess a bit short of 25hp at the back wheel.

Weight wise if you use the wet weight then 135kg.

If there is a kick at about 8k then either it has a working power valve (so not that much of a kick) or the power valve stuck fully open (rather bigger kick). Restricted it would go to sleep just past 8k (would still rev out, just not do anything useful if you rev it further).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[HD]

Definately doesn't go to sleep haha.

Well the exhaust is an arrow. It was a full system but he got a hole in the front pipe. Not sure if the front pipe is now an arrow or an original but it still has the arrow can.

Again, not sure about the carb size.

Guess before I buy it I may do a dyno. How much would I be looking at?

So it is looking as though it will be legal to ride on A2 then?
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Rusty '02 Vito Camper + CBR600F3

[Kickstart]

Hi

The can alone won't do much other than make it noisier.

Carb will be a 28mm one unless someone has changed it (they used the 34mm up until about 1997).

Dyno run should be cheap. Suspect it will produce something just under 25hp.

A2 legal is going to be fun to prove either way as the power limit is at the crank, and realistically you can't measure that (even pulling the clutch and measuring the drag in the transmission to try and guess it will mean ignoring drag in the primary drive).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[HD]

I'll have a look at the carb next time I see him.

Also, if I lift up the tank, will I be able to see the power valve and if or if not its working?

I thought they measured the bhp from the back wheel? I could have sworn thats what happened to that guy on that sv650 forum I read?

Cheers for the help anyway!
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Rusty '02 Vito Camper + CBR600F3

[P.addy]

You'll be fine.

Seriously, I wouldnt say my RS was putting out much more than 20-22 and that had a full arrow system, rebuilt and run in correctly and was running tip top indicating around 100.

It would probably work out cheaper to get the bandit, or look at smaller cc, such as the CB400SF... heck a B King is cheaper for me than a Bandit

[Kickstart]

[ace-card]

When I had mine, I took it to be dyno'd, having just rebuilt it and just "run it in"........26bhp at the back wheel with a 34mm carb, pipercross cone and standard exhaust (didn't have the money for a performance one after MAJORLY blowing my budget ). The guy reckoned that after a few more miles, when everything loosened up, I'd achieve possibly a couple more bhp........sold it six months later, so we will never know! With regards to the powervalve, make sure you have the correct slack on the cable....needs to be adjust to between 7 and 8mm IIRC.

Think you'll be fine with regards to riding it on an A2....I was riding around on mine with just a CBT (not condoning this though )
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2007 Skyjet SJ-125, 2001 Aprillia RS125, 1988 Honda CG125, 1997 Yamaha YZF600R
Mama said "life is like a box o' chocolates....have what's nice, then offload the crap to everyone else!"

[HD]

Cheers for the help guys.

Paddy - Looked at lots and lots of options and the Bandit seem(ed) to be the best option but am liking the idea of an rs, plus its cheaper!

Keith - I'll have a look for the pv next time then, thanks!

ace-card - See this is what I'm thinking about haha. I think they allow about 10% over the bhp limit so would they allow that over the weight limit? But there's small chance of me being tested anyway. Shit loads of people ride around here illegally on CBT's here too haha! I just want to not get raped if I do get caught and it goes further How much was your dyno? And was it purely just power figures or did they test other things?
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Rusty '02 Vito Camper + CBR600F3

[P.addy]

[HD]

[clancy]

the RS may be cheaper but youll probably end up spending the same amount fixing it. not to mention the pain in the ass of it breaking.

personally i would buy a different bike, better condition more reliable one. and one thats easier to prove that its legal for you to drive.

money wise i doubt theres much difference in it for you, when i got my 400, quotes for 400/600s where cheaper than 125s with a full liscence. have a look at insurance prices for loads of bigger bikes, might find one you like that really cheap to insure
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KLX 300r

[HD]

[N cee thirty]

you looked up fazers?

faster and better built than the bandit
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[clancy]

insurance cant be guessed, changes to much for anyone mate. best bet would be to look on ebay/bike trader for bikes in your budget you like, then check insurance at same time. get a list of affordable bikes and go from there

bare in mind one bike might not be the same to insure as an identical bike, dont ask me why but thats what happens
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KLX 300r

[HD]

[kawakid]

Good luck on doing it in December.

Hopefully it will be milder than last year, I usually commute 365, but it was impossible last year.
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I've a twin and a 4.

[HD]

[clancy]

[HD]

[P.addy]

The cc and hp jump does not matter dude.
I went from 100hp car to like 600hp
Bike was 11hp > 50hp then back down to 9hp > 110hp... its fine, just get used to it before you wind the bike up and shoot off

All I can say is my 750 is sterling, I cant really fault it...enough power to do most things

[HD]