nr's blog

Pipe & Slippers 14 June, 2016

Filed under: Motorcycling — nr @ 8:43 am

Out of all the TZRs that I’ve built & raced, one thing has remained constant – I’ve always used the stock pipes. (Well, to be honest, there’s been a common theme of mechanical mediocrity and dubious aesthetic taste, but we’ll skip over that for now). There’s been a couple of reasons for this:

  • They make pretty good midrange power.
  • They came with the bike.
  • When I started racing, they fitted into the class rules.

Of these, the second is obviously the most important, as it meant that I had no need to go out and buy new pipes. Now, while the stock pipes were OK for performance, they do weigh quite a bit (I’ll come back to that in a minute), and they won’t let the bike rev past about 10,000rpm. I’m actually OK with this rev limit though. A lot of racers will use pipes that go to 12,000 or so, which is great for performance, but engine longevity can suffer.

So, what has all this got to do with a road bike? Well, a couple of weeks ago I started looking around at my bent and scratched stock pipes, and decided I could do better than that. First thought was to give them a really good clean up and a coat of high temperature paint, and while this certainly helped them look better, I started to look around for something to replace them with. First thing that turned up was, I kid you not, a genuine set of YEC FIII kit pipes. These are vanishingly rare and lovely things. But at £800 for the pipes, and then you need the electronics, and engine and carb tuning to make the most of them, that was a bit optimistic. So I looked at a set of K2TEC pipes from Japan, which looked well priced, but information about them was scarce (for example, the manufacturer couldn’t tell me whether they were designed for road or race, and whether any other work would be needed) and besides, if they were wrong, sending them back to Japan would be a massive pain in the neck. And then I remembered back when I was more involved in the TZR scene a few years ago, a chap called Martin. He had a TDR250 which needed new pipes, so he did the only obvious thing. Taught himself how to design, hydroform, and weld pipes from scratch. These pipes were light, and designed for the road rather than the racetrack. Five minutes of searching put me in touch, and about 10 minutes after that, I’d asked him to build a set of TZR pipes for me. Well, that was easy, right? What could go wrong?

Absolutely nothing went wrong at all. A few days after placing the order, the postie turned up with a large box. And although I was meant to be working, I instantly scuttled out to the garage, and about 20 minutes of spanner twiddling later, I had this:

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So, safe to say that they’ve obviously improved the looks of the bike straight away. It looks 20mph faster, even while it’s standing still. The Tyga cans were ordered separately, as I just like the look of them. Another option was to buy a set of four TZ750 cans and sell two of them, but I didn’t do that on the grounds that I’d hold on to the other two for ever just because they look nice. Oh, and remember what I was saying earlier about the stock pipes being rather heavy? They come in at about 6kgs each. The new pipes and cans are about 2ks each. So that’s 8kgs saved straight away.

At the same time all this was going on, my friend Rik posted up a programmable YPVS controller that he’d bought from http://www.2t-racelab.com/ a while back, but never used. I’d always had an itch to try one of these, so as well as fitting the new pipes I also nailed on the YPVS controller, set it to stock settings, and went for a little whizz. My seat-of-the-pants dyno isn’t that well calibrated, but I could tell that there wasn’t a great deal more power available. However, two things were immediately apparent. Firstly, the carburation was noticeably cleaner at about 5000rpm, but more importantly, the noise. Oh, the noise. A lovely two-stroke crackle and burble when  gently pottering, culminating in that lovely rasping noise when pushing on a bit. It sounds more like my old TZ than anything else now. So that was good. But I hadn’t touched the YPVS controller yet… I set it with a more aggressive program, and off I went again.

It’s safe to say I probably haven’t stopped smiling since. OK, so the program I chose was possibly slightly too sharp in that it seemed to leave a bit of a hole at around 6500 or so, but anything after that the thing took off like a firework rocket – one moment just a bit of fizzling and burbling, the next moment, whoooosh – gone. Brilliant fun.

And I probably should have left it there really. Just enjoying things. But on Saturday, I popped down to see the splendid chaps at Cambridge Motorcycles as they had an RC30 in for servicing, and I wanted to have a look. (As an aside, if anyone has an RC30 that they’d like to sell to me for £4.62, please do get in touch. It’s still my perfect roadbike, and would take slot #2 in the fantasy garage next to the Britten V1100). So I turned up, and Spike took one look at the new pipes, gave me the keys to the dyno room, and told me to get it run up. Now, I’ve never operated a dyno before. But what’s the worst that could happen? Well, as it happens, quite a lot. It’s pretty easy to lose a leg in a dyno room. Or, worse than that, blow up your engine. But, none of that happened. A few dyno runs later proved that the new pipes were just what I needed, with a nice smooth curve right through the revs. The programmable YPVS unit definitely made a difference, lopping 10% off the peak power when I set it to stock settings, and I had a pretty lean midrange. Time was against me, so I had to leave it there – but when I got home I raised the needles a couple of notches to try to richen up the midrange, and also took a look at the reed blocks as I suspected a small leak there. Indeed, I found a bit of old gasket stuck to the back of one of them, which maybe didn’t make any difference, but definitely wouldn’t have helped. However, all was not well in YPVS world… when I switched the ignition back on, there was nothing from the YPVS motor. Not a sausage. Sure enough, it had blown the fuse. Which was odd – I’ve never seen that before. I replaced it with another 5A fuse, but still nothing. Fearing the worst for Rik’s programmable YPVS unit, I swapped it for my standard one, and sure enough, the motor sprang into life. So I did the only decent thing, and went out for a ride. And it’s safe to say that the changes worked. It’s now beautifully smooth and clean, from 4000 all the way up. And while it’s noticeable that the top end is a little bit less frantic on the stock YPVS unit, I can live with that. For now. That’s the problem with power. It corrupts. Now I’ve seen what’s available by twiddling the powervalve timings, I want more. A taste of honey is worse than none at all.

PS. Sorry Rik.

 

 
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