more derbi content... a couple questions

pertaining to the differances between pyramid, flat reed, and piston ported engines..

i have a couple pyramid style engines that im about to rebuild..

i was wondering if i would be able to swap all the contents of a pyramid style engine into a flat reed case? i know the stroke length is different, but isnt that determined by the front end of the engine.. crank, mounting block.. etc..? wouldnt all the internal gears be the same?

also, not to sound like an asshole but my laguna sport (which is casually for $ale) has a piston port engine.... whats the stroke length of the piston port?

and lastly, any speculation about

why the pyramid kits look so inferior and less aggressive than the flat reed?

pyramid:

flat reed:

alos..anyone have a trashed flat reed engine? or cases that i can experiment around with? c.judemc@gmail.com

Re: more derbi content... a couple questions

duhhh

Piston port engines

cylinder inducted

stroke: 43mm

bore: 38mm

displacement: 48.7cc

compression 8.5:1

direction of rotation: counter clockwise facing magneto

Pyramid reed engines

Pyramid 3-reed valve, Crankcase mounted

stroke: 43mm

bore: 38mm

displacement: 48.6cc

compression 8.5:1

direction of rotation: counter clockwise facing magneto.

Flat reed engines

Crankcase 2-reed valve induction with triple transfer port distribution

stroke: 40mm

bore: 39.87mm

displacement: 49cc

compression: 10:1

direction of rotation: clockwise facing magneto.

Max engine RPM: 6500

Re: more derbi content... a couple questions

now over your opinions whats the best of the three?

flat reed tops out at 65k? cuz of the reeds?

~SABAT!

Re: more derbi content... a couple questions

the compression and bore size is a bit more advanced too.. dont know what the others top out at...

you would think the pyramid cage would be better than the flat reed..

my next question..couldnt you change the stroke length to 40mm in the pyramid and piston port engines, by simply using a flat reed-style crank?

Re: more derbi content... a couple questions

) Cupermcnewbster ( /

I'm pretty sure the problem lies in the internals, namely the bearings, but I bet it could be done.

How much for the laguna?

Re: more derbi content... a couple questions

🇮🇹💦 Of the Loin /

ill give you a flat reed ds50 for a laguna

hehe

Re: more derbi content... a couple questions

me also,

what about the stroke on the start, is it something like 37mm?

fred

Re: more derbi content... a couple questions

pyramid/piston port have way different internals than a flat reed. the output sprocket and pedal mode engagement system is radicaly different for starters.

I wouldnt worry about the 6500rpm figure, that goes up drasticly when you stop using the stock cylinder.

swapping cranks could change the stroke concievably, I've never compared the two styles side by side.

hey jude, im using that gilardoni i got off you on my laguna btw.

Re: more derbi content... a couple questions

heyyy good to know

good luck with that! when i had that gilardoni, it was like glass, all i thought about was breaking it

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