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Full circle crank question...............

Posted: Wed Feb 01, 2012 10:44 pm
by fastfreddiescat
Hi guys

I am thinking of a cylinder conversion that would need a crankcase induction, I an only at the thinking stage at the moment but my first thought is will a full circle lambretta crankshaft work well with a crankcase reed induction?

thanks

fastfreddiescat :bouncyeng:

Re: Full circle crank question...............

Posted: Thu Feb 02, 2012 1:42 am
by Darrell Taylor
it would be better and easier to install a reed inlet onto the chosen cylinder than mount to and modify the cases although mounted to cases youd want the reed mounted above the crank webs directing flow into the transfers and under the piston which would leave the crankshaft choice not as important

Re: Full circle crank question...............

Posted: Thu Feb 02, 2012 1:52 am
by RICSPEED
i guess with out seeing the barrel in question its not easy to suggest but either way way your sugestion or darrals involves ally welding

Re: Full circle crank question...............

Posted: Thu Feb 02, 2012 8:14 am
by fastfreddiescat
The cylinder I am thinking about comes off an engine which is reedcrank inducted & the prospect of s**t loads of ali welding really is not an issue for me, I was just thinking of the viabillity of the standard style crank.

Re: Full circle crank question...............

Posted: Thu Feb 02, 2012 2:05 pm
by RICSPEED
there was a thread ..ages ago now with a pic ..cant recall who owned it ( anyone )

either that or look at the crank induction on the dac cutdown .... but i think what Darrell was saying as long as the reed feeds between the webs and does not have the crank pin in the way during the induction cycle the crank doesn't effect things

Re: Full circle crank question...............

Posted: Thu Feb 02, 2012 10:02 pm
by Darrell Taylor
if allly welding isnt a probllem and machining etc then just copy the crankcase of the donor engine matching the flow pattern and reed installation conrod length/stroke and case volume as best can be adapted to the lambretta casing if the donor has full circle then match it, modern motors have highly developed design processes/formula that are difficult to improve upon so no one could really advise better than the original designers specification

Re: Full circle crank question...............

Posted: Thu Feb 02, 2012 10:26 pm
by fastfreddiescat
Good call. Thanks.