Port measuring


depth gauge as well, you can use the opposite end of your sliding calipers. Not sure if this is what your looking for. Ports are measured a couple ways, size, from the top, for comparing to other cylinders but the other way is in port timing. This is measured by degrees of crank rotation to edge of piston. This is done with a degree wheel on the crank end, and set to tdc, then as the crank is turned, notation is taken where the piston is in relation to the port. The ports location in a way, is the camshaft of the motor, opening and closing flow at different times, for different amounts of time. Changing these a degree or two, can mean a lot in the amount of power, efficiency, and the rpm where these occur. That is leaving out the other side of this which is pipe timing.
 
The best way if your not real familiar with other methods is to make a port map and then you can accurately measure the ports height and widths from a flat peice of paper. You take a white peice of paper and stick it inside the cylinder align the topedge to that top edge of the cylinder as this is where all your port measurements are based from. If the paper is too long trim it so it doesnt overlap more then a inch and place a small peice of tape on the bottom edge to hold it together inside the cylinder, then take a lead pencil and scratch flatly around all your port openings and it will transfer the openings to the peice of paper, when you do this to all the ports and remove the paper it will be mapped out for you and you can accurately measure the ports.
The same port map you see in the yamaha tech books and such is exactly what you will reproduce. Nothing wrong with a degree wheel but it doesnt give you the port measurements only the durations the ports are open and close.
 
Is there anyway to clean up the ports without pulling the engine apart? Maybe with a dremel tool and a shop vac for the particles? Looking to smooth out the intake and exhaust. Or is it a waste of time with out port work?
 
RB2001SRX700 said:
Is there anyway to clean up the ports without pulling the engine apart? Maybe with a dremel tool and a shop vac for the particles? Looking to smooth out the intake and exhaust. Or is it a waste of time with out port work?
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The answer is no. The intake ports are located on the bottom of the cylinders and you cannot see them no less port them. There is no reason to not remove the cylinders. It really is just another five minutes work to dissemble. Any time an engine is honed or ported it is extremely important to wash the cylinders perfectly clean. If any loose material is inside the engine..... well you should know what happens next.


nelsonhouse said:
what is the purpose of making a port map?
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In this case and on another thread the sled owner reported having two ported cylinders and one stock cylinder on the same motor. His plan was to port the stock cylinder. So making a port map allows him to copy the porting and transfer to the stock cylinder.
---mac---
 
Did I read somewhere that having a "textured" as opposed to smooth intake port helps with fuel atomization. Or am I confused with something else.
 
Yes Corey you read correct. The reason some guys like to polish the exhaust ports is for reducing carbon buildup. Polishing the other ports will give no performance gains and some theorize that polishing the intake and transfers actually reduces power.
 
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