Post-Grattan sportbike surgery - 954 style

DaveF had a few issues with the 954 at Grattan, it was making a chuffing sound after coming back in from a session. I originally thought it might be a loose exhaust flange, but we did some digging and found that the spark plug on cyl #2 had popped out. #1 was loose as well, but it tightened back up without much fuss. After trying to re-tap the threads, we discovered that there weren't any threads left .

We were hoping to have everything ready to go for a complete fix today, but Fedex didn't want to play along. The thread repair kit is somewhere in Fedex limbo, and hopefully will get here by Wednesday, but we still managed to get the head pulled and have everything ready to go for reassembly.

According to the manual, you need to pull the motor to remove the head, but we found an alternative after several failed attempts. I'm going to talk to a couple of local machine shops about having the plug threads renewed/fixed and we'll see what happens. The threads on cyl #1 were just barely in better shape than cyl #2, and there are traces of aluminum on the threads of the plugs that came out of 3 and 4, so while it's apart they're all getting fixed.

On a good note, the engine looks amazingly clean inside for a bike with almost 40k miles on it, so once we get this issue sorted it should last a long time.

We did notice the root cause of the problem, though. While we were cleaning up the head, we noticed that while Dave just wanted to ride the bike and not have to do a bunch of head repairs, apparently the head had other plans and simply said "F.U."

And since CBR929RE was the last one out on the track with the 954....

That's because he rides the thing so damn slow...

What causes the threads to get all messed up like that? Was it FUBAR'd while installing plugs or something else?

Not sure, but he investigated it a bit after Grattan and it seems to be not that uncommon. He also had the same thing happen with a 600 years ago.

The only way to get the whole bike in the picture is to take it from just outside my garage at the back door. Any closer and the bike won't fit in the image (except the YSR ).

Dave said he torqued them to factory spec, so I'm not sure what the root cause of the failure is, I'm just tasked with fixing it.

Yikes! Port that head while you are at it!

Ohh Brian, can you come pull my motor next please. :notworthy:

At least mill the head a bit.

the bike knew I was gonna run a faster time on it than he did, so it set the self destruct function

I held back cause I knew Dave didn't need me beating his time for more motivation. Worked great the other way around though

I wanted to say thanks to Brian for all his help and for foolishly volunteering to tear it down at his house. What a super garage he has! The rest of the house is cool too but I have some serious garage envy.

Yeah, the first time I saw it I was blown away. I'm hoping to visit again when it comes time to reassemble the XRR motor.

The grounding electrode was missing from the plug, but luckily we didn't see any damage to the piston or the cylinder from errant metal bits. Must have just blown out.

Check the valves. Just had a jet engine where we did a routine check of the ignitors and found the electrode in one of them had left the building. I'm currently in the process of coordinating a new turbine wheel due to damage on three turbine blades. Moral of the story: if something of that size departs the engine, it will leave evidence.

Just for shits and grins, take a good look.

I plan on checking for valve leakage after getting the plugs sorted. Install plugs, leave head turned over with valves up, fill chambers and check for drainage.

Mine.

Did Brett ride yours, too?