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The story of ThorCap

When I was restoring my vintage motorcycle, a BSA M33 from 1954, I bought an "original" condenser (capacitor) for the ignition system. During my first trips on the bike, there already appeared to be problems with the motor. When the speed was above 70 km/h the engine began to misfire. Several things were examined on the bike, and it turned out to be the condenser that was causing the problem. When the engine was warm, the problem was particularly bad. We got hold of a new "original" condenser (again) and it ran without problems for a few days, then the problem was back.

I would like to keep the motorcycle close to 100% original, however, many replica parts of a restored vintage motorcycle corresponds more or less to the original ex. hoses, oil, bulbs, spark plugs, brakes, chains, voltage regulators, condenser etc. This does not have any effect on original appearance of the motorcycle. Most importantly is that it can start and run without ignition problems! I took matters into my own hands, and the first copy of the ThorCap condenser was made. I am a qualified electrical engineer and work with power electronics, so I know about capacitors and their properties. The choice fell on a ceramic capacitor of the highest quality. These are typically used in circuits with high voltage changes (can handle high dv/dt), high temperature and where a compact design is required. Furthermore they do not dry out like some other capacitors do over time, why these capacitors life is significantly longer. Finally the selected condenser type has an operating temperature up to 125 degrees Celsius.

I decided a double insulation in the condenser. In the very unlikely event that a single "630V cell" in the condenser breaks down, I would then be able to continue to run the motorcycle until I got the opportunity to change it (which is nice if you are far away from home). Further, I wanted to ensure that the capacitor could handle high voltage spikes that can occur over the contact breaker, so I chose 1260V. The capacitor is able to withstand 1890V for one to five seconds (less than 50mA and discharge current). 1260V continuous isolation might be "overkill" but I wanted the ThorCap to be a particularly robust condenser. This increases production costs, since four times as many ceramic capacitor "cells" are required to achieve the same capacity with double insulation voltage (1260V), but this makes the ThorCap the ultimate rugged and durable condenser.

Since the first ThorCap was tested on my BSA, a large number of vintage motorcycles and cars from different brands and ignition systems have been driven tested with customized variants of the ThorCap successfully.

Many miles have been driven with the condenser over the past two years without any problems.


My BSA M33 from 1954


I assemble and test all ThorCap condensors, so I can personally vouch 100% for the quality.

ThorCap - the ultimate condensor. 


Thor, the mythological god who had the ability to control lightning