Derbi GPR - Honda CBR250R Forum : Honda CBR 250 Forums
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Old 03-23-2015, 02:00 PM Thread Starter
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Derbi GPR

Picked this up last week -



Needs a bit of clean-up, but overall it's in pretty good shape.

It's a 2000 Derbi GPR 50. Water-cooled, reed valve, 6-speed, 50cc 2-stroke. It has an Arrow chamber and a Mikuni Flatslide carb on it. Probably 200 pounds wet.

Pulls pretty strong, once you get past about 7500, all the way to 11,000.

Planning to powder coat the wheels to match the blue on the graphics, remove a few things, and get a new set of tires ASAP.
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Old 03-24-2015, 12:21 PM
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Fun! watched vids of them after seeing this.

17" wheels?




Sent from my mobile phone while driving, waiting for a vigilante Motovlogger to star in his own train wreck.
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Old 03-24-2015, 02:08 PM Thread Starter
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Fun! watched vids of them after seeing this.

17" wheels?
This is a 2000 model, so it has 16s. But the older 50 engines are better than the newer ones. Piaggio made some changes in 2007 and messed it up. I think they did go to 17s in something like 2003. I would have preferred 17s.

This is only the 2nd one I've ever seen anywhere (and I've gone to a lot of cycle shows and meets over the years), so I snapped it up. It was only about 40 miles from here, which was a plus.

It sounds and pulls like a stock 125 for the most part once it's rolling, but it's not fast (of course). It is super light, which makes it a lot of fun!
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Old 03-26-2015, 09:40 AM Thread Starter
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Cleaning it up -


Plan to pull the carb and check the jetting. Probably replace the reeds, change the trans fluid, brake fluid, and coolant while it's apart.
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Old 03-26-2015, 12:32 PM
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Very cool bike!
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Old 03-26-2015, 05:22 PM Thread Starter
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Made a couple mods to eliminate passenger accommodations (like it could ever carry a passenger...) -

Milled the mount for the rear footpeg off of the bracket holding the silencer -



and cut off the passenger grab bars -

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Old 03-27-2015, 12:49 AM
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Had the 1999 model when i was 16. Great little bike. Spend a few quid & bang in the 80cc kit, new reeds & carb. You won't be disappointed.

However im not familiar with the new engines. I used to work & rebuild AM6 engines on a weekly basis. Loads of " secret " things you can do to that engine

One thing i would recommend Is to bin the oil pump & go full premix. These things had a problem with failing or the adjuster getting loose over time. Good luck with the build. Can't wait to see more pics

Take care & ride safe.

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2013 CBR 600RR, Sold.
2013 Kawasaki Ninja 650R, Road. (wife's)
2015 Kawasaki Z300, Road. (wife's)
2014 BMW S1000RR HP4, Road / Flying Machine. (Traded in the wife for it)
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Old 03-27-2015, 10:28 AM Thread Starter
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Originally Posted by midgeinc View Post
Had the 1999 model when i was 16. Great little bike. Spend a few quid & bang in the 80cc kit, new reeds & carb. You won't be disappointed.

However im not familiar with the new engines. I used to work & rebuild AM6 engines on a weekly basis. Loads of " secret " things you can do to that engine

One thing i would recommend Is to bin the oil pump & go full premix. These things had a problem with failing or the adjuster getting loose over time. Good luck with the build. Can't wait to see more pics
The big bore kits are few and far between at this point from what I'm hearing.

Is the engine designation EBE050 on the 2000 model?

It has been running premix since almost new - so that's good.

The tiny 24mm Mikuni Flatslide is legit -


the offset intake manifold, not so much -



I plan to check with an engine builder I know that does a lot of porting to get his ideas on how it should be opened up. The round opening is only 19mm and the backside contour looks like a mess.
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Old 03-28-2015, 12:40 AM
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I used these guys exclusively. Good service & good prices. If you can't find what you want for a 50cc here. It don't exist Hope this helps.

50cc.eu, parts for scooters, mopeds and 2-stroke bikes

Take care & ride safe.

2012 Honda CBR 250RAb, Sold.
2013 CBR 600RR, Sold.
2013 Kawasaki Ninja 650R, Road. (wife's)
2015 Kawasaki Z300, Road. (wife's)
2014 BMW S1000RR HP4, Road / Flying Machine. (Traded in the wife for it)
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Old 03-30-2015, 09:42 AM Thread Starter
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Replaced the chain with a new gold RK -



The chain is super long, but it does have top and bottom rollers. It surprises me sometimes the small details that they put into a cycle this size. I wouldn't expect it to have roller guides. They don't even make a chain that long in gold, so I had to buy 2 and pin them together to make one long one.

If you look closely at the photo you will notice one of the sprocket bolts isn't fully tightened down. Actually that the second one that's not fully seated. I will most likely replace the bolts with buttonheads and locktite them, but I have no idea why they wouldn't be tightened correctly before bending over the locking tab...

Last edited by jkv357; 03-30-2015 at 09:45 AM.
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