Lead Replacement Petroleum 

(LRP) Fuel

In the early days of motoring there was no lead in the fuel. After the Great War WWI there was a need to build aero engines with a higher power output. This led to higher compression ratios resulting in the problem of pre-ignition. The answer to this was to add lead to the fuel. This had an added effect of  placing a coating on the valve seat faces which reduced the added wear caused by using heavier springs and higher revs. The valve seats were generally made from iron whereas the valves from steel, and so it was always the softer iron which would lose out. After the World War II motor vehicles on the road became more obtainable and the public were also looking for more performance, so the same technology was applied. 

This was OK until traffic on the roads grew to higher levels in the 1980's and lead emissions into the air became a concern. Unleaded fuel was introduced at the pump and vehicles were manufactured to run on it. Leaded fuel was finally banned on the forecourt from about the year 2000, although the greatest offender the aero industry still has leaded fuel. This created a problem for the classic vehicle owner as most modern vehicles had now fitted steel valve seats and were set-up to run on unleaded fuel, but not so the pre 1980 engines. LRP was offered on the forecourt as  one way forward. The other being an additive which is mixed with ordinary unleaded pump fuel.

LRP Pump Fuel

LRP is basically a fuel with the additive already added. It is generally available at most petrol stations. If you use any of the LRP fuels available at the pumps you will probably have to retard the ignition slightly to take account of the lower octane rating and this will result in a loss of power. You must not swap from one LRP pump fuel to another, as they use different chemicals which can cancel out the effects. 

Fuel Additive

There are several fuel additives which you mix with normal unleaded fuel and again you should choose a make and stick with it. The one I use is Castrol Valvemaster Plus is available from motoring shops like Halfords. The Plus means that it has an octane booster which means that you will not have to retard the ignition. The down side to additives is that you have to carry the bottle around with you, but you can mix it with any make of unleaded fuel. You could get the standard Valvemaster and mix it with Super Unleaded fuel to achieve the same result or mix it with normal unleaded, but you would have to retard the ignition.

Replacement Valve Seats

If you are planning on using your bike on a daily basis, you might find over a prolonged period of time that new valve seats would be the answer. There are many specialist companies that will remove the old Iron seat and fit new Steel seats, but the cost of such work does not come cheap. So unless you are going to do a high mileage, this is probably not the way forward.