Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Testing clutch springs from this set with the stock clutch shoes: http://www.treatland.tv/polini-clutch-springs-set-for-piaggio-scooters-and-p/polini-springs-245.030.htm

Black springs (weakest): 5500 RPM stall. These springs slide right on by hand. Not much preload.

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

What are you using for calculating desired tuned length?

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Calculations from Jennings 2 stroke handbook. 177 exhaust port timing and 11,500 RPM.

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Cool, that's what I figured. There's some stuff out there about determining your own static coefficient for your own engine. I need to get a tach or a light with a tach on it

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Now that I'm thinking about it, I don't remember if I checked the port timing on this cylinder...

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

If you don't want to take your cylinder off, I can check port timing on one some time tomorrow

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Wow Beautiful bike

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Swapped the green clutch springs in and 2.8g variator roller weights. Stall is just over 7k.

Took the cylinder off and did a port map.

Used this: http://concubidated.com/ignition.php?stroke=39&length=85

My piston stops about .5mm away from the top of the cylinder so I get:

Exhaust: 22mm = 178*

Transfer open: 31mm = 120*

Blowdown: (178-120)/2 = 29*

Made a fresh base gasket to match the cylinder.

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Sounds like the connecting rod may be 80 mm, not 85. That may effect my timing numbers some, but it's not a big deal. I'm losing interest in the metrakit quickly.

Here's a teaser, more pictures will come later today.

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Current state of the bike. Yes, the rear exhaust mount broke off:

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

So I picked this kit up. 20 HP!

NOTE: this kit will not fit in the cases without case boring and relocating studs. This is not for beginners.

http://www.sip-scootershop.com/en/products/racing+cylinder+polini+big_p1660110

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Custom assembled small end roller bearing.

Checking stud locations. NOPE. Must relocate.

Need to weld/beef up the outside of the transfers and deck the cases/transfer match. No big deal, right?

Pictures of the cylinder/head/etc.

Goofy looking exhaust port, 3 flange exhaust mount (love this)

Everyone loves head.

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Please post pic's of the relocating of the the studs please. Interested in doing the same.

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Pulled apart the cases to mock up the kit before having the cases bored.

I don't think I can make it work without an 85mm connecting rod. With the stock crank/rod my piston is 7.5mm below the deck of the cylinder.

I'm debating having an 85mm rod pressed in my crank or trying to adapt a minarelli horizontal aftermarket crank with an 85mm rod.

190 exhaust port timing.

A few casting imperfections below the edges of the ports to clean up. Also need to make sure the top of the exhaust port is angled to prevent ring snagging.

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

To relocate the studs I am going to get 7mm x 1mm threaded aluminum bolts (or thread my own solid rod) and epoxy them in place, then mill them flat. After that I will drill and tap the new mounting locations.

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Jake. i might have a metrakit 'stroker' rod that might work. i'll have dig in my pile.

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Sent you a PM Marvin. :)

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Yeah, Tyler if you're on amigosdesderbisvariants forum they have a bunch there. Also look for the "culmination" thread on here

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Here's an example of moving the studs for a watercooled kit on a derbi.

https://www.mopedarmy.com/forums/read.php?1,3051023,page=1

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

This is going to be soooooooooooo good!

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Minarelli cranks fit in there without too much work...

IMG_20141220_114711.jpg
2014-12-21.jpg

Granted this one is 45 stroke, and has a YZ 80 rod pressed in.

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

Tyler,

What does your variator spacing end up like? What's your ignition solution?

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

You can put the variator where ever you like because it is a splined crank (same spline as a the stock start3/5 cranks). So no issue there.

Same taper as Puch, just larger diameter. I cut an HPI for one, pretty straight forward. The revo seletra ignition fit right on as well.

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

RTFO!

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

@Tyler: you have to machine the throws/bearing saddle right?

This would definitely make it easier on my start 3 builds

Re: My new Freespirit Build (Part 3?) w/ Derbi Motor

🇮🇹💦 Of the Loin /

i came to say ugh derbi motor on another non-derbi frame

just a travesty

but I do appreciate the work going into the motor

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