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Derbi GPR Track Bike

The development of a GPR for the track

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toratora
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GPR Track Bike: Older GPR Showa Forks

Post by toratora » Sat Sep 12, 2015 9:39 am

I found the photos of the Showa forks I resealed for the Red GPR. Near as I can tell the design is the same. Could the parts be interchanged? It's possible. The sliding tubes (the lowers) are 35, so you could run 35mm seals. The potential issue would be if the Showa bottoms would work with the Sebac bushings. I don't have a measuring tool with enough resolution to check the dimensions. But what I might be able to do is see if the Sebac bushing would fit on a Showa sliding tube. It's entirely possible that Sebac just specs a slightly tighter seal for the same size sliding tube. I'll soon find out if a 35mm seal works on the Sebac forks. :eek:

Here are the numbers:

Code: Select all

front fork seal set 	size		all balls individual seal	all balls seal set	
GPR 1999-2001		35 x 48 x 11	35-1011				55-108
			
oil seals w/ dust ring	dust ring kit
56-115			57-112
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User avatar
toratora
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GPR Track Bike: Clocks, The Metrakit MRD Dashboard

Post by toratora » Sun Sep 13, 2015 9:39 am

Here's a fun little gadget that I picked up for the Monza only to find out that it didn't have a speedometer. That's fine I'll put it on the Track Bike. :P

Metrakit for a while made a unit sourced from Koso that features a tachometer, a temperature gauge, and a settable shift light. It comes with a couple of seeing units for the temp for use depending on the cylinder head, and a couple of wires for the tach, depending on the ignition system of the bike.

The red sending unit is the one employed with the Derbi, and for the ignition you can either go with the wire wrapped around the plug wire, or connect directly to the ignition. I'm probably going to go with the wrap wire as I've see people mess these up by connecting them incorrectly.

The unit is powered by a nine volt battery. This may seem weird, but most track bikes don't generate power, and all accessories tend to run on a constant loss battery. Since for the Metrakit bikes most folks only run this dash a nine volt is all you need.

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toratora
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GPR Track Bike: GPR's First Day At The Track!

Post by toratora » Mon Sep 14, 2015 9:39 am

I'm pretty sure Koso makes these for MRD, however modded to go over 16k RPM. The inductance seemed to work today. I have to make a proper mounting plate for it. I just zipped tied it on the tripples for today, and it angled a bit which was hard to see while riding. Really though, the temp gauge is of more importance to me. :P I like the trail tech temp gauge, but the MRD temp display is really large, so you can actual see it at track speed. :D

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Today was the first day I ever got to ride slicks at the track. It's really nice. :P The Derbi had some issues today, but none of them were the fault of the bike--my mechanic needs to do better. :eek:

I was having a lot of trouble getting the bike to run. With a bit of investigation I found that my intake manifold had deteriorated massively.

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While I got the fork seals in time, I didn't have the opportunity to install them. So I grabbed the forks from the Red bike for today. :roll:

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But pretty quickly things went together this time. Got the forks installed, installed the MRD, but then had issues with the intake.

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Near the end of the day things cooled down a lot, and the Derbi started running decently enough that I decided to take it out on the track. It was nice because most folks had already gone home, and there were only four or five of us on the track. This allowed me to do some sorting of the bike on the track. The bike is a lot faster than I am. These Derbis really like to be ridden. They want to go fast. Which is great, but it helps if you are a fast rider. I'm going to have to work on that one! :lol:

Ed came out on one of his bikes, and gave me a tour of the track showing me some lines. This greatly improved my getting around the track. Thanks Ed! :)

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There are still a bunch of things I plan to do on this bike, but for now it running, and it was a total blast to be riding it out at the track. :lover:

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Miku daiyou!

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toratora
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GPR Track Bike: More Fun at the Track

Post by toratora » Fri Sep 18, 2015 9:39 am

Found some of the Moped action that's been happening, and a photo from Sonoma back in 2013 when I took the Monza to the track.

