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[Ivor]

Finally got my Super Meteor running and MOT`d. Trouble is it smokes like a steam train and seems to leak from just about everywhere. Oil was even coming out of the exhausts!

I didn`t build this bike but bought it from our hosts as an unregistered non runner so did expect a few problems.

Today I pulled the heads and barrels off as I guessed the ring gaps were not set 120 degrees to each other. Sure enough the oil ring and second ring had their gaps aligned while the top one was set different. I`m hoping that this is why the oil was going down the exhaust and the other leaks were from the head gaskets. I have replaced the little ball valve and spring that`s in the timing case as I had no oil feed to the rockers when I first started it.

I have a Bullet that I know inside out but am unfamiliar with the twins.Is there anything else I should check while I am in there? I have about 4-6 weeks, hopefully, before I get my reg number so time to sort any problems.

[stinkwheel]

Check the crankcase breather isn't blocked.

[vince]

Hi, check the scavenge oilways are not blocked and try running the engine with the oil cap off to ensure that you are getting correct oil return. The chances are its wet sumping. Vince

[Ivor]

I don`t think the oilways are blocked. I have run it with the cap off and there is a good pulse of oil coming back into the filler neck.
Which way does the breather work? From the side of the crankcase round to the top behind the barrels or the other way round. I did replace the breather discs in there and scraped out a load of blue hylomar. Perhaps I need to have another look at it.

[stinkwheel]

I mentioned breather because positive crankcase pressure is one sure-fire way to make a motorbike engine piss oil out of every orifice and seam.

Not sure on the complexities of how the breather works on an enfield twin but if there is a slight vaccuum in the crankcase, the oil will want to stay inside it.

[Cranky]

Would be nice if one piston was going up while the other is going down= kinda even it all out except for leakage.

I don't know if the Re does this ---does it? I would imagine it does or an ideal opportunity for a low breather would be lost.

2 going down at the same time would be very silly.

[vince]

Hi, the pistons go up and down together. So do all classic british vertical twins . It give an even firing. With regard to breather pulses its the same as a single. Vince

[Presto]

The new 650 RE twins have a staggered crank. Generally Japanese lightweight twins had a 180 degree crank (one up one down). This always seemed to me the better arrangement. The following may be of interest – not all my own work!

The new Enfield 650 twins have a 270 degree crank, a wise choice and the configuration of the Enfield engine crank and balance shaft seems directly derived from a very successful Yamaha twin. The 270° crank is a fairly recent development of the straight-twin engine, which imitates the sound and feel of a 90° V-twin, but requires a balance shaft to reduce vibration. Effectively, the 270° crank is a compromise which allows a more regular firing pattern than a 180° crank and less vibration than a 360° crank. In a 270° parallel twin engine, as with a 90° V-twin, the pistons are never both stationary at the same time, thereby reducing the net momentum exchange between the crank and pistons during a full rotation. The oscillating momentum manifests itself as an oscillating crank rotation speed, which, when paired with a driven-wheel rotating at the more steady road speed, will introduce an oscillating torque in the drivetrain and at the tyre contact patch.

Examples of 270° parallel-twin motorcycles have been the Donnington Norton Commando, Triumph Thunderbird, Honda CTX700, and Triumph Scrambler.

A feature of the 270° parallel twin is that it provides most of the benefits of the popular V-twin layout, along with further advantages: it is simpler and cheaper both to produce and to maintain than a V-twin; it needs only a single cylinder block and head; induction, exhaust and cooling are simpler; the engine is lighter and has better potential for an optimum CG position; battery location is easier; rear suspension design is simpler; and it allows a shorter wheelbase for sharper handling.

Yamaha devoted much time and effort to the “quality” of the torque produced by the 270 degree engine. While analysing the power and torque produced by combustion inside the chamber, a theory emerged: maybe the unevenness in the torque curve is created by the forces acting on the two moving pistons when converting the power created by combustion into drive force.

This led the team to alter the angle of the two connecting rods where they couple to the crank, and the prototype engine they produced smoothed the torque curve. While doing prototype test rides in the Algerian desert, the engine’s uneven firing interval (combustion) resulted in a machine that was easier to ride. The torque characteristics were very similar to those of a 90° V-twin, but the new 270° engine was shorter in length. This parallel 2-cylinder engine configuration represented an innovation.

Norton Motorsports' earlier prototypes had 360-degree crankshafts, like the original Commando. "We were aiming to retain the classic Commando sound," said R&D; chief Paul Gaudio, "but even with a counter-balancer, vibration was too intense. That's why we switched to a 270-degree crank."

[Presto]

A very nice picture of a very nice engine!

[stinkwheel]

The yamaha in question being the TRX which do indeed sound very nice.