Practical Sportsbikes (UK)
Gary, MG, Jmac, Alan, and a has-been called Mark Forsyth
he problem with a drag meeting is you get limited track time – every run is obviously ten seconds, one clutch release and four gear changes wrong. You don’t get another lap to try stuff – if you get more than a handful of runs in a day you’re doing well. We usually end up sticking with what we know delivers the times, rather than testing a different approach that might, possibly, set us back.
I’ve been in and out of furlough with the day job recently, so I’ve had time to think about where to go with it. And I can now go places (in relative freedom, Peterborough being in Tier 2), so when Chris offers to share some time he’d booked at a local airfield for a feature, I grabbed it.
I’ve been wondering how the bike would react to shifting at different revs
– we’ve been hitting the airshifter at about 10,000rpm, but it’ll go further than that. Or maybe less – it’s a big grunty motor, so it might be better to lean on the torque more.
It was a bit disappointing when the day came and it was hosing with rain, but Chris assured me it’d be OK. We wouldn’t get the bikes out of the van at a meeting – a drag strip is covered in rubber that’s super sticky in the dry, but like ice in the wet. But the airfield is graded, abrasive concrete that’s kept clean, so it’s way grippier in the wet than most places. So, I got wrapped up, Chris taped his datalogger on, and I got on with it.
I tried a few runs shifting at 9000rpm, before experimenting with 10,000, and then 11,000. It was obvious, without checking what the computer said, that it liked the extra revs, especially with cool, damp air to breathe. It was absolutely motoring. Thinking about it, a lot of tachos over-read anyway, so 11,000 on the dial is probably nearer the 10,000rpm you’d see on a dyno’s accurate display, and it’s where peak power is going to be, so that makes sense.
One issue the back-to-back launches created was clutch slip – usually the heat from a hard start is long gone by the time you go again, but I was doing two a minute, and all the slack went from the clutch. It was OK if I stopped and went again, but it does show the clutch is on the limit of what it can take. So I put the money down on a lock-up clutch I’ve been considering for a while anyway – it’s the right time to try and get more out of the bike anyway.
Talking of things getting out of the bike, the cold must have got to me: I handed it over to Newbigging – and then winced – it only went and missed a shift from third to fourth, just as my GSX1100EX did when he blew it up… The Bandit motor was fine though, no piston smacking the head this time. It was the same old issue – not quite enough pressure in the air-shifter tank. A few extra seconds allowing the onboard compressor to pressurise itself enough for four shifts was all it took. No harm done, unlike last time. But I’m not bitter.
He brought it back in one piece, impressed by it. “It’s much faster than the GSX once you’ve got the clutch out, it pulls harder and longer. When it has a lock-up like the EX had, it’ll really go.” Then he pulled the logger off the bike and went though the figures. It confirmed what I felt – you could see which runs he’d gone from 9000 to 10,000 on, and
then to 11,000rpm. It got faster and faster. Although I’d not actually managed to complete a full quarter of a mile – with no finish line
I’d shut off a a bit early so we didn’t get the usual end time and speed. But the 0-60 and 0-100mph times fell and fell.
The Bike Destroying One managed the fastest time. I was impressed, though I didn’t tell him that. On wet concrete, it did 0-60mph in 3.19s. He reckons his R1M on a dry day (short and tall admittedly, but over 190bhp too) after loads of runs, hit a best of 3.1s, and Michael Rutter/richard Cooper can do just under 3s on their superstock bikes. Considering we have about 120bhp, I’m pleased – it demonstrates the bike is already strong off the line. But resetting the shift light at higher rpm, plus that lock-up clutch, should get it doing the quarter a bit faster.
I HANDED IT OVER TO NEWBIGGING – AND THEN WINCED – IT ONLY WENT AND MISSED A SHIFT FROM THIRD TO FOURTH