Kawasaki ZX14

I was quite excited when a good customer of our’s asked me what we could do to his Kawasaki ZX14R to make it beefier, not that this bike needs to beefier at all. Without hesitation I worked out a quote and a plus minus recipe without having stripped one of these motors before. After a couple of days the bike was delivered to us and to be quite honest, I think I was more excited than the customer......it was way too long since I have had the opportunity to do one these builds. This beautiful example of a well kept ZX arrived.

If you had to line up ten, red  ZX14s, this one would stand out.

I soon got to stripping the motor out, and started the measuring process.

First we had to understand what type of clearances and measurements Kawasaki had chosen for this engine. So, off with the valve cover and measure the valve clearances. Every measurement taken has to be taken thoroughly and accurately in order to get the ingredients for a good recipe.

....and without giving too much away, the valve clearance sheet before the strip down is about all I am willing to share.

Next was measuring the standard piston to valve clearances. These numbers are critical as far as safety and reliability go. Horsepower and performance are always secondary to this (but at the same time relative to it).

All this measuring can be tedious, but as I noted earlier, is critical to safety and performance of the engine.

Measuring the squish.

After confirming a couple of measurements with Eddie Henry, he of MotoGP and WSBK fame, and my long time pal and master engine builder, I knew what recipe I was aiming for.

Once the cylinder head was off, I started the very time consuming porting job. On first inspection, Kawasaki's cylinder head finishes look pretty good. But on closer examination you soon realize how bad these heads are, which is typical on a production engine. Below is a picture of the stock head.

After spending loads and loads of time grinding and grinding, finishing and polishing as guru Dave Caine has taught me...

... the head was finally done.

Due to unwillingness of third parties and time deadlines, I had to do the valves myself which I would have preferred to outsource.

With the chosen measurement skimmed off the head and valves seated, it was finally done. Because of an oversight of mine there are no pictures of the exhaust ports, but I am sure you get the idea.

Once I got to my desired squish clearance I could assemble and slot in the camshafts which we licked very slightly to get some extra lift. The stock cams are already pretty aggressive. Slotting the camshaft wheels is a pretty standard thing to do on a build like this as a lot of clearances have changed and more adjustment on the cams needs to be made.

I have to mention I was pretty surprised to see a well worn timing chain on a motor that was less than 10'000 km’s old.

Top is the old chain and the bottom is the new.

This is due to the fact that the hydraulic adjuster over-tensions the chain and wears the pins. Fortunately I have a solution for this, my good buddy Tertius milled a couple of manual tensioners for me.

There have been many cases where the factory tensioner has failed and resulted in this:

Okay, so just to confirm piston to valve clearances again after valve clearances had been done and the engine was ready to go back into the frame and onto the dyno.

Eventually the re-assembled ZX14 was on the dyno. My target was 225Hp and +/- 173Nm.
After doing the first pull I knew that after tuning I would exceed 225Hp.

Builds like these are very rewarding and I thank the customer for affording our business the opportunity. Results below.

Aprilia RSV4

Aprilia RSV4s are seriously nice bikes and are possibly the closest to a race bike that we can currently get our hands on. That being said, they are not without problems. Aprilia’s oil-pressurized tensioners are lacking, and the bike has quite a serious fuelling issue at 7200 rpm.

JP contacted me via our page and told me about the issues he was having with his RSV4. He also wanted to be sure that bike was properly set up after fitting an Arrow slip on.

After lengthy discussions and a dyno assessment, JP decided to leave the bike with me for tuning.

The first pull I did was with the dB killer fitted and there did not seem to be an issue. Only once the dB killer was removed, could you feel the problem at 7200 rpm. The dyno graph confirmed what I was feeling.

At first I thought this was an injector phasing issue; I was sure Aprilia was switching the primary injectors off and switching the secondary injectors on a couple of milliseconds later. I was wrong! But we will get back to that later.

I searched the web for someone experiencing the same issue and found a forum where an RSV guru claimed that the only way the issue could be sorted was with an aftermarket ECU like Magneti Marelli or Motec. This was obviously out of the question because of the expense. I advised JP that we should try flashing the ECU with a Rexxer map from Germany through a Cape Town supplier. This obviously adds quite a bit to the total invoice but we were determined to get a good result.

I had previously installed a Power Commander 5 and Secondary Fuel Module to another customer's RSV4. He was not entirely happy with the result and eventually the kit was removed from the bike.

So I was hesitant to fit the PC5 and SFM because of this previous experience, but I figured a Rexxer map would definitely resolve the injector issue, and I could take control of the fuelling via the Dynojet kit.

There is just something about the way Italians build bikes, man it is so tight, it’s like the manufacturer doesn’t want you to work on it.

After fitting the PCV and SFM, it’s quite a battle getting the tank to fit properly.

Stock graph.

The torque curve reveals the hesitation at 7200 rpm.

I contacted Redewaan for the Rexxer map and he was there in a ‘flash’, pardon the pun.

First Rexxer map versus stock.

Because the change was hardly noticeable, we moved onto the next map.

Second Rexxer map versus stock

The power was increasing but the problem remained.

Third Rexxer map versus stock.

By this time both Redewaan and I were pretty frustrated and reverted back to the first map.

I made the decision to go ahead and custom map the bike and see how the bike responded.

After mapping 2% to 10% Throttle Position (TP) with Tuning link, I decided to stop and just run the PC5 software.

I was curious to see what the injector duty cycle was doing. To my surprise the primary injectors fire for the total RPM and TP range. Then spotting the secondary injectors, regardless of TP, at 7200 rpm the two rear secondary injectors come on at a whopping fifty percent duty cycle and 400 rpm later the two front secondary injectors come on with 40% duty cycle.

With my tuning experience, this seemed like an easy fix; just pull out the fuel at these points.  I was wrong again. Instead I found myself adding heaps of fuel to both primary and secondary injectors at these points. This did not make any sense but I carried on mapping as I was keen to get the bike back to JP. Worryingly, my other work was piling up with one staff member lost to another shop.

Eventually I got the tuning done on each cylinder and could do a final run.

Final Run

As you can see there is still an issue at 7200 Rpm, but that is because the power has been optimized before and after the problem area.

I then softened the power quite a bit before this area and slightly less after.
Below is a graph showing stock with the dB killer fitted, stock without the dB killer, and tuned with the midrange softened.

The bike is now silky smooth and the rider cannot find the problem even if he spends all day looking for it.

Now!!! That’s all fine and dandy but what is causing the lean fuelling in this area? Again getting into the very bright brain of Eddie Henry, he suggested “fuel pressure”. How obvious is that?!

So I plumbed into the fuel line with a pressure gauge and guess what? The fuel pressure drops from +/- 3 bar to sometimes as low as 1.3 bar for just a split second. This means that when the two rear, secondary injectors come on at this huge duty cycle the fuel pressure drops to ALL the injectors.

Our next exercise is to prevent the fuel pressure drop without causing negative effects elsewhere.
I just need to find the time to do all of this.

JP’s feedback has been very positive and he now seems to be enjoying his RSV4. 

Julian, Superbike Solutions