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2018 Aprilia RS4 50 Euro 4 Upgrade Project

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jkv357
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Re: Ride & upgrade?????

Post by jkv357 » Mon Aug 19, 2019 6:18 am

Berkeley wrote:
Mon Aug 19, 2019 12:14 am
(SNIP)
The bike for sure needs more power and thinking how hard would it be to fit a 125 engine into it?? both the 50 and the 125 are the same size ( at least thats how I saw them side by side ) just wondering about mounting points and whether you could put an older 2 stroke engine into it or have to go for a new 4 stoke engine??

thoughts most welcome cheers
2-stroke > 4-stroke!

Especially in small displacement, a 4-stroke at twice the displacement is about what is required to get the same power - and then there's all the added weight and complexity.

125cc 2-strokes seem like a good compromise for a smaller bike with a smaller rider.

My 75cc Derbi with a pipe and 24mm Flatslide is almost adequate for me at 180# - once it's rolling - but you need to pay close attention to the tach the entire time. I would think a 125 with a milder tune would be quicker and easier to ride.
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Berkeley
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by Berkeley » Mon Aug 19, 2019 6:35 am

Great, thanks for your take on it. Amaya will be 16 yrs old in 7 months so can move up to a 125. So now just considering all the options... Upgrade the RS4 50 to a bigger engine? or look for a new or second hand 125? This way I have some time to tweak and prep the bike.. almost another project bike to get underway.
I've done so much to the 50, it seems a shame to then Park or sell it.. then have to do it all again when an engine upgrade is all thats really needed.

Looking to have something with a meatier sound and lower end power, trying to avoid having the power kick in at 10k+ all the time. :D
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by jkv357 » Mon Aug 19, 2019 7:07 am

Because a 125 2-stroke is an option for you (unfortunately not much of an option here) I'd say making the switch to a new bike would be the best move. You could keep it mostly stock for a while and mod it as she progressed.

Swapping a 125 into the 50 would be much more difficult in the end I would say, and all the 50 upgrades wouldn't be used anyway. If you sell the 50 as a complete cycle you would have a better chance to get some of the money back. I don't think you would have as much luck with selling just the bare engine.
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Berkeley
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by Berkeley » Mon Aug 19, 2019 2:08 pm

Just looking around maybe a bidalot or a 2 fast cc will do (anyone have any hp figures?
I guess no ones tried the 110 parmakit???.. this is another option!!!
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kaldis12
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2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by kaldis12 » Mon Aug 19, 2019 2:31 pm

You can look at those cylinders but they are all the same. Power starts around 9-10k.
I didnt owe a parmakit 110 but that cylinser is a piece of a shit. Excuse me for saying that. If you want more power before 10k then you should go for a rotax 125 engine. Not the DT125! You can beat the DT with a mild 80cc kit. Rotax engines are the best in they own category. It can output 33-35hp with stock ported cylinder, with better exhaust.
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by Berkeley » Mon Aug 19, 2019 9:23 pm

Cheers bud! Was just checking out the top speed videos on you tube of the 125... standard is coming out at 122 km/hr which is not too great, however the modified ones hit 175 to 190 which is more like it..

Do you have any idea if the rotax engine can fit in the frame with the same mounting positions? If not I guess it's a case of comparing drawings ...

Also reading your comments from toras red rocket project...where can you get a complete d50B0 engine for 160 $ ??

Thanks for your input
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Powaa

Post by toratora » Tue Aug 20, 2019 1:39 am

Yeah if you know where to get a Euro3 engine with the balancer for that amount let me know!!

Engine Swaps
I personally don’t think engine swaps are, in general, a good way to go. Most people don’t have the proper resources to do a swap. And when they do then there is the subject of upgrading the rest of the bike to deal with the additional power. I almost never see this factored into the bikes with swaps.

Power
As for needing more power, I would be surprised if that’s the actual case—very surprised. Expecting one of these bikes to be able to perform like a liter bike is really asking too much for a novice rider. This is why I suggested very early in this thread that you get two of these bikes. Because asking a novice rider to ride one of these bikes with liter bikes is just wrong—the styles are totally incompatible. These bikes are at their most fun when everyone in the group is riding one. But they will be extremely frustrating to ride in a group with liter bikes (unless you are at the level where you can school the liter bike riders).

Shaming the “Leader”
Is it possible to shame liter bike riders with these bikes? Sure, under the right conditions, and if the liter bike riders are rather poor riders (which is unfortunately most of them). But novice riders are not going to have the ability to keep up with, let alone out ride the folks on larger bikes—unless those folks are riding rather slow. But even then the slow four stroke riders are going to constantly destroy the two stroke rider’s flow. This is a horrible condition under which to place the novice two stroke rider. You might as well be punching them in the stomach at each corner.

