Went to see Ken Fox's Wall Of Death fairground attraction at the weekend.

Two big vintage Indian Chief motorbikes, three old Hondas and a GoCart racing around nearly horizontal.

Now I know the tyres are pressed into the vertical wall by centripetal effect (centrifugal force as was) and that also presses the rider into the seat and the fuel to the bottom of the tank and into the carbs, so why did the Indian Chief bikes backfire, but the Hondas run smooth?

GoCart was well behaved too. (Perhaps it had a Honda engine).

Edited 10 September, 201214 yr by dvderlm

I recon they'd have probably backfired upright. Unburnt fuel in the exhaust doesn't strike me as a fuelling issue, but one of ignition.

Unless metal floats in the carb, compared to Honda's plastic floats, were more sensitive to stronger gravity and caused carb flooding - and rich running as a result?

Float weight - maybe.

They tended to backfire as the rider eased off before nearly running off the top of the wall.

Very impressive inches away from you.

Read about V twin bikes not having air cutoff valves, but Honda's do.

Witout air cutoff cam overlap lets air and fuel through to the hot exhaust on deceleration.

They definitely were not braking or declutching at that point.

v twin backfire

I've heard about that sort of backfiring before - in fact a mates Pulsar used to pop blue flame initiated by a lift-off of the throttle, he could just tease a little mixture into the exhaust and it'd pop. That certainly due to the modifications (around 300bhp).

I've never worked on bike engines, myself.

I've not worked on Japanese engines.

Though I once had a Mazda 323SP with go faster stripes which backfired its way down hills in Scotland.

Thought you had bike carbs - Keihins I assume.

Edited 13 September, 201214 yr by dvderlm

Yep, never experienced backfiring though. But then, i've never driven the car up a wall.