Bikesales Staff•12 Jan 2012

ADVICE

Advice: Technical Q & A

Motorcycle treader's Spannerman address all your mechanical woes

GETTING WARMER

I was interested to read Greg Leech’s piece in the last issue on his (and your) fuel leaks and, in particular, his comment about a 10-minute warm-up for his Triumph.

When I started driving in the ’60s, it was common for people to warm up for three minutes before driving off, but since then – and with the introduction of automatic chokes and fuel injection – the advice for cars has been that there is no need to warm up provided you take off without stressing the engine and allow it warm up on the go.

I now have a Triumph Thunderbird 900 with carburettors and a manual choke. It fires up first time and runs smoothly so I just take off gently and progressively reduce the choke.

Googling the question only leads to conflicting advice – what do you think?

Roger Foot,

rfoot@bigpond.com

Spannerman: My dear old Uncle Ken had a 36hp Volkswagen Beetle. The engine looked like two BMW flat-twins glued together and, like the older BMs, the engine was air-cooled.

He lived in Pymble in Sydney and he let the engine warm up for three minutes before he took off for his job as a bank manager.

If the garden hose was across the driveway, he had to let the engine warm up for four minutes as so little power was available from the cold engine that the front wheels would hit the hose and the car would stop.

Air-cooled engines need a warm-up period so heat can expand the metal bits and reduce the tolerances to the point where some actual power can be produced.

Bikes with electronic fuel injection, electronic ignition and sophisticated engine management computers will start easily and create the impression they’re instantly ready for action.

Keep in mind, though, that engine oil has to reach a certain temperature before it provides maximum protection and there’s a very good argument for letting it do this before you make any performance demands on the engine.

Liquid-cooled bikes have a thermostat that hastens the warm-up process by not letting the coolant circulate until it’s hot enough. If your bike has a temperature gauge, you’ll notice how quickly it gets to its normal operating temperature.

Sometimes, the pressures of daily modern life demand you just start and go and it’s certainly less harmful to do that than it used to be.

With your Triumph Thunderbird, Roger, I’d start it with the choke but close it as soon as possible, allowing the engine to warm up without extra fuel washing the oil off the cylinder walls, encouraging rapid wear and contaminating the sump.

Even in hectic 2011, waiting for three minutes isn’t too long, is it?

CLUNK GO THE GEARS

I own a 1981 Yamaha TT250H with a particularly irritating carburetion issue. The engine has a habit of suddenly stopping following a splutter (or two) from the carburetor at idle.

This is especially prone to occurring at traffic lights immediately after I have jumped the queue and zipped in front of someone, and immediately before the lights change to green. This does not usually endear me to the drivers behind.

I have checked for air leaks around the manifold joint and tried playing with low-speed mixture settings, but the problem persists. I suspect it has something to do with the pod air filter, which I quite like and do not want to remove.

I was wondering if a larger pilot jet might do the trick and, if so, how much larger and where might I find such a thing?

The second problem has surfaced only recently and may, in fact, render any carburettor improvements entirely redundant. My bike is sometimes (albeit rarely) reluctant to go into first gear from second. Mechanically it feels as if it has only been half engaged.

I seem to have drive, but with clunking and what feels like hugely increased drivetrain free play – if such a thing is possible. As I said, this happens only rarely and usually when I’ve been coasting in second gear with the clutch disengaged for a few seconds before trying to change down to first.

Any suggestions you can offer pertaining to either sputtering or clunking will be greatly appreciated.

Ruben Cooper,

rwcooper88@netscape.net

Don’t you hate that – cut up the commuters and then hold them all up while you furiously kick at the starter lever, not making eye contact because the dudes in the car immediately behind you might be in the All Blacks?

Take the carburetor off, remove the float bowl and soak it all in carburetor cleaner for a couple of days. Dry it with compressed air and put it back on the bike. Your pod filter probably lets more air into the idle circuit than the standard filter so you can reduce this slightly by turning the air bleed screw in until it seats and then just turn it out one full turn.

There’s a good chance the carb is worn to the point where minor adjustments aren’t going to make much difference, but it’s certainly worth a try.

Idle problems are often valve related as well, so check valve clearances while the carb is having its bath. If this doesn’t solve the problem, set the idle speed higher (around 1200 to 1400rpm) as this will encourage the right amount of electricity to keep the engine running.

