dellorto SHA, dumb; running derbi, awesome

Just before the reno rally I spent a few days trying to get my thrown together derbi variant running. That should have been a relatively simple process figuring that the motor was running fine about a year ago in stock form. This clearly wasn’t the case. I did change a few things, primarily the top end, to a stock jug bored (long ago) to 60cc. I threw on the stock intake and carb and it ran rather well with decent pep and seemingly unlimited top speed. I went to ride it home (as I built it at Matt’s house way back in January) and it made it 1 float bowl in the stupid sha. I pedaled the rest of the way home.

So I tried cleaning the first carb, taking compressed air and carb cleaner to it twice. Same result, it died. So I tried a second 14.12 body with the same result. I asked Tom to borrow one, and this was even worse. It would kinda idle, but when reved it sounded like it was burping like there was a huge leak, but the seals were fine. So I tried cleaning that SHA again today to no avail (and why should anything change, the derbi has a spotless plastic tank).

Pissed off I finally decided to throw on Tom’s custom intake, his first from 3 or 4 years ago, 19mm funneled down to 14mm. My least favorite task on mopeds is running throttle cables, so I just pulled the throttle off ferbi which conveniently was already hooked to my dellorto phbg cap. I didn’t feel like routing the cable through the frame just yet, but I got it all bolted on and of course it fires right up and rides like a dream. It also fits in there super easy! Lesson learned: never use a SHA.

While working I also fixed the wiring which I kludged together back when I built the bike. Everything is much cleaner, the kill switch works as do the lights. So now the bike is almost done. It still needs fine tuning because all my dellorto jets are missing and my randomly picked phbg (84 main, 48 idle, needle ?) only works so well. The variator also needs some fine tuning to fully variate and reach higher RPMs. Despite it all, I think its a pretty cool bike that is fun to ride. With an air box it will keep the neighbors happy as well.

I’ve seen some stuff asking about switching derbi mags between bikes, and because all derbis have very subtle differences, the solution you come up with may be unique. This bike is older (PP) and had spoke wheels. Late bikes, or at least the Variant Sports, have brake hub tabs that are longer (they go lower towards the axle). I switched to a set of lowers from the variant sport so that the tab better held the revo hub, but the wheel couldn’t be properly centered. We then ground the hub down a bit so it all fit together. Fortunately rear wheels are easier as it seems just about all (but of course there are exceptions) have the same size tab for the hub regardless of the swingarm configuration. The biggest issue going to the revo mags is the cables as the ends on the newest variants are different. This is nothing some strong knarps cannot fix.

Finally a note if you are doing this: buy the fork lowers for whatever set of wheels you are switching to. All Derbi variants have the same fork uppers which allow all lowers to be 100% interchangeable. Tom had a spare set of revo mags and conviently forks, so he just swapped the lowers over and avoided ugly half-assed attempts at removing forks and grinding hubs.


Derbi CDI installation step-by-step
June 11, 2009, 3:58 am
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So derbi owners have pretty much always only had one ignition choice: stock (points or for some the electronic ignition found on the ds50). Now I’m going to show how the CDI treats sells can be adapted to fit your derbi. This is going to be for piston port bikes, but the same procedure will work for pyramid reeds, and should work for flat reed as well, just ignore the coil flip.

Buy CDI here

Ok, so you got your CDI which has a new stator, flywheel, cdi box/coil and maybe a regulator. This was on my race bike, so I pulled the lighting coil just to clean up the wiring a tad. Your going to need a dremmel or files to slightly modify the stator, a m4 tap and appropriate sized drill bit, and maybe some lock-tight.

The first obvious complication is mounting the stator in place of the old one. You’ll notice the diameter is a tad smaller, and you want it centered as well as possible for the best pickup to be sent to the box. So you are going to have to slightly enlarge the center hole (towards the lighting coil). Next you need to enlarge one of the screw holes so you can use two screws to hold the stator to your cases. I ended up using 2 screws, one just to the right side of the main ignition coil, and the one right above the lighting coil (see photo). The one above the lighting coil needs to be enlarged about 5mm to the left. You may need to pull the lighting coil off to mount the stator to your cases, but you can just re-install it once mounted.

Basically the lower screw is tightened and the plate shifted as far counterclockwise as you can get, so just enlarge the hole above the lighting coil so you can rotate the stator to that position and screw in the bolt. This position (with the pickup relocated) got me right at 1.8 mm btdc)

So now the stator is lined up, but the case is getting in the way of you wires out of the stator. You need to dremmel open the little supports for the crank bearings/seals (see photo). I believe you will only need to open up 2, the one just above the lower screw hole, and the one to the left of it.

With those done, the stator will just bolt on with the cables out of the way. You will still need to relocate the pickup (tap and locktight) and possible flip your ignition coil. I am running a za50 cdi box (counterclockwise spin), and had to flip my coil (note the position of the blue wire from the coil to see which direction). If you have an e50 box, I don’t think you will need to flip it, but always check with a timing light to make sure it sparks through the range.

