Dateline, February, 2007


By Bill Hoddinott

Jon Wennerberg and his photogenic wife Nancy, of northern Michigan, have become familiar figures at Bonneville and East Coast Timing Association in recent years as fast and serious motorcycle racers both! The couple has a potent ZX 12R sportbike which got Jon in the ECTA 2 Club in June 2003 with a 203.454 mph pass and the Bonneville 2 Club with a record of 207.065 mph at Speed Week 2003. Nancy has run this bike at 185+ mph at Speed Week. They have been featured on Speed Channel Salt Flats TV shows, and Jon serves nowadays as one of the MC Tech Inspectors at both Maxton and Bonneville.

Your scribe's interest was especially piqued this summer ('06) by news that Jon and Nancy had finished the conversion of their stock '96 Kawasaki 250 Ninja into a full-race turbo bike and had taken it to Speed Week '06 where it posted some very respectable new records! Both Nancy and Jon rode it, recording marks of 116.076 mph with fairing, and 113.987 mph without in classes 250 APS/BF and 250 A/BF respectively. They returned to Bonneville for World of Speed later, and on September 14, 2006, Nancy set an even higher record in 250 APS/BG at 120.289 mph.

This model is of special interest to the present writer because I have covered over 100K road miles on my own '88, which is identical to their stock '96 as it was, and also to the '07 models presently in the dealers' shops. This little gem has been a great success for Kawasaki and is still sold in large numbers after 21 years production. It lists for $3K new, cruises at 75 mph forever, top speed stock is 100, and it gives 70 mpg in road use. It is a comfortable 300 lb bike that handles like a road racer and is very, very safe with powerful brakes.

  • Bill: Jon, thank you for agreeing to an interview for Bonneville Racing News about your new turbo 250 Ninja and congratulations to you and Nancy on the excellent records you have set with it already! I think there is much technical interest in the story of how you have converted such a small engine to turbocharged successfully.

  • Jon: Thank you, Bill; we've had a lot of fun with this little bike. We got it for Nancy to ride on the street a few years ago, and she liked it so much she started talking about turbocharging to get more speed and putting it on the track!

    Far as I know, no-one has ever tried to apply a turbo to one of these before, so it wasn't too easy to find a shop that could take on the job. I talked to a couple of them and we worked on it a while, but never quite managed to get everything to a practical racing form.

    But, we didn't give up. I knew we needed to use a Motec racing EFI computer for the turbo equipment. I asked Dave Dahlgren, who's the Motec vendor, for his recommendation for someone to do the engine building and turbo installation. Since the Motec system would have to interface with the rest of the bike we wanted someone that could work closely with him.

    Dave recommended Mike Rich, of Mike Rich Motorsports in Pennsylvania, so we went to see him. He turned out to be just the right man to handle the job. Mike built everything as you see it, and he came out to Speed Week for a few days and helped us run the bike. I'll put you in touch with him and he'll tell you what-all he did to it.

  • Bill: That'll be great, Jon, but first tell us what it's like to handle the bike and run it at a meet.

  • Jon: Well, first off the riding position is racier than the stocker. We have clip-on bars on the fork tubes two inches under the top clamp so we can tuck in as flat as possible. The stock fairings were replaced with a 250 Aprilia real racing fairing from Kent Riches at Air-Tech. This bodywork, by the way, is a bit skimpy for me, since I'm so tall. I stick out the sides and top of it. We need to do some more work on the fairing so I don't drag so much wind. It's okay for Nancy.

    We have Dunlop K591 V-rated tires on the original 16-inch wheels. These tires are the same sizes as the OEM tires, but a speed rating upgrade. And of course we have the regulation metal valve stems and caps in place.

  • Bill: What's it like to make a run with the bike?

  • Jon: One problem we ran into is that this 250cc twin is really almost too small a capacity to suit the smallest turbochargers available. Mike was able to make something work, but the result was a torque curve very much like the older two-stroke racing engines. It has almost no torque whatsoever at the bottom end, to the point that the rider has to be very careful starting off. You scream the engine and slip the clutch furiously, to get enough power to move the bike off in first gear without killing the engine. It takes at least 6000 rpm to make any power at all. We were in a rush-job mode, naturally, trying to get everything ready to go to Speed Week. One result of this was that the Motec wasn't compatible with the Kawasaki tachometer and we had no time to get something to match the two. So we had a rev-limiter at 14K which is the stock red-line, but no tach to use for starting and shifting!

  • Bill: I can see where you're going with this...

  • Jon: Right, it meant screaming the engine to start, then holding full throttle and running into the rev-limiter in all the gears and then shifting. This sounds pretty brutal, but Kawasaki made their equipment so tough that it's taken it with no complaints or failures so far. Nothing at all, even after going back out to World of Speed, except one cracked rear 520 chain link which we caught in time.

    Notwithstanding all this, once the turbo spools up and starts to put some pressure into the engine, the torque does jump up much stronger than stock. It peaks right around 10,000 rpm just like the stock engine does, and it pulls hard to the rev-limiter in all but fifth and top gear when the air load is building up. At Bonneville we can afford to wait for the limiter in fifth, even with the new "short-short" course, but at Maxton we re-geared one tooth bigger on the rear to get up to speed quicker. We ran nearly as fast there, even with the quicker gearing.

  • Bill: You and Nancy have set what I consider very good speed marks for a turbocharged 250 converted from an everyday road bike sold in large numbers to the public. How did you get even more speed at the WOS meet?

  • Jon: Bill, we used VP C16 race gas at Speed Week. The engine had been set up for that by Mike on his dyno, and ran in fuel class. At WOS we ran on ERC event gas, now in gas class, and somehow it gave a bit more speed. We don't really understand why, but we brought some of the ERC back so Mike can use it for more tests on his dyno and see what's going on. Most likely it's a simple matter of slightly different conditions of atmosphere and wind - the speeds weren't all that different.

    I think that's about everything I can tell you, so let me turn you over to Mike and he'll tell you all he did to the engine.

  • Bill: Jon, many thanks for this very interesting story!

  • Jon: You're quite welcome, Bill.
  • Reprinted with permission from Bonneville Racing News. Copyrightę, 2007 William Richard Hoddinott.
    Reproduction without permission of the author is prohibited.


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