Tuesday, 2 February 2021

Triumph 250 Trail Blazer

 

I should've been suspicious but the immaculate 1972 Triumph 250 Trail Blazer stood before me in all its single cylinder glory. Making me forget all those horror stories about its OHV engine, which wasn't that different to the even more notorious B25 BSA mill. The owner was a typical British bike fanatic with a garage full of old Triumph twins and who looked upon my hack CB250K4 with total disdain. Despite the fact that it was over twenty years old and still running strong.

The Blazer was a rival of sorts for the Honda back then but it never caught on. But these days they have a certain retro funkiness and the guy only wanted £995. He only agreed to let me buy it after I'd concurred that I was pissed off with Jap crap and not out for a quick profit. Luckily, I'd worn my ancient leather jacket that day, had enough credibility to get away with the lies.

The Blazer wasn't really meant as a trail bike, it was just following the craze of the day that saw enthusiasm for road bikes that looked like trailsters. That did mean that the Triumph had huge ape-hangers that felt well strange after the compactness of the Honda. I felt precariously perched upon a rather narrow machine that rumbled with the tickover vibes - the front end pattered away viciously from the buzz.

The CB250 has been described as rough and ready (by the UMG, no less) but in comparison to the Great Thrummer it was suddenly smooth and sophisticated. Torque the Blazer definitely had in excess, allied to a minimal mass, meant it shifted up to 70mph in an impressive manner - better than the Honda and many of the more moderate modern 250 twins. Thereafter it was a waste of time. Not only did power dissipate but vibes poured in so fiercely that it felt like the whole bike was breaking up.

This is pretty much what you should expect from an old British single. More impressive was the lack of knocks or rattles and an exhaust that stayed resolutely clear even on the overrun. (By the way, on old Honda's the first sign of ill-health comes from the engine breather not the exhaust.) Handling was much better than the Honda, though, especially from the front end, the Triumph having a directional accuracy far in excess of the somewhat loose Honda, which often felt as if it was working through rubber bearings.

After the deal was done, I was soon beginning to wonder what I'd let myself in for. Less than five miles before the clutch cable broke. These engines have a bit of a reputation for disintegrating gearboxes; judging by the grating noises during clutchless changes it was a far from a myth. Several kangaroo hops later, I managed to roll up to my palatial mansion (sick joke). I make up my own cables, so soon fixed up the Triumph.

Looking the machine over I found a couple of bodges. The large silencer chamber was patched in several places. The seat base was cobbled together with disparate bits of sheet metal. And the electrics were a mess but managed to work okay.

One good point was the economy. 70 to 80mpg (just as well as the fuel tank was small), thanks to a newish Amal carb and the kind of lean running that made the motor quite temperamental for the first ten minutes until the engine was fully warmed up. Of course, it was impossible to thrash the engine because revs were effectively limited by the amount of vibration that poured out of the mill. But under normal riding down country lanes and through town, the bike could push along faster than the CB250, which itself would turn in around 55mpg. So one up for old British bikes - the lack of frugality of modern Jap's is appalling!

Handling and braking were more than adequate. Conical hub drums, originally designed for the big twins, had both power and feel (though the front's difficult to set up correctly), were better than the Honda's. Handling was heavier than you'd expect from this kind of bike but easier than the CB, with a degree of security and stability which that era of Jap machines could only dream of.

I was mulling these things over when the second problem occurred. I was blatting through town, grinning inanely at the joyous bleat of the exhaust, when the revs suddenly rose to a frightening level as second gear became neutral. I went wild on the gear lever, ended up in fourth! There was enough torque to pull from 25mph but below that the final drive tried to imitate a chainsaw. By the time I reached work I was left with only first and fourth gears! The engine could just about cope with the huge gap between these two ratios but the resulting vibes, flat out in first, had my eyeballs whirling in my head. This happened some 770 miles into my ownership.

It was then I discovered that the lack of oil leaks was down to the previous owner bonding the engine cases with something like Araldite. It reminds me of the one-liners in Haynes manuals - remove cover...three hours, two broken hammers, bruised fingers and much hollering later I finally had access to the gearbox. Teeth were missing off the cogs and the selectors were bent. Spares are still available but expensive new. Luckily, there was a local autojumble a week away and some hard bargaining secured a large pile of engine bits - not just the gearbox, I wanted to be prepared for the worst.

The gearbox never really worked well after being rebuilt. I had all four cogs but engaging them was a major hassle, even compared to the Honda which had as many neutrals as working ratios. I hate gearboxes, didn't want to do another strip down to sort it out. I always felt that the mill could run taller gearing, as well, but the sprockets and chain showed absolutely no sign of wear. Amazing, compared to the junk on the Honda.

I didn't really trust the motor for long distance work whereas I'd quite happily go off touring on the Honda. Both needed 500 mile maintenance sessions and regular oil changes, but given their age you wouldn't expect anything else. The BSA needed its bolts going over every 100 miles whereas all the screws in the Honda had permanently corroded in their threads!

The bikes were very different in their character but I enjoyed riding both, although, economy aside, the Honda was much more practical and has outlived all those nasty Superdreams (the K4's faster, hurray!). My joy with the BSA did a runner when the cylinder head began to rattle after a mere 3200 miles. Mileage on these old bikes is pretty meaningless because of frequent rebuilds and short-lived speedo's.

The cylinder head came off without recourse to the hammer. Rockers and valve guides were shagged. I already had used spares. Worse still, the bore was scored and the oil ring gummed up in its groove. The big-end was a bit loose...ohmigod, the main bearings were about to start knocking. This is pretty typical of British engines, start taking them apart, all kind of horrors revealed...which is why many old British singles end up running Japanese thumper engines!

Not having a crankshaft (about £475 for a rebuilt one!) and knowing that a rebuilt engine from disparate parts wasn't going to inspire much faith in its performance or longevity, I rebuilt the top end, polished up the bike and went the rounds with a couple of British bike dealers. £800 was the best offer (it was advertised at £1950 with main bearings about a 100 miles off going knock-knock!).

The big problem with these kind of bikes is that there's no real way of knowing the state of the engine internals and even when properly rebuilt they ain't going to last for huge mileages. As a riding experience they are quite interesting, exciting even! I was tempted to keep the chassis and fit a Jap engine (I wanted a DR350 bored out to 441cc!) but in the end the £800 in used fifties won out. I bought a tatty CB450 Black Bomber; much better value for money.

Dave Hills