Tuning Bike Carbs

[Guest salty_monk]

depends on the carb set. It's more usual to put in a restriction than to block them off completely.

 

Dan

[Guest SEgan]

I found this information on another site

 

LINK

 

I thought post no.17 was an interesting read.

 

Thoughts ?

 

Sean

[Guest salty_monk]

He's giving out good information. I have played with bike carbs a lot recently on 4 or 5 bikes & it really isn't as easy as everyone seems to think.

Spring weight, air correctors, main jet, needle height etc all work together across the throttle opening range & need to be adjusted accordingly as he says.

 

It's also very important that they are balanced.

 

When you take an airbox off of this type of carb & fit K&N pod filters on a bike it's normal to fit a DYNOJET kit (hence DJ jets that he talks about).

 

Depending on bike these have bigger main jets (definitely) brass air corrector restriction bush (maybe), Tapered needle (bigger taper with a thinner tip) with slots for adjustment & you have to drill the vacuum lift holes in the slides bigger to get them to lift faster (always).

 

I can't see why you would need any less work than this to get a similar performance lift when mounted to a car. Of course you might "get by" but if someone had a car, 2 weeks & a dyno I bet they could get a lot more by playing with different sizes in all the above, that's what Dynojet do at their research facility with the bikes.

 

Dan

[Guest woolly]

Sean thanks for that link, a few more questions answered.

 

GBS are struggling to supply manifolds at the moment so using the time to about setting up and wideband lambda.

 

i cant seam to find solder less cable nipples, tried 3 push bike shops.

 

woolly

[Guest paul c]

Hi Wooley

Try lawn mower repair shop they usually have boxes of assorted nipples and cable adjusters

PAUL C

[speedtripledan]

Found this link which may be helpful if your doing or thinking of a a Bike carb conversion

 

http://www.totalvauxhall.co.uk/resources/t...4.tech60697.pdf

 

There seems to be nothing about the air corrector jet though. Is it normal to block them or does

it depend on which bike the carbs come from ?

blocking the correctors was something this guy did on my carbs (1999 fireblade) the prove is in the dyno runs with the 1.6mm fitted the car was rich as hell ! with around 92bhp at the wheels by blocking the correctors and reducing the mains to 1.3mm it went to 102bhp smelt better and sounded better he did it to get a particular lamba reading accross the rev range which he claims is the optimum for the pinto.

Right or wrong i don,t know but my car runs bang on

[Guest woolly]

Hi Wooley

Try lawn mower repair shop they usually have boxes of assorted nipples and cable adjusters

PAUL C

 

 

good idea thank you

 

woolly

[Guest salty_monk]

blocking the correctors was something this guy did on my carbs (1999 fireblade) the prove is in the dyno runs with the 1.6mm fitted the car was rich as hell ! with around 92bhp at the wheels by blocking the correctors and reducing the mains to 1.3mm it went to 102bhp smelt better and sounded better he did it to get a particular lamba reading accross the rev range which he claims is the optimum for the pinto.

Right or wrong i don,t know but my car runs bang on

 

It's possibly he could have got the same effect with smaller mains & leaving the air correctors open (such as 1.5's for example) or by restricting them rather than blocking completely. It's certainly a valid tuning technique & he's proved it works in this case.

 

On the Lambda he'd be looking for optimum combustion throughout the range.

[Guest Ace Fettler]

Just following on from Salty Monks' post, the 'Blade engine in my westy is running a Dynojet kit to compensate for the panel air filter in place of the bike airbox. The kit included blanking plugs for the air correctors, without which the thing wont rev much above 6500 rpm.

 

Richard

[Guest JoeW]

Hi all Ive just fitted a 2litre pinto to my hood with uprated cam and lightened fly wheel adn ive fitted bike carbs from gbs

Ive tapped all 4 intakes for my vac advance in the dizzy as just the one was making it clunk i think the cam is a fast road piper

it goes like a rocket when I get above about 3 000 revs but upto that its spluttery and got no pull

Ive checked the timing and adjusted the idles to wot ive read on here

it starts first turn and idles nicely but no go upto about 3000 rpm any ideas ?????

Please help been messing about for weeks now and losing patience !!

[Peter Bell]

Joe, try blocking off all the vacuum tappings and forget about the vac advance.

[Guest SEgan]

Sorry miss-read the problem please disregard this post

[Andi]

Mine was exactly the same till I tried smaller main jets than GBS do.

I plan another rolling road session soon and I suspect the jets may have to come down in size even more.

You could try soldering them up and re-drilling.

 

Andi