Hi guys

The ongoing saga of my NSR track bike continues. I've replaced a melted piston, fixed a couple of coolant leaks and for 99% of the time it running fine (actually better than fine cause it feels super quick ). But i'm having some trouble with what appears to be fuelling on one particular corner at my local track, eastern creek, and i'm after some help.

Coming down the straight, i've been just about maxing out 6th nudging 12k rpm (stock gearing/sprockets). I back off at about 150m for turn one, coast into it the corner then gently wind on the throttle about a third of the way through (still in 6th, maybe 9k rpm). The problem is that when i get on the gas again, it feels like it's running out of fuel for a second or two, then it kicks back in and takes off towards turn 2.

Any ideas what could be causing this? It's a long corner, and i'm probably doing it at about 160 i guess, is it possible that the constant lean angle and no throttle for a couple of secs could be causing the carb bowls or something to get low on fuel? Or going from 10 secs full throttle on the straight to a few seconds shut off could cause it? And before anyone says chek how much fuel i have in it, i went out with my tank full to the filler cap. It's really affecting my confidence because i'm anxious about getting back onto the power as i'm worried it will all come in a rush mid corner. I tried turning the idle up to keep the throttle a little open but that didn't help.

A friend recorded me for a lap (on a still photo camera), you can kinda hear it getting a little irratic at the end as i get back on the gas. Not sure if that's the problem though, and please ignore the average camera work!



Once again, thanks in advance everyone for the help!


PS.. for those who don't know the track, its the first corner at the end of the straight on this video: http://www.youtube.com/watch?v=8qtQA_zjgrk (great race too
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BJ

First thing I would do is check the float bowl heights. If they are out, it's a simple job to bent the tabs on the float to increase the amount of fuel in the bowls before the flow is cut off, this will help to avoid fuel starvation.

If it wasn't just in one corner I'd suggest you also look at the needle, size and circlip posityion.... It's less likely to be the problem, but you could try changing needles or the circlip position. The safe route first is to put the needle circlip a notch lower down to richen it up in the midrange (9k was the problem area you said) and if this makes it worse, go the other way. Take care though as if you go too weak you will seize.

Good luck

Dan

As dan mentioned, check your float heights first. I know this caused the same issue for me a couple times.

The other thing to do is to run all the time on reserve, or even better? Pull your petcock, and yank out the cooper reserve tube. Then it's always on. If your racing the bike all the time, getting some foam baffles in the tank can also help keep the fuel from sloshing around and causing "issues" on long corners.
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Charles Gallant