When John Ellwood sent in this first photograph (1), we weren't quite sure what it was we were looking at, but slowly, the story and concept behind this unusual looking motor developed.
This is my bike, a mixture of 2 and 4 stroke techniques. I have permission from both the F.I.M. and S.V.E.M.O. to test it here in Sweden. It's ran for 5 years without breaking, and has a brutal bottom end torque. The basic engine is Jawa, then I add two reed valves to crankcase and use crank pressure to pump to head. It's not supercharged in this single form, but would be if it was a parallel twin.
I have been working on this project since 1994, when I worked in Kazakhstan and had mega toothache because of -40c, drank a lot of strong vodka for four months, and dreamed about engine in a half delirium. I have heard that other guys have also had the same idea, but have never managed to get it to work properly.
Suck - Piston goes down, inlet valve opens, compressed mixture in pipe flows into cylinder. Piston pumps extra charge, via reed valve B and connecting pipe, to cylinder.
Squeeze - Piston moves upwards, compressing mixture in cylinder. Piston underside draws in new mixture via reed valve A.
Bang - Piston moves down, giving power and pumping mixture into connecting pipe via reed valve B.
Blow - Piston moves up, exhaust valve opens. Piston underside draws in mixture via reed valve A. [Image not available]
I race with M'chk old boys here in Sweden, they seem to like the idea. I am not a good speedway rider, but usually win my heats anyway, and I've actually never ridden a normal speedway bike.
The hybrid has given 46 hp in 1996 on Hasse Holmqvist's brake bench, he was impressed with acceleration, (he tuned ice racing Posa Serenius's bike). If i can make 200 engines, then I can then use them in proper races. Well so far I've adapted 3, but hope to cast my own crankcases next year, so I just bolt on the reedvalves and a bit of pipe.
John has also built what he names an Ellwood-Hybrid Supermono , with adapted Godden engine running on petrol and with Haltech injection. Despite his efforts, John has received no help from manufacturers to help develop this idea and has done the work entirely on his own, just maybe, someone might take an interest. John can be contacted at ellwoodhybrid at hotmail.com
Latest news is that John Ellwood now has his own website for the full story behind the idea and which includes the Weslake Hybrid, To see the pages, visit The Ellwood Hybrid pages.
1. Images are missing from archive.