Some Important Useful – More Technical Advice For Hardcore Petrol-Head Harley Riders


Harley Technical AdviceIf you ride faster and harder than the rest and or you have had performance work done on your Harley then this is for you. The majority of Harley Riders in South Africa ride their bikes in the manner that it was intended to be done. These bikes are all capable of riding between 100-120km/h forever, they use little fuel roughly between 16-20km/l and use no oil between services. They run very hot when riding slowly in a pack formation and more so in a big group- stop-start for long periods of time like on a toy-run or something similar i.e. Sunday morning site seeing breakfast run through heavy traffic. The reason for this is simply put, they are air-cooled and rely on only wind from the front and the little oil in the engine to keep them cool. The life expectancy of a Harley if it is ridden in this manner is, who knows? These bikes can do between 100-300 thousand km’s it all depends on the riding style, service intervals and most important of all – how much mechanical mercy we have for them. One thing that they don’t like is to stand and idle while not moving -they should not idle for longer than 3 or 4 minutes while standing stationary at filling stations or before riding in the mornings while warming up.

Some detail and the pain

The following words are important for you petrol heads out there because you need to understand these bikes a little better so that you can fuel your passion and ride fast or hard and use the extra power on tap reliably. Over the last 10 years we have built a number of very quick bikes that are capable of riding between 140-180km/h or more for long periods of time or long distances. This is fine if you have some mechanical mercy for your bike and a good understanding of the relationship between power, speed and thermal temperature. Mostly we ride fast and hard because we can but in our country our summer riding is often done at ambient conditions, 30ᵒc and in some cases as much as 40ᵒc or more and we have nice long roads – 200 or more kilometres between stops. So, if you’re on a bike that has been tweaked, chances are good that you would be sitting at a high speed for a long while. Now we all know that Harleys don’t have much information on the dash but if you had the luxury of an oil temp and or cylinder head temperatures gauge to monitor you would understand my concern. A well-tuned strong Harley, riding along at 160km/h in 40ᵒc would eventually see cylinder head temperatures in access of 150ᵒc and oil temperatures around 140ᵒc or more, the further you ride like this the more the temperatures creep and there is nothing that can stop this from happening other than slowing down and reducing the revs for a while. The more power your bike has on tap the more heat it generates and with the V-twin engine configuration, the rear cylinder can easily self-destruct because it’s cooling air comes via or through the front cylinder first, so it sees much hotter air and is unable to dissipate this efficiently. So, you think that the oil-cooler and good oil can save the day – no it can’t! The modern Harley Davidson engine has built in safety features or a safety net – but even those can’t save the day. What they do is, dump extra fuel, auto torque control and remove timing when a certain temperature is reached – the result – a misfire every now and then and or a loss of performance while the engine is trying to look after itself. In these riding conditions the bikes use excessive oil and plenty of fuel not to mention heating up the tyres far past their capability.

The fix – Remedy

There are several ways that we can reduce or minimize the risk of something going wrong, I’m only going to speak about a few but the bottom line is you need to prepare your bike for these riding and ambient conditions.

  • Firstly, always ensure that you use the highest octane best quality fuel available
  • Let your engine tuner know – and be honest, how you intend on riding (at what speeds and for how long). To a large extent the tuning can go a long way to protect the engine if you are doing an – Iron butt run or similar: a Colesburg, Laingsburg, Beaufort West fast Karoo run in the summer. You need to dyna tune more regularly and more specifically.
  • Insist on 100% fully synthetic engine oil. A better-quality oil than SE-3 in 1. You need at least a 5W-60 grade of oil.
  • You can consider a better than standard oil cooler with additional electric fan cooling on the engine barrels as well as the oil cooler.
  • There are bigger capacity oil sumps available for the touring bikes, the more oil the cooler it runs but never over fill. The oil just ends up coming out under the air cleaner or by the breathers.
  • We are investigating an engine condition monitor, oil temp and engine temp ext.
  • Insure that your cold tyre pressures are correct i.e. 2.8 front and 2.9 rear before embarking on such a ride.
  • Also consider good quality tyre pressure and temperature monitors.

The only Harley engine failures that we have seen in our workshop have been directly related to stupid temperatures and or engine oil shortage – thermal temperature overload.

Vital Signs (example only)

Vital signs

So now you decide for yourself, how much mechanical mercy do you have and who is responsible for the consequential damage?

More interesting pages:

harley dyna tuning explained

Harley stage 1 to 4

Harley decat catalytic converters