TRIUMPH 70-3753 Tappet 5TA

( Manufacturer Part Number: 70-3753 ), ( Part Type: Tappet ), ( Unit Type: Unit ), ( Vintage Part: Yes ), ( Compatible Year: 1974 )

Review TRIUMPH Tappet 3ta 5ta fits T90 T100 500 1961-74

The Triumph 70-3753 engine, spanning the iconic models from the 1961 to 1974 era including the legendary **T90, T100, 500 Triple, and 3TA/5TA variants** represents a pinnacle of British motorcycle engineering, blending raw performance with timeless craftsmanship. This air-cooled, overhead-valve powerplant is a masterclass in simplicity and efficiency, featuring a **500cc parallel-twin cylinder design** that delivers a throaty, growling exhaust note synonymous with the era. The engine s **tappet-adjustable valve mechanism** ensures precise timing and longevity, a hallmark of Triumph s attention to detail, while the **three- or five-speed gearbox** (depending on the model) offers a smooth, engaging shift feel that remains unmatched in its class. The **T90 and T100** iterations, in particular, are celebrated for their lightweight yet robust construction, with the T100 s slightly refined handling and improved suspension making it a favorite among both purists and enthusiasts. The **3TA and 5TA** variants, often found in the **Tiger 90 and Tiger 100** models, retain the same core engine but are paired with a more upright riding position and a slightly different chassis, catering to a broader range of riders. Whether stripped down for track use or dressed up with period-correct accessories, this engine embodies the spirit of the British motorcycle revival, offering a perfect blend of nostalgia and performance. Its timeless design, coupled with the unmistakable sound of its twin-pot exhaust, makes it a sought-after centerpiece for custom builds, restorations, and daily riding machines alike.

### **Pros and Cons of Buying a Triumph 500cc Tappet-Over Engine (1961 1974) Motorcycle**

#### **Pros**

1. **Classic Design and Heritage**

The Triumph 500cc models (T90, T100, 5TA, 3TA) are iconic British motorcycles with a strong following among enthusiasts. Their timeless styling, including the distinctive fuel tank, handlebars, and frame, makes them visually appealing and instantly recognizable.

2. **Mechanical Simplicity and Durability**

The tappet-over valve train (pushrods and rocker arms) is a robust design that has stood the test of time. When properly maintained, these engines can last for decades with relatively straightforward repairs compared to modern overhead-camshaft setups.

3. **Strong Performance for Its Era**

The 500cc parallel-twin engine (especially in the 5TA and 3TA variants) produces a smooth, torquey power delivery that was well-suited for touring and cruising in the 1960s and 70s. The T90 and T100, while slightly less powerful, offer a more relaxed riding experience.

4. **Modification Potential**

These bikes are highly modifiable. Aftermarket support includes performance upgrades (e.g., carburetor swaps, exhaust systems, crankshaft balancing), cosmetic restorations, and even modern engine swaps (e.g., replacing the 500cc engine with a 650cc or 885cc Triumph unit).

5. **Community and Support**

The Triumph 500cc community is active, with clubs, forums (e.g., Triumph500.org, Classic Triumph Owners), and readily available parts. Many enthusiasts share knowledge on restoration, maintenance, and troubleshooting.

6. **Lower Running Costs (Compared to Modern Bikes)**

Fuel efficiency is decent for its class, and basic maintenance (oil changes, chain adjustments) is inexpensive. While parts can be costly for rare models, the overall ownership cost is lower than that of a modern sportbike or adventure bike.

7. **Riding Experience**

The ergonomics of these bikes particularly the T90 and T100 are comfortable for taller riders, with a relaxed seating position and good ground clearance. The weight (around 400 450 lbs) makes them manageable for solo riders but can be tiring on long rides.

8. **Investment Potential**

Well-restored examples, especially rare models like the T100 or early 5TA, can appreciate in value over time, particularly if demand from collectors continues to grow.

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#### **Cons**

1. **High Maintenance Requirements**

The tappet-over engine is not "set and forget." Regular valve adjustments (every 3,000 5,000 miles), tappet wear, and potential for oil leaks (especially in older models) require diligent upkeep. Neglect can lead to expensive repairs.

2. **Parts Availability and Cost**

While not as scarce as some vintage bikes, parts for Triumph 500cc models can be expensive, especially for rare or discontinued components. Some aftermarket suppliers may charge premium prices for reproduction parts.

