Build advice please?

[rosscla]

Am finally getting my act together and getting my motor built.

It's a 225 rapido classic, avanti piston with 58/107 crank AF 9.5 - 1 head.

I've tried a couple of ways to take the measurements to work out what the timings are, but. I'm not that sure I'm getting it right....

I put the degree disk on and set 0 as tdc and took the following measurements

Exhaust opens 90 ATDC
Exhaust closes 269 ATDC

Giving a duration of 179

Transfers open 113 ATDC
Transfers close 244 ATDC

Giving a duration of 131

Inlet opens 69 BTDC
Inlet closes 77 ATDC

Giving a duration of 146

I make the exhaust 34.93mm from the top of the cylinder and the transfers 44.3. I have a deck height of 1mm with a 0.55mm base gasket.

I hacked those figures into the port timing calculator and got -

Exhaust 176.33
Transfers 135.99
Inlet 139.27

Q1. Do these figures seem about right ? Which are closer?

Q2. When it comes to setting the squish if I use a 0.7 mm Head gasket then I'll have 1.7 squish which is probably too big. If I take the base gasket out then I'll get back to about 1.25. Will this make much of a difference or how do I deal with this?

[coaster]

Somethings not right there, either youre measurements are awry or the cylinder has been played with, the Race Rapido only has 130 transfers

As for squish, I'd leave the base gasket out and use a smear of silicon instead, i.25 is nearly perfect.

[rosscla]

I went and checked here's what I got, this time with no base gasket.



Transfers at bdc




Exhaust just opening-172.1



Transfers just opening- this gives a more sensible 126.7

To base of inlet floor is 94.06 for 141.8

[guygrrr]

yr going to want to bolt the cylinder down with a base gasket or whatever you plan on using under the cylinder and torque it down to the recommend amount (i use sockets to take up the slack under the cylinder nuts). this way you can expect the port measurements to accurately reflect what they'll be when the engine is assembled.