This old GSX-R we’ll badge as an ongoing project as the owner’s still having some problems; he brought it in initially for a Dyno run a long while ago, and we found it was running over-rich, mainly on three cylinders. At some point in its life it had had a Dynojet kit fitted, but the carbs were basically knackered with leaky needle valves.
We advised the owner to get a good stock set of secondhand carbs, which unfortunately are now as rare as hen’s teeth as these bikes are now over 20 years old. He found a set, eventually, and we effectively built one good bank of carbs out of the two. We got the bike running OK and got the horsepower back, and while he wanted some other work doing we held him off a bit and told him to run round on it a bit to make sure it stays fine.
On the way home from here he ran out of petrol, so we’re not sure whether some sediment from the tank has made its way to the carbs, as he did a further 100 miles and it was perfect, then took it out and it started spluttering again. But, one of the truths of this particular case is just because you fix one thing doesn’t mean you’ve cured the problem overall.
On an old bike like this, even though it looks tidy, is that you’re likely dealing with a rotten wiring harness and this one has had various coils fitted, including the 3 Ω Dyna coils fitted now (standard is 2 Ω) which tend to overload the standard CDI unit. Also, the standard airbox was long gone, with individual K&N filters fitted in place – fashionable, once but not overly useful for usable road performance.
So what you see is not always what you get, especially with an older bike. We’ll keep you posted on this ol’ gurl!