Restoration Derbi GPR 50 R . France project

[RemS]

Hi kaldis12

yes the 2win is a good one. but I think the Vforce3 Cr85 remains THE reference.
you had the opportunity to test that two products?
what did you feel like improvement in low rpm?

[RemS]

Hi berleley
can you rephrase, I do not understand anything
please??

[kaldis12]

you had the opportunity to test that two products?
what did you feel like improvement in low rpm?

Yes I did. It was one of my friends bike. The bike was stronger in the low rpm range. Thats all. You can reach your powerband easier. That was a 99cc engine, so it was pretty noticable. The smaller the engine(in hp) the less difference you feel. If you even feel it.

In overall it was a pretty strong build, approx. 31hp. Cant really remember how much more the dyno showed though.

Would be interesting to see what it does on a smaller engine. [Maybe Tora knows ]

[Berkeley]

here are some pictures of the engine I wanted to mount at the start.
with:
Stage6 cylinder BIGRACING 77
malossi crankshaft RHQ (THE reference!)
valves VFORCE3 (honda CR 85cc)

Crankcases machined and microbilled

if someone is interested, I can sell the crankcases and the cylinder kit (new )

How much? Is this the db050?

[toratora]

How much? Is this the db050?

That’s not a Euro 3 engine, it’s a Euro 2.

To answer your previous question Remi is doing a restoration, and while he’s going to put a kit and pipe on the bike he want’s those pieces to be contemporary with the bike. The Stage6 parts are at least a decade too new.

[toratora]

Would be interesting to see what it does on a smaller engine. [Maybe Tora knows ]

So far I've only picked up one of the fancy style reed blocks—the Stage6 version. I ran it on the 2Fast 100cc, and now it’s currently installed on the DRP with the BR88 kit. There’s so many variables on that bike that it would be difficult to address. In addition to the reeds there’s a boost bottle, and the HPI ignition. While I don’t have the tuning worked out yet it is getting close, and the system is impressive.

I haven’t done any proper scientific type testing so I can only conjecture. My personal take is that they don’t really add anything over a decent set of reeds, but hey they look cool as fuck.

[kaldis12]

My personal take is that they don’t really add anything over a decent set of reeds, but hey they look cool as fuck.

Yeah maybe they dont give too much more, altough I felt a more dynamic low rpm. Was kinda satisfying, better than the CR85.

But yeah they look fuckin cool, that was the main reason why he bought it

[toratora]

Here’s what I was talking about previously. Upon more consideration I now understand what’s going on. When they switched to the Second Edition of the bike (2002) they stoped employing the chrome adjuster plates.

This made things just thin enough that the axels couldn’t properly bind the rear wheel. The fix was to place a second washer on the right side of the bike. Total kludge, but it works.

[RemS]

Hi Following on hard work the crankcases ...
I finished aligning the crankcases with the base of the Metrakit Pro Race 70 cc cylinder. the passage of the valve v force 85 cr was already done, and the removal of the bump (on the crankcases, under the exhaust of the cylinder) was also done.
Then a small sanding of the whole and it is very correct!

I want to specify that the preparation of the casings was intentionally soft.
I want a simple "assembly" racing part on the motor of a collector motorcycle (Yes, that's right, apart from the machining for valves ... )
no gas passages dug or other.
simple alignment and good metrology.

[RemS]

Information

If you remove the “shelf” on the crankcase (under the front skirt of the cylinder) alternative pistons become available for the Metrakit big bore kits.

For instance the Stage6 R/T 47.6mm piston (piston for cylinder kit 70cc stage6 R/T Piaggio scooter) is the same diameter, but with slightly longer skirts.

In an effort to make installation easy Metrakit cut the piston skirts, making them slightly shorter, so that they can be use with the Derbi crankcases without modification. That’s why it’s interesting to remove the shelf in the crankcase, allowing for the longer pistons to be used.

Polini have similar pistons of still higher quality.