Hi Guy’s

 

Well went to the drags on Saturday and broke the bike. As always, was on the quickest run of the arvo when all shut down. Was mowing down a Dyna and got him at half track in 7.991sec, then NOTHING. It just coasted, so pulled in the clutch and went down the gears and rolled through the trap and back around as far as it would roll then started pushing it back. Tried the starter button and all it would do was spin, no compression. First thought was that I blew the clutch as never replaced it after the rebuild and wasn’t getting any compression. Other learned people thought that I had dropped a valve, no matter what it was not going and time to get the trailer. Well the run was my slowest ever but still managed to keep it under 14 sec with a 13.989 run.

Broke the news to the Missus, she was less than impressed as more money would be spent on the bike, but not till after Xmas.

After I got the bike home (3 1/2 hours later), I pulled the exhaust off the bike and checked for valves, both in there. Turned it on and cranked the motor over, no valve movement at all, clutch theory still in place. Had another beer, pulled the chain inspection cover off and checked for tension, all was good. Turned the motor over again and it was spinning, so it wasn’t the clutch (damn), now to next theory, sheared shaft. Got another beer scratched my head and balls was not thinking straight so started draining the oil from the tranny had a shower and went to bed, too buggered and pissed off to work on the bike, wrong frame of mind.

Went out to breakfast and did some chores around the house till after lunch before attacking the bike problem as all was planned before the drags. Also had a heated discussion about the bike at lunch and how much it is costing and only being 3 years old with sooo many drama’s with it (no sh!t Sherlock), as if I planned all this to hamper the house renovations.

Any way enough venting, the postmortem of the bike is as follows. Started on the clutch side (easiest), removed both pegs, clutch cable and ramp, released tension and removed cover. I checked all over the bits and pieces, all looked fine and dandy. Pulled the spark plugs out and put socket on the crank and turned over by hand. The pistons were moving up and down and felt OK, theory that the shaft sheared off behind the rotor sprocket assembly and near the stator was gone. I decided to just find the problem, no more theories. Well not that side, so put it all back together. I now moved over to the cam chest side. Off with the seat, tank, steering damper, disconnect wires and move harness, get coil out of way and then start on the rocker box covers. I got out my old faithful blue buckets (from first rebuild) ready to start putting bits in from the front and the rear cylinders. Pulled off both the outer covers and all valves were there, off to a good start. I removed the inner rocker box covers and the push rods putting cable ties on them, white for inlet and black for exhaust. Checked them for any bends, all seem good and nice and straight. Now to the cam cover, I removed both pegs and then the cover. Sh!t what a mess, the bushing of the rear intake cam had fallen on the floor and had a massive amount of wearing in the cam cover from where it had been. The cam itself has score marks on the bearing surface and is now toast. The Pinion gear had sheared the T key off and was spinning freely on the shaft, hence no valve movement. Other than that, all was fine in there. Now off with the heads. I removed the carby, choke and brackets to allow for the head removal. Took the heads off the motor and all the valves were open and bent. That was the no compression problem solved. The pistons have marks on them from where they hit the valves (not bad). I pressed the valves out of the heads and both the exhausts are the worst with S bends while the inlets are only tilted. One of the valve guides has a piece missing from it and luckily there are no marks on the heads or pistons from this departing object.

So what I think has happened: the movement in the rear inlet cam has allowed the pinion gear to slip over a tooth or two putting the valves out of timing and then the pistons hit the valves and in doing so has sheared the T key off the shaft at the pinion gear and then the drag run was no more (end of fun and beginning of expenses). There was no noise that I could tell from this to alert me of the problem other than I had one valve noisier than the others. This noise was from the beginning of the rebuild and sounded like it was coming from front exhaust and had put it down to the SE double valve springs and 536 cams.

Now the fun begins in trying to get all the bits and pieces to put it back together and what’s needed and what’s not.

Needed: Cam cover (25252-04), cams, cam bushes (25598-91), T key (11317), pinion gear (24047-00), intake valves (18053-04), exhaust valves (18059-04), guides (16461-02) and head gaskets (16664-86B).

Suspect list: Rocker arms (17360/17375-83A), shafts (17611-83), tappets, push rods, crank (again), pistons and oil pump.

Have I missed anything out?

Has anyone out there got a 2005 silver cam cover that they no longer need? That one is going to be my biggest head ache I think out of all the things required in the rebuild. Biggest issue is to get a matching colour with the rest of the motor and not stand out.

 

So I am not sure how the problem started at the cam bearing but the main thing is that it failed under a controlled condition and not out on the road going around corners etc. I may have been drag racing the bike but the motor would’ve failed later anyway due to the problem it had, a case of not if but when, the racing just speed the failure up.