Some useful measurements for 612 builders?

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Some useful measurements for 612 builders?#8244

By stinkwheel - Sun Apr 01, 2018 10:34 am

- Sun Apr 01, 2018 10:34 am #8244

There seem to be a few of these builds going on at the moment. I've had my burette out and thought people might like to know a couple of the more esoteric measurements on the hitchcocks kit.

Cylinder head volume measured to flush with gasket face = 145.6ml

Calculated cylinder head combustion chamber volume to level with spigot recess = 130.29ml. My spigot recess depth being 5.30mm as measured on my head.

Piston dome volume = 85.18ml

Some useful measurements for 612 builders?#75454

By Blown265 - Tue Apr 03, 2018 11:19 am

- Tue Apr 03, 2018 11:19 am #75454

It may just be the photo, but the barrel appears to have skirt marks from a possible over heat. The cross hatch looks worn, but again, it could just be the picture.
Which method did you use for calculating the dome volume?
Regards
Paul

Some useful measurements for 612 builders?#75455

By Alan R - Tue Apr 03, 2018 11:43 am

- Tue Apr 03, 2018 11:43 am #75455

Hi Guys--as I understand it with fluids 1ml = 1cc.

Some useful measurements for 612 builders?#75456

By Alan R - Tue Apr 03, 2018 11:46 am

- Tue Apr 03, 2018 11:46 am #75456

what's intriguing me is just where the salt and pepper comes into all this ??--LoL !!

Some useful measurements for 612 builders?#75457

By stinkwheel - Tue Apr 03, 2018 11:55 am

- Tue Apr 03, 2018 11:55 am #75457

Hope it's just the photo, it's brand new and never been on a bike before. Or it had better not have been for what it cost!

Dome volume. Bore is 103mm, piston crown height 14.34mm. So volume of a cylinder with those dimensions would be 119.48mm. As you see on the picture above, I set the piston crown level with the top of the liner and filled with ATF from a burette giving the volume above the piston to level with the top of the crown as 34.3ml. Subtracting one from the other gives the volume of the domed section of piston crown. Right?

Some useful measurements for 612 builders?#75462

By stinkwheel - Tue Apr 03, 2018 1:54 pm

- Tue Apr 03, 2018 1:54 pm #75462

As the more mathematically astute may have noticed, I have cocked up my maths. The volume of a cylinder 103mm diameter x 14.34mm height is 113.28ml (or cc if you prefer). So the dome volume is 78.98ml.

I suspect I may have repeated the same silly error on the spigot volume for the head volume but I need to look up my measurements. Watch this space.

Some useful measurements for 612 builders?#75464

By stinkwheel - Tue Apr 03, 2018 2:25 pm

- Tue Apr 03, 2018 2:25 pm #75464

Yes. I did the same there. The volume of the spigot section is actually 35.23ml so the corrected head volume is 110.37ml.

Some useful measurements for 612 builders?#75465

By stinkwheel - Tue Apr 03, 2018 2:42 pm

- Tue Apr 03, 2018 2:42 pm #75465

Damnit. I've used the wrong figure for the bore diameter too. It's an 87mm bore, 103 is the stroke!

Sorry folks. This is why I'm not a mathematician. Dome volume is 50.93ml.

Some useful measurements for 612 builders?#75468

By Bullet Whisperer - Tue Apr 03, 2018 6:12 pm

- Tue Apr 03, 2018 6:12 pm #75468

Hi stinkwheel, this might be of some interest to you, under the circumstances. Regards, Paul. https://youtu.be/4p-5hgbwLYE

Some useful measurements for 612 builders?#75470

By vince - Tue Apr 03, 2018 8:23 pm

- Tue Apr 03, 2018 8:23 pm #75470

Hi, and the resulting compression ratio will be? Answers to. Horace Bachelor,Dept one, Keynsham, Bristol.