• 4 Stroke Husqvarna Motorcycles Made In Italy - About 1989 to 2014
     TE = 4st Enduro & TC = 4st Cross

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No go after piston change - timing issue?

Peter Nilsson

Peter Nilsson

Husqvarna
Hi all,
I just reassembled my TE-250 2010 after top end overhaul. New piston, cleaned up the top, valve adjustment. After reassembly when I try to fire her up, nothing... There is a spark, there is gas. Ignition is set at TDC with aligned timing marks n the cams. BUT, I cant help thinking that I might have the timing one stroke off!! How can I tell if the piston is one turn off? I cant find anything in the shop manual for this, any marking on the ignition somehow? I mean, the spark may not come in the compression stroke if you see what I mean.

If not this, what else should I be looking for? Maybe it is common to have a really hard starting engine after piston change? I emptied the battery (quite quickly) and spent some minutes on the kick...

Thanks for all help/input.
Peter
 
I don't think it can be one turn off. the IGN is a wasted spark IGN and it sparks every revolution.

When I put mine together I used a straw in the plug hole to make sure it was TDC and set the cam dots to the middle of the cam bores as per the manual.

Make sure your fuel pump is priming when you turn the key on.
 
R_Little said:
I don't think it can be one turn off. the IGN is a wasted spark IGN and it sparks every revolution.

When I put mine together I used a straw in the plug hole to make sure it was TDC and set the cam dots to the middle of the cam bores as per the manual.

Make sure your fuel pump is priming when you turn the key on.
Click to expand...
Wasted spark huh, didn't know that, it seems right. Ok, then one less source of error. The fuel pump is running fine. Spark gets soaked with gas actually. More ideas what to check for?
 
Cam timing and valve clearence.

Make sure it is not so off that the piston hits the valves. Double check.
 
R_Little said:
Cam timing and valve clearence.

Make sure it is not so off that the piston hits the valves. Double check.
Click to expand...

...Being off a tooth or 2 on the cam timing might stop the engine from starting and probably will not cause engine damage such as valves hitting the piston ....

You might get some popping back through the intake or exhaust side if you are off on the timing ... No pops?

Always spin the engine over by hand a few times after any changes to ensure the engine does not bind up ...
 
I just did the cam chain replacement on my 630 and had the exhaust cam timing off by one tooth. If it would start at all, it ran pretty badly. Most of the time, it would just backfire instead of start. I cracked it back open, moved the cam, and all is well.
 
The cam dots are supposed to line up with the seam on the cam caps.....they do NOT point to one another. You can see one cam cap seam is higher than the other.

Put a straw in the plug hole to make sure the Piston is at TDC. Don't use just the crank timing marks they may be off or you might use the IGN mark by mistake. Sometimes the flywheel slips anyway. The good news is the cam chain just needs to be on the sprocket in any position....on the x lights the cam chain does not control cam timing.


Double check the valave clearance. The clearance on the left exhaust cam is hard to check because of the decompressor tang. check it 3 times at least.
 
R_Little said:
The cam dots are supposed to line up with the seam on the cam caps.....they do NOT point to one another. You can see one cam cap seam is higher than the other.

Put a straw in the plug hole to make sure the Piston is at TDC. Don't use just the crank timing marks they may be off or you might use the IGN mark by mistake. Sometimes the flywheel slips anyway. The good news is the cam chain just needs to be on the sprocket in any position....on the x lights the cam chain does not control cam timing.


Double check the valave clearance. The clearance on the left exhaust cam is hard to check because of the decompressor tang. check it 3 times at least.
Click to expand...

THanks, clearance is ok, checked many times. Although I was a bit worried because one ex valve was loose at 0.65mm (0.20)! Found no damage or unnormal wear however. Brought it down to 0.20 and double checked. Is this kind of increased clearance something you have seen before?

Anyways, piston at TDC, as much in the middle as I can get it. I can see the edge between the top and the cam caps, in the middle of the holes in both cams. This is the procedure according to my understanding from the shop manual. Anyways the marks in the cams line up with the center of the holes. Is this the way?
 
It sounds like you have it right. If you look through those holes, the seam between the head and cam caps should bisect the hole. The marks on the cams should line up with the seam between the head and cam caps. When looking at it straight on, the lines on the cams will NOT point straight at one another. One will be slightly higher than the other. The cam lobes should point inward at a 45 degree angle. Look at this thread for a pretty good pic. I usually have to get it close and then tap tap tap the kick start lever since it seems to love to sail past top dead center.

http://www.cafehusky.com/threads/2010-txc-250-valve-adjustment.17188/

That .65 sounds really odd. Are the shims seated on top of the valve nicely? I've had one scoot out in the process of getting everything installed one time on a different bike.
 
Dudes! Not sure what I did, after maybe five times tearing of the cams and moving them, all hopes gone, she finally boots up, beautifully. Wow I can not understand how the cams might have been of. Byt regardless, now shes alive. Thanks for all comments, they kept me going :-)
 
Cool.....just make sure that exhaust valve is right.

If it is the valve that the decompressor hits it is a PITA to set.

I thought mine was tight and I loosened it too far and the E start was affected. It tends to hang open when checking.
 
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