At present I own three triples - a 1972 H1A purchased for £250 as an unfinished project, an H1F purchased for £325, now fitted with an Hi-Power Nitrous system (yes, I know I’m a head banger), and also an original 1972 H2 750 for £675. Thus for a total outlay of £1380 I own three of the most lunatic bikes any self-respecting psychopath would wish to possess. That said, I’ve spent £1000 in the last 6 months modifying these machines.
The H1A was the quickest, lightest and worst handling variant of the H1 series. It was certainly the worst braked, having an old style TLS drum which even when set up properly (and that proved to be virtually impossible) was soggy at the lever end, and hopelessly unprogressive in action. It was also prone to fade if used too much at high speed. The best modification is to junk the whole front end and fit something like GPz750 front forks, made easy as the yoke diameters are the same. It’s quite easy to fit the H1 or H2 front ends with single discs, which can then quite easily be uprated by fitting an extra disc.
A much less expensive procedure is to fit Ferodo AM4 competition linings and brake shoes. This gives a marginal improvement in braking and less brake fade from high speed, but the drum has to be sent off for relining. The earlier bikes had really flimsy forks and later models were not much better. I use 20/50 instead of ATF which gives a harsher ride but removes most of the pronounced dip under braking and damps down the oscillation endemic to triples on long fast bends. This oscillation is, in my opinion, caused by the combination of un-damped front and rear suspension, and is the main cause of the infamous Kwacker tank slapper on fast bends and high speed bursts. Fitting even a used pair of Konis effects a great improvement.
Further handling improvements are limited to throwing away the flimsy swinging arm, a KH250 arm will fit straight in or an RD250/350 arm can be made to fit. Some people have fitted the monoshock unit off an LC, the single shock mated to the top cross member on the 500 frame. Welding a suitable mounting is necessary - I have a friend who’s done it and it does work. Fitting ace-bars or clip-ons and rear-sets, gives a much more sporting riding position that helps stability but hurts wrists in town traffic. On later bikes, the front brake needs enormous pressure to stop the machine smartly. Fitting SBS brake pads helps but fitment of a Z900 caliper (and master cylinder and lever if you feel so inclined) transforms the braking performance.
The H1A that I own has contact breakers but these need setting every 300 miles, with a dial gauge and meter, plus lotsa patience. Ignition timing is not only critical for performance it’s neglected at the cost of holed pistons, partial or full seizure and terrible fuel consumption. In this regard, the later CDI units are much superior. Using the old bulb across the points or Norton Special (cigarette paper) will wreck the triples timing. It will run and not even misfire with poorly set timing, but it’ll overheat very quickly.
Because of the poor quality of eighties petrol, it’s better to set the timing at 2mm BTDC on all models (it varies between 2.23 and 3.45mm depending on the model, according to the manual). I have not noted any lack of power with this setting and my pistons are still intact.
Each point should be set up using a dial gauge on each piston and meter across the points. A set of three points costs £21 and you can’t bodge on other points - they last 4000 miles if well looked after. The recommended plugs are NGK B9HS, but I’ve found the best plugs for stock or tuned engines to be Nippon Denso W27FSZU (imported by Andover-Norton). The plug is a three point, laser welded, gold palladium type, with a special ground electrode. Not cheap at £4 each, but they give a better pick-up, no spluttering in town and a broad enough heat range to cope with 90-100mph cruising. They also last three times as long as other plugs.
Out of all the lubricants I’ve tried, I prefer Silkolene Comp Injector 2, a semi synthetic oil made for strokers that inject the oil. Good petrol is crucial to good performance of the H series, even more so if they’re tuned. On my H1F I used an octane booster (adds lead to unleaded petrol) to feed its 11:1 compression ratio.
Along with the ignition timing, the three carbs have to be balanced every 300 miles. Remove the air filters, open the throttle about a quarter and let it snap shut. If you hear one click as all the slides hit their stops, then the carbs are probably as well in line as you'll get them. Easy? Well, not really, nine times out of ten there'll be a succession of clicks. Insert your finger in one carb, twist throttle until tension is taken up (it won’t move, just a slight tremble). Hold the throttle in this position, insert finger into one of the other carbs, release throttle slowly - if the slide moves then turn the adjuster clockwise, if it doesn’t turn it anticlockwise. Keep trying and checking until all three slides line up.
Older bikes with stock silencers will be all gunged up with carbon deposits that has a very restrictive effect on power production - it’s worth checking the exhaust ports for carbon when the exhausts are removed. The use of modern oils and the occasional blast will negate the need for regular decokes. Rebores are generally needed every 15000 miles if you take the amount of engine rattling as a guide. Despite the noise, it doesn’t have much effect on power production. Get all the little things right, and the whole will add up to a hell of a lot more than the parts. Once you’ve experienced the joy of the triple on song you'll never want to give it up.
G W Henry