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DRP: Derbi Reactivation Project

The Return of the Wicked GPR

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toratora
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DRP: Year End Shopping Action

Post by toratora » Fri Jan 11, 2019 2:39 am

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WIFI Borescope
Just before the year ended I took care of some last minute shopping to prep for 2019. Both of my bore scopes failed, so I order a new one. This time I got the extended warranty on it. :flushed:

This new one tested okay this evening so hopefully I’ll be able to make some very forward tuning action this week—dependent upon the weather of course! :monocle:

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Nuzari Bike Cover
I also got another red Nuzari bike cover. This time for the DRP. The current cover just isn’t dealing well, and the Nuzari that I got for the 899 has done a rather fine job of protecting the bike. :starry:

The Nuzari holds up well to the sun, and it has a limited life time warranty. Hopefully that means if the fabric starts to tear due to the sun, which a lot of covers do, then they’ll send me a replacement. Another feature I really like is the highly reflective piping on the two main seams. It really makes the entire silhouette of the bike stand out. :heart_eyes_cat:

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License Plate Mount
I also picked up some license plate holders. The laws have changed in CA, and it’s time to make adjustments. :grimacing:

These holders are sort of a hinge so I should be able to get whatever appropriate angle is required. The mounting side for the bike is cut out for a lamp. For the DRP I’m going to try and wrap it around the silencer since there’s absolutely no place to mount a plate on the bike. :raised:

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RedLine 2T
While it’s still a ways off I figured this was a good time to take advantage of the holiday pricing, and pick up some two stroke oil for GPR Camp. This time I decided to try the RedLine. Okay yes I did buy it because the bottle is red. :scream_cat:

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Lightning to USB-C
I’ve had a rather terrible time finding decent Lightning to USB-C cables. This set I just ordered notwithstanding. They don’t reliably connect to the phone, even when not in a case, but especially when in a case. :expressionless:
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toratora
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DRP: Timing

Post by toratora » Sat Jan 12, 2019 7:39 pm

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Getting Back to Work
It was time to get back at it today. There was a respite of the rain, and it’s starting to look like there might be again tomorrow, which would be great, because I didn’t get to finish as much as I would have liked to do today. :grimacing:

I made some progress with the DRP, and even started moving forward again with the Silver bike, but was only able to start some diagnostics with it. You can read about that in the Red Power thread. :paw_prints:

Inspection One
With this bike I started off with the new bore scope. Thankfully it worked! From the wash it’s clear that the bike had still been running rich.

There was no carbon to be seen anywhere. Not even in the exhaust port. I wonder how much of this is due to running the cleaner oils. Still there should have been some sort of build up with all the riding I did with these settings.

The plug still looked okay. Maybe a little on the rich side.
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The Adjustment
The next thing to work on was the timing. The first photo is where it was previously, the second was the second change, and where it is currently. I intentionally went too far with the first change, which is the third photo, to give me a reading of what it would be like, then I reverted back towards where it started out. Ultimately I added just a little bit more advance.

From these tests it became fairly obvious that I wasn’t likely to solve the hesitation/sputtering with just a timing change. The changes don’t look like a lot of movement, but for timing adjustments they are quite a bit.

The first adjustment was nearly unrideable. The second one brought the bike back to ridable, but still didn’t get the bike running like it should.
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Inspection Two
I thought I saw major scoring on the exhaust bridge, but that was really just a reflection of the piston. Moving the piston up and down elucidated this discovery.

Anyway, with the timing change things didn’t look all that different, so it was time to adjust the carburetor.
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Needles and Clips
I decided to try moving the needle down one notch to see if I could take out some of the mid throttle richness. I did a short test run up and down the street.

There was still a slight hesitation, but I think it’s ready for a longer test. Based on that I’ll have more information with which to decide what to do next.

It’s a bit crazy, but on this bike with this carb it’s actually more complicated, and difficult to move the clip on the needle, than to change the main jet. Changing the pilot jet would be probably somewhere in-between.
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Step Up
I also noticed that the rear sets were loose. With these fresh built bikes one has to be vigilant with inspections. That’s one of the benefits to regularly cleaning the bike—you find these sorts of issues before they cause real trouble.
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The Ultimate Coverup
When it came time to wrap things up for the night I put on the new Nuzari cover. It’s truly amazing between the cover that’s been out there for a year or so. They don’t even look like the same cover. :paw_prints:
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kaldis12
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Re: DRP: Derbi Reactivation Project

Post by kaldis12 » Sun Jan 13, 2019 12:04 am

Woah thats some bad lookin piston wash :idea:
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toratora
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DRP: The Wash

Post by toratora » Sun Jan 13, 2019 3:39 am

It’s really not bad per se, it just means that the bike is running rich—which in this case in fine as I’m still running the top end in, and tuning. If it was totally black with no half moons, then that would be bad, because it would mean that it was too lean. And too lean is the path to friesville. :handovermouth:
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kaldis12
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Re: DRP: Derbi Reactivation Project

