Took a plunge... trying a PP LXR250 EFI

ChondaChondaChonda · 12-29-2017, 09:21 AM

So, I noticed a small oil leak coming from the front of my rocker box and decided to reseal it last night. While I was there it occurred to me that I haven't seen any information about the camshafts in these NC250 motors.

My tools aren't calibrated pro quality, so take all this with a grain of salt. I did the best I could with the tools I have. I printed a degree wheel which worked, but is probably not as large as it should be for accuracy.

What I found is that the NC250 rocker arms have about a 1.12:1 ratio.

The cam lobe lift on the intake is 0.267 in (6.85mm). Actual measured lift of valve was 0.303in (7.69mm)

The cam lobe lift on the exhaust is 0.277 in (7.05mm). Actual measured lift 0.311 in (7.89mm)

At 0.050 in the duration of the intake is about 217 degrees.
At 0.050 in the duration of the exhaust is about 222 degrees.

My confidence in these is lower than the lift numbers as the small degree wheel made is difficult to be 100% certain. They are ballpark.

Lobe separation angle using these numbers is about 110 degrees.

The overlap @ 0.050in is from about 4 BTDC to about 2 ATDC. Doesn't seem like much, but I dunno.

I'm not well versed in the intricacies of cams, but maybe some who are can glean something from the above.

12-29-2017, 09:21 AM	#11
ChondaChondaChonda Join Date: Oct 2016 Posts: 547	Some information about the camshaft So, I noticed a small oil leak coming from the front of my rocker box and decided to reseal it last night. While I was there it occurred to me that I haven't seen any information about the camshafts in these NC250 motors. My tools aren't calibrated pro quality, so take all this with a grain of salt. I did the best I could with the tools I have. I printed a degree wheel which worked, but is probably not as large as it should be for accuracy. What I found is that the NC250 rocker arms have about a 1.12:1 ratio. The cam lobe lift on the intake is 0.267 in (6.85mm). Actual measured lift of valve was 0.303in (7.69mm) The cam lobe lift on the exhaust is 0.277 in (7.05mm). Actual measured lift 0.311 in (7.89mm) At 0.050 in the duration of the intake is about 217 degrees. At 0.050 in the duration of the exhaust is about 222 degrees. My confidence in these is lower than the lift numbers as the small degree wheel made is difficult to be 100% certain. They are ballpark. Lobe separation angle using these numbers is about 110 degrees. The overlap @ 0.050in is from about 4 BTDC to about 2 ATDC. Doesn't seem like much, but I dunno. I'm not well versed in the intricacies of cams, but maybe some who are can glean something from the above.
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