So thats it, just a little modifications and this wonderful and cheap cdi works, and quite well at that. It really brought my bike to life, and is a nice departure from points. Now your only issue is figuring out where to mount the cdi box and coil. Also note, on one of our 5 piston port derbis, the cases were super weird with extra large supports for the crank bearings, thus not allowing the flywheel to fit inside. You could likely dremmel everything out, but I’d be careful.

cuperteens race team that stinks at racing because we are newb tuners and kinda crummy riders
May 5, 2009, 1:48 am
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Ok, so polini cup #2 is over, and I’m here to report on the cuperteens.

So yet again, we suck. Matt got his derbi up and running well during the week all to be destroyed 1st practice on saturday. He was going fast, jetting looked good, but upon really opening it up on the front straight, it super seized. It was a 4 corner seize flaking the nikisil on all 4 points. Cylinder death. On sunday he saw that his fuel line was kinked, meaning the float bowl didn’t fill fast enough, so when that mikuni was dumping fuel on the straight, it ran out, leaned out and broke. That was dumb, but won’t happen again, at least that way.

Tom was back out there on his gilarderbi. Round one was tough with a nasty soft seize followed by a crank big end bearing seizure. With a new crank in, his bike was actually quite reliable, but it was slow. The weather was weird this weekend with high humidity and higher temps than we saw last week. Needless to say, he wasn’t jetted correctly, and wasn’t making enough power to fully variate despite changing the weights a few times. I think he finished 19th the 1st race (he fell) and did better the 2nd, but not top 10. So even though it wasn’t awesome, his bike survived some abuse, evoking more confidence in the setup.

We had an extra derbi flatreed variant that sean ended up riding in Matt’s place. It only did 35-maybe 40, but he actually held up well before everyone dusted him on the straight. He didn’t block anyone too bad, so that was good. He had a lot of fun on the track despite being the slowest. Crashes and others not starting meant he wasn’t last place. I don’t know if thats good or not.

Lets pretend tom held onto this one.

justin blasted everyone on magnumx

So it was a fun weekend again, but tons of mopeds. It looked like a rally pack on the track, and seemed unsafe. The fastest 6 or so lapped just about everyone else, so I think we need to lobby polini to split the heats up next time as there will likely be even more bikes. Sure its fun racing with a bunch of people, but I’d hate to see anyone hurt.

I might (hopefulllly!) be out there next month. My derbi is almost back alive. Its had some upgrades, so it should be quite competitive if I can get out there. Look for those updates soonish after a few stupid midterms.

PS, I should add that I do not represent the riding styles or mistakes my friends made on the track. That said, watch out for them, they all went down, and they all get in the way. We should be the “cuperteens race team that stinks at racing because we are newb tuners and kinda crummy riders”.

Cuperteens Derbi Arsenal.
April 3, 2009, 6:12 am
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We are trying to get as many derbis as possible. Our current collection includes:
1980 SLE Red
1979 SL Green
1979 SL Black
1978 TT Green
1980 TT Yellow
1987? SLE Red
+ 3 flat reed motors going on various bikes.

We are working on acquiring a red TT, a Laguna, and a C5. Derbis are sick! Piston port is currently the shit.

December 3, 2008, 2:00 am
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So it turns out we will be doing some real moped racing this coming spring and summer. I am pretty excited, and I’ve been talking to everyone to see who wants to race and what they might be riding. I think the main factor of people not racing will simply be purchasing full leathers and boots. New they can be very expensive, but in a few quick searches I’ve found some on ebay for $150 and some nice ones locally for $125. So I’m not too worried about that. Boots will be easy, and I’ll probably splurge on some good gloves.

I’ve also been curious as to what the other teams will be racing upon. I’ve heard 77 will be building 2 or 3 racer peugeots, and that rafter and motomatic are building some crazy variated minarelli and others. I think I know whats best, and thats my build!

So I’ve got a solid derbi variant, but unfortunately its piston port. There are zero piston port kits out there (everything is for those flat-reeders), but I do have an advantage: puch kits! So I am going to pick up a Gilardoni kit tomorrow, as well as a 75cc derbi zen pipe (hydroformed beauty), and I’ve already got the carb. I’m waiting on benji to get some more variators, but thats it! Derbi builds are cheap:

  • Gilardoni – $150 used
  • Derbi Zen Pipe – $175
  • TJT Variator – $100 or so
  • Belt – $35
  • 21 PHBG – $90
  • 2.5×17 Michelin m29s slicks – $50

So for a mere $550 (well 400 as I’ve got the carb) I’ll have a blast monster derbi that can probably take on the best. I’m pretty excited because for under $700 (the bike was $150) I’ll have something really fun to ride. I’ve definitely got a lot to learn as far as actual racing goes, but I know my bike will be there. Derbi’s are the best handling and most comfortable moped I’ve ridden so far.

I’ll be tearing the derbi down probably starting wednesday next week, prep it for paint (black and green), and build up the motor. I’ve heard the stock cranks can be iffy, but replacements are available and I’ll take my chances initially. If I blow it up, I’ll then rebuild the bottom end. Many might not agree, but whatever. The motor should be up and running in no time, and if everything goes to plan, I’ll be blasting before the new year! 

Watch out for the Cuperteens Race Team. 2 Gila-Derbi’s and some other nasty concoctions.