Carby Kit Problem

[Craigs902]

The needle was the first part i was going to replace, didn't even think it wouldn't fit straight away in the sliders. I was able to get the the needle about 1/2way then it got stuck. I went WT !! then had a look at the needles, not thinking they would be different and i thought oh shite (that was more colourful at the time) look at that totally different taper. I didn't even try to replace the needle body.

Now, if i do replace the needle body in the carbs i'll be able to use the new needles correct? All i have to do is make the hole bigger in the plastic sliders, True??

You can see me apprehension on this, as i don't want to be drilling sliders and then F it up in some way.

I'm going to pull them apart again tomorrow and have another look see. I'll let you all know how it all goes.

[dicky]

All the hole in the bottom of the slide needs to do is allow the top needle to poke through. The circlip stops it from dropping, the nylon bush stop it from lifting. A bit oversize won't screw anything up.
I'd be very reluctant to fit needles with a different taper unless you knew exactly how this will affect the fuel/air delivery and have a range of fuel and air jets to tune the carb properly.
I bought a Factory Pro carb kit to replace the emulsion tubes but it ran like shit with their needles so I went back to the originals.
You can see in the pic from Dandy that the Factory Pro needle is a bit different. They Keyster one looks like even more of a departure from standard.
Maybe the new tube is different internally than the original, but without a data sheet or something similar from the manufacturer I wouldn't touch them.
Like I said earlier, the needles hardly wear, only the tubes, so you can keep running the originals in the new tubes (assuming that the tubes are not different internally).

[Con Rod]

yes replace the needle jet and the jet needle. oyu wont need to adjust the white plastic thing that holds the needle jet, but it is a snug fit

[pom in nz]

now im confused, are these kits any good? I was about to get 2 so I can freshen up my carbs, but now im not so sure.
any other feedback on these kits people?

[dandywarhol]

Like Dicky, I tried the Facrory Pro needles and had a real problem with fuelling - they are more suited to either a tuned motor or a motor using the top end of the throttle range - look at the taper. The ones you posted look similar. I got another set of stock Mikuni needles to match the Factory Pro emulsion tubes as you can see the wear on the original lower needle in my pic.

The type of riding determines the wear pattern on the needles - the rider who "lugs" the engine from low revs will wear faster cos the needles slap back and forward in the tubes.

[Rod.s]

If you got the correct kit it would all fit….. send them back and get the correct kit

[Rod.s]

Like Dicky, I tried the Facrory Pro needles and had a real problem with fuelling - they are more suited to either a tuned motor or a motor using the top end of the throttle range - look at the taper. The ones you posted look similar. I got another set of stock Mikuni needles to match the Factory Pro emulsion tubes as you can see the wear on the original lower needle in my pic.

The type of riding determines the wear pattern on the needles - the rider who "lugs" the engine from low revs will wear faster cos the needles slap back and forward in the tubes.

Don't use factory pro kits, they are poorly engineered and corrode severely due to the use of the same material in both the needle and the emulsion tube, this leads to a greater potential between the two resulting in the needles cording severely at the point where the needle sits regularly. Ken in Toowoomba had this very problem to the point that the last â…“ of the needle tip just fell off!
They are also tuned for the 180deg TDM engine that the Yanks got, which uses a different cam profile etc..

[Rod.s]

The type of riding determines the wear pattern on the needles - the rider who "lugs" the engine from low revs will wear faster cos the needles slap back and forward in the tubes.

Mate, a carburettor needle should not "slap" if designed well, as the flow of fuel should spiral around the needle keeping it central in the emulsion tube, in this way the emulsion tube will wear first allowing the needle to sit central (the genuine needle and tube are made from dissimilar materials). As the tube wears the shape become erratic and the overall fuel delivery increases….so we drop the needle down further into the emulsion tube and take up some of the clearance etc. This is deliberately created to give a service life to the carbs, if not, you would be replacing the needle and tube every other service.

[Rod.s]

now im confused, are these kits any good? I was about to get 2 so I can freshen up my carbs, but now im not so sure.
any other feedback on these kits people?

Mate if you get the correct kit they are a fresh kit in the pants when riding, if you try to use the incorrect kit …..then again you could always buy the parts from Yamaha, at last count that's around $400Aust

[dandywarhol]

The type of riding determines the wear pattern on the needles - the rider who "lugs" the engine from low revs will wear faster cos the needles slap back and forward in the tubes.

Mate, a carburettor needle should not "slap" if designed well, as the flow of fuel should spiral around the needle keeping it central in the emulsion tube, in this way the emulsion tube will wear first allowing the needle to sit central (the genuine needle and tube are made from dissimilar materials). As the tube wears the shape become erratic and the overall fuel delivery increases….so we drop the needle down further into the emulsion tube and take up some of the clearance etc. This is deliberately created to give a service life to the carbs, if not, you would be replacing the needle and tube every other service.

Mate, the needle will "slap" if the throttle is opened hard from low revs as the needle is horizontally in the downdraught carb. Most affected engines are the cruiser type which are used in this manner - the needle slaps back and forward in the airstream with the intake pulses

[Rod.s]

.

[Rod.s]

The type of riding determines the wear pattern on the needles - the rider who "lugs" the engine from low revs will wear faster cos the needles slap back and forward in the tubes.

Mate, a carburettor needle should not "slap" if designed well, as the flow of fuel should spiral around the needle keeping it central in the emulsion tube, in this way the emulsion tube will wear first allowing the needle to sit central (the genuine needle and tube are made from dissimilar materials). As the tube wears the shape become erratic and the overall fuel delivery increases….so we drop the needle down further into the emulsion tube and take up some of the clearance etc. This is deliberately created to give a service life to the carbs, if not, you would be replacing the needle and tube every other service.

Mate, the needle will "slap" if the throttle is opened hard from low revs as the needle is horizontally in the downdraught carb. Most affected engines are the cruiser type which are used in this manner - the needle slaps back and forward in the airstream with the intake pulses

To true, but only under those conditions