Scooterotica

Just fitting my new gt186 kit and currently trying to measure the squish with the twist of solder method. I'm having a job getting an accurate reading, is there any other method of doing this?
Thanks
Dave

Some find Plasticene or BluTac works. Roll out a ring roughly where the squish band should be, a smear of oil on cyl head so it doesn't stick. Chilling it would help it not be too squidgy.

I'm putting a twist of solder in measuring 3.5mm, moving the piston up and it's not even pinching it
I have a new base gasket and a head gasket measuring 0.55 mm, what's my next move?

Dave

with head on
then feed thru plug hole to the left or right side on the line of the gudgeon pin , theres rock front and rear so dont try that ,make sure piston is above ex port height or u could feed into that or the transfers and chop the end off ,feed the solder in till u feel it touch the side of the bore then turn the motor over and check the size it may differ from inner to outer edge use the smallest dimension.the dimensions can change if the head isnt central.

with head off
cut a length of solder a bit longer than the bore size and lay it across the crown in line with the gudgeon pin then bolt head on 2 bolts on diagonals is fine until u get close then a final check with all 4

u can also check with a vernier by measuring the piston height/head gasket/and cyl head rebate or spigot
for example a piston sat 0.5mm below the top of cylinder plus a 0.7mm compressed head gasket plus a head with no rebate or spigot = 1.2mm

heres a question for those in the know!
if the above example is 1.2mm why does a solder squish test show 1.4mm but the actual squish is 1mm and tighter ???????????

At a guess, as I thi k you you know the answer is because the solder doesn't actually compress that well? And can rock the piston?

What I did was take the head off and get my twist of solder and tape them in place on the squish band (tape them in conbustion chamber). I found this better than just sticking in some solder and hoping it'll go to the right place. I got a reading of around 1.4

I think I'm getting the solder in the right position, but the squish is about 3mm!

djh66 wrote:I think I'm getting the solder in the right position, but the squish is about 3mm!

then you probably dont need the the gaskets, build it up without them and try again. if you get what you are looking for (1-1.5mm ) then strip again and use a sealant instead of gaskets. clean the surfaces with brake cleaner first and the sealant will stick well.

tape the solder on if need be and pull it apart again

cezeta wrote:

djh66 wrote:I think I'm getting the solder in the right position, but the squish is about 3mm!

then you probably dont need the the gaskets, build it up without them and try again. if you get what you are looking for (1-1.5mm ) then strip again and use a sealant instead of gaskets. clean the surfaces with brake cleaner first and the sealant will stick well.

tape the solder on if need be and pull it apart again

Built it up again, without any gaskets. Taped a 3mm twist of solder to piston crown and still didn't compress!!!!!!!!!

servetta
no piston rock and soft core solder used


djh66 whats the recommended squish for the 186 kit and how does the piston sit at bottom dead centre in alignment with the bottom edge of the transfers/exhaust port
its not just a case of setting squish/the port set up needs to be correct too

clutching at straws here but you ve not got the piston for a tv175 crank on a 107 rod have you? what casings?