Red Rocket: 2012 Red Derbi GPR

[jkv357]

That is one sharp looking bike!

How does this new design handle compared to the older, steel-framed, design?

What years did they produce this model?

[toratora]

These came out in 2010, or 11. But the first ones were the 4T 125, then the next year the sold them with the Euro3 two stroke. Since I changed the tires (Sava/Mitas MC50), and forks (Malossi F38R) the bike should handle better than stock, but I didn't really have any time to make adjustments. Comparing my 05 to the Cagiva generation of GPRs though I would say that the skinnier wheels and tires make for a quicker turning bike. In 05 they went with the newer wider, and much heavier wheels. This dramatically effects the handling in a negative way. Sure the contact patch is bigger, but the mass is a big issue.

The little bit that I was riding this bike without the heavy gear hanging on the back was quite limited, and I had been riding a scooter with 12" wheels so my perspective was all messed up. The bike felt a little heavy to turn, but I think that had more to do with me having been on the scooter which I kept over steering because it requires so little input. So I wont be able to give you a proper analysis of the bike until next year when I go back. Still I think the Cagiva Derbi is probably a better handling bike. I felt that way with it compared to my first RS50, but that bike didn't have proper tires either. It's going to be interesting when the day comes along when I have the current RS shod with MC16s, the ProRace (Cagiva style GPR with 17s), the 05, and the 12 all together, and can compare them.

If you want to improve your bike I'd say source some 17" wheels, and get some Sava/Mitas MC18s. Those tires are truly magical. I have way more confidence on the bike with those tires. And a better rear shock wouldn't hurt either.

[racer162]

Nice to see ya got the write up finished. Bike looks good anyways . Good luck with it next year

[toratora]

It's mostly done. I have more photos, and more to post. Just so much to do at the moment!! lolz

[kaldis12]

How much did you grind away from the case for the Vforce reed?

[toratora]

The Stage6 reed block (Vforce copy) fits into the cases, but the mounting holes don't line up. Thus there's the need to modify it. I used a rotary tool to achieve the mod. I also found that these reeds don't seal as well due to their smaller platform, so I had to apply sealant between the intake and reed. Usually this step is unnecessary as the rubber from the intake generally makes a good seal.

[Berkeley]

hey tora,

I took the 50 out last night for a test drive .. when i did some test breaking with the front I wasnt impressed.. so especially now that im going to give it some more power i would like that it has some stopping power.

How were the brembos on yours? did it make a difference and was the installation easy apart from the bolts?? thanks

[toratora]

I usually attempt to improve the brakes on all of my bikes. The easiest method tends to be a good flush (since I can only get these bikes used), and Ferodo pads. But sometimes on bikes like this one, and the DRP I will go a lot further.

The upgrades on this bike include a better caliper, master, and disc. These bikes already come with braided lines so I didn't feel compelled to upgrade the line. The results are a system that is pretty fantastic on a bike of this level. The modulation is better than you'll find on some $20k bikes, and way better than anything I've ever experience on a stock Japanese bike.

In this case the master is a Brembo RCS14. I installed an RCS15 on the DRP, and well that's a bit much. Eventually I'll install a 14 on that one too. The Mito will receive the 15. The RCS is about the best master you can get without spending crazy money, and supposedly employs some of the same parts found in the MotoGP masters. When considering other options the RCS may seem to be expensive (they are about $230 from Kurvey Girl), but the performance is so much better than anything else I tried, and I did a lot of experimentation.

The caliper upgrade is effectively the same caliper as fitted on the 125 2T GPRs from around 2005. This is a much better four piston caliper. The newer bikes are being fitted with a four piston caliper so this may not be as necessary, but I went for it anyway. I buy the black version to go with the upgraded forks. This caliper is actually from a MetraKit track bike. But other than color it is the same as the AJP four piston unit found on the 2005 125 2T GPR. I found my on the German eBay.

For the disc I went with one from NG. They make a nice unit that both looks good, and is lighter than the stock unit. NG also makes stock replacements if you ever need to replace the stock unit. I bought these from eBay as well, but you can get them from EasyParts.

For fluid I usually get the Motul 5.1 from Treats.

If you intend to experiment with other masters let me caution you about getting larger sizes. I've found that when employing a larger master the result is a system without modulation, and the brakes become rock hard. I had heard of people putting a Brembo master from an R6 on their RS50, so I tried that, and it is way too much master for the stock caliper. I currently have one on the Mito, and it's too much for it too (which is why it's going to get replaced!).

A 14 is about the right size for these bikes, but there will be some functional range depending on the brand/model chosen. Nothing I tried (and I tried a lot of them) came anywhere close to the RCS, so for me it's not worth trying to save a few dollars, and end up with significantly less performance. Brakes are one of the most important parts of the bike. For this reason I like to get the best setup I can, and this one is pretty darn awesome.

[Berkeley]

Awesome.. thanks for the years of experience that you pass down!!
100% agree with the brake upgrade, just thinking of all the cars that pull out, doors that open .. and ppl J walking.. you need to be able to stop. ill see if i can find that set in europe as they wont deliver internationally. I take it the rear brakes are standard and no upgrade as breaking is done with the front mainly? if it vital to upgrade the discs or is that more of a case of weight/looks? The same goes with the upgraded forks.. do they help with the setup for breaking ie the load on the front end , or are the two not that interlinked?

Looking at my 2018 bike I have the 4 piston calliper with a 300mm stainless steel disc that looks to be the same as yours in terms of no of holes for cooling etc, so is not worth buying race ones of these but just buying the brembo cylinder kit?

many thanks

[toratora]

I think this bike came with one of the newer 4 piston calipers like your bike has. I don't have any experience with it, and I know the performance of the AJP caliper that I fitted. Since building this bike was a SWAT mission I knew I wouldn't have time to source parts once I arrived in Japan. I pretty much had to bring everything I would want/need. The stock caliper was pulled, and this one was fitted. In this case though it was a very good decision, because the bike I bought is not the one that I got, and the one that I got had lots and lots of issues. Replacing the caliper, and disc would probably have been necessary on this bike.

You could start off with the RCS master, and see how it goes. At least you are starting with new parts, so that should be a huge advantage. I would also get Ferodo pads, but if you decide to swap calipers than you'll probably have to get different pads—I'm not sure on that point though.

Kurvey probably has limited distribution of the Brembo products. They are great though, and everyone of us that have ordered from them has had a good experience.

Anyway, I'm looking forward to seeing photos of the bike. Go ahead and make a thread for it in the Projects section. I'm sure with all the cool stuff you've been doing people would love to read about it.