Unleaded in old bikes

[Tenko]

Hi,

I went across to look at an old Triumph 350 'Bathtub' with a friend today. He asked the salesman whether it would take unleaded petrol, and the salesman didn't know. I asked whether the engine had been 'done' so it could (pretended I knew what I was talking about - really I know Jack about old bikes...), and he said he didn't know.

To cut a long story short he bought the bike and it is to be delivered this week. Trouble is, he still doesn't know if he can run it on unleaded or if it will need an addative of some kind.

Any help would be much appreciated!

[Bloggsy]

It will run on unleaded only though with lots of use the valve seats will wear most people use an additive others go the unleaded conversion route, that is new stainless valve seats and valves but that can be expensive I had a triumph head converted in 1998 and it cost me three hundred pounds. If your not going to use it as a commuter but only for nice sunny days just use it as it is with an additive, of course a previous owner could have had it converted .

[Tenko]

Cheers mate.

He is going to use it for sunny days only. He'd better get ont'net to source a suitable additive....

[mr jamez]

Castrol valvemaster is what I put in my MK2 escort. Pretty much the standard stuff to use in cars/bikes that need leaded petrol.
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NSR 125F > BROS 400 > NC30 > BROS 400 > Trumpet S4 > '97 VFR 750

[stinkwheel]

Most people I know with old Brit bikes just use unleaded in them.

To have an old engine made suitable for unleaded... you have to remove the cylinder head and replace the valve seats with hardened ones.

To fix an engine that has receeding valve seats due to running on unleaded when it should have leaded... you have to remove the cylinder head and replace the valve seats with hardened ones.

I think you can see where this is going.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[temeluchus]

May be worth checking if the bike is specced for old 4 star petrol, if so you may need to retard the ignition a little as well.

In the long run having the valve seats done would be a good idea-also a good excuse to overhaul all the valvegear.
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Some shite cruiser. Now with guns and FREEDOM!

[temeluchus]

Also, you can probably just replace the valve and seat on the exhaust side as that's where they really suffer.

My old R100/7 motor fried its exhaust valves after a nasty bit of recession, but the inlet valves looked to be in excellent nick. I replaced the exhaust seats and valves to suitable ones for unleaded and the bike is running fine. The inlet valve still shows no obvious recession and the engine has over 100k on it.
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Some shite cruiser. Now with guns and FREEDOM!

[Tenko]

Thanks folks - I shall pass your words of wisdom on....

[hmmmnz]

a tspoon of kerosene with every tank,
sorted
also handy for keeping the mozzies away as well
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the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

[.Chris.]

I've got an old car which originally ran on leaded fuel and there's several schools of thought as to what to do.

1) Stinkwheel's suggestion - run it until the valves/seats burn out, and either swap another head on, or have the existing one converted. This is a particularly good option if heads are cheap and readily available, as even if you do manage to completely bugger one up, you can just put another one on. Valve seat recession also tends to take many thousands of miles to show, so if you do a low mileage it won't be a problem for ages.

2) Use additives. Be careful what you buy if you decide to do this, as not all of them work properly. The FBHVC did tests shortly before leaded fuel disappeared and not all of the additives tested worked correctly. Castrol valvemaster is approved, and readily available. Costs about £10 for bottle that treats 250l of fuel, so adds about 4p/l to fuel costs. Don't bother with any of the 'fuel catalyst' things you put in the tank - they're pure snake oil.

3) Have it converted. Shouldn't cost too much for a 4v twin - £300 seems very steep, seeing as I had an 8v car head converted for £140 a few years ago.

Any of these routes are equally valid to be honest. If he's only using the bike occasionally, and being gentle with it, I'd be tempted to go with the first suggestion. Particularly so if he can find a spare cylinder head to keep 'in stock', ready to swap over.
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Chris
1985 Kawasaki Z550F

[HD]

When was unleaded fuel first introduced and leaded abolished? And why?
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Rusty '02 Vito Camper + CBR600F3

[reggie]

https://lmgtfy.com/?q=leaded+petrol&l=1
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when the shit hits the fan make sure its facing the other way.

[Kickstart]

[HD]

Thanks! So when looking at bikes (and cars) around mid-late 80's and below I should check the fuel type?
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Rusty '02 Vito Camper + CBR600F3

[Kickstart]

Hi

Less of a problem with bikes as most were built also for the US market and so needed to cope with unleaded. Think it is any bike built post 1976 from Honda (for example) that is OK for unleaded (although quite often bikes might have been built before that but not sold until afterwards - possibility that all the CB400/4s fall into that category).

The lead was added to increase the octane rating, but was also found to protect valve seats allowing cheaper ones to be used.

A hell of a lot of bikes do not need even 95 RON fuel, so the octane rating isn't an issue for them (exceptions are mainly European bikes). However it was a problem for cars but most can easily have the ignition timing adjusted to cope with unleaded rather than 4* (will lose a bit of power).

The valve seats are a bigger problem but only to far less vehicles. Without the protection from the lead residue they wear out (and one they start they will fail to seal and burn out even more quickly). You can avoid the problem by either using a suitable additive or replacing the valve seats.

If you are looking at a 1980s car then it almost certainly will have had the timing retarded by now, but might not have had the valve seats done.

All the best

Keith
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