Getting to know the Derbi Variant TT

So, I've been texting this guy on craigslist lately... He had this Derbi listed for $1200 that didn't run, was missing a pedal, and NO other details. Pretty easy to see why nobody had contacted him.

Me being bored, on craigslist and spazing out about a derbi being in TN and for sale, I text the guy even though it's a low hope situation with it being listed at $1200. I send him a real long, drawn out super tactful text that I'm into the bike, but it's not worth anywhere near $1200. We text, I find he's interested in me and likes that I'm into mopeds, and we agree I'll come kick the tires during my break and that he may or may not be interested in trading me for a project motorcycle or running moped.

I show up to meet the guy and he's much younger than I anticipated - this I was excited about because the dudes who have old mopeds are typically crazy and really do want tons of money for them. We talk, I look it over, we talk some more about what Derbis sell for in their stock condition on MA and chit chat. I got to talking to him about what I could trade him and ask him just for kicks and giggles after our convo what he might want for the bike in cash. He pauses, and says "well, I think my absolute bottom dollar would be $250". I was a bit surprised in how much he had come down, but I'd tried to get him to be half as excited about me owning the bike as I was. I'm not sure what the most I would have paid was, but I was happy with $250. It didn't run, I'd driven from Franklin to Clarksville and $250 I could come up rather quickly.

I had a "fire sale" on MA and raised the money in just two hours. Drove up there the next day and picked it up.

 

After I got it home, I started getting to work getting the thing running. Ended up only needing the points cleaned, point cam polished and lubed, a new plug boot, carb cleaned, fuel line and some other odds and ends. Fired right up.

Then it was time to start getting it road worthy. Greased the chain, changed the gear oil, set the timing, installed a new baffle, installed some tires I had sitting around (17x2.75 rear and had to go .25 smaller in the front with a 17x2.25), cleaned and greased the forks, took some rubbing compound to the whole bike and get a socket so I could take the vario off and mess with the weights!

The stock vario weight caps were pretty heavily worn and out of round and one of them wasn't even making contact with the ramp plate, so I decided to find some new stuff if I could. Got to the hardware store and found some nylon tube that was the right size. Stock outside diameter that presses against the ramp plate was .57 inches and the caps were narrower - finding something that was the same diameter all the way across and still rode correctly means that the nylon tubes I found that were .56 inches in diameter were basically the ideal size - I had to take into account the difference in diameter where the caps rode and where the weight rode against the ramp plate. Then I found some steel spacers that fit inside the nylon tubes and boom - vario weight = created.

Here's the packaging from the pieces I used:

Then I just put it together and did it. I drilled the steel spacers out to 7.5mm to remove ALOT of weight from them and make them extra light.

 Then I put the Nylon spacers on the Steel spacers and cut the nylon down.

They fit quite excelently in the stock vario. Resting height is the same and the width of the steel spacers was PERFECT. I cut the nylon flush with the spacers on each end. I also roughed up the steel spacer surface to get more of a press fit in the nylon, although that probably isn't totally necessary.

The stock design of the derbi was neat, beacause the weights rolled in the caps, but it was also bad, because it wore the caps out and the steel doesn't slide as well on the vario ramps as the plastic does.

Here it is!

 Works great. Half the weight of stock. I'm hitting full variation at 30mph. I took the restrictor spacer out of the vario, but I think I might have a little travel left yet to find. I'm hitting 35 right now. I need to come up with a less restrictive baffle, maybe even a cone insert for the stock exhaust? (stock was missing and had to use the one out of a Sachs) and I need to dial the jetting in on the 14.14. I'm at a 64 right now. I get the feeling it's going to want a 68. No leaks anywhere.

So far so good. Once I get it to 40, I'll be leaving it alone for a while and just riding it. I want to buy or fab a pipe for it, but I don't have a sheet metal roller yet... Was thinking I'd try to steal the homoet 4p dimensions.

It'll be interesting to see how the nylon holds up in the vario. I'll make sure to do an update after a couple hundred miles. Probably won't hit 1000mi until this summer.