hi in starting to rebuild my engine it a 1.3 out of a mk2 puting a gt cam in it. I'm looking at bike carbing it but not sure on what carb to use any help please

thanks

i have honda cbr 600's on mine with 4 branch p+p head and 2 inch strait through exhaust produces 90bhp at the fly wheel but I'm going to get some cbr900 carbs as with the 32mm cbr600's it lacking power up top end of the revs firstly I'm going to try a newman cam and see if that will release some top end power

it all depends on how much you are going to mod it over time if you are staying with the gt cam go for 600's

gaz

i have honda cbr 600's on mine with 4 branch p+p head and 2 inch strait through exhaust produces 90bhp at the fly wheel but I'm going to get some cbr900 carbs as with the 32mm cbr600's it lacking power up top end of the revs firstly I'm going to try a newman cam and see if that will release some top end power

it all depends on how much you are going to mod it over time if you are staying with the gt cam go for 600's

gaz

900's will be overkill surely? i know people on 2.0ltr engines running these... wouldn't it make more sense just to open up the jets a touch so that you gain the top end? i reckon 900's would open up the top, but your low end will suck and unless it's a track car, it will drive poo most of the time!

i have honda cbr 600's on mine with 4 branch p+p head and 2 inch strait through exhaust produces 90bhp at the fly wheel but I'm going to get some cbr900 carbs as with the 32mm cbr600's it lacking power up top end of the revs firstly I'm going to try a newman cam and see if that will release some top end power

it all depends on how much you are going to mod it over time if you are staying with the gt cam go for 600's

gaz

900's will be overkill surely? i know people on 2.0ltr engines running these... wouldn't it make more sense just to open up the jets a touch so that you gain the top end? i reckon 900's would open up the top, but your low end will suck and unless it's a track car, it will drive poo most of the time!

iv seen a 1.3 polo with cbr1100's on lol because they a flate slide carbs with an auto adjusting choke as you put your foot down the choke opens up the carbs are set up spot on and opening the jets any more would cors it to over fuel if you can get more air in there then you can put more fuel in with the 600's there is only so much air that they can pull in and at full tilt the chokes are full open

when i do put 900's on then they will be running with 38mm inlet and 32mm exhaust valves with a 272degree cam the head is already ported and polished and am running with a 4 branch with a 2inch exhaust system so i think as the carbs are restricting air flow at the min the engine with those mods will defo benafit from the 900cc carbs john at john sleath race cars said that it would deffo benafit from the bigger carbs but not untill the valves are in and i get the cam

gaz

more gospel from gaz !

more gospel from gaz !

whats that suposed to mean dude? lol

I'm running CBR600 on my 1.4 16v... had it on a rolling road and they are perfect for the car.. I find it hard to believe that you need 900's for a 1.3. They will work but I would have thought that to make use of them would be outside of the engine capabilities.

if you can get more air in there then you can put more fuel in with the 600's there is only so much air that they can pull in and at full tilt the chokes are full open

whilst i agree with this no doubt... i was merely questioning that a 1.3 could pull sufficient air in, and that at low revs the draw would be so weak that not enough fuel would get pulled in? fair enough if it's some super lairy spec engine, i've seen plenty of wee xflows on 48's, but they were mental engines!

http://www.pumaracing.co.uk/Chokes.htm

this is always a good guide... but looking at it now and what you said about the adjusting choke (very cool) maybe your right?

i was always lead to believe that a 38mm choke is ideal for 2.0?

damn, now i'm more confused then when i first posted

A good mate of mine runs a 44mm on a 1.3 mini, Hes built a turbo mini and he thinks that the 44mm is the ideal size for his other normally aspirated 1.3

A good mate of mine runs a 44mm on a 1.3 mini, Hes built a turbo mini and he thinks that the 44mm is the ideal size for his other normally aspirated 1.3

is that 44mm venturi or choke... big difference!

running twin 45's on a 38 choke is ideal for most NA road going 2ltrs

Thats the choke mate sorry.

I wasnt saying your wrong , nothing like lol , just saying thats what he thought and wondered what you had to say about it haha.