These are a couple of race mopeds. The white one is a Derbi Variant, and the black one is a Derbi Revolution. These bikes are screaming fast. Not your grandma's mopeds. They were actually able to out ride Garret when he was one the Kayo at the race last month.

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Here we have me with the Monza, MT Mike with his RS80, Speedy with his RS85 (it's now got a KX100 in it), and Paz with his RS250F!

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toratora
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GPR Track Bike: Chasing the bits

Post by toratora » Tue Sep 22, 2015 3:39 am

I've been working on another project which I'll probably start posting about tonight. While going at it I found some bits for the track bike. I sadly admit my bike isn't up to spec yet. I have some things to do like catch bottles. Thankfully I found them tonight. :D I also found some nice Malossi reeds, and a silencer that's better fitted for the track--it's going to need some cleanup, and probably a repacking too. The carbon Jolly Moto is just too nice for the track.

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toratora
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GPR Track Bike: Water Bottle

Post by toratora » Tue Sep 22, 2015 9:39 am

I bought a bunch of parts from Todd--he had bought out all of the Rocket Ranch bikes. Lots of strange stuff showed up. I've been enjoying the bits from that haul for years, as have my friends. :P Although the bottle could have come from somewhere else too.

Yes all of that, and more fit into the Saab. :eek:

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toratora
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GPR Track Bike: Seating for one

Post by toratora » Thu Sep 24, 2015 3:39 am

I was out on the BMX bike today, and stopped into visit my moped buddies. Paz had this for me. Some seat padding for the tank area. :D

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toratora
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GPR Track Bike: Where do the parts go?

Post by toratora » Tue Sep 29, 2015 9:39 am

I've been putting so much effort into the street bike that the Track Bike hasn't been getting much attention. Since I posted about the things I got from Todd it seemed like a nice time to highlight the effort of my buddy Levi who is nearly finished with his Senda project. I hooked him up with a bunch of things including the frame, forks, seat, tank, and a bunch of other bits, but really the magic of this build was all Levi. He's a master with this stuff. He's got a build thread up on AVrider that's totally worth checking out.

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toratora
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GPR Track Bike: At the Dyno

Post by toratora » Sun Oct 11, 2015 3:39 am

Found this today. :)

These results are from when the engine was installed on another bike with a different pipe, and stock ignition. I'm sure things are likely to be a bit different now. :lol:

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toratora
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GPR Track Bike: Ignition Alternatives for Ducati CDI on AM6, and GPR engines

Post by toratora » Sat Oct 24, 2015 3:39 pm

The stock ignition on the GPR is made by Ducati. It is a CDI, and the CDI unit and coil are one integrated piece. Now a couple of companies make an aftermarket CDI unit for the Ducati ignition. These have a better curve with a higher peak value. I think Treats sells them. But before I get to that, and I will cover it in detail, I would like to address the fact that these mods don't take into account the weight of the flywheel.

When going for a performance ignition this is a crucial aspect. So I personally wouldn't bother with any of these solutions. Instead I'd look for a better suited ignition such as the HPI mini rotor. It's easy to put this on the Derbi engine because it shares the same taper as the Puch. I don't know the taper on the AM6 crank, but I'm sure it could be looked up, and then correlated to the proper HPI unit. For a track bike I would suggest the HPI inner rotor.
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Okay so here's the Top Red Box CDI unit on Treats
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And here is some info on this ignition that is posted up on Two Stroke SE.
google trans of TwoStrokeSE wrote:Top Performance - CDI / ignition coil (Digital)
Price SEK 1299.00

In Stock
Art.nr: TOP-9921690
Unthrottled Digital CDI with variable ignition point

CDI box with ignition coil from Top Performance with variable ignition point.

An absolutely brilliant product for those who want to trim their moped and do not want to replace the entire ignition system and keep on setting the ignition manually.

This CDI box has been designed for Minar Ellis AM6 engine with the 6-spoliga Ducati ignition plate but also works to Derbis ignitions which also has the 6-spoliga Ducati ignition plate.

