engine #s

[GNEPIG]

.. does anyone know how to tell what year and model an engine is by the numbers stamped in the case?. i have a pile of motors sitting around and just about everyone of them has a different number. except 3, three of them start with the #s 3H3
.. i have seen a list of numbers/dates and models on a XS650 site, cant seem to find such a list here
thanx for the help in advance
Gene

[Artic_rider]

This should help you out
Serial Numbers

[GNEPIG]

.. thanx Robert, that was a lightning fast response
now if someone can tell me how to tell the difference between the early cams and the later ones just by looking at them i can put my Red bike back together. other than the numbers stamped on the cams i cant see any other difference. . i have a set of cams that i removed from a motor that has the #s 10M stamped on it and they look just like the ones i pulled out of a motor that has the 3H3 mark. i want to make sure that i dont put the late model cams in my early motor.

[John]

The 10m cams are from an XJ 11. The part numbers for the 78-79 cams will start with 2H7. The 80-81 should start with 3H3, I believe.

[mro]

1980 cam part #'s

3H5-12171-01-00 intake
3H5-12181-01-00 exhaust



mro

[TopCatGr58]

Hey GNEPIG,

I tried to access the Yamaha fiche site, but the SERVICE data sheets weren't popping up, and I've found info about the Cam Lobe Heights before, and I believe the older cams had the taller lobes, vs. the newer later model cams, so with a caliper, you could measure the total size of the lobes, and the ones that are taller are probably from the older earlier engine, the lower shorter lobes would be from the later model, ie. 81xs and XJ!
T.C.

[roosterd]

My '79xs1100sf starts with 3h3- 00059etc

[GNEPIG]

.. ok, after checking the cam lobes with a dial caliper, other than the cams from the newer motor being less worn than the older ones[more in spec] i still cant see a difference. i will pull a set of cams from another motor and have a look again tomorrow.
.. there are no part numbers stamped in the cams like 3H3 or 10M, those numbers were stamped in the motors i removed them from, but there is a number and a letter opposite of the casted in letters IN and EX. after looking one more time none of the numbers/letters are the same so i am guessing that they are just casting numbers.. sorry for any confusion, and thanx for everyones responces

[pggg]

Hey GNE the difference is easy to tell just by eye if you have the two types side by side. The 80's lobes are more rounded than the 78's.

[GNEPIG]

.. after studying the part numbers on Lamrics website, i have noticed something strange. the part numbers for the 78 and 79 standard cams are the same, and the part numbers for everything newer [1980 and up] are the same, but the part numbers for the 79 special cams are different again.. what is the difference between the 79 special cams and the 78/79 standard cams?
.. i'm thinking someone has put the early cams in the later motor that i have removed them from
..i have a carb tool that i might be able to use to check the distance across with. thanx Pggg

[GNEPIG]

i can see them, i see the bunnies George

.. i have found a set of late model cams, they look way different. the lobes are real pointy and they have the 3H3 mark cast in them.
..now i wonder if using the late model cams would help me cover the 1/4 mile faster, since they bring the power on lower in the RPMs and these bikes are geared so high that you dont even use 5th gear
hmm, late model cams with early heads= lots of low end and midrange torque/power?

[GNEPIG]

.. now you can see the bunnies too
in the first pic the cam on the left is from a motor of 1980 up
the cam on the right is from an early motor 78/79.
in the second pic is what's stamped on the early cam
the third pic is of the late cam
on all 4 of the early cams that i have sitting on the bench, all of the numbers/letters are different
all three pictures are of intake cams
.. on the late model cams, the lobes on the exhaust cams are the same hight as the lobes on the intake cams,
.. does anyone have any comments/thoughts about using late model cams in an early motor

[GNEPIG]

.. i have found a set of late model cams, they look way different. the lobes are real pointy and they have the 3H3 mark cast in them.

.. my bad, i ment to write 3H5

[mro]

bunny power???

If both same height?........ then same "lift"

1st pic, cam on right holds valve open longer, thus more fuel,
.........longer "duration", and should allow more power.

Think 80/newer heads have larger valves. That w/longer duration cam should give most power



mro

[pggg]

The exhaust cam that matches that cam on the left, should have more lift than both those intake cams.