Age is not a Factor
I think you know that many of us on this forum are well into our 50s. Age really isn’t a factor with regards to riding these bikes. Sure the bikes are marketed as “learner” bikes, but that doesn’t limit their appeal, nor their ability. Most of the Replicas that were sold into the States were not sold to “new,” or even young riders. They were bought by folks that understood the gestalt.

As Steve over at AF-1 told me, these bikes handle very much like the 125 GP bikes. That’s a pretty amazing stat to achieve considering that these Replicas are that inexpensive (compared to 125 GP bikes). So being able to get that same experience for such a reasonable cash outlay is just awesome.

Four Strokes
The four stroke engine found in these bikes are really just Piaggio bending to the current trends. The four stroke is not a better technology (for this class of bike—nor is it for GP bikes, but that’s a different conversation). The 125 four stroke isn’t going to provide the exhilaration of the two stroke engine. This is why I didn’t purchase the four stroke version of the bike in Japan. But the four stroke is easy to market (today), because the masses have been convinced that it is a better technology (which it absolutely is not!!!).

The four stroke is easier to ride in some instances (because while you can tune a 2T to be a dull experience most people don’t), and the 125 4T bike is probably quite docile. But that’s not going to be a solution for you either. So putting one of these engines in the bike would be a complete, and total waste of effort.

125 2T Engines
If you think that she is at the level where she could properly ride a 125 2T bike, then you should just go buy a bake that was made for a 125 2T engine. Personally I don’t think anyone with as little time as she’s had on this bike is really going to be at the level where they have out grown this bike. Heck, most people probably can’t out ride this bike even with decades of experience (because most of that experience is probably quite poor). Seat time doesn’t mean jack. If you spend a lot of time doing something poorly, you are just going to be very good at being poor.

Power Reprise
Power isn’t what makes you fast on a bike. Skill is what makes you fast, and it is a whole lot easier to develop said skill on these little bikes. Getting a bigger bike before developing the skill just means it is going to take longer (and this translates to never for most people) to become a skillful rider.

I still clearly remember the last day of the first GPR Camp where Speedy schooled us with my Silver bike. The Silver bike is a 2003 Derbi GPR50 with a stock 50cc engine. It has the Sava MC18s, and a JollyMoto pipe, but that’s it. He was able to out ride all of us on HWY 1. It didn’t matter if it was uphill, downhill, or flat. He had way less power than any of the other bikes, and yet we could not keep up with him. It all came down to skill level. For me seeing him ride the bike this way opened my eyes to how these bikes can be really fast., and it had absolutely nothing to do with power.

So take the plunge. Get another little bike (preferably one with less power than her bike), and go riding with the smaller bikes. This is by far the best solution to your current situation. With some effort on your part you won’t believe how much better of a rider you’ll become, and you’ll be able to dispel this power myth. :paw_prints:
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kaldis12
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2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by kaldis12 » Tue Aug 20, 2019 1:56 am

D50b balancer engines are available in Hungary for that price, they are just used. A bit of a cleaning and they are new.

Aa for the speed rotax bikes can go 160kmh with stock unrestricted setup.
But I totally agree with Tora, skill is what you need not power. Thats what I discovered when I rode my bike. I was unable (and still unable) to ride it good enough. The powerband is just too narrow. Will have to learn how to ride a bike again. Its not like riding a 50cc, 80cc or a 125cc bike. Its much harder, but I kinda like it :D
Last edited by kaldis12 on Tue Aug 20, 2019 11:09 am, edited 2 times in total.
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Berkeley
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Re: 2018 Aprilia RS4 50 Euro 4 Upgrade Project

Post by Berkeley » Tue Aug 20, 2019 1:58 am

Thanks Toro for your advise.... well appreciated!

Not too many small biker groups around here. most of the groups all have bigger bikes, but the guys who I've been riding with for the past few months have a lot of skill as well.. can leave me for dust in the mountain roads!!!

It was awesome the other day riding with amaya, in the group, she learnt a lot and the guys giving her tips along the way. Everyone waits for each other at the end of each road so no problem there.

The other advice im getting from her driving instructor at the track is that she should forget the 125s completely and just move up to a 300cc and do track days... so just saying a lot of advise out there. If i had buckets of cash id do it all lol. :D

Hence spending a bit of time seeing which way to go.
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Berkeley
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Re: Powaa

Post by Berkeley » Wed Aug 21, 2019 5:55 am

toratora wrote:
Tue Aug 20, 2019 1:39 am
Yeah if you know where to get a Euro3 engine with the balancer for that amount let me know!!
Hi Tora, I found this site in Hungary. see a couple of motors there, this one for 180 euros and another without cylinder and carb for 137 euros... bargain!

https://auto.jofogas.hu/bacs_kiskun/Apr ... 792079.htm

also quite a few GPR's here:

https://www.kepesmotor.hu/derbi-motor/p1978452

A very nice 125 here for only 1100!!!

https://www.kepesmotor.hu/derbi-sportmotor/p2077010
Last edited by Berkeley on Wed Aug 21, 2019 6:22 am, edited 1 time in total.
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