When the original CDI are equipped with the ignition point throughout the registry to have the Top Performance have developed this product which has an internal microprocessor that allows the spark advance automatically adjusted the more speed engine and thus optimize the ignition point.

The CDI also has a very good ignition control called "Power Control", which ensures that pre-ignition is prevented, which leads to a cleaner ignition.

This ignition control also ensures that you get a longer life for both ignition systems and spark plugs.

Other great advantages are that fuel consumption is reduced by this also air pollution.

This kit contains the following:
1 st - CDI
1 st - Coil with 5 kOhm spark plug cap + cable
4x - Kardborrebitar for mounting

NOTE! This product is intended to be combined with Top Performance 70-75cc cylinderkit in their Redline series but also functions to be combined with the equivalent cylinder kit.

IMPORTANT NOTE!: this CDI kit is not combined kits in the 85cc class or cylinderkit with extended stroke bout as this may cause damage to the ignition and cylinder inserts.
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Metrakit makes a CDI unit for the Ducati ignition too, part number: MK846R0311
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google trans of TwoStroke SE wrote:Metrakit - CDI (unrestricted)
Price SEK 549.00

In Stock
Art.nr: MK 846R0311
High quality CDI from Metrakit
A high performance CDI from Metrakit.
Delivered completely unrestricted, which gives you the right effect!
This CDI ensures that you get a higher speed stop and a better accelleration.
To mount the CDI is very simple, to simply remove the original CDI box and replace it. To then connect the cables is very simple as the colors are the same as those used on the original CDI'n.
On this CDI'n is 4 pins:
-1 Red
White -1
-2 Green
NOTE! This CDI is only compatible with Ducati ignition system with six coils.
Not suitable scooter models 2007 -> with the new ignition system from Dellorto
And Top has another unit, the Yellow one.
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google translation of TwoStrokeSE wrote:Top Performances - CDI box (Ducati) unthrottled
Price SEK 499.00

In Stock
Art.nr: TOP-9910150
Unthrottled CDI box with '' Power Control ''

Top Performances - unrestricted CDI box to Ducati ignition.

An unrestricted CDI box without revolutions stop and the "Power Control" from Top Performances.
The box is of high quality and is designed and developed to optimize ignition on your moped.

The CDI also has a very good ignition control called "Power Control", it ensures that the pre-ignition is prevented, which leads to a cleaner ignition.

This ignition control also ensures that you get a longer life for both ignition systems and spark plugs. Other great advantages are that fuel consumption is reduced by this also air pollution.

Motoparts CDI-box fit 6-speed Minarelli AM6 engine and other mopeds / motor models that use Ducati ignition with six coils.

To mount the CDI is very simple, to simply remove the original CDI box and replace it. To then connect the cables is very simple as the colors are the same as those used on the original CDI'n.

OBS !! This is a product developed for competition use only and may not be used if the vehicle will be used on public roads NOTE !!

Not suitable for: Yamaha / CPI-models from 2007 ->

NOTE! It is important that the earth wire on the CDI box proper contact when mounting otherwise there is a risk of CDI box damaged.
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(Note: the text below only applies motocross scooters from the CPI)

To use this box on the CPI:
On CPI-models the cables different original equipment, but this CDI can be used if you connect as follows:

- There are five wires to the original CDI's:
Black, Black / White, Black / Red, Orange and Red / White (All of these, you should cut off so you can connect them to Stylepro CDI's).

- Black / white cable to the outer green pin on Stylepro CDI: n (stop button function).
- Black / Red connected to the other (penultimate) of the green pins on Stylepro CDI: n (ie, the next stop button).
- Orange connected to the white pin on Stylepro CDI: n.
- Red / White cable is connected to the red pin on Stylepro CDI: n.

- The black wire is the ground wire to the original CDI set, it does not need to be grounded when Stylepro CDI are equipped with their own ground wire (black with cable lug).
The black cable on Stylepro CDI: n connects you to the earth.

- The black and orange cable to the original ignition coil need not connect to anything. They can cut and Stripa to the frame or similar.
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