Derbi DRD [81,4cc] | Testing.. 7.5.

[tracing]

Nice can't wait! It's gonna be a good build

[J11]

Not finished. Didn't have enough time to get cylinder and crankcases finished.. probably finished on saturday.

Still A LOT to do.

I ordered a Vertex 47,90mm piston (TM 85MX).. the piston to cylinder clearance is 0,08mm, which is a little bit too much but should do okay 'till next piston change. I need to ask, if Wössner or other fine quality piston manufacturer could produce 47,93mm size piston.

The carburetor and intake manifold should arrive tomorrow.. Koso PWK 32mm and Malossi 32/40mm intake manifold.

Edit: Rest of the parts should arrive on thursday or friday (week 47).

[Ezasta]

Cant see the pictures

[J11]

I uploaded them to Photobucket now. Hopefully their visible now.
If your using Google Chrome, try turning AdBlock off. That might cause pictures not to load.

Tomorrow I'll upload better pics. Getting the cylinder and crankcases finished.
Also going to modify the V-Force 3 reedvalve, after I have received the Koso PWK 32mm carb and Malossi 32/40mm intake manifold.. it has a ø28mm hole, so it needs to be enlarged to ø32mm.

Next weekend (47) the bike should be running.. then I'll borrow my friend's GoPro and record Derbi vs. KTM EXC 125 drag race. But only IF somebody with a KTM EXC 125 has enough balls to race against me. If none of KTM riders have enough balls, then I need to race against my friend with a GasGas EC 125.

Also on week 48 I get the bike dyno'ed.

[Baskevdb]

they do work now! great looking project you started there, can't wait to see the dragrace

[rené]

nice work! I'm curious for the power results

[Ezasta]

2nd pic looks cute ^.^

[J11]

Exhaust port Doesn't look too good on the picture, but on portmap it looks the same as Hebo Pata Negra's exhaust port.
It has 195 degrees and about 85% width (for two piece exhaust port the maximum width is about 90%)

Exhaust channel Tomorrow sanding the whole channel; p180 to p500

Crankcase & cylinder Tomorrow I'll finish the cylinder sleeves, so they won't block the gas flow


There should be great gains on power, mostly on high rpm's (from 9 000 till the end of powerband).

The transfer ports (or actually channels) are very small in Airsal 70cc cylinder. It's just liked a bored out 50cc.
The channels are smaller than Airsal 50cc has. I noticed more power on high rpm's, without losing any power from bottom-mid end when I modified slightly larger the transfer channels.

Exhaust channel is now ø30mm. Now I need to modify the exhaust pipe adapter a little bit.

I've been thinking about the compression ratio.. most high-end or hyper racing cylinders have combustion chambers with 15,1:1 or even higher compression ratio! And I'm going to be running on E85 fuel. So I might raise the compression ratio from 14,6:1 to 15,2-15,8:1.

[tracing]

Comin along nicely, can't wait to see it rip!

[J11]

I probably have to change the tires.. my other bike (Yamaha YZF-R125) has Michelin Pilot Road 3 120/60-17 and Pirelli Diablo Rosso II 150/60-17 tires, so I might change them to Derbi.

But now I have the Brembo 2-piston caliper attached to the fork. Should stop way more quickly than on a 1-piston Ajp caliper!

I ordered a RM-Z numberplate and Renthal grips on thursday.. they should arrive on monday or tuesday. The bike should look a lot better with the RM-Z numberplate!

[J11]

The project has progressed a little bit..

