big bore cylinders, has anybody done the mod?

s.w.blackwell · Derestricted Danger Joined: 03 Jun 2002 Karma :

Hi sorry for dragging up and old topic

Ive looked through old messages etc about this, BUT has anybody actually done this mod? exactly what was done? and whats the verdict?

my barrel is wrecked, replating/ sleeving costs loads so do i try the big bore?

thanks

stephen
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Thanks

Stephen

Ropehead · Could Be A Chat Bot Joined: 02 May 2002 Karma :

Keigh posted the address of a place that specilised in that, it was somthing SMOKERS. urm dont know

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Not sure it was me, but I think PJ Engineering do it (https://www.prox.co.uk I think)

All the best

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

Scotty · Scooter Boi Joined: 31 Jul 2002 Karma :

The are 10 kinds of people in the world. Those who understand binary and those who dont.

^^^^^^^Very clever Keith.

(i know it was off subject but i had to say something)

scott

s.w.blackwell · Derestricted Danger Joined: 03 Jun 2002 Karma :

hi all.

i have a little more info.

www.beedspeed.com do kits for £239 this includes head/cyclinder/piston/gaskets made by malossi

On asking for more info this was the reply:-

Although it is not essential to change the carb and exhaust I would advice it.

Putting a bigger barrel on doesn’t give you a big increase in speed but seems to give the bike more pulling power.

You could leave your standard carb and exhaust on but you would have to up jet the carb.

If you put a bigger carb on you would get a higher airflow which would give the big bike faster acceleration and Make it more responsive.

With a combination of the big bore, exhaust and carb you would have good pulling power, faster acceleration and A higher top end.

im in two minds, do i do it? or do i continue the hunt for a new barrel?

Is rejetting a pain? how much are new exhausts and carbs? Its starting to sound costly!!

thanks
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Thanks

Stephen

Hunter · Nitrous Nuisance Joined: 01 Mar 2002 Karma :

Drop in a big bore! We need more big bore NSRs here. I'm really interested in knowing the performance boost gained.

My bore is too good at the moment, but when its wrecked i'll get a big bore Smile

Maku · Guest

well polig ini makes big bore kits too! visit www.polini.com i know that theres no link for bore. but i know that polini makes it for honda but they say that it is for competitons. friend of mine just bought them...

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Think they say the bore kits are for off road use to cover themselves legally. I have an old PB article from about 10 years ago covering an NSR125RK with a Malossi big bore kit on it

All the best

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

Dylan · Trackday Trickster Joined: 03 Feb 2002 Karma :

What was the result from the mag then keith???
Confused

Dyl

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

They dyno tested the bike and got 29.4hp out of it (a stock RS125 gave about 28.5 at the rear wheel in their tests, for comparison). Performance was standing quarter in 15.27@87mph, top speed prone 89mph into the wind and 103.5 with the wind (so realistically 96). This is with the 180 big bore kit and from the pictures an aftermarket exhaust / silencer (not sure whether it is just the silencer). They mention the 30mm carb but they dont say whether the bike they tested had the larger carb or not

The shape of the power curve is quite good. The bike was making 12hp at just over 6000rpm and 20hp at 7500rpm and over 25hp from about 8250 until the graph ends at 10500.

All the best

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

Hunter · Nitrous Nuisance Joined: 01 Mar 2002 Karma :

Keith!

Is there anyway you could scan that in for us to take a look at by email or on a website?

Smile

Dylan · Trackday Trickster Joined: 03 Feb 2002 Karma :

Thanks for that Keith! Bit too much wor for me though. Think ime gonna take mine in for a dyno run, but it might be a bit embarassing taking in a 125 when there powere running there milles!!! Will a DEP silencer make any differance to power, because i can get a cheap one, but will it actuially make any differance??
Thanks
Dylan

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Realistically I dont think a silencer(?) will make that much difference, except on a bike which is restricted in the silencer (NS125F/R I think). After all, the important bit of the exhaust for power is the expansion chamber.

As to scanning the article, we will see

All the best

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