2018 Aprilia RS4 50 Euro 4 Upgrade Project

[kaldis12]

Thanks mate

Maybe later on I will contact you with this now Im learning for a job. Sadly these bikes can eat a lot of money. Will need to gather some for this

[toratora]

The stock bikes will rev over 11K unless they are restricted via things like the pipe (with an insert), or ignition. This bike did have an ignition restriction, and a gearing restriction that reduced its top speed.

Setting this bike to rev into the 13.5K area I feel is a total mistake when you consider who’s riding it. These bikes become very persnickety when they are set up that way. Again, if the bike was for you I would say sure go for it, but since this bike is for someone that is essentially a new rider it is an unwise course to follow. Additionally, when you consider that she will be commuting to school, which mean city riding, having a bike that doesn’t like low RPMs is going to make this sort of riding all the more difficult.

With regards to shocks. The length of the shock isn’t the determining factor. None of those shocks you’ve see are going to work, even if the lengths where exactly the same as the stock shock. The issue is having enough clearance around the mounting points. Derbi for some reason requires a significantly longer distance between the mount, and the spring on both ends of the shock.

The guy you have spoken with sounds like he doesn’t understand the issues with fitting a shock to these bikes, and is asking for an exorbitant amount of money. To me those are the sounds of bells telling you to run away.

You can ignore me, it has happened by plenty of people in the past, but they always find out that what I’ve told them would have saved them much pain and agony. Really at this point just let her ride the bike—even now it can exceed her ability by magnitudes. Pick up an older pre-2005 GPR maybe something between 2002-2004 (they handle better than the later GPRs and the various RS50s), and build that bike up for yourself. On that you can go hog wild, and you’ll get a really fun bike to enjoy. As for this one put a 15 tooth sprocket on the front, as it will eccenually address the issue for which you have posted.

Eventually I will get the whole Öhlins thing sorted out, and for those with the patients it will be worth the wait. It will be done right. It will have been properly research (which I’ve already done), and properly put together.

[Berkeley]

Thanks tora for your input, will consider your view point and the issues around the existing shocks.

As I may have mentioned before the swing arm bracket of the RS4 50 looks to have different geometry then the GPR. The angle and horizontal extension seems to be less so as an initial estimate it looks to have better clearance to fit the ohlins shock?so will discuss this and make sure it wont be an issue.. I will know then if something can be done..



Anyway as its rainy/cold season here I'm up for a bit of experimentation.

[kaldis12]

Perfect time for experiments you can variate with different exhaust, and let her try it out. The best one she likes, will be left on.

I would say later on when she will get better at riding, try out the inner rotor ignitions, but you would lose the electric start option, so thats kinda bad. They are just fuckin fun.

Soon I will post some info from Ignitech programmable cdi. Will try them out, while I design my own. Programmable CDI could be an other option to increase performance though.

[Berkeley]

Cool, keep me posted on that stuff seems interesting

With the geometry of the bike like it is and another chat today with James at JHS Racing I'm going to give it a go.

[toratora]

There are many GPRs, one of which is the same as your bike. I own one of those too, and I am intimately familiar with its requirements. Yes is it different than the 2005 bike, and it is also different than the 2000 era bikes, but they all feature the same issue of needing more clearance in order to mount the shock. The swing arm mount isn’t the only mounting point that requires the clearance. The upper shock mount is where it is most difficult. You can see this just from looking at the shock you pulled out of the bike.

The photo you selected is of just one GPR (2005), and that photo doesn’t reveal the modifications I made to the swing arm, the shock, and the frame. All of those components had to be modified to get that setup to work. Material had to be removed, or “manipulated” from the frame, the shock, and the swing arm in order to gain the necessary clearances. I don’t recommend that anyone do it the way that I did on that bike, especially now that I have gained more knowledge on the subject.

I have the proper information to have a shock built for the current bikes (and the older ones too). I have found an Öhlins distributer that is able (and willing) to build custom shocks from the necessary parts. All of this work I accomplished last year before I went to Japan. The schedule got too tight so some things had to be set aside, and one of those was finishing up with the shock. That doesn’t mean I gave up on it—just that it was delayed. The current intent is to move forward with it for the next trip—which unfortunately has also taken on some delays—but I am working on solutions for it, and like I’ve been saying for those with patients it will pay off.

If you can hold off just a bit on the shock thing. Apologies for how long it is taking me, but as I have told you I’m suffering some difficult health issues.

[Berkeley]

Hey Tora, I completely understand your situation btw so no hassles if things are delayed on your side. Its all good.

The day I contacted them I already paid a deposit and the shock in the post to them as I write this.
Like I say its the beginning of the rainy season soon so its as good as time as any for the bike to be off the road as it will take approx 6 weeks to build the new shock and get it reinstalled etc.

I've asked him to document the making of the shock so could giveback some knowledge into the community. If you get your custom one made then we could compare see if there are any difference and for pricing as well.

After speaking to 3 other shock workshops this is the one thats given me confidence to move forward and hopefully walks the walk.

If it fucks up, it fucks up 'c'est la vie' and ill buy you a pint. ill just have to buy your shock, modify the bike to get this one to fit, or go back to the std shock.

If you want to share your research and or preliminary info then do as this will aid the build of this one.. if not then we compare later on. no problem

Cheers

[toratora]

I was going to make a push to move forward with it, but since you couldn’t wait I wont bother. When I’m ready to do something then I’ll pick it up again.

[Berkeley]

Cheers Rj_666 for the link to the swing arm socket, only £20,00 inc delivery which is a bit of a bargain. For my VFR 400 I purchased one from the dealer but that was about £70.00 so glad you posted it.

GB Motorcycle Products


[/quote]

Hi guys,

Does anyone know if there should be any difference in the rs50 and rs4 50 swing arm nut?

I say this because I brought the above tool and it doesnt fit .( its smaller) the inner dimension is 27mm on the bike and the tool is 24mm. Ill send and email to the supplier but seeing if anyone knows ? cheers

[toratora]

Last week I measured the castle nut on the RS 50, and posted it in the thread on castle sockets.

Could you measure the new RS castle nut, and post those dimensions?