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Wed May 18, 2016 1:28 pm

Hello everybody, I am planning to build a 1600(i have the pistons and cylinders) and i found a really nice set of cb cylinder heads, the trouble is that their diameter where the cylinder goes is 98mm and i measure the 1600 ones and they seem to be 94, is there any way i can use the cb ones on the 1600 and if not what cc's are they fore?

Wed May 18, 2016 2:16 pm

They're cut for 90.5mm cylinders. 1776cc

Wed May 18, 2016 6:59 pm

so....put some 90.5 in or 88 machine in's or 92's or...... well it kinda depends if the chambers were opened up or not if you could make spacers to use the 85's, but...why use such tiny pistons.....

Wed May 18, 2016 9:16 pm

Look at the valve sizes as well- anything bigger than stock (35x32mm) is probably too big for a 1600 unless it's a high winder and making power above 6500rpm or so. Take Mark's advice and make it bigger, as displacement equals torque, which makes everyday driving so much easier! Al

Thu May 19, 2016 12:18 am

Will the 88 ones be ok with the big valves or will they be making no power at low rpm? Also will the fuel consumption be very different from a 1600?

Thu May 19, 2016 6:46 am

Fuel consumption should be the same or even a little better as the engine doesn't have to work as hard to get you up to speed.
It kinda depends on how big the valves are if it will work with 88's. Building a 1849 (76x88) myself and using stock heads and valves.

Thu May 19, 2016 9:11 am

Vw1600dellortoGR wrote: Hello everybody, I am planning to build a 1600(i have the pistons and cylinders) and i found a really nice set of cb cylinder heads, the trouble is that their diameter where the cylinder goes is 98mm and i measure the 1600 ones and they seem to be 94, is there any way i can use the cb ones on the 1600 and if not what cc's are they fore?

You should check the valve size, just so you know what you are installing. As for the outer bore, it has nothing to do with how the head seals, performs or lasts. You can use those heads for 85.5 without any sealing problems.

Thu May 19, 2016 9:18 am

They look like 40mm intake and 35.5 exhaust what cc's would you recommend them for?

Thu May 19, 2016 9:39 am

Vw1600dellortoGR wrote: They look like 40mm intake and 35.5 exhaust what cc's would you recommend them for?

depends on cam and carb choice....

Thu May 19, 2016 9:41 am

Two 36 drla carbs and a small cam such as a c25

Thu May 19, 2016 9:46 am

I would run 88's or if you want to bore the case out, run 90.5's

Thu May 19, 2016 9:48 am

Will they kill the bottom end torque? I really like bottom end torque

Thu May 19, 2016 11:39 am

[email protected] wrote: Vw1600dellortoGR wrote: Hello everybody, I am planning to build a 1600(i have the pistons and cylinders) and i found a really nice set of cb cylinder heads, the trouble is that their diameter where the cylinder goes is 98mm and i measure the 1600 ones and they seem to be 94, is there any way i can use the cb ones on the 1600 and if not what cc's are they fore?

You should check the valve size, just so you know what you are installing. As for the outer bore, it has nothing to do with how the head seals, performs or lasts. You can use those heads for 85.5 without any sealing problems. hmm so I can take my heads that have been opened up to the bore 94mm bore size unshrouding the valves the 85's will seal just fine....wow Ida never thunk that.
I dont see valve size a consideration like" oh no a big valve wont work with a 1600" bs

Thu May 19, 2016 2:17 pm

mark tucker wrote: [email protected] wrote: Vw1600dellortoGR wrote: Hello everybody, I am planning to build a 1600(i have the pistons and cylinders) and i found a really nice set of cb cylinder heads, the trouble is that their diameter where the cylinder goes is 98mm and i measure the 1600 ones and they seem to be 94, is there any way i can use the cb ones on the 1600 and if not what cc's are they fore?

You should check the valve size, just so you know what you are installing. As for the outer bore, it has nothing to do with how the head seals, performs or lasts. You can use those heads for 85.5 without any sealing problems. hmm so I can take my heads that have been opened up to the bore 94mm bore size unshrouding the valves the 85's will seal just fine....wow Ida never thunk that.
I dont see valve size a consideration like" oh no a big valve wont work with a 1600" bs

Well....if you grind the sealing surface away....obviously it won't seal. Jesus, everyone has to be the "smart guy"

Fri May 20, 2016 8:33 pm

Vw1600dellortoGR wrote: Will they kill the bottom end torque? I really like bottom end torque

If it's a set like thier 044s yeah. Port velocity is what gives low end torque. As you increase port size (and valves) velocity goes down but flow goes up. The flow helps with higher end power. You can google it and learn a lot. There's some people who will disagree, research it and decide yourself.