Iv got a single 38mm on my 1.3

Max

didn't think you were saying i was wrong... i thought you were questioning your mate

on my cappa i have got a 32/36 twin choke carb... progressive, so the 32 opens first for economy but press the peddle all the way to unleash both! will be getting a set of CBR 900's for the capri soon though!

http://www.kitpartsdirect.com/page18.htm - absolute bargain from kitparts direct for £280, jetted and ready to bolt on!

i forgot to mention i will also be running with race bearings that would alow me to rev right through to 7500rpm safely so so the 900's which are 38mm will run better at high revs and with the bigger valves and ports will draw more air in at low revs so the 900's will run well they will not be any good on a standard engine though

I still wouldnt run the 900's mate, but its your car at the end of the day. Just wondering how often you would be right at the top of the revs even on a track, Id personally rather have a much stronger mid range and loose slight amounts in the very top.

Id concentrate on shaping the heads more than getting anymore air in than what the 600's can offer. All well and good putting loads of air in but if your head doesnt mix it well its pretty much pointless.

Either way id back to back test on a rr

Edited 13 May, 201016 yr by shaun_89

I still wouldnt run the 900's mate, but its your car at the end of the day. Just wondering how often you would be right at the top of the revs even on a track, Id personally rather have a much stronger mid range and loose slight amounts in the very top.

Id concentrate on shaping the heads more than getting anymore air in than what the 600's can offer. All well and good putting loads of air in but if your head doesnt mix it well its pretty much pointless.

Either way id back to back test on a rr

when i drive I'm in the top of the revs most of the time alot of boy racers around here in their shity corsa's

yer the heads coming off in the next few week to have the valve seats put in for the bigger valves so i wil be sorting out the ports then and was planning on a few rolling road sessions to work out what will work best i do no of a polo with simalar spec to what i will be running and that runs on 1100cc 41mm flat slide carbs

If you want to know how many millilitres are in a pint,ask a milkman.

Think you're clever enough to work it out for yourself and you're in for a hard life.

Putting bigger carbs on will slow the car down. You need high intake speed for a clean burn. I'm running a 1.6 16v on 600's because i know what I'm doing. Your mates mini is not a Polo. It has only two inlet ports - the Polo has four. He has ONE 44mm carb. I have FOUR 36mm carbs.

Now I'm no mathematician,but..

If you dont know what you're talking about,shut up and listen to those who do.

If you want to know how many millilitres are in a pint,ask a milkman.

Think you're clever enough to work it out for yourself and you're in for a hard life.

Putting bigger carbs on will slow the car down. You need high intake speed for a clean burn. I'm running a 1.6 16v on 600's because i know what I'm doing. Your mates mini is not a Polo. It has only two inlet ports - the Polo has four. He has ONE 44mm carb. I have FOUR 36mm carbs.

Now I'm no mathematician,but..

If you dont know what you're talking about,shut up and listen to those who do.

why all the...

because it's false information!

If you want to know how many millilitres are in a pint,ask a milkman.

Think you're clever enough to work it out for yourself and you're in for a hard life.

Putting bigger carbs on will slow the car down. You need high intake speed for a clean burn. I'm running a 1.6 16v on 600's because i know what I'm doing. Your mates mini is not a Polo. It has only two inlet ports - the Polo has four. He has ONE 44mm carb. I have FOUR 36mm carbs.

Now I'm no mathematician,but..

If you dont know what you're talking about,shut up and listen to those who do.

Gaz wasnt talking about any mini's??? That was me. I was putting that because he thinks that a 44mm is best for his turbo mini, but doesnt know why (if that makes sence) So i put that up for someone to give some info about and see if he is correct.

And theres about 473.5 millitres in a pint.

Max

Edited 8 June, 201016 yr by Gozzard-Coupe

LOL

I got a few more slices yet,punks - late 600s are 37.5mm so you cant just say 600s and 900s because the size varies amongst different ages and editions.

Flat slide 44's still have chokes only a fifth the size of a standard 1.3 manifold,so they're more than small enough. The problem with carbs too big is the useable needle profile.

Plus its all been said before,and those in the know cant be bothered to come in here and repeat themselves for the 842nd time,when they took the time to say so in established topics on carbs found in the faq section.

And if you know what i was talking about,then it was for you. I dont care who wrote what,take from it as you will.

No gravy.

Btw,there's 568ml in a pint.

Listen to mikey he knows what he is on about i have taken all advise from him and my polo is flying with no problems with the aid of a AEM Gauge . I have done 2100miles on bike carbs with out a single problem. Pointless fitting larger carbs coz its the valves and ports that restrict the gas flow.

Btw,there's 568ml in a pint.

Depends on what kind of pint your talking about

> UK pint

> US Dry pint

> US liquid pint

lol, if i went to tesco bought a pint of milk and 100 ml was missing id be fumin

even more so if the bitch behind the bar pulled a pint and there was 100ml missing!