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post #21 of 74 Old 07-07-2015, 05:10 AM
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Great work on the little Derbi. When you figure out range / mpg, let us know. I bet the little engine uses about the same or more gas than the CBRs as it zings along. I used to mess with my Suzuki GT380, 2-stroke triple back in the day and it gulped the gas and translated into propulsion, noise, and a streaming blue haze behind me.
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post #22 of 74 Old 07-07-2015, 10:27 AM Thread Starter
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Thanks - will do. I need to get some more oil and mix up more gas. I'm running Redline Ester 2-stroke race oil premixed at 32:1. I need to check the plug color, but I think the jetting and oil mixture are pretty close. It will smoke some when the engine is cold, but only smokes occasionally during shifts when warm - smells good too. Reminds me of my kart racing days.

I'm guessing the mileage will be somewhere in the 30 to 35 mpg range, judging from what I can tell from looking in the tank - which is about 2 feet long and runs from under the passenger seat (where the filler is) to the back of the "gas tank".

Back in the day I rode with a buddy that had a GT550 (3cyl) with pipes - boy that sounded good! Just did some work on a GT250 of his that he is trying to get going again. Got to keep the old smokers on the road!
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post #23 of 74 Old 07-07-2015, 12:31 PM
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Wow! That is a queer fuel tank, for sure! You can't even take the cap off and rock it back and forth whilst straddled, like the old days!

You are making me regret selling my Honda Dream 50... (there was a brand new one for sale up your way somewhere several years back...)


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post #24 of 74 Old 07-07-2015, 01:39 PM Thread Starter
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Quote:
Originally Posted by don'tpanic View Post
Wow! That is a queer fuel tank, for sure! You can't even take the cap off and rock it back and forth whilst straddled, like the old days!

You are making me regret selling my Honda Dream 50... (there was a brand new one for sale up your way somewhere several years back...)
You had a Dream 50 - and sold it??? You don't see them at all.

That's pretty collectible at this point.
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post #25 of 74 Old 07-07-2015, 01:54 PM
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You had a Dream 50 - and sold it??? You don't see them at all.

That's pretty collectible at this point.
It was a turbulent time in my life...


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post #26 of 74 Old 07-23-2015, 12:31 AM Thread Starter
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Well, my estimation of the amount of gas we used last time out was way off.

Turns out I only added 1 gallon of premix to the tank to fill it for the 65 miles we rode - so that's easy - 65 mpg. I was expecting half that.

Pretty surprising, as it's running 8000 to 9000 most of the time, with frequent spirts over 10,000. The stock carb was a 14mm, the flatslide is a 24mm.

I just got a 15T countershaft (EDIT: +1 tooth to drop some revs) sprocket to try when we get a chance. Looked at the plug color from the last time out, and it was medium-tan - almost perfect.

Had it out again tonight for about an hour or so, and it's a bit rich on top. Ambient temps are up about 15 degrees from the last time out, and the jetting needs to be leaned to match the reduced air density.

EDIT: Went to the 170 main jet (down from 175) and it pulls cleaner on top now. It will cruise at almost 70 reasonably well and not at WOT.
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Last edited by jkv357; 08-13-2015 at 11:21 AM.
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post #27 of 74 Old 07-23-2015, 12:19 PM Thread Starter
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A couple pictures from last night's local Bike Night -


My daily-driver SV and the Derbi parked in a sea of Harleys...


The Derbi's regular pilot -



Being a smart-ass teenager (if you look closely) ...
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post #28 of 74 Old 09-20-2015, 09:58 AM Thread Starter
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Just a quick update on where we are now.



I'm about 1/2 way done with the changes I want to make. I toned-down the graphics with a single "Derbi" logo on the side and a Derbi "D" on the tank. I may take the "D" down in size a bit. I added a "R" graphic from the windshield to the side above the Derbi and removed it from the windshield. The wheels will be blue to match the graphics color and I'll get new tires by spring.

Probably get the +1T countershaft sprocket on this week.

It's running strong now, and we will have it out for the fall cycle gathering (Slimey Crud Run) the first Sunday in Oct. Jetting was just a touch rich last time out (170 Main) but it's getting cooler so it should be pretty close now.

I'm thinking the next thing, after the other stuff is done, might be painting it. I'm not really digging the black/silver, and may go with all silver with the blue graphics and wheels.

Also added some new artwork at the shop. Bought a signed drawing (looks like a photo, but it's not) of Kenny Roberts OW-35K and framed it along with a couple B&W photos I took back in the '90s (both are Yamahas). The one on the left is Kenny Roberts Jr. on a TZ-250.



The GPR may be slightly intimidated...

Last edited by jkv357; 09-23-2015 at 11:33 AM. Reason: Added additional photo
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post #29 of 74 Old 09-21-2015, 06:58 PM Thread Starter
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Bought a rare, very expensive, factory Derbi paddock stand -



..ok...really just a $22 Harbor Freight stand with new steel wheels, silver vein/gloss clear powder coat, and some vinyl graphics...
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post #30 of 74 Old 09-21-2015, 10:36 PM
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When I bought my new XS750SE in 1978, the full-line sales brochure that year included the TZ750.
Dam! I wanted to buy one of those so bad and put lights on it!
(I was 21 at the time...)
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Last edited by don'tpanic; 09-21-2015 at 10:39 PM. Reason: clean up profanity.
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