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Red Rocket: 2012 Red Derbi GPR

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User avatar
toratora
Posts: 3161
Joined: Wed Oct 11, 2017 1:05 am
Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
x 1768
x 1977
Contact:

Red Rocket: Top End Time

Post by toratora » Sun May 13, 2018 4:39 pm

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With the proper studs in place the top end could finally be fitted. It was so much effort to get to this point, and it sure felt good to finally have accomplished what had seemed to be something that would be so easy.

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User avatar
toratora
Posts: 3161
Joined: Wed Oct 11, 2017 1:05 am
Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
x 1768
x 1977
Contact:

Red Rocket: Stopping

Post by toratora » Sun May 13, 2018 5:39 pm

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One of the disparities I ran into with this project where the front caliper bolts. Previously on the 05 I had to source longer bolts. With this bike the stock bolts were too long, and I had to source shorter bolts. I picked these up when I got the the bolts that became the cylinder studs.

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User avatar
toratora
Posts: 3161
Joined: Wed Oct 11, 2017 1:05 am
Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
x 1768
x 1977
Contact:

Red Rocket: Installation

Post by toratora » Sun May 13, 2018 6:39 pm

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With the top end accomplished it was time to install the engine into the bike.

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User avatar
toratora
Posts: 3161
Joined: Wed Oct 11, 2017 1:05 am
Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
x 1768
x 1977
Contact:

Red Rocket: Leak Master

Post by toratora » Sun May 13, 2018 7:39 pm

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Once the engine was installed I could pop in the plug, and do a leak down test. It turned out that for the most part things were in good shape, but the aforementioned intake leak was exposed. I had brought my leak test kit with me, but I didn't have a plug large enough for the exhaust. I ended up wrapping it with a rubber glove. This worked pretty well. There was some seepage out of the glove, but it was good enough to get the test accomplished. You do what you have to when resources are in short supply!

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User avatar
toratora
Posts: 3161
Joined: Wed Oct 11, 2017 1:05 am
Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
x 1768
x 1977
Contact:

Red Rocket: Chamber of Commerce

Post by toratora » Sun May 13, 2018 8:39 pm

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Next up was the pipe, or as the Japanese call it the chamber. I was expecting to have some difficulty here, but the pipe fit in quite nicely. I will eventually fashion a proper bracket for it. What I did as a stop gap was a friction pinch fit by relocating the rear mount to the rear set front bolt, and then used some larger washers to bind it. It worked quite well.

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User avatar
toratora
Posts: 3161
Joined: Wed Oct 11, 2017 1:05 am
Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
x 1768
x 1977
Contact:

Red Rocket: Detuning

Post by toratora » Sun May 13, 2018 9:39 pm

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The 2Fast crank/cylinder/pipe combination was developed as a race performance product. I wanted to employ it on a street bike. To do so I would have to detune it a bit. I achieved this by going to a 28mm carb, the stock air box, and lowering the compression with a couple of spark plug washers.

I went for the washers to lower the compression in order to keep the port timing correct. I could have used more base gaskets, but that would mess with the squish, and the port timing. By using two spark plug washers I obtained a small drop in compression without giving up the other objectives. Big thanks to Dai for teaching me this technique, and hooking me up with the washers.

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User avatar
toratora
Posts: 3161
Joined: Wed Oct 11, 2017 1:05 am
Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
x 1768
x 1977
Contact:

Red Rocket: Control

Post by toratora » Sun May 13, 2018 10:39 pm

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I had a fair amount of updating to do with the controls. I did repaint the bars because they had issues—same with the bar ends, and top triple. They came out great. John has a media blaster, and he showed me his painting technique. It worked out fantastic, and helped the look of the bike significantly. One thing I missed was the clutch lever. Have to pick that up next time out.

When going to the larger carb you have to change throttles. I went with a Domino MX throttle like I have done with many of my bikes. I asked Benji to order me the first one, and since then he's been stocking them, which makes it easy to upgrade the bikes. The pulley can be either brass, or sealed bearing. I went with the brass one this time, but I can always upgrade to the sealed one later. The reason I went this way is because I wanted to get red grips. I also get the MotionPro throttle cable. I actually don't like it much because of the built in throttle adjuster. They have to be ground off, and it's a hassle. There must be a cable out there that's a direct fit.

