Left Side Cylinder Stud Helicoil Repair
At the 6,600km mark I noticed an oil leak on the left side of the motor. At first I thought it was coming from the oil pump cap on top of the engine casing as there was a small dribble emanating from that point. I tightened the cap and wiped off the oil, but there was still a leak coming from somewhere lower than that point. I had previously re-routed the crank vent hose to dump into a vented bottle instead of into the air filter, but because the bottle kept filling with water from all my snowy rides I removed it and let the hose hang down between the lower frame rail and left exhaust header. I figured the oil mist from this hose was probably spraying all over the place with the help of the wind when I was riding, so it was placed back into the air filter housing and the motor was wiped down again. But the leak was still there and getting worse. At the 6,700km mark I finally flopped my body onto the garage floor and took a peek underneath the left jug and saw that the cylinder fins were all oil soaked. It looked like the leak was coming from the rocker cover gasket, so I removed the rocker cover only to find out the problem was something much worse than a leaky gasket...
	The lower left cylinder head nut had backed off several threads, which meant the head and base gaskets were not clamped down on that corner. Oil had eventually begun to squeeze out from those points and, because the nut also served as the anchor point for one side of the exhaust rocker arm, it had increased the valve lash. This had caused the ticking noise I had at first suspected was simply a valve in need of adjustment. So I figured no problem, I'll just re-torque the nut and be on my merry way.
	Nope. The nut wouldn't tighten because the cylinder head stud hole was stripped in the engine block. Any attempt to tighten the nut resulted in the whole stud turning and chewing up more of the surrounding casting. As the service schedule does not call for a valve adjustment or a head bolt torque until the 10,000km mark I had never mucked about in this area, so it was obviously a condition that existed right from the factory. I pulled the stud clear and was dismayed to see the threads on the engine block end were poorly cut; the crests were flat and the roots shallow, and it was packed with aluminum stripped from the hole.
I called my dealer to ask what the next step was and within a day he had an answer back from Ural Canada - the hole was to be repaired by helicoil insert, under warranty. Problem was, I live 5hrs away from him and don't have a trailer or a vehicle with a hitch, nor was I keen on paying the expenses involved with renting something suitable and having to pay for gas and other associated costs in getting my rig there and back. Having wrenched on bikes for many years and with my mechanical experience as a Millwright, I didn't see any reason why I couldn't perform the repair myself. This meant there would be minimal downtime for my bike... and if you've read all the pages on my website you'll know that I don't tolerate being without a bike for any length of time. If I screwed it up I would take the blame and risk losing warranty coverage, but I was willing to risk it to preserve my own peace of mind.
	I started out by spraying WD-40 onto all the exhaust clamp bolts and the carb bracket bolts to ease the removal process. While the bolts were soaking, I removed both spark plugs, the left side fuel line and intake runner. I removed the carb and hung it safely out of the way, then used the kickstart lever to move the left piston to BDC.
	Both the left and right side exhaust clamps on the front of the catalytic converters were loosened, along with the header clamps secured by the lower motor mount bolt. I also loosened off the finned exhaust header collars at the exhaust port, as I figured they'd probably get in the way during the next step.
	Because the crossover pipe connects the two headers together, both headers had to be moved out of the cylinder heads. A rubber mallet was used to prevent any damage to the pipes and they were knocked forward until they were clear of the cylinder heads.
	The valve adjusters were then backed off...
	...and the remaining cylinder head nuts removed.
	The rocker arm assemblies and pushrods were taken out and placed up on a shelf. I marked the pushrods showing the orientation of the ends and which assembly they belonged to.
	The cylinder head was now ready for removal and with a few strategic taps from the mallet, it broke free from the head gasket.
	DOH!!! Had to remove the left engine guard so the head could slide clear of the studs.
	The piston crown and head gasket was coated with oily soot, so I suspect there was a bit of leakage past the gasket. Fortunately, though, I couldn't see any damage.
	A few more mallet taps and the cylinder barrel came free. I was careful to catch the piston as it popped clear, as the last thing I needed now was broken rings.
	I secured the piston up high and clear of the stud hole I'd be working on.
	With everything removed, it was easy to see the damage to the stud hole. There were only a few faint ridge of threads left, so it was obvious a helicoil was my only repair option. I sourced the inserts, tap and installation tool from our handy stock at work (one of the fringe benefits of being a Millwright).
	First step of the repair was to drill out the hole for the helicoil insert. 10.5mm is the drill size used, but because the shank won't fit into a 3/8" drill chuck I had to turn it down on the lathe at work first before using it. More fringe benefits. If you've never done a helicoil repair before, there are a few things that MUST be done in order to ensure success. The drill bit has to be kept straight while drilling, any movement to either side or up and down will result in the hole being drilled at an angle; this means the stud will not be parallel to the others when installed and the head will not be able to slide over them!
	Because the hole is drilled all the way through the engine block, there is a good chance that metal shards from the drilling process could be pushed out into the oil. To prevent this the drill bit was coated in grease to make the shards stick to it. As this was a fairly deep hole, I pulled the bit out a couple of times to clean and re-grease it.
	The tap was then carefully wound into the hole. As with the drill bit, it must be kept straight or the stud will end up on an angle and totally ruin the repair - and your day. The tap was also coated with grease to keep the metal chips from escaping; after every two turns it was removed to clean and re-grease.
	Once the tapping was completed, I plugged the other end of the hole with a rag and thoroughly flushed it clean with an aerosol parts cleaner.
	The helicoil insert was installed onto the special tool and wound into the hole. The threads were positioned just below the surface of the hole; that way it would not interfere with the seating of the stud.
	Once the tool was removed, the tang at the bottom of the insert had to be knocked out so it wouldn't interfere with the stud when threading it in place.
	The tang was then fished out with a plastic wire tie and a bit of grease.
	I had cleaned and thread-chased the cylinder head stud and it now had lots of meat on the threads, enough to safely re-use it. I screwed it into the hole, then checked it by trying to wiggle it around. It was very solid and, most importantly, nice and straight!
	Everything was then re-assembled in reverse order and I got out the torque wrench. Using a cross-pattern, I tightened the cylinder head nuts in 10lb increments up to 30lb/ft, then in 5lb increments to the factory setting of 40lb/ft. The repair worked - the nut held its torque!
After setting and checking the valve adjustments, I fired up the bike and let it warm up. The motor was nice and quiet (no more tapping from the exhaust valve now) and there were no oil leaks. The next day I took it for a 60km shakedown cruise and there were no leaks, so the repair was officially declared a success.

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