Honda VFR400 NC30 valve clearance and carb balance

By 25th June 2012 Honda, Servicing

The customer who owns this NC30 phoned us up recently; he’d been struggling to find anybody to touch it. In the heyday of these bikes we’d be doing one or two a week and built a good reputation for looking after them well.

Usefully, we worked out then how to get them to pieces quite quickly, which really helps on the cost front. This bike needed its valve clearances sorting out, which we did, and they were out of adjustment. The valves were straightforward, the tricky aspect with these V4s is balancing the carbs; not easy. The bike ran like a bag of spanners, purely because the carbs were out of whack.

As per usual for carb balancing vacuum gauges are needed, but the procedure is hard work because of the engine figuration. The ‘fixed’ cylinder is the front left hand cylinder, and you sync the others to it. It’s not simple because there’s a rod joining the front bank to the rear bank; you get the two rear carbs right but then they’ll be out of sync with the front left… you have to work in a backwards manner, and it takes a while. When it was done we were pleased – it started, ran and idled a treat.

There’s plenty you can do at home, on a bike like this, all we’ve done is the stuff that the average home mechanic would be shy of.

We used to do plenty of these, and still remember how to get 'em apart quickly!