Now on these bikes the starter, kill switch, and mode buttons are all integrated into the throttle housing. If you replace the throttle you have to deal with this issue. I chose to forgo the kill switch since the kill will turn off the engine. I used the red button for the starter, and the yellow button for the mode control.

For the front master the upgrade included the Brembo RCS14 and Brembo reservoir from Kurvey Girl. The buttons are designed to replace the bar clamp for the controls. One of these was placed on the front brake master. The second one was mounted employing the clamp from stock master, and a couple of bolts. I would have probably mounted the mode button on the clutch lever if it employed the same mechanism, but it doesn't. For grips I went with the Red Domino waffles from Treats. Because these components weren't designed to go together it was a little tricky getting it sorted. Eventually though it worked out, and they look pretty nice.

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User avatar
toratora
Posts: 3161
Joined: Wed Oct 11, 2017 1:05 am
Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
x 1768
x 1977
Contact:

Red Rocket: The All Nighter

Post by toratora » Thu May 17, 2018 5:39 pm

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Things were coming along, but the shop was closing because the guys were heading off to the C2C ride. I was pretty sure I wasn't going to make it, but I might as well keep working the bike. Kanai decided to pitch in, and we ended up wrenching all through the night. I probably should have taken more photos.

Once it was running I did some heat cycles in between getting the plastics on the bike. Both Kanai and I took it out for test rides. He came back with a big smile on his face. The bike really goes.

Kanai is really good with putting bikes together. It was great working with him on the bike.

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User avatar
toratora
Posts: 3161
Joined: Wed Oct 11, 2017 1:05 am
Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
x 1768
x 1977
Contact:

Red Rocket: The Total Package

Post by toratora » Thu May 17, 2018 6:39 pm

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While the bike wasn't ready for C2C it was super close. The next thing to do was take it for a proper test ride, but before that it was time to get some photos of it in the sun.

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User avatar
toratora
Posts: 3161
Joined: Wed Oct 11, 2017 1:05 am
Location: San Francisco
Replica: Derbi GPR
Cagiva Mito
Cobra CX65
Aprilia RS50
x 1768
x 1977
Contact:

Red Rocket: On the Road

Post by toratora » Fri May 18, 2018 11:39 pm

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While I didn't get to ride it much I did get to ride it some. The bike is quite dreamy in so many ways. The throttle response is great, and the throttle feels snappy. The brakes have lots of modulation. It's all so nice.

I did run into one issue though. For the first time on a Derbi I fouled a plug. This is probably because I'm usually riding these bikes at high RPMs and what not, but because the speed limits are so low I was putting around more, and this fouled the plug. Because I've never had this issue previously I thought it was a fuel issue, and spent quite a bit of time chasing it down.

¯\_(ツ)_/¯

The Quad Lock setup worked out great. I used a bicycle accessory mount to create a space for mounting the Quad Lock mounts. A new feature with Quad Locks is color release levers. The matching red levers just look right, where as the blue would look out of place.

The Giant Loop bags fit the bike well, and look like they belong. The Diablo tank bag with the easy fill mode, and release design is really convenient. Unzip part way to fill, unzip all the way to remove. The mounting straps remain with the bike.

For saddle bags I went with the Coyote soft bag. Mounting it on the bike was quite easy, but it doesn't support any sort of quick release like the tank bag, and I found this to be a little inconvenient. I would like to be able to remove them quickly if needed. I may get some quick release buckles to enable this mode.

The dry bags that come with the Giant Loop gear are great. The air valve makes it much easier to compact them, and they are quick and easy to open and close. I still needed more space though, because the camping gear takes a lot of space. For this I employed the REI duffle bag that I've had for about twenty years now—I can't find it in their current catalog. It still works fantastic though, and it is color coordinated too.

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