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1978 Yamaha YZ125

Up for auction is an exceptional 1978 Yamaha YZ125, a true icon from the golden era of motocross. The late-1970s were a turning point in off-road motorcycle development, and the 1978 YZ125 represents the peak of development for Yamaha’s air-cooled two-stroke race bikes. Featuring advanced drum brakes, longer-travel suspension, and Yamaha’s revolutionary Monoshock (Unishock) rear suspension, this model helped define modern motocross performance.

Today, these bikes are increasingly sought after by collectors and vintage racers alike. Riders competing in modern vintage motocross events are pushing these machines harder than ever—clearing jumps, railing berms, and proving just how capable these classic machines still are. For many enthusiasts now in their 50s and 60s, the YZ125 was the bike to have back in the day, and the market for clean survivors like this one is heating up rapidly.

This particular bike came to us as part of a 50+ motorcycle collector purchase out of Utica, New York, where it had been carefully stored away for years. Our team at Kaplan Cycles / Kaplan America performed a comprehensive service and preservation process to bring the bike back to excellent running condition while maintaining its original character.

Condition & Originality Highlights

A thorough look up close reveals this unit as an impressive survivor. Very very nice!!!

Even the kickstand mount is still present, which is often removed on vintage race bikes.

The swingarm is especially impressive—carefully Scotch-Brite finished and polished by our staff, with no dents or gouges.

Overall, this bike retains the type of “good bones” collectors look for, something that cannot be replicated with rough project bikes often found on the market.

Mechanical Service & Preservation Work

Our service department performed a full inspection and tuning process to ensure the bike runs strong and presents beautifully.

Service highlights include:

Throttle operation is smooth with the original Whirlpool-style throttle assembly intact, and all cables have been lubricated and correctly routed.

This is the type of careful preparation our shop is known for—a machine that is ready for display or ready to ride.

Engine Note

The motorcycle runs excellent and starts easily, with a strong top end and healthy compression.

However, our technicians noted that the original crankshaft bearings are no longer within ideal spec. The bike runs great as it sits and does not show excessive vibration, but for someone planning to race the bike aggressively, the team recommends installing a new crank.

This is a straightforward job for vintage engine specialists such as Tom Morgan or Ken O’Connor, and the engine can be rebuilt economically if desired.

Due to our 200+ motorcycle restoration backlog, we are offering the bike as-is, giving the next owner the option to ride it, display it, or build the engine further.

Why This Bike Is Special

Clean, original survivors like this are getting harder to find. Many bikes from this era were heavily raced and modified. This one retains:

Whether you're looking for:

…this YZ125 is an outstanding candidate.

Shipping

We can arrange fully insured, enclosed motorcycle shipping anywhere in the United States.

Typical rates:

Send us your ZIP code for an exact quote and we’ll handle all the logistics.

Contact

For additional information or a Buy-It-Now price, contact us:

📞 860-471-0192

About Kaplan Cycles

Kaplan Cycles has built a national reputation for properly servicing, restoring, and preserving classic motorcycles. Every bike we sell is carefully inspected by our technicians and presented honestly so collectors and enthusiasts can buy with confidence.

Good luck bidding, and God Bless America.

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WHY SHOULD YOU BUY FROM KAPLAN? WHAT DO YOU GET?

“You are buying from the Kaplan Cycles Family. We are not just another big auction house. We are family-owned and operated and have been buying, servicing, and selling motorcycles since 1975. You will work directly with Ken Jr., Ken Sr., and/or one of the 22 experts on our team. We provide museum-quality, white-glove concierge service from start to finish. Every motorcycle we sell is inspected, serviced, and supported by our team, and we stand behind it after the sale. You’re not on your own — we back what we build and what we sell.

With over 17,000 units sold and still 100% positive feedback, we are the best stress-free buying experience you can have. From the first call to delivery at your door, we will handle it all — because vintage motorcycles deserve support, and so do you.

With every bike we curate you get:
• museum-level inspection & preservation services
• every machine is professionally evaluated, serviced, & rotisserie detailed
• all critical systems are checked, adjusted, or renewed
• you get professional setup, tuning, and delivery prep
• done by the best experts in the industry — we ride and restore every day
• you get post-sale phone support
• you get white-glove, insured, always-enclosed shipping to your door anywhere in the country

You’re buying from Kaplan Cycles at the New England Motorcycle Museum, one of the largest vintage motorcycle collections in North America. Free museum tours and tickets are included with every bike sold. With every bike you purchase, a portion of the proceeds is used to support, continue, and improve the 501(c)(3) nonprofit New England Motorcycle Museum.

