Start with the bad. The vertical twin, OHC engine is famous for the way the lack of oil supply to the cylinder head ruins the camshaft bearings (in turn part of the head). My G5 is on its third head (the first went after 8000 miles). The latest has plain bearings machined in and has done 35000 miles. I always give the bike time to warm up properly.
The camchain and tensioner are quite good as Honda products go. I’m only on my second, the first set lasted to 40000 miles. I've also only had to rebore the engine once, at 42000 miles. It’s easy to see when the rings or valves go as dense white fumes emerge from the engine breather tube.
The gearbox lost top gear after 23000 miles. This is OK, as I just used a bigger gearbox sprocket to compensate. Never very smooth, other people find it almost impossible to use the box without missed changes. Myself, I must’ve adapted to it as it gradually wore out.
At 32000 miles the clutch stopped dragging at slow speeds and slipping at high engine revs... but only because it stopped working altogether. A slightly used unit from a breaker was bought for a tenner and has worked fine ever since. The clutch still has a light feel and a progressive action.
The engine has gear primary drive and no balance shafts (so no horrible chains as per Superdreams). A persistent, but small, oil leak between head and cylinder has never been cured since new but has never gotten much worse. Oil consumption is still negligible but only because I change the oil every 600 miles. If I don’t, then the gearbox becomes unusable and the engine starts to vibrate. One reason the engine has lasted so long is that I've always stuck to frequent oil changes.
Maintenance couldn’t be simpler. I find points and tappets can be left untouched for 8000 miles. Carb balance stays spot on for yonks. A tweak on the camchain adjuster every 10000 miles suffices. The bike has never left me stranded in the middle of nowhere. I still have the confidence in the machine to leap on and do 400 miles in a day.
The chassis was quite good when new. Less than 400lbs is well distributed. It could be flicked through town like a 125. Up to 80mph there were no signs of weaves or wobbles. Faster speeds showed up the suspension’s lack of damping. Flat out, with just over a ton on the clock, there was a weave that threatened to turn nasty but never actually did. The bike could be flicked through S bends with ease as long as the surface was smooth. If it turned bumpy, the suspension couldn't keep up with undulations. The bike often turned into a violent pogo stick.
By 10000 miles the swinging arm bearings were shot and the suspension had lost what little damping it might once have had. Beyond 60mph it became a bucking, careering nightmare. New phosphor bronze swinging arm bearings (made up in work), Girling shocks and an improved CB350K4 front end cleared all that up. It was then better than new.
I used a CB350 front end because the single disc brake fitted to the G5 was bloody awful. When brand new it had a little more power than the TLS drum fitted to the Honda. But, come some rain it all but disappeared. When the disc gummed up after 5000 miles that was enough for me to tear off the whole front end. The CB350 forks, never very good, were improved with stronger springs and thicker oil. Gaiters were already fitted on the forks, an act that paid off as I've never had to replace the fork seals.
I then had a bike that had some of the tautness associated with British bikes and was steady right up to the top speed. That maximum velocity has deteriorated with age, reaching a low of 90mph just before the rebore. It now seems happy to do about 95mph on the flat in still conditions. - I could probably wrestle a ton out of it but as long as it'll cruise at 80mph I’m a happy man.
The Honda is basically a very easy bike to ride in all conditions. Power delivery is far from peaky, it’s just a matter of opening up the throttle in relation to the amount of go required. It'll potter around town with the finesse of a moped or cruise at up to 80mph with none of the vibes associated with British twins. Vibration does start coming in at 85mph and then just gets worse the faster you go. This is probably Honda’s way of telling you to stop revving the engine so much.
Fuel economy has varied between 35mpg (ton up thrash) and 75mpg (30mph country gallop). Normally, I get around 60mpg. It seems to have got no worse with age. Which can’t be said of the paint. By 12000 miles the bike was beginning to look a mess. At 20000 miles I felt duty bound to do a complete respray. But by 35000 miles rust had started creeping out from under the paint so I had to repeat the process. That lasted to 50000 miles when I had to do it yet again, although it’s still in good condition now.
The same lack of quality is apparent in the engine alloy. The number of times I’ve had to bead blast the outer cases does not bear thinking about. A mate with a CB250K1 can still get his alloy to shine up with Solvol. My only consolation is that the Superdreams use even cheaper stuff. However, whenever I’ve taken the engine apart I have always been impressed with the condition of the engine internals - and that’s where it really matters.
The original alternator is still churning out the goods. The rectifier was replaced with a Superdream item at 18000 miles when it started playing up. Both front light and horn were replaced with superior items. The back bulb had a spate of blowing out until the rear lamp was given extra rubber mounting thanks to a bit of old inner tube. Batteries last around 17500 miles, which is really not good enough. I tried using a big capacitor in its place but the engine kept cutting out at low revs. The indicators were dumped at 25000 miles when they started flashing crazily.
Drive chains lasted only 9000 miles until I fitted a ScottOiler, which made them last 16000 miles. With a bigger gearbox sprocket and a highly modified CD chain enclosure, as well as the oiler, the last chain has lasted 23000 miles and is only halfway through its adjustment. I find Roadrunners suit the bike well - front 14000 and rear 10500 miles. The front shoes last 19000 miles and the rear 25000 miles. Clutch cables kept snapping after only 8000 miles until I made my own up, which manage twice that. The throttle cable is still original (it gets squirted full of grease every 20000 miles).
I've only fallen off three times. The first two happened when I was foolish enough to ride in the snow. The third time some shithead in a car did the usual trick of putting his vehicle in the wrong place at the wrong time. Damage to the Honda was minimal - it really is one of those bikes you can whack with a big hammer until it straightens out.
One of the advantages of the G5 is that its poor engine reputation means non-runners can be picked up for a song. In the last year I've filled the back room up with three of ‘em at a total cost of less than a hundred notes. The reason for such activity is that I'm so unimpressed with the new machinery available that I’ve decided to keep on running the Honda for as long as possible - I hope to do 100000 miles on her!
Already, I’ve renovated one cylinder head, salvaged a set of barrels and pistons, found some gearbox internals that look almost new (one bike only had 5000 miles on the clock but had been left to rust in a garden) and have started to rebuild one engine to as new spec. With the ability to swap over engines whenever one gives any trouble, I think this is one bike that'll run and run.
Steve Jones