TY: too keen ?

The joys of Old Bikes

Although startingly lustily at the first kick (unlike my Duke…), an hour or two’s ride around the farm showed that the TY was demonstrating an almost Velocette Thruxton-like unwillingness to idle. Rather more seriously, after warming up, fuel began to pour from one of the carb vent hoses and collect in the inside of the bashplate.

On the up side, this means the TY has probably the cleanest bashplate of any twinshock in Britain. On the down side, it’s patently not a sustainable lifestyle for any bike. Consultations over, and with the arrival of a CD containing the workshop manual anticipated, plans were in place for removal of the carb and a good seeing-to. For the carb, that is.

JK Hirst supplied a new valve float needle and holder (for elimination of the obvious suspect), float bowl gasket, main jet and slide spring (just for kicks), as well as a new air filter. If there’s one thing I hate more than oiling a new foam filter, it’s cleaning a used one. And knowing the effect I usually have on fork sliders, a set of tasteful black gaiters was also obtained.

Reviewing the recommended service intervals had me falling off my chair. I had thought you only got a chart like that with a new RS125! As a practising four-stroke owner, I contemplated the likelihood of inspecting and cleaning the cylinder bore, piston and rings after every 20 hours and, simultaneously, the likely number of hours before the first seizure (the piston’s and Nick’s, in that order). I was amazed to see that there’s an integrated chain oiler in the swingarm. Hold on, why doesn’t every bike have one of these? As someone had plugged up the filler, maybe there’s an answer to that.

This weekend, with tools arranged tastefully in the dirt, the TY hauled onto a handy stand (try that with a Duke!) and Nick tucked up in his bed with “Blanky”, it was time to see how many of the Phillips-head screws (!) holding the TY together had been touched since 1976. The shocking state of the fork top bolts sent mixed messages.

Falling at the first hurdle, I completely failed to remove the seat. In my defence, this is not anywhere in the manual. After removing the side panel and loosening the clamp under the front of the seat, vigourous peering failed completely to reveal what the fudge was retaining the rest of the seat unit. The swearing, creaking of plastics and carefully moderated straining familiar to amateur bike mechanics ensued, until inspiration hit. Which is to say, I gave up completely and resolved to crawl meekly to a trials forum. Or Malc.

With some trepidation, I attacked the carb instead. To my amazement, the screws holding the carb rubber clamps slackened off without complaint, together with the float bowl screws. Obviously the TY was made of sterner stuff than my TRX, whose float bowls are held on with patented ’90s Yamaha “Shitmetal” (TM)(R). Having unhooked the slide and its collection of dirt, the float bowl gasket’s resistance was overcome with a sharp tap from a drift.

Copious amounts of degreaser and carb cleaner followed. All the brass showed evidence that the bike had been left for at least the known couple of years in a shed, with a dull brown layer of varnish coating everything and having pooled on one side of the float bowl cover. More scouring! With the help of the settings in the manual, mixture screw and idle speed adjuster were cleaned and re-set. The mixture screw, which was supposed to be 1 3/4 turns from fully closed, had been set, well, let’s just say many turns out.

After some purple-faced moments swearing at the slide spring (cured by adjusting the throttle cable all the way out) and more swearing at the carb rubbers (which would only seat properly on one or the other end of the carb, but not both), an inspection of the plug was made. This revealed quite a bit of carbon buildup, and after a quick go with a wire brush, a mental note to just buy a new one. It didn’t seem that any torque had been applied to the plug at all, which seemed incorrect. As I didn’t have a 20mm spanner and had resorted to a plumber’s adjustable wotsit, I wasn’t really in a position to be judgemental.

With some fresh petrol and fingers crossed, it was time to see how badly I’d buggered it. Well, after belatedly reattaching the fuel feed hose and cleaning a lot of petrol off the cases, anyway.

After a little time for the fuel to get to the float bowl and a couple of preparatory kicks, it fired up and proceeded to immediately idle at about 5,000 rpm. This was progress, as last Sunday I spent about 30 minutes trying to get it to stay running. The idle speed screw appearing to do precisely bugger all, so in desperation I backed the mixture screw out a couple of turns. Result – we were back to a fast idle. This explained why the mixture screw had been wandering in the wilderness of many turns out. A quick trundle down the drive revealed a happier sounding two stroke (less popping, more whizzing) with fuelling more like Malc’s 350 jumbo – hanging onto its revs on a closed throttle. This may not actually be “spec”, but at least it starts easily.

The lesson I have learned after all of this is that I should have just ordered a spanking new carb and throttle for £39.99 rather than spend £25 on parts and freezing in a barn for a couple of hours. But now at least I have a joyful, relaxed 4 hours of trialling before the piston welds itself to the bore!

In our next episode – Nick struggles from his bed and fixes the horn so we can get an MOT. Um, well, maybe.

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