Hitchcocks Forum

What is the experience and consensus about petrol additives; lead replacement ones. For my 1961 Crusader 250, would this be a good idea, considering the ethanol situation?

This is a subject that people will have differing views on.

Given the age of the bike it was probably not designed to run on unleaded, unless you have had the valve seats changed.

So assuming that it is still has the same seats using lead replacement additive would make sense to protect the seats - especially if you are going to use the bike hard.

Some additives also contain an octane booster - so if you have any pinkiing issues it might be worthwhile using that.

As I say, someone will probably be along with a different point of view, but if it was me I would as a minimum use a lead additive to protect the valve seats - especially if you plan to use the bike hard.

I have a 1956 Bullet engine in my Crusader, I just use Super Unleaded as it has less ethanol in it and nothing else. I have never had any problems with valve seat damage.
Being an alloy head, it does have steel inserts as standard, I think that valve seat recession is more of a problem with cars that have soft cast iron cylinder heads.
I used to run a Land Rover with an alloy V8 engine, I used normal unleaded in that for years without problems.
The worst case scenario is that you have to fit a hardened exhaust valve seat to your existing head if you experience problems.

An additive is OK for a temporary fix, I suppose, but I have seen a number of vehicles with valve seat recession problems. My Indian home market Bullet 350 WAS one of them. When I bought it it had just 3,000 miles on the clock but it lost compression on a regular basis. I got used to resetting the tappets at the side of the road - the exhaust valve clearance kept on closing right up after about 50 miles. Coupled with its ongoing fuel starvation problem, which I eventually cured by fitting a "concentric" carburettor, I suspect this is why the bike had 4 previous owners!

I stripped the top end and was amazed how far the exhaust valve had recessed in the seat, as if the latter was made of something only slightly harder than aluminium. The only cure was an engineering one so I had a hardened valve seat fitted, job done. Unless the engine has a very high compression ratio, it shouldn't pink - especially if super unleaded is used.

So...I think I will leave it, not use an additive. Thanks.

Hi I use Castro calender in my crusader and bullet. It seems also to stop the petrol going stale, i also use the highest octagon possible both bikes run well on it.

Steve, maybe I give that a try this weekend, thanks. If I can fine any that is.

Sorry just read my post it should say Castrol valvemaster.

A mate of mine who even runs pre-war stuff reckons it doesn't cost any more to fix a head with valve recession than to modify it to take unleaded. The fix is exactly the same (fit a hardened seat) so he just keeps an eye on the valve clearance. Apparently some are totally fine, others have problems and he has them done.

I have heard tales of some of the phosphate lead replacement additives producing quite tenaceous deposits in the top-end.

Ethanol is another matter. I've even had japanese bikes suffer from problems with ethanol. One actually caught fire when I was riding it because of ethanol corrosion causing a needle valve to stick open! Luckily it self-extinguished leaving a large hole metled in the airbox.

My VFR750 is a 1991 bike and it's not designed for ethanol fuels either, it attacks the fuel lines, fuel pump and carb internals.

As such, I'm using frost automotives anti ethanol additive "Ethomix" in it. Especially when it Europe where E5 is standard and E10 is usually placed next to it. It's also a fuel stabiliser so parking it up with a full tank of stabilised fuel overwinter is my go-to strategy. Unstabilised ethanol fuel will tend to split over time, leaving you with a layer of rusty water at the bottom of your tank.

What I would do at a minimum for your own safety is make sure the fuel line is ethanol safe. I fitted a piece of old (but unused, stored in a jiffy bag inside) fuel line on my 350 bullet and it went like playdough. Broke off under the clip while parked up overnight after the first ride. Luckily I turned the fuel off or it would have been all over the garage floor!

Fortunately for enfield owners, there are fewer complex parts ethanol would damage and most are in the carb. Most are amals and they are still making them new in an ethanol-proof form. So if you have an issue, it's easily fixed.

Octane boost? I get pinking on my 612 bullet if I use standard unleaded so I've started carrying a shot of octane booster. On the advice of friends who are running highly stressed, race-tuned, japanese endurance bikes competatively, I've been using Royal Purple octane boost.

Personally I have never experienced valve seat recession in 20 years of classic biking on mainly Triumphs. However I do know that others have suffered from this problem. I have therefore never used lead substitutes in the past.

The Crusader may be a different proposition. Because ethanol eats glass fibre tanks (and I’m not 100% confident of the effectiveness of liners) I use alkylyte petrol without any additives on my GT’s. Due to the expense I obviously do not do much mileage!

I have not suffered any valve seat recession yet and hope that remains the case. The Crusader has an odd- one piece valve seat arrangement which is cast directly into the aluminium head. Replacing an exhaust valve seat may therefore be tricky – I’m not sure how it would be done. For that reason using an additive may be advisable to avoid the issue arising in the first place.