Honda Spree and Elite 50 Forums

I did a 44mm ministroke crank with a 85cc bbk so if I am understanding correctly a stock crank is 41.4 so I did 2- 1mm gaskets and a .5mm gasket at base of cylinder to block to compensate for the crank stroke difference, this should get me close to where I need to be, would that be a correct statement?

Greetings:

This is in the realm of Alchemy, where trial-and-error determine success. Only problem is you don't have a hundred cylinder castings and cranks to try out like the Factory if the first guess blows up.

44.1 (the "standard" MiniStroke crank from various places...) minus 41.4 equals 2.7 mm, so it seems logical to add about 2.5mm of base gasket to whatever Stock thickness is, right? But hold on, the Stroke is the WHOLE distance of piston travel. Going up, the crown will arrive at TDC only HALF of that 2.7mm higher than the stock crank. That means only 1.35mm closer to clanking on the head. At the bottom, it will also drop 1.35 mm below the stock design, which may actually take it below the bottoms of the lowest ports.

So even with adding an undetermined number of mms to the base gasket, your port timing will have to be adjusted (Grinding and ?maybe? Filling in?) to achieve Perfection. Check the "Squish" very carefully too. I'm rootin' for ya, and I'll be pleased if you have a good outcome.

so what I am hearing from your explanation Wheelman is that 2.5mm base gaskets should be more like 1.5 instead and with the 2.5mm base gaskets now the edge of piston at TDC is right below top of cyclinder now, so if I did 1.5mm base it is gonna be near even with top of cyclinder

Greetings:

I'd need to know the Stock base gasket thickness. You add to that.

I did 2 -1mm and a .5 mm

the 85cc kit was made for the 43.4 or something like that mini stroker crank and originally prolly came with a 1mm stock gasket

at 2.5mm base gasketing I am not even touching the soft wire to check squish band at tdc

okay Wheeleman I just looked the 85cc kit up and is made to be used with the 43.2 ministroke crank and my crank is 44.1

and the stock base gasket that came with the kit measures .85 for the 43.2 stroke

Greetings:

Lots to think about, and I haven't devoted nearly enough time to this subject. Still there's piston height at TDC, BDC, the compression ratio you get depends on the combustion chamber and piston dish, and then port timing that will vary a bit with gasket thickness. Polini and Malossi have all this sorted out using the 41.4 crank. It's not uncommon for performance to DEcrease, despite the bigger displacement, when you make these stroke mods without considering all this.