The Harley Davidson 88 sports the signature Twin Cam engine, manufactured by Harley from 1998 to 2017.
The Twin Cam has since been dethroned by Harley’s newest millennial enigma – the high-powered Milwaukee Eight engine model.
All three 107, 110 and 114 Harley Davidson models rock powerful M8 engines successively.
This article explains the 9 biggest engine problems with Harley Davidson 88, 107, 110 & 114…
Table of Contents
The 9 Biggest Engine Problems With Harley Davidson 88, 107, 110 & 114 Are:
The 9 biggest engine problems with Harley Davidson 88, 107, 110 & 114 Are:
• Inadequate Cam Chain Tensioners
• Unreliable Crankshaft
• Oil Pump Issues
• Wet Sumping
• Heating Issues
• OEM Lifters Issues
• Loose Pistons
• Oil Aeration
• Slow/Cold Starting
What Are The 2 Biggest Engine Problems With Harley Davidson 88?
Inadequate Cam Chain Tensioners
The plastic cam chain tensioners can’t take as much stress from the pinion shafts.
They require regular inspections and need to be frequently changed every few miles.
If they disintegrate from weariness, the metal-to-metal contact in the shaft will generate heat issues and subsequent engine failure.
Unreliable Crankshaft
The pressed-up crankshafts were one of the biggest issues with the Twin cams.
Harley assembled the engine models in this manner to reduce the production costs back in ’98.
Users discovered that the pressed-up crank resulted in complete engine breakdown in less than 2000-3000 miles.
Especially if you were riding fast and hot.
Essentially, the spline shaft from the back would force down on the left flywheel, causing misalignment.
The misaligned flywheel would then shift or even bend the crankpin, causing engine failure.
Most Possible Solutions?
If the crankpin shifts or breaks off, it can tear off the entire cam system.
The broken parts will circulate through the system, and do more damage to the healthy body parts.
Hence, the primary solution is to locate the broken pin and remove it completely.
Multiple mechanical experts suggest replacing the unreliable crankshaft altogether.
You can escape both crankshaft and tensioner issues with an upgraded and balanced Harley 88.
What Are The 2 Biggest Engine Problems With Harley Davidson 107?
Oil Pump Issues
The Harley Davidson 107 suffers from major oil pump issues attributed to the low-quality cam chain tensioners.
The disintegrated plastic components can badly jam up the oil supply chain and disrupt the usual flow to the engine.
Wet Sumping
The used oil gets deposited either in the gear case or the crank instead of the oil tank.
The gradual build-up can cause a major imbalance within the engine components.
Most Possible Solutions?
The cam chain tensioners should be checked and replaced periodically to prevent blockades.
And to prevent wet sumping, the supply line needs regular monitoring with upgraded pumps.
What Are The 3 Biggest Engine Problems With Harley Davidson 110?
Heat Problems
Compared to the 107 and 114, the 110 M8 engine tends to heat up a lot faster.
The wet sumping causes oil to leak into the gasket.
The bearings get jammed due to improper lubrication and the engine heats up.
Loose Pistons
The powerful M8 engine can render the pistons very loose when revs get too intense.
The metal-to-metal friction between the loose pistons can contribute to heating issues.
OEM Lifter Failure
After 20,000 miles or more, the OEM lifters can suddenly become dysfunctional.
The poor quality lifters should be replaced with S&S ones in advance to prevent engine failure.
Most Possible Solutions?
The major heating issues have since been resolved by Harley in the newer models.
Anything from 2009 and up shouldn’t have any significant heating problems.
Different specialists suggest removing the stock head pipe and placing a catless pipe instead for better circulation of air.
If the heating issues are due to sumping, upgrade the oil pump and the head gasket.
What Are The 2 Biggest Engine Problems With Harley Davidson 114?
Oil Aeration
Oil aeration occurs when wet sumping keeps happening without any preventative measures.
The aeration decreases power within the engine and incurs further stress to it, causing further damage to engine components.
Slow Starting
The engine, despite being in pristine condition, can take a long time to start, especially in low temperatures.
Under 50-60° F, the charged battery takes longer to heat up the engine, which contributes to the slow response.
Most Possible Solutions?
For slow or cold starting, try switching to a different oil with low viscosity.
The aeration issues can be prevented by changing the head gasket and switching to S&S lifters in advance.
What Do Other Harley-Owners Say?
If you look through multiple Harley Davidson forums on the internet, you’ll find the Harley- owners sharing their love for their beloved motorbikes.
Besides the appreciation, you’ll see them sharing the problems and possible solutions as well.
An avid Harley-owner pointed out in one such forum how the 114 is almost similar to the 117 in terms of power, despite the differences in their compression magnitude.
Both sport the same crank, but the 114 engine comes with more compression, leading it to pack as much power as the 117 in the streets.
