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Hi jvk. Looking good buddy.

I can't wait to see the front end :) Just wondering what gearing you will be using? 12-47? or 14-52?
 

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Discussion Starter #62
Hi jvk. Looking good buddy.

I can't wait to see the front end :) Just wondering what gearing you will be using? 12-47? or 14-52?
Thanks.

The countershaft sprocket is now a 15T. The rear is a 42.

We felt is was geared a bit too low as it was. With the larger carb and performance pipe on the 75cc engine it has a bit more power than it did originally. My son thinks it may now be geared a bit too high, but the new rear tire is not as tall so it will drop the ratio somewhat. We'll have to see.
 

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Discussion Starter #65
Cool project. Love the look of that top yoke, the wrinkle charcoal finish looks real good.
Thanks. It needed something real bad. It was originally solid (no openings) and bare aluminum. Looked way too big, heavy, and boring...
 

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Discussion Starter #66
Got it back together and took it for a spin last night -



Starter has been temperamental, but it stopped working completely. Bump starts really easy though.
 

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Thanks. It needed something real bad. It was originally solid (no openings) and bare aluminum. Looked way too big, heavy, and boring...
You are certain about strength? I know it is a light bike, but wow, that is spindly!

I'm assuming it was recessed on the bottom, and that is where you took your cues?
 

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Discussion Starter #68
You are certain about strength? I know it is a light bike, but wow, that is spindly!

I'm assuming it was recessed on the bottom, and that is where you took your cues?
The material that was removed was just the top of the casing pockets.

Pretty similar to the Aprilia clamp -



I'm thinking it will be fine, but there's no guarantee. I couldn't stand the way it looked before. Looked like a part off of a Harley.
 

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Discussion Starter #69
Had the Derbi out again last night. Oldest boy (6', 140#) aboard. He loves the thing. Wishes it had a bit more acceleration, but once it's above 40 or so it's not bad at all. We were running 75 a few times and he said there was plenty left. The taller gearing (+1T countershaft) helps on that end, but is a slight disadvantage off the line.



Made some slight adjustments to the idle mixture screw and idle speed to get it to 1500. Idles smooth and pulls clean all the way. I've found that adjusting the idle mixture screw to get the highest RPM, then going richer until you hear a slight drop in RPM gets you a good idle and a nice transition off-idle. It's giving you a slightly rich setting that keeps the transition smooth. After that's set, turn the idle speed screw to get the speed you want. That's the system I use for almost every cycle with a carb.
 

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Discussion Starter #71
Had the Derbi out this weekend and put about 80 mi on it. Took it to a local cycle meet with over 500 cycles in attendance. Plenty of interesting looks and a fair amount of attention.






Ran pretty well. Temps were in the high 40F to low 50F range, and I richened the needle slightly the day before. Lots of fun on the backroads and curves, but struggles with me on it (175#) from a stop. Once it hits 7500 of so it takes off, but not much going on below that...
 

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Discussion Starter #72
Just in case you wanted to view the Photbucket images in this thread and haven't installed the "Photobucket Fixer" extension, here's the info -

This is a link to a "Photobucket Fixer" extension for Chrome - https://chrome.google.com/webstore/d...giikdkpmcpkaon - you will need to search "Photobucket Fixer" by Jesse Evers.

There is also one available for Firefox - https://addons.mozilla.org/en-US/fir...obucket-fixer/

It makes all the dead photos alive again, so you can view them as usual. It works only for the computer that has it installed, and doesn't fix the thread itself.
 

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Discussion Starter #74
Had the Derbi out this weekend, and rode about 60 miles with me aboard. Kinda windy, and the Derbi struggled a bit on the hills with the wind and a 180# rider.

Went to the semi-annual Slimey Crud Run in Pine Bluff, WI, and pulled-in next to this beauty -







Bimota V-Due 500cc 2-stroke - https://en.wikipedia.org/wiki/Bimota_V_Due

This one has been totally redone to actually work. Long story, that I got from the owner, but basically the engine cases were a problem originally. By the time Bimota figured it out they were almost broke.

Factory engineer bought everything (bikes that were bought back, unassembled bikes, all parts) and had new cases made, as well as going to carbs instead of the problematic F.I.

First one I've ever seen.
 
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