Camshaft identification

[3wheelerdan]

In rebuilding the motor for my 250sx I realized the cam and journals were were in bad shape. I picked up a high school shop motor that was never ran but do not know what 250cc quad/atc it was from. Does anyone know how to identify the cams in these 250cc motors? The only ID marks I can find are dots. The sx has 5 dots and the shop motor cam has 2. I can take pictures when I get home if that will help. Thanks all.

[3wheelerdan]

10-4. I'll post up some pics later this evening.

I know this isn't a build thread here's some pics of the sx that needs her heartbeat back.246555246556

[fabiodriven]

What did you do to lift it?

[barnett468]

Are you saying that you want to know if the shop motor has an aftermarket cam, and if so, exactly which one it is?

If not, then exactly what do you want to know?


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[3wheelerdan]

It's a 350x front end and 300ex rear shock at its firmest setting so it's sitting high without the weight of the motor. I'll adjust it to my liking once I get the motor in.

I was wondering if there's a way to identify cams to make sure I'm not putting in a less aggressive cam. I don't know what atv the shop motor came from and if they put an aftermarket cam in it. I'll take some pictures once I get home of the serial number on the motor and the only identifying marks i could find on the cam.

[barnett468]

I was wondering if there's a way to identify cams to make sure I'm not putting in a less aggressive cam.

Yup, piece of cake. Just put them in a lathe and bolt a degree wheel to them then put a dial indicator on them then measure the lift and total (advertised) duration of both lobes. Then measure the duration again at .050" lobe lift, however, you can not use the duration you get at .050" of lobe lift to compare with other mfgs cam specs as some like Mega Cycles are measured differently. You could also make a graph by measuring lift at ever 10 degrees of duration and this will give you the lobe shape which will basically tell you how "steep" the ramp is and this can be used to calculate the "acceleration rate" of the lobe. It will also tell you if the the ramps on each lobe are symmetrical or asymmetrical.



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[3wheelerdan]

Unfortunately I don't have a lathe or any equipment to measure the lift and duration. I was hoping that the marks would be enough to ID the cams.

Here's the pics of the 2 cams and the serial number on the case. The cam with 5 dots is a stock 85 250sx cam. The cam with 2 dots came with the shop motor.

246583
246584
246585 TE04E-6026903

[barnett468]

Unfortunately I don't have a lathe or any equipment to measure the lift and duration. I was hoping that the marks would be enough to ID the cams.

Nope.


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