I’ve been missing for a bit, but am still around. The frevolution has been kicking it, and I finally pulled the custom built pipe from my derbi race bike off so it doesn’t get destroyed by the streets (and fog) of SF. I got one of those fasmem pipes from treats and had to add a little bracket and trim my transmission cover a tad to get the fit. I had a little electrical issue (read: custom construction = melted headlight) and got a replacement that was creating some gremlins. Some crafty work and now all systems are a go. It doesn’t run nearly as well as it did with the simoni pipe, but a little tuning ought to help out. It does fit on nicely though.

Next up might be a throwback: decking out my clean newport with a gila/phbg ripper setup and mobbing that around town. The details are unclear, but I have a few kits sitting and I want something a little different for the city. I love the start 3 derbi motor but I don’t want to go all crazy with it and unfortunately am limited on gearing by preserving the puch swingarm/wheels. So I’m thinking simple e50 build on a nice base. Should be simple and fun to ride around. With some luck I’ll have a post or two about it.

Oh yeah, got another toy, but it still needs a little work. More on that later.


they all work!
December 24, 2011, 6:15 pm
Filed under: repairs | Tags: , , ,

All my bikes that can run are ! Newport still needs a tube and the frev needs the 19t sprocket put on and the chain run, but still, 4 running bikes plus my bros tomos. The frev turned out pretty decent. It runs fine, brake light works, and a 55w headlight! The seat mount isn’t perfect but it looks pretty good. Changes will come later when its all dolled up, but for now I’d like to just ride it. I can’t wait to take it for a spin! Riding chappy around again was a blast, especially after seeing some kids scooting around the hood on a pair of fa50s.

A Frevolution is Coming
August 15, 2011, 8:02 pm
Filed under: Uncategorized | Tags: , , , , ,

A work in progress. Plans are for a 50cc ripper. All brackets built, pedals will be functional, ripping pipe clears all, together maybe the best moped ever Next up is some cosmetics, welding and assembly. If the 50 doesn’t deliver, maybe a 20+ hp scooter cylinder. Coming soon to a rally near you.

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.

race bikes
March 21, 2011, 9:50 am
Filed under: Uncategorized | Tags:

so it totally rained saturday, so we didn’t go racing. That and I was stuck in SF with Tom and Rahul, and we had some events we had to attend to, like the bar that was full at 8:30 in the morning, or the person lying (most likely dead) in the middle of the street and the cops put a blanket over their face, or Tom’s new umbrella that matches his party shirt.

So we decided to work on mopeds yesterday. I went to sean’s house, and he had just finished everything and just needed the electric starter. We gave it a charge and the beast fired right up. No leaks or anything weird, and it FLEW down the street. Pretty nuts.

Of course any day of race related anything requires video games, so we played some double dash and unlocked the special cup.

We went over to my house then to change the jet in the race derbi and clean the carb in the green one. Sean documented the process of changing the jet, which as you can probably tell is really really annoying. But we got it changed with minimal leakage of race gas, and it fired right up and went down the street REALLY fast. Pretty rad! It still needs a few bits, primarily a different frame because good god, it should not take 30 minutes (or even more than 5) to change a jet, especially on a race bike. So at some point I’ll have to do an old switcheroo, probably similar to what rufus did on his, grafting it to a magnum frame.

I took some pictures but they were really crummy because taking pictures with a broken arm is surprisingly difficult.

Derbi SL Build Part 1

Matt and I started getting the SL all put together. We started with this:

Plans are to use the Rev mags, his green frame, my c-5 piston port motor with a bored stock cylinder, tjt, some pipe, treats cdi, dellorto sha, etc.

Of course in building any bike nothing is as ever as easy as it should be. For example, we had to mess with the forks because of course (as its a derbi) the brake hub tab on there differ for every year of production. Older bikes have smaller tabs higher up. These barely work with the rev hubs, and we determined it unsafe. Fortunately Matt has a set of never Variant Sport forks which have tabs that run much lower (to down closer to the axle), so we decided to use those.

If you’ve ever messed with derbi forks this picture should ring true. Gosh what a mess, and how it is NEVER easy to get those little rods in the hole (that’s what she said?). After much fandangeling, I got them in but turns out the wheel spacing is still wrong. So we sawzalled the tab in half on the fork arm to shimmy the wheel over, but even still its way off. So now we have to mod the hub plate to get that wheel centered so we can run a fender.

So its almost done and looking pretty cool. The big pirellis have about the same profile as a regular 2.25×17, so the little wheels don’t look too stupid (meaning big ‘ol fender gaps). We have to figure out the exhaust situation, find a carb, hook up the ignition, and get the front fender shored up. Exciting times. Oh yea, gotta find brake cables that work too.

Derbi Day

Today was a busy day getting all my derbi junk together.

Tony hooked it up with pretty much all the plastics, controls and other bits from the revolution, the complete revolution motor (which someone managed to strip in one of the swingarm bolts and cut off the head, extracted it wrong and drilled a new hole at an angle to hold it together, wonderful!), the revolution wheels with new 2.75 Pirelli ML75, Rev. shocks, the messy pyramid reed motor (missing clutch, variator, cylinder and head), and a ducati cdi stator and flywheel. Oh yea, also a spare new revolution crankshaft. So yea, quite the collection.

First order of business was comparing fitment of the revolution motor in the c5 frame. Obviously its going to take some work but its not too far. A fellow down in the LA area put a Flat-reed motor on his rd50 (same frame) and basically had to modify the kickstand/motor holder and add an upper bar to support the upper/front bolts on the case. I’ll be doing much of the same. The rear holes in the mount will need to be slightly modified but beyond that it should all fit very well.

Here is the frame with the original piston port and another with the start motor. Kickstart lines up perfectly!

To keep everything simple to work on I will have to drill out the stud holes in the cylinder and head to fit the funny c5 mini-studs and bolts. All easy. Much of this will be on hold until school is up in may. So yea, just getting excited about what is to come.

To keep things complicated I’m going to be putting together another derbi with the help of Matt who has a really spiffy green Variant frame. We are going to build it mostly as a loaner for friends or us when all our stuff is broken. The setup will be simple, piston port bottom, stock cylinder bored out to 60cc, homeot 4p, milled flat reed head, tjt, malossi clutch springs, 20×30 gearing, 19phbg, revolution mags, and so on.

Tom had this cylinder on his Variant a few years ago and hit a hair under 50 with an estoril with a janky header. So optimized it ought to be a pretty rad bike that is decently reliable and quick. I’m going to try and get most of it together tomorrow, but I gotta switch a water pump on the diesel first.

Lastly, here is the nasty pyramid reed. Crank actually turns pretty well but it sure is crusty.