You don’t just win an auction — YOU are creating & helping to preserve motorcycle history, and you become part of our family, a Kaplan Cycles client for life.

We do not take new clients off the street.
We do not service bikes purchased elsewhere.
We only take new exclusive clients who purchase a motorcycle from us.

You get a guided purchase experience with, and from, the experts who care about the bike as much as you do. If there’s a problem, you don’t get ghosted. You call us — you will have our cell phone numbers — we will answer your call on weekends, and we will help make it right.

Auction platforms = listing only. No support. No accountability.

Kaplan Cycles = we stand behind what we sell.

You are buying museum-curated provenance. That means:
• expert evaluation
• documented condition
• professional presentation
• long-term preservation mindset

You’re not just buying a motorcycle — you’re buying a curated piece of motorcycling history.

From the #1 family in this business — Kaplan Cycles & the New England Motorcycle Museum.

Sincerely,

Ken Kaplan Sr.
12/28/2025”

AUCTION TERMS:

All motorcycles & vehicles are sold as-is where-is.

Kaplan Cycles guarantees all motorcycles are as-described. Please read the entire description and watch the entire video before bidding.

A non-refundable deposit is due immediately on purchase. PayPal or Credit Card is accepted for the deposit.

Cash (In-Person), Card (+3% fee), or Wire Transfer are our only accepted forms of final payment.

Full payment must be made within 7 days of auction close.

Your motorcycle must be picked up within 30 days of auction close. 

Exceptions are made only for international buyers OR buyers who have ALREADY made transport arrangements with a third party.

If a motorcycle is purchased and left here for longer than 30 days without written permission from Kaplan Cycles it will be resold. In the case of a re-sale, the owner will be entitled to a refund less storage fees ($25/ day beginning 30 days from auction close) ONLY if the motorcycle was paid in full on-time within the auction terms.

We always describe our motorcycles as accurately as possible.

You are purchasing a classic motorcycle. Even in cases where a bike may be in good running/ operating condition, new problems & idiosyncrasies can arise over-time from sitting or regular use.

If you have an issue with the motorcycle you’ve received, contact us within 24 hours of delivery and before leaving feedback so that we can address your concerns.

It is important you have at least a basic mechanical knowledge before purchasing and operating a classic motorcycle.

Due to our backlog, we cannot perform any additional service work or modifications on your motorcycle after the sale (ie; adding a light kit, different tires, etc.)

We respond quickly between the hours of 9am and 5pm EST, Monday - Friday

For our fastest service please call Ken Kaplan Jr directly at 860-471-0192

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We will not charge out-of-state buyers sales tax.
Out of state residents will pay sales tax with their DMV. 

We are not a registering dealership. You will receive only the documents required to register your vehicle in your state.

In our listings, title status is always listed directly below the main description.

In some cases we will sell motorcycles without title or registration. In these cases we guarantee all motorcycles sold are free and clear. We will always provide a route to obtaining title. Generally in these cases, the motorcycle will be sold at a discount to accommodate expenses involved.

Documents are mailed via USPS priority mail with a tracking number. Please allow up to 14 days after payment in full for your documents to be processed and mailed.

Keys will be shipped with the motorcycle.

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Warranty:

All Motorycles sold "as is, where is" and Kaplan Cycles does not warranty any motorcycle sold. No express warranty and/or implied warranty are made by Kaplan Cycles. No statements by us give an implied warranty.

SHIPPING:

SEND US YOUR ZIP FOR A SHIPPING QUOTE!
WE WILL MAKE ALL ARRANGEMENTS!

We have the best shipping contacts in the nation who will provide the FASTEST transport times, have a perfect track record, and are always insured and ENCLOSED! All motorcycles are shipped WHOLE (roll-on, roll-off). We do not offer a pallet or crate service.

International shipping specialist contacts are available! They will assist in ground freight, customs clearance, and ocean freight to your country. International buyers will be required to work directly with our third party shipping contacts.

We strongly recommend you insure your motorcycle at the time of purchase.

PICKUP:

We require a 24 hour notice prior to pick-up. Please call us at 860-454-7024 during office hours Monday – Friday 9am – 5pm EST.

We will provide ramps, a dock for loading, and assistance to load for free.