-Better condition rear plastics (used) ordered yesterday, should arrive on Friday or Monday.
-Parts from Animotos and Maxiscoot are here on Tuesday. Then the fun will begin!
-Vertex 47,90mm piston kit (TM 85MX) is out of stock. Arrives on next week's Thursday or Friday.
-Koso PWK 32mm carb has arrived, now I'm fabricating a new intake manifold for it.
-Cylinder got some more porting. Mostly to exhaust port.
-Cylinder head is getting finished on Monday.
-I bought 6203 C3 bearings for transmission and clutch. The 6204 C3/Tn9 bearings are coming next week on Friday
-V-Force 3 reedcage is getting new reeds, made from Barikit's 0.35mm carbonfiber. The reedcage has been now modified for 32mm carburetor.
-46H rear sprocket is getting painted as matte black (new holes drilled and now fits to CPI rear wheel).
-RM-Z numberplate and Renthal Dual layer grips installed

Here's a pic, what the bike looks now;

Better or worse?

Parts..


The bike is going to be running on E85 + Klotz Super Techniplate. Difference between Super Techniplate and BeNOL is, the ST can be used as low as in -22C degrees. In Finland the winter can be as cold as -35C degrees! But for past few years it's been less than -25C degrees.

Inner rotor kit (HPI) is out of stock from the shop I was going to buy it.. probably buy the inner rotor kit on December.
There's no really hurry for the ignition, because the bike already has enough power for snowy roads.

[Mclaren]

Starting look to great man, do you have a gopro?
I would love to see some videos when it's done.

[J11]

Thanks! I don't have a GoPro, but 1 of my friends have. He might borrow it for me, so I could make a onboard video.

I'm starting on tearing up the current engine to see all the damages the conrod failure caused. I have the another engine ready for re-build.

[tracing]

Sick looking bike! Would love to be able to do that, but tight money budget and dont have a shed with nice tools, so thats a no for me.

[J11]

Yep, well I have spent on this bike about 1,100-1,200€ now including the price I bought it.
Quite well for a high-end moped?

Right now I'm building the moped outside, where's less than -5 celsius. But thank god my parents allowed me to re-build the engine in my room.

Also getting a larger radiator (from KTM EXC 450) after I have got some more money.

[Schakelman]

Where about do you live in Finland? My girlfriend is Finnish. I like the fact that I Finland you see more Derbi bikes in a day than in Holland in one month..

[J11]

Southern-Karjala (Etelä-Karjala).
And yes, Derbi moped's are very popular in Finland.

I'm ordering a Kawasaki KX 125 '97 radiator, because I found one for cheap. If there'll be some heat problems on summer, I'll get another radiator from Aprilia SX 125 on the left side. The current YZ80 radiator + stock on the left wasn't the best possible setup.. and the YZ80 radiator started leaking. + I'm going to buy a Koso temperature meter (digital) on December.

When the cylinder is in size 48,00mm, I'll start using forged Wössner Suzuki RM 85 pistons (47,95mm) and MXS GP 14x17x16,6mm small end needle bearing. Current size of the cylinder is 47,98mm and the piston is cast Vertex 47,90mm + Stage6 13x17x15mm small end needle bearing.

Seriously I cannot wait for the parts!! I'm very excited to ride this bike with the new engine.
But I need to keep in my mind, that I need to re-build the engine very carefully.

Edit: Looks like Animotos haven't even sent the parts.. I ordered from them 6 days ago, but I haven't received the tracking code.

[Alfred]

Looks amazing !

[rené]

it is a nice project! but i still dont get why u did chose to take the airsal 70cc cylinder.. because of its one of the slowest 70cc cylinders made for Derbi.. if u place the bidalot 94cc cylinder on this crankshaft u will get way more power than now.

[J11]

@Alfred - Thanks!

@rené - Thank you.
The reason for Airsal D. 48mm cylinder is mainly the price (costs only 120€ as new) and the bike had it already, when I bought it.
So I've kept the build in budget.

Bidalot 94cc cylinder kit requires a 48mm stroke crankshaft with 95mm long conrod.

I can quarantee it for you, that the Airsal D. 48mm cylinder I have, isn't even near what you can buy from a shop.
Dyno test is going to be in 1-2 weeks.. Animotos has sent the parts 26.11. and right now they should be in Netherlands.
The parts will arrive on this week, then I'll build the engine and abjust the carb + ignition.

I'll post some pics for you on Friday or Saturday.