Would you run this Cross cylinder as is?

[srcarr52]

Thank you sir. Is this a center to center measurement or OAL?

Center to center. It's a really close estimate since I didn't have the rod separate from the crank.

 

[brshephard]

Special thanks to Shaun for that measurement. Here is a chart specific to this saw that shows the bore distance across various timing changes.
It works as follows:
1. Find your current port timing number.
2. Follow the row across until you find the timing number you want.
3. The corresponding value is the distance between the two in ten thousands of an inch.
4. A positive value means you would need to grind material. Negative would require decking or epoxy.

Example: Suppose I dropped the exhaust to 105 and I want to go to 90 to do sick piss revs. Go to the 105 row, then look at the 90 column. I would have to grind up .1961" (highlighted yellow).

You can also use the tables to predict where timing will end up when decking. Suppose my transfers are at 115 and I knock .050 off the base. Go to 115 and scan across the row for .050. 120 is at .0528 so I'll end up around 119.5.

Let me know if it works for you guys

Exhaust


Transfers


Intake

 

[srcarr52]

Special thanks to Shaun for that measurement. Here is a chart specific to this saw that shows the bore distance across various timing changes.
It works as follows:
1. Find your current port timing number.
2. Follow the row across until you find the timing number you want.
3. The corresponding value is the distance between the two in ten thousands of an inch.
4. A positive value means you would need to grind material. Negative would require decking or epoxy.

Example: Suppose I dropped the exhaust to 105 and I want to go to 90 to do sick piss revs. Go to the 105 row, then look at the 90 column. I would have to grind up .1961" (highlighted yellow).

You can also use the tables to predict where timing will end up when decking. Suppose my transfers are at 115 and I knock .050 off the base. Go to 115 and scan across the row for .050. 120 is at .0528 so I'll end up around 119.5.

Let me know if it works for you guys

Exhaust
View attachment 122894

Transfers
View attachment 122892

Intake
View attachment 122893

I’ll double check your charts with my program tomorrow but I think you forgot to add in for a normal squish clearance, say 0.020”.

 

[srcarr52]

I had to get my computer out for something else so I checked your numbers... everything is correct except for the numbers across the top of the intake chart. If someone wants to measure to the squish band they just need to add their squish clearance to the number across the top of the chart.

For example: To get 99 ex opening take the number above 99 and add the squish clearance (0.020"). 1.020" + 0.020" = 1.040" from squish band.

 

[brshephard]

Well thanks again!

Your tip will be slick for raising transfers.
A guy could cut some card stock dead nuts and grind right to it.
I've ground past my sharpie line doing the piston ring trick.

Also, I need to add the piston height to the intake distance then I'll repost it.

 

[Wonkydonkey]

Well that all looks very good, but my pea brain. Just see lots and lots of numbers,
I think I need to try a working example first.



And you say it’s only for a 660.

 

[srcarr52]

Well thanks again!

Your tip will be slick for raising transfers.
A guy could cut some card stock dead nuts and grind right to it.
I've ground past my sharpie line doing the piston ring trick.

Also, I need to add the piston height to the intake distance then I'll repost it.

I use a dial caliper and measure to the squish band. I can check many times and sneak up on the height I want, and keep the port stagger and side to side very tight.

 

[brshephard]

Got a chance to run this saw today.
I was super impressed. These Cross cylinders are sweet.