I used a little roots style blower. The brand was Hanson superchargers it was built for a 200cc Briggs go kart engine. http://www.hansen-engine.com/
It actually came with a plenum chamber. It was a crazy looking thing. Ran with that for a couple years then just ran with no plenum chamber plumbed with radiator hose. The hose would swell on boost. It ran best on methanol. It also was a draw through system. Apparently not the most reliable and tuneable option but it works I will try a round up a picture of my old bike
Jeez Blokey, you're a talented man. Was it quicker with wire wheels or the lightweight alloys? What was your best run? What're the records for ABF and ABG class?
Faster with the lightweight carbon fibre rims My fastest run was 84 mph. I was way over geared. If I had a better sprocket selection I think I would have been near 100mph. The records for ABF 99.9 ABG 105.5
That's beautiful. I think I have a front sprocket somewhere that has more teeth than the rear sprocket on your bike. I contacted Hansen last night and their VP of R&D said they couldn't help me with a supercharger for my engine. Not to worry, there are plenty of options for me to investigate and I'd prefer a screw rather than roots style supercharger. When was your last trip down the salt? Sounds like your bike might give the record a nudge with better gearing.
What about the small Japanese superchargers that the importers get in? They were used on 550cc cars like the Diahatsu and Suzuki cappachino. I have one on my historic open wheel racing car attached to a 950cc Morris Minor engine and fed by a 1 3/4" SU carby. It spins at twice crank speed and makes 8lb of boost (above atmospheric, 22lb absolute). They usually sell for around $100. To buy a new Lysholm screw type will be a few thousands of $$$$.
Hey Murdo, Yep, I need to make sure I can afford to do this. It would be great if someone had a bolt-on kit, but that's unlikely. Having seen plenty of drag racing trailblazers blow buckets of cash trying to make unusual combinations work, I'd prefer to spend a few extra up front and not blow anything up. You have to remember I'm not a mechanic and I'm drag racing for fun. I just think it would be cool to see how fast a 250cc 4-stroke motorcycle can get down the track. What brand is the supercharger on your Morris Minor engine? Does anyone have any comments regarding running a single carb instead of the four that are normally on the standard 250/4 engine? I'm assuming the manufacturers used one carb for each cylinder for a reason (other than upsetting FZR owners!). Frank
Haha yea it was a small rear sprocket. Hopefully you find a screw style supercharger small enough to work with your bike. As for the 175cc class I have make 40mm pistons and am getting a fzr260 engine sleeved down to make a four cyd 175. Huge amounts of work..... Just getting some machining done on the sleeves need to bore out notches for the valves then see what is next? If I can make it run, I should really bump up the record...
One carb per cylinder gives much better air flow than using a manifold with 90 deg bends. The little blowers are 'Aisain' brand from Jap land. They are a two lobe roots type with self contained oiling and driven by a multi rib belt. About 300mm long, 150mm high and 100mm wide. That is it behind the carb manifold under the silver plate. Only need one carb because only one intake hole in blower. Must always use a backfire valve (the triangular plate on top of pipe) to prevent blower damage in the case of engine backfire (the yanks call them 'sneeze valves' ).
Thanks Murdo. That might actually do the trick. I will do some investigation and see what I dig up. TURBO says a single 36mm carb so I'll need to see what's available there. I don't understand flow rates...if my bike has 4 x 30mm carbs, would a single 36mm carb be enough? I'm assuming I'll need to fiddle with my CDI to get everything working in sync? My head hurts.
Today was quite productive. My throttle bodies are in place and was able to do lots of temporary wiring for the new ECU. Now I have to wait for more parts an time... Hopefully I will be able to run the bike in about a week or so.