2018 Aprilia RS4 50 Euro 4 Upgrade Project

[Berkeley]

Hi Guys,

Complete rooky question here, I looked online for a diagram but to no avail.

But what are the 2 black pipes coming off for and do you need them? I swear one went to the radiator water hose and the other to the top of the cylinder head before? For the new 19mm carb In the box there are two black bungs.. so do you just block them off?

The copper gold nipple on the side I take it that its for the oil form the pump?
.

Also on the 14mm old carb there are so may nipples coming off the thing and on the 19mm there are just a few so are all needed?

I had one coming off the carb and going to this, looks like a sensor or switch? What is it, and is it needed?
.

Also before the vent pipe from the tank went to the old carb.. so on this one there's no nipple on the carb for it.. so I take it the vent pipe is just left hanging down but secured to where the rest of the overflow pipes go?

[kaldis12]

The water hose on the carb you dont need to worry. Its for warming up the fuel so when its cold out there it warms up faster. I always disconnect it for better cooling. As for the electronic i have no idea. Never saw any electronics on a carb. Just connect what you have on the new carb

[toratora]

Polini CP 21

There are a number of different things going on here. Some of it relates to the new Euro4 smog equipment, some if it to vacuum lines, oil injectors etc.

On the CP carb the two nipples at the front of the carb are vacuum lines. These can be employed for a number of different things. In your case one line (the smaller of the two) should be used for the oil feed from the oil pump. The second larger one could be used for the petcock if you have a vacuum controlled pet cock. The nipple on the side of the carb pointing up is the fuel feed, the one on the other side is a vent, and the one on the bottom is an over flow. You can probably see photos of some of these things in the Red Power thread.

The water lines from the old head to the old carb wont exist on this setup. The electric switch might be something that opened up to the old pipe. That wont be used either. You are the first in this group to have a Euro4 bike so the more photos you post of the Euro4 stuff the more we learn about it.

[Berkeley]

Thanks guys,

Tried to start the bike tonight and wouldnt run. every now and then it sounded like something was beginning to fire out of the exhaust,, tried putting a bit of petrol in the cylinder head as was dry but no luck . Choke in choke out, throttle left open , shock the bike a bit .......Any ideas of getting her going?

During the build there was a couple of sticking points..

1 was the cylinder head studs.. one must had rounded off using an worn out nut so tried many things to get the thread to work.. lost a bit of length but luckily is was just enough for the job.
.

2. The piston rings were soo tight, took forever to get it in, I've never known them to be that difficult before.

Doing the squish test with play doh.. worked well

Got the correct amount the first time, pretty good
.

Had to use parts of the old cable so the throttle and choke were the right length. Seems all good but the metal stopper on the old cable are so small and just about worked. Could do with a size bigger.
.

And finally:

The only thing that didn't fit was the temperature sensor as the hole is too big hopefully the koso adapter will fit!

[kaldis12]

So if I understand it right then you said there is no traces of fuel on the sparkplug? Right? If then you should check the entire fuel line. From the tank to the carb. If you pull of the fuel hose from the carb does the fuel flow? Check if it gives spark or not. Just to be sure.

[Berkeley]

Will Check the spark.. and fuel yes as I hooked it up wrong before and fuel went everywhere so I know that's good cheers

[toratora]

Spark is what I would probably check first. If the plug is wet then you know you have fuel. I'm a bit concerned about the ring. Did the instructions talk about ring gap?

You should be able to hear the slide in the carb hit the idle screw when you let go of the throttle. If not then it's not closing all the way.

Looking at the photos I see the way the ignition triggers is different too. Maybe some of the Euro4 stuff has a sensor that needs to be triggered to allow for spark. I don't know because I've not had my hands on a Euro4 yet, but this could be a possibility.

[kaldis12]

Yes, just check the spark. About the tight rings. Did you rotate them to their places? There is a little notch. I had a metrakit SP, I had the same issue the rings was waay too tight. But dont worry if you put them to the right orientation then its good. I talked about this with the metrakit guys. They said its normal, thats how they produce it. But I cant remembet what was my ring gap. I can remember that it was very tight

[Berkeley]

Hey guys thanks.
Yes the slide hits idle.. so closes properly.
Charged the battery up..Spark looks good but not wet as per expected. Took the sensor off. Plugged it back up .connected the thermosat took it off.put some more fuel in the tank. Took off the carb. Feels wet. Sprayed engine starter in the head .tried it in the carb. Checked the reed valve and ok.. Didn't check the float bowl for fuel yet. Not sure what to do next.
Hmm

Any ideas???

[kaldis12]

Does it give spark?