Post by kaldis12 » Sun Jan 13, 2019 9:56 pm

Yeah thats for sure. I never ever run in an alu cylinder. Let the bike warm up at idle for at least 3 times( cooling them down between sequences) after that warming up and go a few kms with half throttle. Not more. I cab do it in a few hours and I had no problems with it.
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toratora
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DRP: To the D-Store

Post by toratora » Sat Jan 26, 2019 3:39 pm

Image . The D-Store started their winter sale on Friday. GX and I went there to check it out. My boots are on their second soles, and they have gone pretty far. I was hoping that there might be some red boots on sale, but they don’t even offer red boots anymore. :crying_cat_face:

GX picked up some red knee sliders, and then we went to Ted’s for sandwiches. The weather was great, and it was nice to be outside for a bit.

On the ride home I went up to Twin Peaks to have some fun. The bike still needs more tuning, but it is running well enough that it’s a whole lot of fun. :paw_prints:









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toratora
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DRP: Wrenching

Post by toratora » Sat Jan 26, 2019 6:39 pm

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It was time to get a little bit of wrenching in on the bikes today. The weather was perfect, and much was accomplished. Mostly little stuff, but I needed to know it out. On this bike it basically meant changing the main jet. It had a 102 in it, and I wanted to go to 100, but I couldn’t find the box with the 100, so I settled with a 98.


The wash is still barely visible, which basically translates to too rich.








There’s a pretty bad exhaust leak. Eventually I’m going to have to deal with it.




I noticed what looked like a broken engine mount. So far it just seems to be a crack in the powder coating. I'm hoping that’s all it is, because pulling out the engine cradle to have it welded would be a real pain. One of the other mounting tabs broke previously. Seems to be a common issue with higher revving setups.

I also had to charge up the battery since the HPI seems to be unable to step up to the task. :flushed:

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toratora
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DRP: A Little Test Ride

Post by toratora » Thu Jan 31, 2019 7:39 pm

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I only got one snap shot today, and as you can see it is blurry as fuck. But that’s actually how it felt to ride the bike today. With the 98 jet installed I expected the bike to be even closer to optimal, and yet it took a turn for the worse. The mid-throttle sputter was pretty horrible. Starting was more challenging too. Once on the pipe things were better, but I did’t get a real opportunity to open it up.

Once the rain stops I’ll pull the plug, and check out the wash. Not even sure what to expect. It’s acting like it was richer, but the main jet is smaller than previously. Also, the battery has flaked out again. Even with a fresh charge on the bench it couldn’t last for even a short ride to run some errands.

Another issue that is really bothering me now that I’ve been riding the PMPR again is the overwhelmingly soft suspension. Because it is so soft the brakes can easily overwhelm it. Everything has to be so smooth to ride this bike. The throttle, the brakes, everything, or the bike gets destabilized. So yeah this photo turns out to be a perfect representation of the bike’s current state. :paw_prints:
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jkv357
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Re: DRP: A Little Test Ride

Post by jkv357 » Fri Feb 01, 2019 6:12 am

toratora wrote:
Thu Jan 31, 2019 7:39 pm
I only got one snap shot today, and as you can see it is blurry as fuck. But that’s actually how it felt to ride the bike today. With the 98 jet installed I expected the bike to be even closer to optimal, and yet it took a turn for the worse. The mid-throttle sputter was pretty horrible. Starting was more challenging too. Once on the pipe things were better, but I did’t get a real opportunity to open it up.

Once the rain stops I’ll pull the plug, and check out the wash. Not even sure what to expect. It’s acting like it was richer, but the main jet is smaller than previously. Also, the battery has flaked out again. Even with a fresh charge on the bench it couldn’t last for even a short ride to run some errands.
When I was tuning the GPR's Flatslide, it would stumble and stutter terribly in the midrange, just like yours, then clean out and pull strong at WOT.

It took numerous steps to lean out the midrange enough to keep it running clean. It was so rich I needed to find the leanest Needle Jet and Jet Needle they made in order to get it right.

Low battery voltage could be making things worse. Some bike won't run right at all with less than full battery voltage.
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DRP: In the Middle of the Throttle

Post by toratora » Fri Feb 01, 2019 8:39 am

jkv357 wrote:
Fri Feb 01, 2019 6:12 am
When I was tuning the GPR’s Flatslide, it would stumble and stutter terribly in the midrange, just like yours, then clean out and pull strong at WOT.

It took numerous steps to lean out the midrange enough to keep it running clean. It was so rich I needed to find the leanest Needle Jet and Jet Needle they made in order to get it right.

Low battery voltage could be making things worse. Some bike won't run right at all with less than full battery voltage.
It seems that this bike is also going to need a fair amount of mid throttle tuning.

As for the battery I’m rather disappointed that these batteries didn’t work out. :?
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