Skoda Rally Blog

I’ve been putting the injection off for a long time. This was mainly because of the most difficult part to manufacture. There are some manifolds available for the Skoda engine to fit side-draught carbs (like DCOE and DHLAs), but they won’t help if you’re fitting motorbike throttle bodies. So the only option there is to make your own. Which sounds simple in principle – after all, it’s just four tubes, isn’t it? Unfortunately there’s a fair bit more to it than that – firstly there’s the issue of spacing – the ports on the head are in two pairs, which need to go to four reasonably evenly spaced ones. This makes things difficult. On top of that, the throttle bodies I have are 34mm I.D. and the ports are more like 25mm, so the pipes aren’t just off-the-shelf items, they’re tapered. Which is a pain to make. And finally (for now), the manifold needs to be strong; the mating faces need to be 5mm or so thick, and the tubes need to be thick enough to be strong, and also be capable of being welded to the thicker plates without problems.

Cutting the plates out proved to take a LOT longer than I initially thought – the two plates that fit to the head took about 3 hours. I gave up using the jigsaw in the end, and used a cutting disc on an angle grinder, and then grinding these rough shapes down to size. And then there was the big plate for the throttle bodies to bolt to (via GSXR1100 carb rubbers), and so on. I won’t go into the details, but it took a lot longer than I thought, and it’s definitely a “Mk.1” version; I think it will be functional, but there are some allignment issues which isn’t fantastic, but it’s the best I can do considering I was cutting the holes out with a hole-cutter mounted to a drill. Next time I’ll find someone sympathetic to make the plates up with a mill – perfect accuracy.

But it’s finished – there’s no vacuum tapping for the servo done yet, or inlet temperature sensor mounting, but that aside it’s just in need of some dressing and a paint. So here it is!

So, now I guess I need to get the fuel return sorted out, and get wiring! Can I really get this done in time?