Forum

[geoffro]

Hello Noddy,
With the modern two stroke oil you need 150ml to 5 litres of petrol so get yourself a measuring jug as filling the long cap of the Bantam is too much. I have a ex GPO Bantam and i find that one thing they dont like is stale petrol so after a ride i drain out what is left and use it in my lawnmower.

[PeteF]

I agree, too much oil. Running it for short periods in the garage is not good either. You'll find fuel can build up in the crankcase if the engine isn't warmed up.
One of the best tune up's for a two stroke is a good thrashing.

[papasmurf]

Evan back when I had Greeves 250 (1964) the stated petrol oil ratio in the manual was too much as even then oil technology had moved on since the bike had been manufactured. The manual stated 16-1, this is the current advice:-
http://villiersservices.co.uk/index.php ... ucts_id=37

[jefrs]

A carb and injector cleaner spray will remove the gum and varnish but some RedEx in the tank will do the same thing, plus it has a 'petrol preservative' to stop the petrol going stale. The carb slide needs to slide but removing too much of the 'varnish' will make it gappy. On other vehicles I've found using Shell VP clears injectors (jets) out nicely after being forced to use cheapo fuel (which does fur them up); always use the very best fuel. Depending on model the Bantam can be rather high compression and needs a high octane (RON) fuel, too high is just right.

If the Bantam is only used for short periods it is better to use too much 2T than too little but it has to (must) be well mixed; rock the bike to mix the tank up every time or the 2T will have settled out and will plug the fuel hose; I dimly remember the complete filler cap measure is correct for a full tank 1.4 gallons(?), and is there not a 1 gallon mark inside it?. Put oil down the RHS of the tank away from the stopcock then fill with petrol, then mix it up thoroughly! It may look like a Villiers but it's not; the D14/4 I had was a fair bit quicker than a 350 Bullet.

If the bike has been laid up for a while it may be a good idea to add a little upper cylinder lubricant (UCL), 2T or RedEx, through the spark plug hole and gently turn it over, before putting the plug back in and attempting to start her up.

[PeteF]

I once had an ancient Seagull outboard which called for 10/1

[jefrs]

Just to add, do remember that the Bantam is a 2-stroke; the mains, crank and piston are only lubricated by the 2T in the petrol - modern 2T oils may be better but the Bantam lube distribution system is still very old school, you cannot skimp on the oil or you will get a knackered motor in no time.

[PeteF]

Yes, make sure the oil is mixed in but modern two stroke oils mix so much easier than in the day. They do not separate either.
You should be able to get chapter and verse about fuel/oil ratio from a dedicated Bantam forum.

[papasmurf]

Noddy unless I have missed it you have not specified which model year engine size Bantam. I also suggest looking at the Bantam owners club website when it comes to the CURRENT petrol/oil mix with modern oil.

[Barry_Q]

I've owned and ridden assorted Bantams for over 30 years. The important question has been asked: What model are we dealing with here? 1958 is just to vague. It could be anything from a D1 to a D5. D1's had their main bearings lubricated by the oil in the petrol. D10's and D14's had the main bearings lubricated by the gearbox oil. The correct ratio is 24:1. That's for 2-stroke oil. If you're using engine oil (Castrol GTX, etc. Don't laugh. It's in the book), the correct ratio is 32:1.

[jefrs]

Don't rely on even a D14 lubricating the mains with gearbox oil, they're not that clever. The gear box is behind the motor, you've got the alternator/points on one side and the primary on the other; the primary/clutch runs in oil but the alternator is dry, the oil is not pumped. The gearbox doesn't lose oil, so that oil is not going right through the bearing and it has to be oiled on the crankcase side too, to maintain the seal. A 2-stoke is designed with a gas tight crankcase, if you can't get gas through, you won't get oil through; the crankcase compression tries to blow oil from the inside outwards.

I cannot remember the 2T ratio. Yes use more miscible modern oil but, it's a buzzy motor, don't be stingy with the stuff or it will seize.