Six months after the purchase, I am finally getting started on another XS11 standard. The first thing I like to do is check for spark and compression. The starter button doesn’t work so I had to short a screw driver across the solenoid to get the motor to turn over.
It does have spark and a compression check revealed the following numbers:
The previous owner told me that he replaced the head because it had bent valves and then he was able to get the engine to turn over but never got it started. I suspect that he bent the valves on the new head too, causing the valves to stick open, thus causing no or poor compression. I pulled the valve cover off and found that the cams are not installed with the correct timing. When the dots are lined up on top of the cams, the timing pointer is at 20 degrees on the timing plate rather than TDC where it should be. The valves all appear to moving ok though.
After aligning the cam timing dots it still has bad compression. So now it’s time to pull the head off. The pistons and cylinders look good and I didn’t see any problem with the valves, but I feel sure it has to be one or the other. I called Frank and asked for his opinion. He basically said everything that I had been thinking except he mentioned the head gasket, which I kind of ruled out since a new one and had already been replaced by the previous owner.
I went ahead and pulled out all of the valves just to confirm that none of them were bent. I lapped them all since I had them out, I don’t plan on keeping this bike so I didn’t replace the valve seals but now I think that might have been a mistake. They are really not that expensive. But regardless, I still don’t see anything wrong with the head or the valves. I filled the cylinders with oil and after 2 days they are still full, so I don’t think the rings are leaky.
Searching for any clue at all, I looked at the head gasket again. There are 2 pieces to it; the main head gasket and a smaller gasket section that sits on top of the main gasket. I didn’t remember that being the case on the last engine that I overhauled. I looked it up on the parts list and sure enough, there are 2 gasket sections listed. The smaller section is just as thick as the main gasket, if not a little bit thicker.
I keep thinking to myself: Can you really torque down the head that tight to crush a double layer of gasket and get a tight seal? As usual I go to my main research source…. XS11.com. Apparently the OEM head gasket has a cutout where the smaller section of it sets in. The purpose of the smaller gasket which has a little extra coating to it is to seal out the oil from the cam chain. The replacement head gaskets don’t have that cutout for the smaller gasket insert. It is all one piece. So when the previous owner was putting the head back on, he installed the smaller gasket in the same way that he found it during disassembly. According the the XS11.com forums, he should have left it out. I re-installed the head without the smaller gasket.
That must have been it. I now have 90+ psi compression on all 4 cylinders. That’s still a little low but is typical of a bike that has been sitting for many years. It will be good enough to get the bike started and the psi should increase over time after running it.
I really struggled with the cam timing alignment this time.
For future reference: (note to myself)
Align the 2 timing dots on top with the #1 piston at TDC.
AND THEN be sure to keep pressure on the timing chain with your finger through the cam chain tensioner hole while rotating the cams to install the lower bolts. This is critical, otherwise the chain will have slack and skip teeth on the crank shaft, throwing everything off. Tension on the chain will prevent the slippage and will keep the 2 cams aligned with each other. Also while keeping pressure on the chain, rotate the crankshaft to “C” and then install the chain tensioner. Recheck that the two dots are still aligned on top while at TDC.
All 4 carb intake boots were filled with acorns! I guess the chipmunks thought that was a good storage place. Other than that, the carbs came apart ok and the jets came out ok. Except that I broke 2 of the emulsion tubes that were really corroded. Someone has replaced the stock 137.5 main jets and 42.5 pilot jets with 145 mains and 45 pilots. Probably because of the after market 4 into 1 exhaust that is on the bike.
I got it running! And it sounds pretty good. But with 56,000 miles on it, I don’t really want to put any more time or money into this bike, and besides, I am not really a fan of the standards. I priced this one for a quick sale. It sold to a local guy who I think just flipped it for a quick profit.