Many countries have lead replacement fuel for pre-74 vehicles.
The quality and suitability for an Interceptor probably varies
between countries.

Here in Australia, there are some that use Premium (higher octane)
leadfree petrol plus a separate additive, instead of the lead
replacement fuel off the bowsers (lead replacement which I think is
some calcium derivate).

Reports vary about the lead replacement options, from them being a
bit of an unnecessary scam, to being simply not good enough.
Always remembering that leadfree in one country may be quite
different to lead free in another, as well as the lead replacement
fuels, Nevertheless:

For this knowledgebase, we consider the following:
A) Simply just running on lead free
B) Examining results after having had to switch to these lead replacements fuels they sell at the gas stations.
C) Any Internet resources or articles with experiences on the subject, especially for British Motorcycles, like Interceptor, Norton Commando, Bonneville, etc.
D) Engine modifications in order to be able to run lead free, like harder valve seats, different timing settings, different jets, change of compression ratio, different oils, additives endorsed by un-biased third party, like larger Classic motor clubs and any other measures.

Whilst also interesting to debate theories or stories from friends
heard third hand, maybe it's best to stick to experience, like for
instance and example an owner could say:

I live in France and have used lead free fuel as it is here in my
1969 Interceptor for 22000 kilometers over three years, after which
close inspection revealed NO excessive wear of valves or pistons and
with normal wear of sparkplugs. I even had less carbonisation. My
style of riding is touring averaging 140 k/ph on Freeway and 110 on
other good roads, sometimes a bit fast and aggressive. I have seen no
reason to be concerned.

One thing is, that the Lion part of the Interceptors went to the U.S
and Canada, which started leadfree early. How early? Are the original
valve seats hard enough?

All input on the topic will be included in this knowledgebase, in the

Thanks
Royal

I'm located in Canada, and from my personal experience in riding various Brit bikes, the stories of valve and seat damage from lead free fuel are highly exaggerated. My current Series 1A is very happy running lead free fuel, with no ill effects to date. I have about 5K miles on its rebuilt engine.

The seats are stock, and the inlet valves are NOS. I made the exhaust valves from stainless steel blanks which had hard-chromed stems. For both inlet & exhaust, I optimized the rocker geometry by altering push rod and valve stem lengths, and I also fitted hardened end-caps. I've only had to adjust the valves once since re-assembly.

.. gREgg



I'm in New Jersey,USA, and I've been a motorcycle mechanic for 30 years, and I can corroborate G.R.'s experience. I've seen engines with 30,000 and more miles on them, and the valves and seats are usually not the worst parts I find.

The guides wear, pistons & rings wear, etc. but the valves and seats usually show a predictable and repairable amount of wear. In the states, we just run 'em on what comes out the pump.

Bob A

Tyre Choices for the Interceptor
I use Metzlers on my Series 1a, and as long as you still have an 18" rear wheel, you should have a good choice of sizes. I use an ME1 on the rear, and an ME33 on the front .. they handle very well, look good and wear well too. Both are available in various aspect ratios. About the K70s be sure that they are ofmodern manufacture. The new ones are made from a far superior (Japanese)rubber than the old Brit ones. The main problem with K70s is that when usedon a front end, the tread tends to get scalloped (and lumpy) long before it wears out.

.. gREgg

You can still get Dunlop K70's I think. Made in japan now, not England. They where the original tires on my 65 Series 1 when I bought it .They handle well enough in the wet and dry given the bike's not a crotch rocket, and they look great. Interceptors take 3.50s on the front and 4.00 rear. I put Dunlop K81's on my Series 2 and they are probably even better handling but look much more modern.

I guess you can take your choice and not go wrong! Personally I'd go for theK70s, I have one on the front of my 68 TR6C and a new 4.00-18

Don L

Used Metzelers and K70s on my Triumph (RE is still being
restored), I'd say the Metzelers are much better for handling.

However, the K70s are decent and give a much more authentic period, British
look.

Bob C