Cam Position

[jac_is_smiling]

Hey guys, was checking the valve clearances today, along with checking the current shims to find out what needs to be bought.

Just before removing the cams came across something that I thought was somewhat odd.


This is what the timing marks on the cams look like when the gen rotor T mark is lined up with the rib on the case.



In order to get them properly lined up you have to rotate the engine foward a few degrees (if i had a degree wheel I could actually tell exactly how much (it is on my shopping list))


Question is, is it meant to be like this (or off due to manufacturing tollerances) or has someone gone spannering and put things back slightly wrongly
As a side note the bike ran well all summer, as fast as a mates zxr400, altho it did use approx 1l of oil for every 2000 km travelled.
Any of this due to the above.
Cheers, Jac.

[CMSMJ1]

more likely that your view of the T mark on the rotor is not perfectly straight..unless you are 12 inches tall..

[jac_is_smiling]

aaahhh..that does make sense lol

as a slightly random side note, while the engine is out and appart i thought id try and solve its oil thirst,
thinking of replacing the valve stem oil seals, and maybe the piston rings

question is, is it worth lapping the valves? noticed it in the haynes manual when i was checking the cam removal process
Ive not heard anyone on here mention it, so was wondering if theres much to be gained from it

I do realise however that if I lap the valves my measurments of valve clearance will be out.

[CMSMJ1]

Yeah. get them lapped...

If you have it apart, then why not! I did it to the race bike I built and I'm sure the motor loved me for it!

You could also get radical and remove some of the casting flash in the inlets..not quite a polish job, but it will help..

[jac_is_smiling]

im starting to get excited , had always said id happily spend money making bikes handle well, but not play or spend much money on the engine as im not racing, and its only a 400 etc

Its almost a bad thing I love spannering so much, i think my wallet is about to be torn open
while replacing valve stem oil seals, as you say, makes sense to lap them (only extra cost is grinding paste)
but if i do the pistons rings, its not much extra work to change to nc35 pistons, but that adds a fair bit more costs

and if i remove one little bit of casting flash, i may want to continue...
i think il spend some time on google, try and see if i can make my own flow bench hehehe