Mad Maximum
Getting one turbo to work on your Mad Max motorcycle is tricky. But two? Masochism, surely…
We admire a disregard for common sense so were heartened by James Kauder’s decision to fit twin turbos to his 1982 Yamaha Virago 920, transforming the unloved plodder into a Harley-eating apocalypse machine. We asked James what on earth he was thinking.
Bike: Twin turbos? Virago? Why?
James: My goal was to show people you can build something wild out of anything. I’d seen custom builders use Viragos and admired how they could make something so unique out of such a vanilla motorcycle. But I noticed a tendency for them to gravitate towards the same cafe racer style. I thought I’d try something different.
As for the turbos, I’ve built an assortment of single-turbo bikes, both draw-through [where the carburettor is on the inlet side of the turbo, like the Virago] and blow-through (carburettor in the normal place with the turbo pushing air through it]. I wanted to know if a twin-turbo draw-through would even work.
How difficult was it?
Initially I couldn't get it to make any boost. Then one day I had an epiphany and realised the cold side intake plenums [boxes to smooth out airflow] needed to be joined. This would double the plenum volume and equalise the pressure in both cylinders. After two days of fabrication, I took it for a ride, and the boost gauge swung to 8psi!
What’s the power?
I haven’t put it on a dyno but the generally accepted rule for forced induction is that power is double at 1 bar of boost [14.7 psi], so 8psi would get me a 50 percent improvement [on the 65bhp stock bike]. That feels right – from the saddle it feels like it’s got about 100bhp, which is pretty wild on a Virago.
It appears to have skis…
They are for sand riding in the dunes – they prevent the front end from sinking. They’re made from old rusty chains I welded solid, and are held on via clamps to the fork legs.
What’s the reaction been?
Mostly surprise and intrigue. It usually takes people a minute or two to take it all in. Online, a few people say ‘buy a faster bike’ but I think they’re missing the point. The purpose of customisation is to make something your own, to challenge conventions.
‘Initially I couldn’t get it to make any boost. Then…’
you can watch James building his crazed Virago by searching for Dr Motorcycle on Youtube. Beware: there’s no voiceover and the machinery sounds are addictive.