quiestoion about a stroked engine

dirtbikr99

Member
Nov 21, 2002
180
0
I have a 1999 cr250. (old but I love it) Currently Its stock bore 66.4 I've had a ported, and cut the head to raise the compression a little. I love the motor right now. However, I've come across and amazing deal on a stroked crank 74mm.

1. Is it possible to just put the stroked crank in (check to make sure it clears the cases of course) and put a 2mm spacer plate under the cylinder? Will this have any effect on the porting, timing or compression?

2. What would be the final displacement with a stock bore and a 74 mm crank?

Thank you in advance to whoever can answer these questions for me!
 

hot125mod

Member
Jan 14, 2007
501
0
stock is 72 and you now have a crank that is a 74mm stroke so it is .080 over or 2 mills on a 250 for every 080 that you go over it is about 15cc making it a 265 which is a popular number for 250s
 

Pete Payne

MX-Tech Suspension Agent
Nov 3, 2000
933
38
The displacement would only be 256.246cc's . Remember that on stroking the crank only half is gained. This would be somewhat equivalent to a 1mm overbore (256.887cc's)
 

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