Peter Day

Yamaha FZR750R OW01  & YZF750 specialist

Have you ever wondered how a race prepared FZR750R OW-01 would fare against a race prepared YZF750SP? We have, so there was only one way to find out!

Peter Day has now produced one of the nicest SPs yet seen, and prepared it to his usual standards. I had the pleasure of a full day, an open pitlane at the incredible Cadwell Park, and even an extended 2 hours in the evening. Tired? yes I was! but what a day. Both bikes prepared by the same man, to similar specifications, on the same track with the same test rider.

I thought you might like to read about what happened on here...

First I put my old slippers on, also known as my OW-01, inorder to get  a benchmark set in my head.


Peter had set the chassis of the YZF up in the same manner as my OW race bike. So we are talking same ride heights front and back, same head angle, same yoke offset. Indeed, the forks on both bikes are identical.

So, as the engines are of a similar spec, the YZF should feel quite familar. In theory.

First YZF impressions were that the rear shock was too soft as supplied. As I was running in to start with, I left things alone and thought I'd just see how it felt. Sure enough I felt seasick after a couple of laps with all the pitching and bobbing at the back. The carburation was a bit off at the bottom, as we are using this bike to develop settings for the 41mm FCR carbs. All the other bikes in the past have run with FCR39s.

Despite the spongey rear end, the YZF turned in quickly.


I did some playing on the OW, whilst Peter stripped the carbs on the YZF, changed jets and needles, and wound up the rear shock to better cope with my ample frame.


By this time, both bikes were generating a lot of interest, all of it positive, which is always pleasing.

Back out on the YZF, and what a difference. Things were getting interesting now. The engines do indeed feel similar. The YZF should have more top end, but still felt a little "tight" so I was being careful and conservative with the revs.


The handling was the biggest surprise to me. Despite Peter setting the bikes as closely as possible, the YZF steered very differently. It felt very nimble indeed, very light on its feet and fast to turn. But there was not "flop" in turn-in. The closest thing I have raced lately that I can relate it to, is a Triumph 675 Daytona race bike.

The YZF also felt light, lighter than the OW. This is a neat trick, because it's not!  The OW is lighter. However, the heavier part of the YZF is its frame, so this could contribute to / translate as a higher centre of gravity. Later on, we measured the relative heights of the crankshafts from the ground, and the YZF crank is carried 5mm higher. This was now all starting to make sense. 

Once the GPS datalogger was downloaded, it could be seen that the YZF spent less time at the apex, and leaned over less and got on the power earlier. I didn't expect to gel with the bike quite so quickly, having raced the OW for 12 years, but I was quite taken with it after a very short space of time!

By the end of the day, we had an engine that was nicely run in, a rear shock that was 90% set (we didn't touch the fork settings) carbs that were 90% sweet, worn out slicks and a happy rider and builder.


Next step is to test both a stronger rear spring and also a YEC kit linkage, which changes the rear shock ratio. Peter is also taking the YZF to the dyno to fine tune the carburation. As an aside, I secretly cant wait to see what power it is making too!


Then we need to test again before the International Classic on 25th and 26th July.


The whole experience was hugely positive, and answered a question in my own head as to how the YZF is a forward development of the ow01. In conclusion, the chassis feels more modern, feels lighter (though its not) and more nimble in the way it turns. The OW "steers from the hips" and needs more counter-steering with the 'bars. The YZF is less physical and responds to "foot work" more readily. Both bikes have a remarkable level of feedback built in. I think that given time, more setup and familiarity, I could lap consistently faster on the YZF. It's exciting to be developing a bike from scratch again, as the OW has almost been a "finished" work for some time now. (if a race bike is ever finished)  

                                                                                                                

                                                                                                                Mark Ess.    


So the son and rightful heir has shown his intentions...but the Daddy still cuts the mustard, and still rips when required!