Sport moped exhaust on 66cc (Build thread)

[Vikingimike01]

Hey chris. It's really really similar, just better casting and a bit cleaned up. But I have a Zae80 rod

 

[GreasyChris]

Zae80 38mm crank, long rod, high hole piston.

Zae80 crank and piston assembly with 32mm intake cylinder no gaskets.

Top of cylinder

 

[Vikingimike01]

mine is like that a bit lower I sent pictures a while back.

Would it be OK to take off that 1.5mm from the cylinder then?

 

[gary55]

no one is going to be able to say removing 1.5mm is OK without knowing how the geometry of your head is going to affect your squish gap. Until you find that out it's a guessing game. I have explained how you might get your numbers in replys 437, 439, and 440. Do you really want to trust someone's guess from the other side of the Ocean?

 

[GreasyChris]

I dont want to sound rude but you need to take accurate measurements. All you are doing is guessing. Maybe its 1.5mm maybe its 1.8mm. You'll never know unless you take accurate measurements. And then you'll know exactly what to take off. You spent alot of time and money gathering up all the parts you need, now is not the time to just halfass guess what needs to be done. .5mm could be the difference in your bike running and your bike running well.

 

[GreasyChris]

There has to be a mechanic garage near by that's open. Bring your engine and ask if you can use their vernier caliper to take your measurements there. Then you will know exactly what you have and what your dealing with. Measure the thickness of your gaskets as well. Buy the mechanic a coffee or a beer for the use of him lending you his tools. Or wait until you can get a digital vernier. If we all went by eyeballing we would all say we have 10 inch dinks and our girlfriends and wives would say it's more like 3 inches.

 

[FNTPuck]

mine is like that a bit lower I sent pictures a while back.

Would it be OK to take off that 1.5mm from the cylinder then?

Wont know till you measure. Can't eyeball when you're dealing with sub mm measurements.

Remember that after measuring depth you still need to make sure the head squish band and chamber ring will clear the dome of the piston as well. A lot of heads have bands that stick into the chamber so you cant 0 deck it without reshaping the head with an old piston to set proper squish distance. Can't just start cutting up stuff and hoping it works.

 

[gary55]

I'll just add that the .5mm error could be the difference in it running, running well, or the piston bouncing off the head and not running at all.

 

[Vikingimike01]

I cant buy them beers because I'm not 18 yet.
I destroyed my vernier calipers trying to get the thing to fit in my cylinder. anyways.. accurate measurements:
exhaust 27mm transfers 31mm from top of cylinder (head gasket included)

 

[gary55]

There has to be a mechanic garage near by that's open. Bring your engine and ask if you can use their vernier caliper to take your measurements there. Then you will know exactly what you have and what your dealing with. Measure the thickness of your gaskets as well. Buy the mechanic a coffee or a beer for the use of him lending you his tools. Or wait until you can get a digital vernier. If we all went by eyeballing we would all say we have 10 inch dinks and our girlfriends and wives would say it's more like 3 inches.

Women lie.