Forum

[Thack]

papasmurf writes: "Most British bikes from the 1960s still used and running have had a massive amount of internal re-engineering and modification, that can't been seen."



And external re-engineering, if aluminium patches on the crankcase count! I can recall at least two Brit bikes that punched holes in the crankcase after the conrod let go. Thus followed a trip to a local aluminium welder to get it patched, along with a week's wages to the local parts emporium for a new conrod (and maybe piston, valves, or even a secondhand engine). Legend around my gang was of a Triumph twin that punched a hole in the front, and hole in the bottom, and a third hole into the gearbox.

[Presto]

Another vote for Thack! Having had the joy of working in a dealers in the early 60’s I can confirm that the standard of engineering we saw on the early Hondas, Suzukis and Yamahas was light years ahead of what we saw on British bikes of the time. We had Honda 125 CB92s alongside a 200 James Sports Captain! A Honda CB450 aside a BSA Spitfire! It was light and darkness. Chalk and cheese! Royal Enfield Continental GT 250 and Ariel 250s were the pick of the bunch of the Brit lightweights but even they weren't anywhere near the imported lightweights.

[Thack]

Presto writes: "Royal Enfield Continental GT 250 and Ariel 250s were the pick of the bunch of the Brit lightweights"



My bro had a 250 Crusader which one day started making the most horrendous noises from the bottom end. When easing the engine over on the kickstart I could hear a "tick.... tick.... tick...." noise, which was intriguing.



When we stripped it down the primary drive side main bearing had failed. The cage was an ensemble of shards in the bottom on the engine. The ticking noise was from the ball bearings. As each one got lifted to the top of the bearing it would then fall freely down the other side, landing at the bottom with a tick noise.



The biggest surprise was the bearing itself - it was tiny compared with anything I've seen in a Japanese engine.

[Presto]

Be that as it may, the Crusader engine was a very robust little unit and I can’t think of a better British four stroke 250 of that era. And I doubt that Thack could either!

[Nettshubby]

Deano, if an engine is noisier when cold that`s usually piston slap. ie, until the piston gets warm and expands, it "rattles" or "slaps" aginst the cylinder.

[Thack]

Presto writes: "Be that as it may, the Crusader engine was a very robust little unit and I can’t think of a better British four stroke 250 of that era. And I doubt that Thack could either!"



That is probably true: robust in comparison with its Brit competitors. Obviously the Japanese stuff was in a totally different league.

[Tim NZ]

IF the hydraulic tappets appear noisy, and one is worried about the running clearances. Check ALL valve gear running clearances (not just the tappets) when hot, and again when cold...


(Rocker end-float and lateral deflection)


The older design Over-hung rocker which the UCE runs is an inferior design: they should have stayed with the AVL version (conventional?), plus the single valve spring is overly stiff for the cam and such a light valve.


(It is uses is primarily for cost reasons).

[Tim NZ]

Thack, and others:


The oft repeated story about the Norton-Villiers Commando ‘super-blend’ barrel shaped rollers has become an urban MYTH that has been blown out of all proportion.


The revised design of the so called super-blend’ bearings had nothing to do with Notrun; yes, the Notrun Commode had issues of premature bearing failure with the roller bearings that were fitted to the crankshaft, (and other bearings too). But it was in fact simply coincidental to an Intentional redesign of ALL similar CYLINDRICAL roller bearing elements, which saw the bearing industry wide introduction of reconfigured radii to the ends of the CYLINDRICAL rollers.


Notrun were not the only end-users who had faced the same issues of the ends of the rollers ‘digging’ into the race. Prior to which, the Atlas, the SS and the Dunstals, were frequently fitted with ‘High-Load’ ball bearings to the crankshaft: A loading slot in the non-thrust side of the ball bearing so as to fit additional balls; rolling elements, for high-load/speed use. Up to 20% increased load capacity over a conventional Ball-bearing.


They are Special order, expensive, and not noted in many general bearing catalogues…


The revised specification cylindrical roller bearings are identified by the letter E in the bearings suffix. Code: NU306 E in Notruns case.


Fitting new crank-shaft bearings to your Bullet? If the new roller bearings do not have an ‘E’ somewhere in the suffix code, do not expect them to last as long.

[Thack]

Very interesting and informative - thanks, Tim.

[jefrs]

I believe the noise from an Enfield is like the performance of a Rolls-Royce, "adequate".



The noise from the Bullet is not a design fault but a "feature"



The original UCE motor (Machismo?) got panned by the indians because the engine didn't have the right "thump".

Our old vicar once (in the pub) described the soul as taking a motorbike apart and being left with a bucket of noise.

So they added a bucket of noise for spiritual purposes.





You should have rubbers on the cooling fins which are a futile attempt to reduce the cylinder and head noise, they don't work and fall off by themselves anyway.



The decompressor is triggered below about 900rpm. The brass slot-head air bypass screw is used to raise and lower tickover, the throttle body rotates (Phillips clamp) so you can get a screwdriver to it. Tickover wants to be ~1100rpm. It will tickover slower but then the decompressor clacks and spits.