Harder starting after valve adjustment and crankcase cover replacement. Which is it?

[Toinky]

I just finished adjusting my valves. At the same time (violating a fundamental priniciple of science by changing more than one variable at time), I replaced my left crankcase cover that had been bent. Now the bike's back together and seems to run normally, but seems harder to start. It takes more to fire it up. The engine just sounds less smooth when cranking it, and it seems as though it's not quite timed right.

I have the cams set up as per specs in the manual (TDC with notches aligned with the cylinder head surface). The valve clearances are within specs, too. (I've checked them several times after reshimming.) I did, at one point in the valve adjustment process, turn the crank the wrong way (clockwise) a slight bit (and noticed it felt funny--like it was slipping or something).

I also installed a new left crankcase cover. (Thought it was good to do all the maintenance at one time, but....) In that process, I took the stator and pick up coil from the old crankcase cover and installed them in the new cover. That work seemed really straightforward and like there were no adjustments to be made. However, it seems like the rotor and pickup coil could have something to do with timing and hence, perhaps, the starting peculiarities.

It starts, but with more cranking and more glug-glugging (very technical term, I know) than it had before the "repairs." I've taken the bike out for very brief spin and didn't notice any engine running or power problems. (1) Did spinning the rotor backwards mess somehting up? (2) Is there an adjustment within the rotor/pickup coil assembly that I missed? (3) Is something else the culprit? (4) Should I just stop pretending to be a mechanic and shell out some cash for someone who really is one to deal with it?

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'06 WR450 with all free mods, including grey wire pulled.

[socal_sierra]

I

(3) Is something else the culprit? check your timing, you might be a tooth off, check valve clearences again make sure youre at TDC

(4) Should I just stop pretending to be a mechanic and shell out some cash for someone who really is one to deal with it?no way, learning how to do maintence yourself will help you out a ton and make you understand your bike much better

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'06 WR450 with all free mods, including grey wire pulled.

i answered in bold

[dominator426]

(1) Did spinning the rotor backwards mess somehting up? (2) Is there an adjustment within the rotor/pickup coil assembly that I missed? (3) Is something else the culprit? (4) Should I just stop pretending to be a mechanic and shell out some cash for someone who really is one to deal with it?

(1) No. Check timing after turning forward with chain slack behind at tensioner. TDC mark should be on the '|' of the 'H|' marking. Did you count the chain pins between cam gear marks?

(2) No. There is very little play in the bolt holes.

(3) ?

(4) Hold on. We'll figure it out. Only you can take the time to do it right, and for free...

[Toinky]

I appreciate the feedback, esp. to #4. I am sure I have had the piston at TDC (the I after the H was perfectly aligned with the case marking). I tripple checked the cam rotation, and they seem to be dead on based on the punch marks aligning with the top of the cylinder head (9:00 exhaust/3:00 intake). I have not counted pins. I will do so in the morning. I believe it should be 13 from the 12:00 punch marks, is that correct? I have also tripple checked the valve clearances and all is well there. I did check the clearance after rotating the engine several times and after taking it for a spin. Dominator426 said to check the valves "after turning forward with chain slack behind at tensioner." I'm not sure what that means. I've been checking clearances with the cam chain tensioner engaged (after rotating the crank a few turns).

[ash105]

Turning the crank the wrong way puts too much pressure on the cam chain tensioner and can allow the chain to slip a tooth on the inlet sprocket. I know from experience as I've been trying to retime my 400 for the last couple of days. I also always turn the motor through a full rotation of the cams by crank to make sure I've made no mistakes and the valves aren't going to hit the piston before using the kickstart or electric starter. Just a tip.

[dominator426]

Dominator426 said to check the valves "after turning forward with chain slack behind at tensioner." I'm not sure what that means. I've been checking clearances with the cam chain tensioner engaged (after rotating the crank a few turns).

Check your timing marks and valve clearance after rotating engine by turning the crankshaft counter-clock wise at the flywheel, so that the timing chain is stretched out tight at the front where it's pulling. Any slack should be taken up at the tensioner. If you removed the tensioner, chain slack should be there; 'behind, at tensioner'.

[Toinky]

Well, I went back and tripple checked the valve clearance and timing marks (TDC and cam punch marks). Everything looked spot on, so I wasn't sure what else to try. Low and behold, when I put it back together after rechecking the valves, it started up as it normally did before I adjusted the valves. That is to say, the problem of harder starting seems to be gone. I have no idea why, but can live with not knowing as long as she keeps starting easy.

Thanks to those who posted help.