Scooterotica

Wayne Miller wrote:

Twinny wrote:re bolted on with no gasket i f i take 1mm off bottom the transferes line up with piston ,measurments i have at mo are from top of barell
exhaust38.62 and 18.27 deep
inlet 72.52 and 16.55 deep

Sorry Mate I dont under stand?

Are you saying that if you take out a 1mm gasket then your trans line up with your piston crown @ bdc?
or are you saying that without a gasket your trans are still 1mm above the piston crown @ bdc?

either way @ tdc where does your piston crown now sit? +1mm 0mm -1mm

Also I guess the other measurements are in mm from the top of the cylinder, they dont mean a thing without the stroke and conrod length and deck height. If you can get those details then we can visualise how things are looking

58 stroke 108 rod and without gasket transfer is still 1mm above piston at bdc and at tdc piston is about .5 to 1mm under top of cylinder ,what is deck hieght
cheers

Deck height is distance between cylinder head gasket face and base gasket face on the cylinder (or so I believe).
Piston .5 to1mm below top of cylinder at tdc doesn't sound too bad, but you would have to check squish to be sure.

ok so series three barells are 101mm from face to face i have had 7.5mm taken off that meens my deck hieght is 93.5
once barell is sorted i can then go to head/squish
thanks

done a quick calc before you added the extra info, although ur crank will be 58 107
with barrell set with piston 1mm below top
ex 37.62 161
inlet 88
piston 71 118

with piston edge flush at tdc 157 ex 122 inlet

all are well within useable range as per an old standard engine design ,but transfers need measuring






the deck or piston height is where the edge of piston crown sits at tdc eg level / minus 1mm / plus 1mm
the inlet dimension is to the bottom of inlet so adding the height to top plus the port depth you supplied is the dimension thats needed
the extra info needed is piston length on inlet side i used 71mm but not sure what urs is ?
the height of the transfer ports is needed for any useful recommendation and the intended pipe to be used, are u gonna port it ?

thanks darrell , yeh sorry 107 rod ,piston length is 62mm as per webster manual both sides the same ,hopefully useing jl4 ,hieght of transfers are 45.5 from top and a depth of 12mm and yes was going to port it ,perhaps you can recomend what size ports to be
cheers john

with barrell set with piston 1mm below top

exhaust 37.62 161

transfers 44.5 130

inlet 88
piston 62 = 153




with piston edge flush at tdc this set up is better on transfer timing

ex 38.62 157 / raise to 34mm (176 degrees) widen if u wish based on rings used

tr 45.5 125 / leave top as is but lower bottom so flush with crown at bdc widen and square off if you have tooling

inlet 89
piston 62 =inlet 157 / leave as is ,widen if you have tooling

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so if i take more off bottom to make piston edge level with top of barrel that meens the bottom of transferes will be level with edge of piston at bdc ,so do i lower transfers more ?

if you get the bottom of transfers level with piston at bdc that be fine