This is a take off from a wikipedia discussion on leaded gasoline
Valve Wear Preventive
Would a lead substitute reduce the need for as many valve adjustments/checks?
- Tetraethyllead helps cool intake valves and is an excellent buffer against micro welds forming between exhaust valves and their seats Once these valves reopen, the micro welds pull apart and abrade the valves and seats, leading to valve recession. When TEL began to be phased out, the automotive industry began specifying hardened valve seats and upgraded materials which allow for high wear resistance without requiring lead.
So, yes lead additive would help but it's a band aid as opposed to a cure. Really, if you want to do it right, replace the valves with high quality valves and replace the valve seats. Now Scotch will tell you that you can get 100,000 kilometers out of a valve job before refacing, so why not just live with the issue?
The biggest problem is that little attention is paid to is the carb mixture jetting. Most people just live with how the engine is running and not make any adjustments to correct a bad running engine. Ultimately, if you tune your carbs for a brownish color sparkplug, you should be just fine. The trick is to run lean enough to achieve good fuel mileage and rich enough to keep the valves cool. Light brown sparkplugs is the happy place. white plugs are running hot and you're just asking for trouble. Most automobiles produced in the last 20 years run sparkplugs white hot and they can only do this with fuel injection managed with a closed loop system that continuously monitors the O2 and adjusts the fuel ratio based on a fuel map, engine temp, air temp, throttle position + the O2. So they are able to run extremely lean all the time BUT they also have components that can run hot all the time.
The Zn1300 fuel injection runs in open loop which means it follows a fuel map based on air temp, engine temp, throttle position and RPM's and the fuel map is conservative to the rich side because it doesn't monitor O2 so in reality it's not much better than a well tuned carb
So, what is achievable ?? As per the topic
Defeating the Enemy
Scotch has been able to achieve
52.84 MPG @ 100 KPH (max). .
6214 Kilometers per mile & 4.54 L = 1 Imp. Gal. Used all 3 decimal places
This is the 4th time for this mileage so now have a solid base-line.
Look out "55" .....Next year I'm coming for you !
( Double platinum plugs and Gold Plated Coil and Spark-plug connectors ! )
So, if you're not anywhere close to 50 MPG (imperial) You have work to do. If Scotch can run lean enough to achieve 52.84 MPG and get 100,000 Km out of a valve job and only have to reface the valves and seats without replacement, then you too should be able to tune to that level.