Regarding the gear change, the technique for changing from second to first is to tap it into neutral first, let the clutch lever out, blip the throttle so that the engine is doing roughly the same revs as it would be doing if you were in first gear already, pull the clutch in and tap the lever into first. This takes a lot longer to write than it would take in practice.

It should be a seamless process and your bike should sound like it has an automatic transmission. The fact that the problem only occurs occasionally suggests it’s a technique thing rather than a mechanical problem. Best of luck.

HYDRAULIC FROLIC

I noted in your Retro Heroes comparison in #248 the comments made concerning hydraulic valve lifters on the Enfield and the Harley-Davidson Forty-Eight. Could you please explain the mechanical differences of hydraulic lifters for me?

As I mellow, I’m finding the need to get down and dirty on the bikes stymied by the increasing difficulty of getting up again. Minimal maintenance requirements loom large in the specification of the impending garage re-organisation.

The leisurely Royal Enfield Bullet (some 40 years ago) remains a pleasant time in my memory so the current German-Indian recreation with all its updates is of some interest. While the 32 years I’ve spent with my current Triumph has packed the grey cells with righteous times, it does, however, require quite regular maintenance.

Being a more senior type and being stuck on Phil Irving’s 500 twin mantra, 650 is as far as I’d be prepared to go.

The Kawasaki W650 (even without the hydraulic valve gear) is of equal interest with the Enfield and, pleasingly, both look like motorcycles.

Trusting to read something on this subject.

Rus Dainty,

rmdainty@bigpond.net.au

Of that group of bikes we rode, Rus, the Harley-Davidson Forty-Eight was pretty much maintenance free but you need a certain mindset to come to terms with the riding position. The jury isn’t exactly out on hydraulic valve lifters but you’ll note they’re not used much in motorcycles and particularly those with high-performance capability.

Hydraulic valve lifters consist of a hollow chamber with an expanding plunger located between the camshaft and whatever actuates the valves. Lubricating oil fills the inside of the lifter through a small passageway and, as oil isn’t compressible, the rotation of the camshaft opens and closes the valves without the need for the normal clearances to allow for temperature variations.

Hydraulic valve lifters require no maintenance, ensure the valve gear is always set for full power output and do away with that annoying ticking when normal valve actuation needs adjustment.

What’s not to like? Well, in their own way, they’re complicated little devices. They can wear out and the noise they make then is amazing. Filling and emptying with oil so the valves can open and close works best at lower revs and at high revs; it’s possible for hydraulic lifters to ‘pump up’, not allowing valves to close properly, with potentially disastrous consequences.

Valve recession is less of a problem now but in the changeover to unleaded fuels, bikes with hydraulic lifters like Honda’s CBX750 wouldn’t allow for adjustment, meaning not much valve recession would ruin the head.

Both the H-D and the Bullet have suitable engines for hydraulic lifters but you have to ask if the problem of conventional valve adjustment (shims, buckets, screws, whatever) requires that sledge-hammer solution. There are plenty of big-bore Japanese bikes that live their whole lives with just one valve clearance adjustment.

I certainly wasn’t expecting this when we all set out on that fateful weekend, but I’m now a big fan of Kawasaki’s W800. If you’re climbing off an older Triumph, you’ll think you died and went to heaven. We should have taken a Triumph T100 instead of the Scrambler and that’s another bike you should put on your list to check out.

ON THE REBOUND

I returned to motorcycling a couple of years ago after a marriage breakdown and a mid-life crisis. I first purchased a 2008 GSX-R1000, then traded it in last year on a Suzuki Hayabusa.

My query relates to suspension set-up. While I’m aware the various settings for preload, compression etc should be altered depending on the terrain and the load on the bike, I have no knowledge of what they represent and how to get the settings right on my own bike.

For example, I sometimes have a pillion on the back and recently did an interstate trip loaded with luggage. How should I have altered the suspension? I’m 5ft 11in and I weigh 82kg.

Peter Scott,

pmscott@yahoo.com.au

Now that’s what I’d call an appropriate response to a marriage bust-up and a mid-life crisis: a GSX-R1000 followed by a Hayabusa. Riding a ’Busa as its designers intended leaves very little head space to fret about the past.

