2018 Aprilia RS4 50 Euro 4 Upgrade Project

[Rj_666]

Couldn't agree with tora more... the Brembo RCS was hands down the best mod I ever made. I coupled it with the AF1 spring kit, stainless lines, and a Galfer wavy rotor. Quite awhile back we went in on a group buy of some custom made pre-load adjusters as well.
Unfortunately, all these great mods served to point out how crappy the rear shock is, so I hadda replace that, as well.

It never ends !

[Berkeley]

It could be a number of things since the bike was crashed. I would check to make sure that the carb is on properly, then the air box connection. After that I would try resetting the fuel/air mixture screw. Then after resetting that of course reset the idle screw.

Another possibility could be the float got messed up, and it's not sitting correctly. I don't think I've done a tutorial on that yet, but you can probably find one if you search around.

If that doesn't do it let me know, and I'll think about it some more.

Hi tora,
I looked at some youtube vids as well for setting the air fuel mix.. but that did nothing.. The air screw was hard to reach so didnt know if it was all the way in and hard to keep track of the no. of turns. I thought I had it by the sound, took it out on a test run and still stalling. Adjusted all again but maneuvering the carb for better access. Did 2 turns out .. played with the idle screw.. and it was totally shot.. very high idle speed and kept just over revving.. v strange plus it stalled again.

Its been 15 yrs since I last took a Carb apart and have worked on some right nightmare ones in the past but this time all in all it was ok.. considering I dont have small hands.

I took it all apart, cleaned everything. Re set the air screw to 2 turns out and 5 on the idle. I've never seen that restrictor plate before so left it off. Took the bike for a run and it kept on stalling plus wouldn't get over 7k rpm.. It sounded bad. Put on the plate back on turned the air screw half in...took it for a spin and it sounded as it should . At the lights it was over idling so turned it down.. and now i think its all good. no signs of stalling.. So no idea how I solved it.. when i put it back i made sure I could hear the float bowl move.. if it was that?? or maybe something was stuck or some dirt?? Not really sure.

[kaldis12]

Why dont you remove that restrictor plate? You could just take it out. You get a littlebit Better performance.

[Berkeley]

Why dont you remove that restrictor plate? You could just take it out. You get a little bit Better performance.

Yes I did remove it to start off with but it sounded all messed up and wouldn't go past 7k rpm. So i thought to put it back on then I could see if any real changes from before had any impact. The bike ran fine so for now will leave it on. I guess I would have to change the main jet size up now if i take it off? as there would be too much air now getting in (and probably why the bike ran bad just before when I took it out?)?? any thoughts?

This euro 4 bike has had a load of restrictors put in it.. One by one they have gone. The next mod ill make to it is to put the biggest head on without having to change the conrod then put a bigger carb on.. so dont know if its worth messing around with that now??

[kaldis12]

If it runs good then no. But in my experience if you remove the restrictor you will be able to jet correctly easier and it will ran smoother. And also for bigger top end you need to remove it, im pretty sure.

[Berkeley]

If it runs good then no. But in my experience if you remove the restrictor you will be able to jet correctly easier and it will ran smoother. And also for bigger top end you need to remove it, im pretty sure.

Yeah it runs good so maybe ill experiment at the weekend but know how bad it can go when not set up right.

I think in there is a 30 or 10 for the pilot jet as hard to read and 12 for the main jet. If theres a range of jet sizes to get for this it would be good to know
thanks

[kaldis12]

Your idle jet is 30 and the main is 72. Not 12 that would bee waay small. There is a 70-90 jets from polini if I remember correctly.

[Berkeley]

Your idle jet is 30 and the main is 72. Not 12 that would bee waay small. There is a 70-90 jets from polini if I remember correctly.

hahahahaha yeah i did think.. 'that cant be a 12'.. swear i read 12 and 10 the other night. cheers BTW

[kaldis12]

Thats fine but if you remove the restrictor and jet it up correctly( bigger jets) you will end up with a littlebit better performance on the stock cylinder, but on a bigger cylinder this would have a hugggeee effect on how the bike runs. Experience with it how is your bike reacts to bigger jet(without restrictor) and if you get better performance then keep it but if its the same just put it back because bigger main jet means higher consuption( i dont know how much it matters on these small carbs, but on bigger ones its pretty noticeable.)

[Berkeley]

Finally The his to hers arrived to match the brake lever. 100 euros for it but now its installed it looks good and feels a lot sweeter too.

Found it on Ebay at MCR Motorparts