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DRP: Derbi Reactivation Project

The Return of the Wicked GPR

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Rj_666
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Re: DRP: Derbi Reactivation Project

Post by Rj_666 » Thu Jun 20, 2019 8:43 pm

That RED seat is AWESOME !!
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toratora
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Derbi Reactivation Project

Post by toratora » Mon Jul 22, 2019 12:39 am

Thanks. I hope to be making some progress on this bike soon. I’ve been a little preoccupied with the Zukachi. :paw_prints:
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toratora
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Derbi Reactivation Project: Extraction

Post by toratora » Fri Jul 26, 2019 11:39 pm

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It was time to pull the engine again.


As I started pulling off the body work I noticed this fine sand on the top of the boost bottle. I’m pretty sure this is the sand blasting material coming out of the subframe. This was somewhat strange, but not as bad as the other things I would discover.

As it turns out the lower engine mount tab was broken. So that will have to be welded back together before reassembly can occur. The upper mount broke previously, and was repaired. I’m rather surprised that another one broke. I’ve not seen this happen on the earlier GPRs.

The overflow tank was empty, and very little coolant came out of the system. But it was very pressurized. Considering how long it has been since this engine last ran (back in May) that was surprising. When I pulled the plug I noticed that it was both wet, and had started to oxidize. Once I had the engine out of the bike I removed the head to find it was wet in there. It looks like things were leaking all around the gasket.

Another issue I found was the dented chamber on the Voca pipe. I don’t remember riding this bike over anything that would have caused such damage.

While I didn’t have to pull the carb to remove the engine I did so, because I figured it would need a good cleaning too. There is a significant amount of corrosion all over the bike. This surprised me considering how many things are now powder coated, or stainless.

Lots and lots of photos below!! :paw_prints:

























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toratora
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Derbi Reactivation Project: Bidalot

Post by toratora » Sun Jul 28, 2019 1:39 am

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Bidalot recently introduced a new line of performance top ends including the RF70WR which works with the stock crank dimensions of a 40mm stroke with a 90mm rod. The RF70WR is available for the Derbi Euro2, Euro3, and the AM6 engines. This is the Euro2 version of the kit.

Overall the quality of the RF70WR looks to be incredibly high. There is noticeably a little clean up work that needs to be taken into account, but for the most part the attention to detail is quite impressive. The piston doesn’t come stamped with an arrow indicating the installation direction, and this must be determined by the wrist pin clip access recess which is to be place towards the intake.

The exhaust port employs a four bolt exhaust flange mechanism which is comparable with two bolt variants. Bidalot makes the flanges available in three sizes: Ø28m, Ø30mm, and Ø32mm. The cylinder’s design includes a massive amount of cooling to the exhaust port. Bidalot must have discovered an advantage by cooling the exhaust gases to this degree.

The transfers are fairly large for the sized cylinder, especially the rear transfer which feeds into three C ports at the rear of the cylinder. While this will work with unmachined cases it would be best to case match the carters to take full advantaged of these larger transfers.

While the head isn’t modular it does feature significant cooling, and the casting must be a major contributor to the expense of the kit—it is quite complicated in design. In addition to the four traditional engine studs to secure the head Bidalot chose to add an additional four more bolts to ensure a proper seal.

It is exciting to see this level of kit made available for the Euro2 engine. There are similar kits such as the 2Fast for the Euro3 kits, but those have not been made available for the older Euro2 Derbi engine. This makes the Bidalot RF70WR a unique opportunity for folks still running the earlier engine from Derbi.








Bidalot’s website has a fair amount of information for the RF70WR top end. Here is the Google manglization of the French text:
Here is our latest high engine RF70WR, DERBI 5EBS50 E2.

This high engine is adapted to be mounted with a stroke crankshaft and connecting rod length identical to the origin. However, because of its high performance, we recommend the installation of our crankshaft Racing Factory. Fully modeled in 3D CAD, cylinder sees its water chamber to tour all nuclear transfer and exhaust, with constant thickness, to guarantee high dimensional stability of the cylinder due to optimized cooling.

The cylinder head, heat treated, is also equipped with a water chamber surrounding the combustion chamber, for a good heat dissipation and good cooling. It is self-centered in the cylinder, and returns to 2.4mm in the bore of this release. Fixing the specific exhaust flange, is provided with 4 screws. However, it is possible to mount a mounting flange 2 holes, 48mm spacing.

You will find, sold as accessories, exhaust flanges of different dimensions, allowing the adaptation of practically all the pots market. These flanges are broken down in the following sizes:
Ø28mm x L30mm
Ø30mm x L30mm
Ø32mm x L30mm

Technically, this cylinder unit is composed of:
High engine RF70WR adaptable DERBI E2:
Aluminum cylinder with thermal treatment, coating nikasil Ø47.6mm
Cylinder Aluminum, with heat treatment, self-centered and returning from 2.4mm in the cylinder, high combustion chamber compression
Piston RF50WR hypersilicié Ø47.6mm
7 transfers
Escapement Boosters

New Profile 2018, elliptical, specifically, to reduce the operating clearances
25mm frame size
Chrome steel segment Ø47.6x1, lapped curved, Japanese-made
Axis Piston Ø12x39mm
of base plate gasket set of different thicknesses
Game yoke O-rings
various screws
They also provide a PDF file of the installation guide that come with the kit.


These promotional photos illustrate the transfers and coolant paths of the RF70WR.




Factory photos of the RF70WR.
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toratora
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Derbi Reactivation Project: Bidalot RF70WR Port Map

Post by toratora » Sun Jul 28, 2019 2:39 am

Image

Bidalot RF70WR Derbi Euro2 47mm bore 40mm stroke



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toratora
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Derbi Reactivation Project: Bidalot RF70WR Exhaust Manifolds

Post by toratora » Sun Jul 28, 2019 3:39 am

Image
The Bidalot RFWR cylinders are set up for custom exhaust manifolds with four mounting points rather than the typical two points. Three manifolds are available, and a standard manifold may be used by employing two of the diagonal mounting points.
Bidalot website wrote:Allows adapting your exhaust our high RF50WR and RF70WR engines.

Check interlocking diameter at the entrance of your exhaust, and choose the corresponding flange, depending on its outer diameter.

Available in the following dimensions:
Ø28mm x L30mm
Ø30mm x L30mm
Ø32mm x L30mm
Supplied with one gasket high temperature resistance.
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toratora
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Derbi Reactivation Project: Stage6 Big Racing 88 - BR88 Port Map

Post by toratora » Fri Aug 02, 2019 9:39 pm

Image

Stage6 Big Racing 88 - BR88 Bore 50mm Stroke 45mm





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toratora
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Derbi Reactivation Project: Welding

Post by toratora » Sat Aug 10, 2019 1:39 pm

Image
When I pulled the engine out of the bike it became apparent that the mounting tab did indeed break. A fair amount of effort later, and it is ready for paint. I currently don’t have a welder so I prepped the bike, loaded it up on the Saab, and took it over the Kent at the Moto Garage. He welded the tab back on for me. It came out perfect. :paw_prints:









2 x

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toratora
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Derbi Reactivation Project: Paint

Post by toratora » Sat Aug 10, 2019 9:39 pm

After the welding it was time for a little paint. First I had to clean things up, then do a little sanding, and prep work. After that the painting. It will take time to dry, but hopefully not too much time. :paw_prints:





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toratora
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Derbi Reactivation Project: Bidalot

Post by toratora » Sat Aug 10, 2019 11:39 pm

While the paint was drying I figured I might as well work on the engine a little bit. Mostly I just started to prep the top end. :paw_prints:





3 x

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