As a matter of fact, between 107, 114, and 117, the middle one has the highest compression.
Again, Bard Seven, a racing enthusiast, points out, the 114 still struggles with wet sumping.
Even the upgraded Milwaukee Eight engine is yet to redeem itself from the age-old clutches of oil accumulation and aeration.
Another Harley Street Glide owner shares his own opinion on the aforementioned problem.
By replacing the crankshaft altogether and swapping out the weaker sections for better parts, the mileage can be extended a lot further.
According to him, it’s all about ‘knowing what your baby (the bike) needs to perform the best.’
Where Were These Models Made?
Harley Davidson runs its base operations from Milwaukee, Wisconsin.
All the aforementioned models have been primarily designed and developed here in Harley’s central factory.
What Are The Pros And Cons Of Harley Davidson 88?
For starters, the Twin Cam engine of Harley Davidson 88 has a much better transmission construction compared to the previous Evo engine.
It also features better cam chain tensioner alignment and cam chain system overall.
And as for the cons, the compact crankshaft and flywheel positioning can often result in major heating issues.
The engine lacks appropriate cooling countermeasures.
Additionally, the plastic tensioners can break apart easily from the residual heat.
What Are The Pros And Cons Of Harley Davidson 107, 110 & 114?
The engine is an enigmatic power booster with well-ventilated pipelines.
All three 107, 110, and 114 models have better flow capacity and torque than the Harley Davidson 88.
On the other hand, many M8 engines manufactured before 2009 have extremely poor market value now.
The improved engine is relatively new and they have limited models.
The market value discrepancies also result in deviations in the devaluation percentages.
What Are The Devaluation Percentages – In Resale – Of These Models?
The devaluation percentage depends on these few key points:
• Manufacturing Year
• Engine Condition
• Preemptive Modification
• Factory-Based Modification
• Model Popularity
• Model Rarity
• Total Mileage
The Twin Cam 88, being the outdated model, will have a much lower resale value.
Speculations place the average devaluation percentage rate for 88 around 47.9-51%.
You will need to pay around 2.5K-4K for second-hand bikes with this engine model. Again, the M8 engines can make you spend over 7K, starting from 3/3.5K.
According to speculative statistics, the devaluation percentage rate for the M8 engine model stands anywhere from 47-58.5%.
What Are The Symptoms And Causes Of A Failing Harley Engine?
Harley engines can get quite vocal if they’re about to break down.
Here are the common symptoms of a failing Harley engine:
Rattling Noise
If there’s a heavy rattling noise, the shaft pin may have come undone.
Without removing the broken part immediately, you can risk damaging the other parts of the engine.
Slow Starting
If the engine is failing, it’ll take more time and effort to get it started.
Even in normal temperatures.
Miscalculated Acceleration
The oil pressure can suddenly go high, resulting in miscalculated acceleration.
Slow down immediately if that’s the case – it will produce a burnt odor from the exhaust.
You may also see blue or white fumes (smoke) coming out of the pipes.
Common Causes Behind A Failing Harley Engine:
Too Much Strain
If you’ve been riding hot and fast for too long without proper breaks, the constant strain can cause the engine to fail.
Cam Chain System Breakdown
The plastic tensioners have always been a prominent drawback for Harley engines.
When they come apart, they can jam the cam chain system, causing breakdown.
Excessive Heating
Without proper cooling countermeasures, the oil sumping and aeration will cause the engine to slow down and gradually fail completely.
Cheap Oil
If you’re using cheap oil with Harley engines, the oil will get aerated faster, accelerating the process of engine failure.
Can The Carburetor Be Related To These Problems?
If the carburetor is jammed or clogged by impurities due to improper lubrication, it can cause significant engine problems.
Usually, the carburetor heating up excessively is a dead giveaway of imminent engine failure.
What Is The Rule Of Thumb, When To Call The Mechanic Or Not?
Both Twin Cam and M8 engines have their drawbacks and benefits.
Many consider the Twin Cam to be more reliable wheresoever the M8 is in a whole different league in terms of boosting the overall power.
Between Harley 88, 107, 110, and 114, the M8 engine of 114 is definitely Harley’s strongest contender thus far.
Simplistic interfaces with complex inner workings – that’s just how Harley engines roll.
It’s possible to resolve general heating issues by changing the oil or cleaning the oil pump.
Again, you can check the engine for any loose gears to fix the rattling noises.
But if the rattling noise is due to broken plastic pieces rumbling around, it’s a much different case altogether.
In such cases, it’s best to take the bike to the mechanic before any more important parts get damaged from the broken pieces.
Plus, everyone knows that factory modifications add more to the resale value in the long run.
Hence, see if the issue seems fixable with simple countermeasures. If not, call the mechanic right away and have him check everything out professionally.
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