Multi-adjustable suspension is a mixed blessing for road bikes, Peter. It suits track use, of course, where you can dial in just the right settings for the particular circuit you’re intending to conquer. The trouble with Australian roads is that a typical ride might include smooth freeway, bumpy back roads and, often, sections of dirt. It’s impractical to consider stopping every time the road conditions change to make minor adjustments to springs and damping.

There are standard factory settings for the ’Busa and this is your best starting point. For front spring preload, turning the adjuster clockwise increases preload and anti-clockwise will decrease it. There are eight grooved lines on the side of the adjuster with position eight giving you the minimum preload and position zero giving you the most. The factory setting is position five.

Regarding damping on the front, rebound is at the top of the font fork and the compression damping adjuster is at the bottom. Turn the rebound adjuster clockwise until it can’t be turned any farther (don’t use too much force – you’ll be able to feel when it’s reached its limit). Now back it out three clicks. You can’t hear the ‘clicks’ but you’ll be able to feel them. Do the same with the compression damping adjustment but back it out nine clicks. It’s important that both fork legs be adjusted exactly the same way.

There’s a special service tool for the rear spring preload so chances are it’s already set at five and you don’t need to change that. Even for 300km/h gallops, Suzuki only recommends six and five and this is also the advised setting for two-up riding.

Adjustment for rear damping is located at the left side of the rear suspension damper unit. Again you have rebound and compression damping to adjust. For rebound, turn the adjuster clockwise until it stops, then turn it out 11 clicks and then align the two punch marks.

With the compression damping, turn the adjuster clockwise until it stops and then back it out eight clicks.

You now have the stock, Suzuki-recommended settings and you’ll find this to be a versatile compromise that will cover most of the riding conditions you’re likely to encounter. It’s another way of saying ‘set and forget’.

For day-to-day riding, though, you might want the suspension to be a bit softer and more compliant. Leave the rear spring preload on five but for front rebound, go to four clicks and for compression go to 11. Increasing the numbers (turning the adjusters anti-clockwise) reduces the damping force and makes the suspension less harsh.

For the rear, go to 13 for rebound and nine for compression.

You should feel a significant difference in the ride quality of the bike for around-town and moderate touring use. For two-up riding, return to the standard settings.

As a dumb generalisation, your bike will wallow in corners if the suspension is set too soft and will chatter if it’s set too hard.

Some bikes have it now, Peter, but the future will be electronically controlled suspension adjustment. There’ll be a range of options on a handlebar-mounted switch and you’ll be able to select from normal, comfort, sport and two-up, and the magic of electricity will do all the hard work for you.

SENSOR SCIENCE

I’m hoping you can shed a little light on an issue I have with my 2005 Triumph Speed Triple.

I bought the bike about a year ago with approximately 18,000km on the clock from a private seller and, soon after purchase, realised it needed a bit of work. It came with a set of Micron carbonfibre cans and an intermittent firing issue with one of the cylinders.

After a minor service in a city-based dealership a new fuel map was installed to match the free-flowing cans, new spark plugs were fitted and there was a clean-up of the coil connections, which had developed a bit of corrosion from living outside. They also discovered that the airbox had not been installed correctly at some point, which was also rectified. This seemed to fix the firing issue.

Then in the last few months I noticed another recurring issue: overheating. While out and about in the hills there isn’t a problem but in stop-start traffic the temperature gauge quickly rises and does not always trigger the fan to come on.

The problem always occurs in the same way: get into traffic, temperature gets to bar six out of 10, the fan kicks in and the temperature drops to normal, whereupon the fan, as expected, turns off. When the temperature rises to six or seven bars again, the fan doesn’t switch back on.

The system always works the first (and sometimes the second) time but after that I have to pull over and let the bike cool down.

I took the bike for its 20,000km major service to a Triumph specialist who ‘fixed’ the problem by replacing the radiator cap. The issue persisted, though, and on the second visit he replaced another sensor under the seat. The problem remained and on the third visit the radiator cap was replaced yet again and another sensor at the back of the cylinders was replaced.

Unfortunately, none of this seems to have worked, leaving me thinking the problem isn’t a sensor issue.

I think it might be corrosion related or a grounding issue somewhere in the electrical system. It might be a relay somewhere but I wouldn’t know where to start with that.

