ZX7R
The Build Journal
25/09/08 - 'Big Motor' Update
After blowing up 2 engines, we finally have an idea on what was going on. The 12.5k rpm limit had been disabled by the previous owner which allowed the bike to rev out to 14k rpm. By revving the engine above the 12.5k limiter it caused a shortage of oil at the No.3 rod causing the spun bearing in engine No.1 and the melted rod in engine No.2.
Our plan is to create a 'stroked' motor using the crank from a '93 ZXR750L motor and if possible to also beef up the oil delivery system to the No.3 rod without causing an oil shortage elsewhere.
Installing the 'L' crank is rather straight forward as the only difference in the 'P' model crank and the 'L' model crank is the 'L' gives an extra 2.6mm of stroke over the 'P'. The benefit of stroking the engine capacity (to 793cc) is to increase the amount of torque the engine puts out. This is a handy thing when you are racing 1000cc twins, and the 'biological' mass of the bike is over 100kgs.
The reason that the engine has sat on the work bench for so long is that the 1st hurdle has been working out what main/conrod bearings we needed. The workshop manuals list 3 different bearing sizes and sort them by a coloured band on the bearing. Unfortunately these 'coloured bands' are only visible when new and we had no idea what we had or needed. The good folks at Revhedz Kawasaki in Acacia Ridge, have come to the rescue with a copy of the necessary engine markings to get the right ones.
30/11/07
WARNING! The following images may disturb some people.
It is missing it's heart
Top half of the engine
What is left of the bearings (sorry out the out of focus)
Crank scaring
The shell bearing
But the gearbox is in good nick!
26/10/07
OK the ZX7R is ready for race day. Hopefully all well go well on the day.
08/10/07
Here are a few pics of the bike on it's 1st ever trackday. As you may have read in the New section the day didn't exactly go to plan. The bike now has an awful knocking sound from deep in the motor and is in the shop being looked at. Hopefully it is nothing to expensive, but really everything in this game is.
01/10/07
Well the bike is back from Dave's and it is straight as a gun barrel. I had a few problems with the camera (memory card) so haven't been keeping up the pics as I said I would, but that is now all sorted and we a snapping away again.
While the camera was out of action a few things got sorted out. The carbs have been taken of and given a through cleaning. The amount of crud that was in them was obscene. It took a good couple of hours to get them cleaned up and sorted out. Once done the bike was running on all four cylinders again.
So now that the bike runs I am slowing putting it all together.
The first thing was to paint the tank green, and put on the filler cap and petcock.
The green paint that I had left over from the ZX6R isn't even close to the green paint used on the fairings, so I see a complete rub back and respray of the whole lot in the near future.
Next I needed to fit up the Akrapovic exhaust. I needed to drop the rad (and give it a good flushing) and then remove the old exhaust first.
As you can see from the pics the new exhaust is a multi piece unit and held together by springs.
Finally I got it all on and the rad back in place and refilled. I absolutely needed to give it a run around the back yard just to hear how it sounded. The sound sure is nice.
01/08/07
Well I haven't yet got around to getting the bike started yet, as I have been scavenging parts to make her complete. Below are a few pics of what I have pulled together so far.
I have created bit of a list of things that I need to get her into racing shape. Just small things like getting the rear subframe straightened, new exhaust, air filter, jet kit, new chain and sprockets etc (I hope).
At the moment the bike is down at Dave Kellet's being straightened out. I hope to have it back soon so I can start piecing it together and get it running.
Here is the 1st pic that I took once I got her home.
Here is one from the other side.
I have also managed to pick up some race glass too. It is in pretty good shape and all I need do is get my tank painted to match or the race glass painted to match my tank!