3. **Reliability Issues**

- **Engine wear**: Tappet wear, camshaft and lifter issues, and cylinder head leaks are frequent concerns, particularly in higher-mileage examples.

- **Electrical quirks**: Older wiring harnesses and ignition systems can be finicky, requiring upgrades (e.g., modern CDI units).

- **Frame and suspension**: Some models (e.g., T90) have stiff suspension that may feel harsh on modern roads. Frame cracks can also occur in older bikes.

4. **Performance Limitations**

The 500cc engine is not as powerful as modern bikes, with peak power around 40 50 hp (depending on the model). Acceleration and top speed are modest by today s standards, making them less suitable for aggressive riding or highway cruising without modifications.

5. **Weight and Handling**

These bikes are heavy (400 450 lbs), which can make them tiring to maneuver in traffic or on tight roads. The rigid frame and lack of modern suspension tuning can result in a less forgiving ride than contemporary bikes.

6. **Fuel and Emissions Compliance**

Older models may not meet modern emissions standards, requiring modifications (e.g., catalytic converters, modern carburetors) if used in areas with strict regulations. Fuel quality can also be an issue, as modern gasoline is less compatible with older engines.

7. **Restoration Time and Cost**

Bringing a neglected 500cc Triumph back to running condition can be a significant investment in time and money. Common restoration projects include:

- Engine rebuild or overhaul

- Frame straightening or replacement

- Electrical system upgrades

- Paint and bodywork

- Suspension and brake overhauls

8. **Limited Modern Comfort Features**

Compared to contemporary bikes, these models lack features like ABS, traction control, modern ergonomics, or advanced suspension systems. Riding comfort may feel outdated by today s standards.

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### **Conclusion and Recommendation**

#### **Who Should Buy a Triumph 500cc Tappet-Over Bike?**

- **Enthusiasts who appreciate classic British design and engineering.**

- **Riders who enjoy restoration projects and mechanical work.**

- **Those seeking a comfortable, low-speed cruiser with character.**

- **Collectors or investors willing to spend time and money on maintenance.**

- **Riders who prioritize nostalgia and community over performance.**

#### **Who Should Avoid It?**

- **Casual riders who want a "plug-and-play" modern machine.**

- **Those with limited mechanical skills or patience for frequent maintenance.**

- **Riders who prioritize high speed, advanced electronics, or modern comfort.**

- **Budget-conscious buyers unwilling to invest in repairs or upgrades.**

#### **Final Recommendation**

If you are passionate about vintage motorcycles and willing to commit to the maintenance and restoration process, a Triumph 500cc tappet-over model can be a rewarding and enjoyable ride. Start with a **well-documented, restored example** (preferably with a recent service history) to avoid costly surprises. Prioritize models like the **T100 or 5TA** for better performance, or the **T90** for a more relaxed, touring-oriented experience.

- **Budgeting for at least $5,000 $10,000** for a reliable, restored bike (prices vary widely based on rarity and condition).

- **Joining the Triumph 500cc community** for advice on sourcing parts and finding reputable mechanics.

- **Testing ride multiple examples** to ensure the ergonomics and handling suit your preferences.

Ultimately, this is a bike for those who love the history and craftsmanship of British motorcycles and are prepared for the challenges that come with it.

Details:

TRIUMPH 1961-74 500 TAPPET 3TA 5TA T90 T100 70-3753.

part #: 703753 prices

• $20.95-$127.40

specifications cyclevintagee:

• for models: T90, T100, 500
• for makes: Triumph
• for years: 1961-74
• mpn: 70-3753
• part type: Tappet
• unit type: Unit
• vintage part: Yes
• compatible year: 1974

offer cyclevintagee:

• best offers: True
• sold: 0
• availability: In Stock
• options: Ship-to-home
• started: April 14, 2026

seller cyclevintagee:

• rating: 99.6%
• # reviews: 281
• city: Pensacola, Florida

general cyclevintagee:

• Parts Accessories > Motorcycle Scooter Parts Accessories > Other Motorcycle Scooter Parts Accessories
• condition: Used

returns cyclevintagee:

• time: 30 Days
• policy: Returns Accepted
• paid by: Buyer

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• other
• credit card: Visa
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shipping cyclevintagee:

• class: Standard
• cost: $9.00
• type: Fixed
• carrier: USPS
• service: USPS Ground Advantage
• transit: 4-10 Days

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