honda AF05e BBK opinions on best kit

[harleyracer59]

prices on cranks are from $90 USD to $180 plus shipping. not that bad, I think.

[harleyracer59]

today I got a package from Italy... a cast iron polini bbk for a kymco djx. identical engine to Hondas AF05e aero,vision, Peugeot. i didn't know kymco had a copy. i wonder if sym has one too.
im really shocked at the port durations though. with no basegasket the piston is flush at tdc. at bdc, the exhaust port floor is flush to piston. transfer floors are at least 1.5mm below piston top.
(1) exhaust opens 22.68mm from tdc for a duration of 169.05*
(2) transfers open 30.35mm from tdc for a duration of 114.73*
(3) boosts open 31.26mm from tdc for a duration of 106.89*
these numbers seem crazy low to me. and exhaust port floor will need to be dropped and cylinder top milled to get the transfers flush at bdc. even if i space the cylinder 2mm. exhaust port durations are low compared to boost and transfer #'s. @ E=181.45* T=130.52* and b= 123.54*. and id have to mill 2mm from cylinder top...
ill post pics tonight. any one have any ideas on the path i should take with this?
lucas2t, you said you had this cylinder in the past. did you rock it as is out the box? or did you modify?
lmk what any of yall think. thanks

[190mech]

Raise the cylinder with a spacer,and leave the ex floor alone..Frits Overmars made this comment just yesterday over at the KiwiBiker ESE thread;
"Having the lower part of the exhaust window narrower or non-existent makes it less inviting for the mixture flow coming from the A-ports to turn right into the exhaust. Having the exhaust duct floor higher reduces turbulence in the outgoing exhaust flow during the blowdown phase and it reduces the exhaust duct cross-section,
so the volume of washed-through fresh charge is contained in a longer column, with less contact area with the hot spent gases.
And some time after BDC, that exhaust port puts on a different hat: it becomes a transfer port. The raised exhaust floor guides the fresh charge over the piston top edge, so there is less turbulence here as well. And finally the smaller exhaust window leaves more surface for the piston to lean against, improving load distribution."

www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page2096

Then either deck the cylinder,or even better step cut the head for proper squish;

[Lucass2T]

Feb 6, 2019 22:21:29 GMT -5 harleyracer59 said:

lucas2t, you said you had this cylinder in the past. did you rock it as is out the box? or did you modify?
lmk what any of yall think. thanks

Yup! Straight out of the box. Did some little modifications, you can check my build topic. Ran it with the stock exhaust (not the thin restricted Spree version), 12mm Gurtner (peugeot speedfight) carb and milled head. It ran super nice! Nice torque down low and with a tail wind it would keep going and going, very broad power band. I had some super tall gears in there but still it had very decent acceleration from a stand still. Im a 165lbs guy tho, nothing like the average american.

I also tried the Proma badsnake pipe which SUCKED! But reading now the port durations are suuuper low thats no suprise. I never checked durations but my first tought was that cilinder def needs porting if you want to achieve ANY power beyond stock rpms. Guess i was right...

[harleyracer59]

hey lucass2t, were not all fat... lol. 1m 175-180Lbs and 5'11". yeah those durationbs are way low. i put a thicker gasket on it and it wasn't as bad as i originally thought. must have been bad lighting.... lol
im gonna run it as is and see where i want to go from there. i chamfered the ports, gasket matched cylinder and cases, and cut the cylinder skirt out of the way of the intake track.
put a ct manifold on it with a wb 32 walbro. has a 23ish mm venture. we shall see. ill report back. thanks guys!