2018 Aprilia RS4 50 Euro 4 Upgrade Project

[toratora]

Ducati 899

You do know that I have an 899 yes?I like this bike a lot, and it is a blast to ride. I will say it's not my favorite bike though. The reason being mostly is there's nowhere I can ride it where I can legally, and safely open it up. Sure the track, however, that would get my insurance canceled, so even the track isn't a possibility. But I've come to terms with that reality because !!!! I have little bikes.

Derbi GPR 50R

This little GPR is my favorite bike. Even if I cannot ride it as fast as I can ride the older ones (yeah that's another story). I have ridden this bike with "Leader" bikes, and in some places I can even outride them. But to ask someone fairly new to riding to ride this bike with four stroke bikes would be asking way too much. The riding styles are significantly different/incompatible, and without a lot of technique it would totally suck to have to ride with four stroke bikes.

Riding these little bikes requires carrying your speed. When you go into a corner you want to stay off the brakes, because to get out of the corner you are going to need that momentum. On a four stroke you will see riders go in, park it, and then throttle out. They do this because cornering a big heavy 400+ pound monster is hard. Stoping and throttling out of course is easy. When the two bikes mix the big CC four stroke hauls ass down the straights passing the little bike. Then at a corners the little bike has to either brake, and ruin their corner, or pass the slow as fuck four stroke, which can be rather dangerous at times. Basically it is a repeated exercise in futility, and a guaranteed way to turn someone off of riding. Street riding should be fun, not frustrating.

Seriously, if you want to have fun riding with her then just get another RS. You will have a much better time, and so will she. I cannot count the number of times that I've seen bikes on Craig's list because the guy tried to get his female counter part (GF, Wife, SO, etc.) into bikes, and it failed. Every time I've spoken with them they tried to get them to ride a little bike with their "Leader" bike. It just doesn't work—and they never thought to figure out that the bikes were incompatible.

The only fun that can really be had is when your skill level is high enough that you can totally demolish the ego of those "Leader" bike guys that think they are all that—and really that's a childish behavior that quickly get's out grown.

Also, your riding skill is very likely to improve by riding these little bikes. Your big bike friends will wonder if you've been taking steroids, because all of a sudden your riding will be at a much higher level. That is the gift that riding a Replica Racer provides. Pretty soon all your buddies will be wanting one.

[Berkeley]

Awesome..didn't know that you had an 899. Couldn't agree more about the cornering and the different riding style you have to implement to keep it going as re found out on the 50.
Also that riding the 50 and being on the limit on normal roads is a lot of fun and safer.. on the bigger bikes you are in 2nd or 3rd gear motoring around a lot of the time and when you open up then anything can happen
Sure is something to think about...

[toratora]

Yeah the 899 is a lot of fun. Sadly I actually bought it for commuting. lolz. I no longer have that job so I'm not commuting on it any longer. But I decided to keep it, because it's been such a fun bike.

What might be a nice kit to consider is the Gila Italkit. I've fitted a number of these on bikes for other folks. It's high quality, good performance, but nothing too crazy. I got one for the RS50, but ended up letting someone else have it for their bike since they couldn't get a kit in time, and I knew it would be a while before I'd be putting the bike together.

I had ordered one for a GPR, but it took too long to get here in time for GPR Camp, and I ended up getting two Stage6 BR77s. Dangerous Dave ended up putting it on his GPR. Hopefully he'll post about it. I get them from Treats of course, but you can probably source them in France, and get them quicker. They now make a 50mm bore, and that's what Dave got.

[Berkeley]

Cheers,
Do you have any dyno charts of the Italkit? the one you just sent was that a 90/80/70cc as you have mentioned these other in different posts before? I had a look but coudnt find any to compare how it would handle.

Looking at the stage 6 88cc, it seems like the dyno profile matches how the bike performs at the moment.. ie power band not kicking in til 7,500 rpm and peaking just under 12,000, so apart for the power I imagine it will have the same characteristics.

For the 77 yes its a different story.. coming in at 9.5k and going to 13.5k rpm very much different.

