On the 990, is the crankshaft locking notch the authoritative determiner of TDC? On my front cylinder the camshaft gear marks and the crankshaft locking notch agree precisely on TDC, but on my rear cylinder they are slightly off. Is this normal or has someone in the past put the rear cams in a tooth off?
Yep the locking pin locks the motor at TDC, front and rear cylinders. Could be that your cams are out - but make sure as one has the lobes facing inward at tdc (rear IIRC) and the other has them outward facing. Go to ktm950.info and check in the valve check howtoo. It shows the markings and orientation of the lobes-cylinders. Pete
Don't know if the 950 is the same as the 990, but when I did my valves, I had to do the front cams, then back the crank locking bolt out and rotate the crank 360(?) degrees to get the rear cams positioned correctly. From what I know, if both the front and rear cylinders were at TDC at the same time, the bike would be firing both cylinders at the same time, like a single. I believe the rear is 360 degrees out of phase with the front. From what I remember, Pete's right about the direction the cam lobes are facing at TDC. G
Also make sure you are looking at the correct timing marks. The cam gears have marks on both sides. For both front and rear cylinders, you want to be sighting from the LEFT (clutch) side of the bike.
This is not correct for the 990. The 990's cam and cam gears are forged one piece that have individual timing marks for each cylinder, intake and exhaust. The 950 has one cam gear pressed on all 4 cams. Your statement is correct for the 950. The locking bolt at the crank is law. Once locked in, everything else is assembled around that. Check the "how to" section of the forum or consult a repair manual.
Thanks, that's what I thought, just wanted confirmation. The HOW write ups speak of using the cam gear markings for aligning the cams for measurement and of using the locking bolt to lock up the engine for cam removal, but they don't address the situation where those two things don't agree precisely.
In my experience, it's not uncommon for the cam markings to not quite line up right. I think that if you take the cam out and try it in the next tooth over, it will be even farther away. It's usually pretty clear which way is correct- the cams should both be pointing in/out symmetrically, and the marks should be quite close.
Yup. After trying the cam positions one tooth off, the original one is closest. So, the answer is - with the crank locking bolt in, the cam markings do not necessarily align exactly with the top of the head. In my case on the rear cylinder the exhaust cam mark is half below the edge of the head and the intake mark is a couple millimeters above the head. It's not dramatic, and it's not as out of alignment as any combination of shifting the cams by a tooth, but it's definitely recognizable as a little off.