Slabby 750 jetting

[cullinoc]

Little help needed , been lookin for dynojet kit or simalar for slabby 750 vm29s but cant seem to find any

its got full micron 4-2-1  pipercross filters , original airbox not an option  , whats best jet size to start with?cheers

[Guest YoshiJohnny]

105s (mikuni) would be a good start point, raise needles a clip or 2 and adjust mixture screws from 1/2 a turn out to 1 turn out...

raising needles is easier than you think ...just 2 allen bolts hold the slide rocker in place and once undone gives access to needles

 

[kokolis]

Haha...2posts, two different settings.

110-115 mains mikuni, needles in the middle, mixture screws 2,5 turns out.

[Guest YoshiJohnny]

dyno time will give you YOUR best settings Barry...

mine took a couple of hours setting up but lasted around the IOM..

I know banoffee has 140s in his carbs but I started too rich with 120s and worked backwards

mixture screws are 1/2 a turn out standard and 2.5 turns out is bordering on a pilot jet change .. std setting for needle is 3rd clip so it shows how old motors and carbs can differ..

 

[cullinoc]

Cheers mr oliver will start with advised settings then work from there 

[Guest YoshiJohnny]

do you still have the airbox ? If so use the rubbers instead of the filters you got... and get some ramair socks (£23 a pair of duals offf ramairs Eblag site)

It will run better with that set up than pods

[banoffee]

130DJ in mine.

[KATANAMANGLER]

DJs are smaller than mikuni jets. A DJ130 is a mikuni 122

 

[Guest YoshiJohnny]

130DJ in mine.

I was nearly right lol

 

[canamant]

OK.  Scabby Racer 1 and 2 (before they were renamed Scabby Racer 1 and 2) were nominally the same but the main jets were markedly different.  Scabby Racer 1 had standard needles on the next to bottom notch, 35 pilot jet, screw out 1.5 turns and 140 Main jet.  No filter or airbox. Motad Nexxus downpipes,  homemade link pipe and unknown silencer but believed to be Blue Flame length 16 inches.  AF ratio 12.5 - 13 - 12.5 7000rpm to 11000rpm. 100.25 rwbhp 50.25lbft and power curve as straight as a die.  Scabby Racer 2 differed only by full Micron.  Never got any torque readings on that one because of electrical interference but AF ratio similar but on 132.5 MJ.  All that this information tells you is hat you need to get it set up with a gas analyser under load on a dynamometer by someone who fully understands slide carbs.  The lad I use does understand them so gives me data I can make informed changed against and then re-run.  You need some full throttle runs and some where the carbs are wound open as the revs rise to tell you how the main jet, needle jet and needle are all operating.

[Guest YoshiJohnny]

flatslides need to be run at different throttle openings on the dyno to gauge what is happening with each circuit... crack the throttle open and it will give you an indication of the main jet, main air jet etc and how well it performs as a whole..

CVs open relative to manifold pressure as the revs rise if you crack the throttle open and you can use the data to adjust a bit more with all the circuits

[banoffee]

I fucked about with mine for ages before finally getting it on a dyno for a tenner at a dyno day. Highly recommended, it ended up with smaller mains than I'd previously tried and goes like a rocket.