With your 88 did you have to mill any of the crankcase for the conrod as it says you may have to? i didnt see any post for it if you did.

The same goes for the crankcase, they advertise it as not needing too, but on the dyno chart it sais milled??
88cc dyno chart

As the bike will still rev to 11.5k then do i still need to do a premix the oil and fuel plus take out the oil pump? or will have to anyway as going for the 24mm carb as on your previous post. ... but this was paired with the 77 and high revving?

I take it for the upgrade I will need the clutch springs and domino mx throttle for the larger carb. BTW I ordered some domino handle grips the other week before i started looking at these posts again... just waiting for the mail man
thanks for your input cheers.

[kaldis12]

Firstly, you need to mill the cases anyway if you fit a Big Bore for the maximum performance. You need to mill space for the conrod when you have a bigger stroke crankshaft. (Just make sure you put the correct exhaust to that for max performance)

As for the premix you should remove it anyway, its trash. If you do any modifications on the cylinder then I would remove it.

And yes you will need better clutch springs too. I would recommend Malossi springs, they are the best. If you want to change the clutch plates( for a 20hp-ish bbk its necessary) then the Polini or the Most clutch plates the way to go.

[toratora]

These cases have been bored for the 100cc 2Fast, but they still required a lot more effort after the boring.

To install a crank for the BR88, which is a 45mm stroke, yes you do need to work on the cases for the crank case. It's not as much as you need to do with the longer stroked 2Fast, but you do need to do some work. With the 45mm stroke you can do it with a rotary tool. With longer you need to get a proper boring tool (mill).

If you run a 43mm stroker crank then you don't have to modify the crank case. Metrakit makes some of these, as well as some other companies. Some folks like to run a 43 stroke with a 43 bore to have a 65cc square engine. 40mm strokes are stock on the Euro3 engines. Puch and Derbi mopeds run a 43mm stroke (I know these bikes are called mopeds in Europe, but I'm talking about bikes like the Variant that have variators).

Some top ends have longer pistons, and to install those you need to lower the shelf. This is true even if you don't run a performance crank. This can be done without removing the engine. I've successfully done it a number of times now.

This is an example of before and after lowering the shelf at the exhaust side to clear the piston.

But seriously, you don't want to put the BR88 on the bike for your daughter. It's too high strung—there really isn't anything until about 9K RPM with it. Look at the torque curve. She will spend all her time in the waaaaaaa zone, and that's not a fun place to ride the bike. Get a nice mild kit where she can learn how to keep it on the pipe.

The high strung bikes are heady, but they are very difficult to ride well. Even if you have a decent amount of skill it is still difficult—most people are slower on them than they are on the more mild machines. It's really not the way to go with someone that's still basically new to riding.

[kaldis12]

Agree with tora. My first learning bbk was the airsal 70 2 ring. It has a very good power but its also has pretty low rpms. My second was a barikit 80, thats a pretty high rpm one but I did some modifying and with the correct exhaust i got it down to 8k to 11k rpm. Dont get her the biggest kit ever, they are really hard to ride. Just go with a mild setup. Maybe choose a 80 iron kit like the Top performances pink. Thats a pretty reliable kit too. She need to learn how to ride a bigger bore, thats a completly different world.
As I mentioned go with the tpr pink 80 iron kit. Thats a pretty reliable, has a lot of power but its not that high revving engine.

[Berkeley]

cheers guys... was looking a lot yesterday at the options and whats involved in making the mods. If i can send you the shopping list can u guys have a look to make sure what im ordering is correct and compatible. thanks

[kaldis12]

Yes we can

[Berkeley]

Hi guys,

For a bit of custom modification I decided to fit 2 sets of LED sequential indicators to the rear. I jointed both from the right together and both from the left together but something strange happened

Turing left



Turning right



Could this just be wiring which im sure it not or is there some kind of resistance imbalance in the system causing this . or simply you cannot fit two pairs on the rear for some other reason? maybe a different relay is needed??
If anyone has any ideas on this then would be good to hear thanks