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Derbi GPR100SP Pesek Replica

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scottydog
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Derbi GPR100SP Pesek Replica

Post by scottydog » Fri Oct 30, 2020 10:15 am

Hi Everyone,

I am a long time fan of Derbi GPR50 model 2005 to 2009. When this model came out I thought it was the ultimate sub 125cc bike perfect for the ultimate 100cc street bike project. Where I am from 100cc is the maximum size allowed for twostrokes which were grandfathered back in 2005. All bikes over 50cc now have to be fourstroke and limited to 150cc. This makes my GPR quite rare and especially being such modern looking design 15 years on!

The bike was originally a 50cc Euro 2 model but is now registered as a 100cc with a Euro 3 motor. The current setup is with an Airsal 80cc kit, Malossi underseat exhaust with a 28mm carb. It goes fairly well for now, but the plan is to build it as the ultimate 100cc street legal replica. In time I can talk about the build as I get through the various stages.

The image below is how I envision it will look like when completed! I've always liked my bikes in red and when I saw the Pesek design I felt it was the nicest looking of all the replicas! The plan is to make the bodywork in carbon fibre, then spray but leave the fairly lower in carbon to show it off! :sunglasses:

cheers!
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Last edited by scottydog on Fri Oct 30, 2020 11:52 am, edited 1 time in total.
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Re: Derbi GPR100SP Pesek Replica

Post by scottydog » Fri Oct 30, 2020 10:52 am

Here is the pair I own, the 2005 being an original first year model and the 2009 being the final year I believe Malossi model.

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It is pictured here with a group of newer 125/150cc bikes. In many ways it's much nicer as it has an aluminium frame and swingarm, good quality upside down forks

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Re: Derbi GPR100SP Pesek Replica

Post by scottydog » Fri Oct 30, 2020 11:49 am

To register my bike as 100cc I needed an older Derbi registered as 100cc. I was able to buy a 1999 model GPR75 from a friend, then I swapped the engines and had the paperwork done. After this I sold the older bike off as a 50cc. Was a shame to sell it off, but I have so many bikes that I couldn't justify keeping it.

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Bike minus engine! I kept the bike with the GPR75 engine for a little while, but then later upgraded to a newer Euro 3 motor like that of the Malossi Replica.

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Re: Derbi GPR100SP Pesek Replica

Post by scottydog » Fri Oct 30, 2020 4:29 pm

A few more photos of the other bikes. The Malossi was an extravagant purchase as I really wanted the 2009 model. When I realised they changed the design for 2010 I kinda panicked when the local dealer said they could only get the newer design. So I tracked down a dealer in the UK that had old stock and then went about getting it shipped across the Atlantic! For not much more I could have bought a RS4 125 which was a lovely bike, but I had my heart on a two stroke!

The irony is a few years later I would stumble upon the red 2005 model one of 4 imported at the time and then another red 2005 but in poor shape which I have kept for spares!

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Last edited by scottydog on Fri Oct 30, 2020 4:38 pm, edited 1 time in total.
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Re: Derbi GPR100SP Pesek Replica

Post by scottydog » Fri Oct 30, 2020 4:34 pm

I am generally thinking to make the 2009 into a track day bike using the Euro 2 engine type as I have a crazy amount of spares for this engine series. I would go with the 50mm x 45mm bore stroke in this case at 90cc. The old red GPR came at the perfect time as I needed a set of plastics to make the moulds to make the bodywork from. I didn't want to use the new bodywork from either the Malossi or red GPR. I did look at new fiberglass bodywork from France but the cost would be well over $1000 to bring in. The old red GPR was bought for not much and so I could prep the plastics for mould making! :)


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Re: Derbi GPR100SP Pesek Replica

Post by scottydog » Fri Oct 30, 2020 4:50 pm

What would be my criteria to be a GPR100SP? When you see all the SP or Sport Production bikes from Italy or Japan they were their limited run bikes more suited for track use production racing. They would often have single seat units and have better suspension. The Japanese 250cc SP bikes would come with a dry clutch which for me was a pure drool factor!

My plan is to build a GPR100 in that style, ditch the rear footrests, tune the bike up with every super cool part I could get, but then also keep it fairly civilized with an airbox, starter etc. Should be fun, but alot of work! :-D
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Bodywork Baby!

Post by scottydog » Sat Oct 31, 2020 6:44 am

Was time to decide on which way to go with making the bodywork. I decided to go along the same method as others had before and for the main fairing and tail seat blend several pieces together. These were from a French company I'd seen online where they used the GPR125 lower cowl.

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I started with the full fairing and moulded with the upper and sides as one. Once I pulled out and looked I started a rethink as the complexity and detail would make it hard or near impossible to make the air intakes neatly in carbon! It was alot of work to build, but that is okay as the moulds would work fine to make quick and dirty race bodywork for another time. I decided all the parts would be made one by one in the end.

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Jaxx
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Re: Derbi GPR100SP Pesek Replica

Post by Jaxx » Fri Nov 06, 2020 7:25 am

Hey Scotty, did that GPR75 which you have used for egine swap came with EBE075 engine?
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Re: Derbi GPR100SP Pesek Replica

Post by scottydog » Sat Nov 07, 2020 8:29 am

Jaxx wrote:
Fri Nov 06, 2020 7:25 am
Hey Scotty, did that GPR75 which you have used for egine swap came with EBE075 engine?
Yes it did, it was apparently a complete bike built from spares at the local dealership maybe 8 years ago. The friend who owned the bike rarely used it so I just planted the seed to sell to me when he decided to let it go.
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Re: Derbi GPR100SP Pesek Replica

Post by scottydog » Sat Nov 07, 2020 8:59 am

All went well with bodywork making, I made a full set of moulds and then got to work making the bodywork. It took a while as each part takes around 3 hours to do, the upper cowl being the most complex. In the end I made 2 pairs of bodywork for both bikes except for the fairing lowers which will be with the carbon as a visual component which takes more care to do. When I am ready I will go ahead with these. Each part is made from 2 layers carbon and 2 layers glass and is about 3/4 the weight of the originals on average, but feels similar is stiffness to the originals so happy so far! :sunglasses:

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