Any suggestions?

Matt Rubenstein,

Matt_rubenstein@hotmail.com

This is a tough one, Matt. Frankly, I would have done exactly what your “Triumph specialist” did. The radiator caps on some early Triumph models wouldn’t hold the pressure in the cooling system so that was a good start. Assuming the sensors are all, in fact, functioning, perhaps the problem does lie elsewhere.

Given the somewhat cruel history of your bike’s first 18,000km, I’d be inclined to check the functioning of the radiator as the coolant flow might be affecting what the sensors are actually reading. Remove the radiator and have its core checked for flow, flush the cooling system and refill it with the correct corrosion inhibitor.

I know you want the problem fixed as you should be getting better service from a six-year-old bike but it’s a simple, cheap wiring job to fit a switch to the handlebars so you can turn the fan on and off manually. At least you’d be able to ride in the city again without having to stop to cool down. I’ll make a few enquiries on your behalf with my English contacts to see if any more light can be shed on the subject. Watch this space.

BAD VIBES, MAN…

I have owned several Suzuki Katanas during my time and in recent years I purchased a 1985 Katana 1100. I paid more for this than I did my first one back in ’86! Anyway, the Kat is in mint condition and has been lovingly cared for. It has a problem, though, which I’ve been unable to rectify.

When riding there is an annoying and persistent vibration that makes itself known via the handlebar grips causing pins and needles in my hands after about 10km of riding. The resulting numbness makes riding nigh on impossible.

Riding around town is fine as the constant stopping and riding at lower speeds don’t show up the problem, but once you get over 80km/h the vibrations surface and all the pleasure of riding seeps away.

Can you suggest what may be the cause and a solution?

Michael Tickner,

mtkatana@gmail.com

Since you’ve owned a few Kats, Michael, I can’t fob you off by saying, “They all do that”. Clearly, you know they don’t. It is true, though, that all engines vibrate and this is felt in varying degrees in different parts of the bike and can also vary depending on the engine revs. Many bikes have a rough spot and you hope it doesn’t correspond to posted speed limits. Do the vibes get better at higher revs?

It sounds like your bike is in original condition, meaning the engine hasn’t been rebuilt or modified (a common cause of increased vibration) and the existing handlebars are standard.

First up, check the tension of the engine mounting bolts and the condition of the associated rubber components. Assuming the rubber bits haven’t gone hard or brittle, back the bolts off and then bring them up to the recommended tension with a good tension wrench.

If the carbs are out of synchronisation, it can substantially increase engine vibes. When was the last time this was done?

Do these things anyway but also consider the following. Heavier ’bar end weights should reduce the vibrations. I’ve had good results with replacement foam grips. Buy the most expensive available – they still won’t be more than $40 – as the cheaper ones aren’t as good.

I haven’t used them, but I’ve also seen gloves with gel inserts in the palms designed to reduce the vibrations you feel through your hands.

As is the way with engineering, all production bikes aren’t the same. Modern production technology had dispensed with the ‘Friday afternoon bike’ but it’s still possible for bikes from the same batch to have slightly different characteristics. There are other, more extreme solutions (including the fabrication of aluminium ’bars to replace the existing steel ones) but some or all of the above should do the trick.

Let me know how you get on.

OF SOME IMPORT

I’m currently looking at importing a 1982 Suzuki GS750 from the USA.

Can you recommend an Australian importer who could help me with this task, preferably based in Queensland?

Trevor Brew,

yao572@yahoo.com.au

Since the GS is pre-January 1, 1989, all you need is a Vehicle Import Approval, Trevor. There’s a $50 application fee for this (Department of Infrastructure and Transport) and the application form is on-line (Google Vehicle Import Approval application).

The pre-’89 scheme is a good one and has largely been driven (if you’ll excuse the pun) by lovers of big, old, American cars. It allows the relatively easy import of older cars and bikes for enthusiasts. The GS750 certainly fits here – Suzuki (and Japan) finally cracked handling DNA with this model.

There’s a business named Geezers in Ashmore with some runs on the board in regard to importing. The base fee for your bike would be $1250 but there are some additional costs you may or may not need to pay. You can contact Geezers on (07) 5528 2801 but you can find out more by visiting www.geezers.com.au.

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Advice: Technical Q & A

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