2015-2020 Yamaha XC155 Scooters 990145 Missing Primary Sheave Nut May Cause Engine Stall

April 9, 2021 NHTSA CAMPAIGN NUMBER: 21V251000

Missing Primary Sheave Nut May Cause Engine Stall

A missing primary sheave nut may cause a stall, without the ability to restart the engine, increasing the risk of a crash.

 

NHTSA Campaign Number: 21V251

Manufacturer Yamaha Motor Corporation, USA

Components ENGINE

Potential Number of Units Affected 4,262

 

Summary

Yamaha Motor Corporation, USA (Yamaha) is recalling certain 2015-2020 Yamaha XC155 scooters. The primary sheave nut may loosen and fall off.

 

Remedy

Yamaha will notify owners, and dealers will replace the primary retaining nut and washer with one of a new design, free of charge. Owner notification letters were mailed on April 28, 2021. Owners may contact Yamaha customer service at 1-800-962-7926. Yamaha’s number for this recall is 990145. Note: Owners are advised not to ride their scooter until the remedy has been preformed.

 

Notes

Owners may also contact the National Highway Traffic Safety Administration Vehicle Safety Hotline at 1-888-327-4236 (TTY 1-800-424-9153), or go to www.safercar.gov.

 

Check for Yamaha Recalls

 

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MOTORCYCLE

4/28/2021

M2021-004R

 

SAFETY RECALL

This modification has top priority. This bulletin must be performed immediately to ensure customer safety. NOTE: Bulletins that announce a recall will have an “R” at the end of the bulletin number.

 

2015~2020 MODEL XC155 (SMAX) SCOOTERS

FACTORY MODIFICATION CAMPAIGN – Primary Sheave Nut

 

INTRODUCTION

Yamaha Motor Corporation, U.S.A. has decided that a defect that relates to motor vehicle safety exists in 2015~2020 model XC155 (SMAX) scooters.

 

In affected scooters, there is a possibility that the primary sheave nut could loosen. If this happens, the loosened primary sheave can contact the case cover when the vehicle is in operation, most often causing an abnormal engine noise. If the vehicle continues to be ridden in this condition, the primary sheave nut may fall off. Then it is possible that the engine will stall and cannot be restarted, increasing the risk of loss of control and a crash with injury or death.

 

To correct this defect, Yamaha is initiating a Factory Modification Campaign. Affected units must have the primary sheave nut and washer replaced with a new flanged nut and washer, tightened correctly to a new torque specification.

 

Yamaha is notifying all registered owners of affected scooters by mail. A copy of this letter is included in this bulletin. The customer should take this letter along with the affected scooter to an authorized Yamaha dealer for modification.

 

If your dealership was invoiced for one or more affected units, a computer report listing all affected scooters invoiced to your dealership is included with a mailed copy of this bulletin. Use the list to help ensure all scooters are modified. All sold scooters that have been registered with Yamaha will show the customer’s name and address.

 

Your dealership must notify the owner of any affected scooter that was actually sold but listed as “unsold” in the report. You must modify all affected scooters in your inventory as well as all customer-owned scooters brought to you for this service. Any affected scooter that you purchase from Yamaha in the future may also require modification. If you purchase a scooter from another dealer or Yamaha, check to see if the procedures in this bulletin have already been performed before you sell the scooter.

 

Scooters that are affected should not be operated until they are modified. It is a violation of Yamaha policy for your dealership to deliver any affected scooter to customers until the procedures in this bulletin are performed.

 

When the modification on each scooter is performed, follow the Warranty Information section of this bulletin to receive reimbursement. Be sure to use the Factory Modification Campaign procedures in Chapter 7 of the Warranty and Y.E.S. Handbook (LIT-11760-00-16).

 

Unsold & Sold Units:

Use Unit Status on YDS to check to be sure the unit is affected and that it has not already been modified. Follow the Service Procedures in this bulletin to modify all unmodified affected units.

 

DEALER ACTION SUMMARY

Parts:

Yes. Order a XC155 Primary Sheave Nut Kit for each affected unit. See the Parts Information section of this bulletin for more information.

 

Warranty:

Factory Modification Campaign. See the Warranty Information section of this bulletin.

This modification applies to all affected units regardless of ownership or warranty status.

 

Notify Customers:

Yes, you must immediately contact any customer whose scooter shows as unregistered on the enclosed report. Yamaha has sent letters to customers whose scooters were registered with Yamaha as of 4/27/2021.

 

AFFECTED RANGE

Check Unit Status on YDS to make sure the Primary ID (PID) is in the Affected Range and is eligible for this repair. The affected unit ranges for this issue are:

Model Year	Model	Model Code	Primary ID
			Prefix	From	To
2015	XC155	2SW1	SG30Y	0000101	0003052
2016~2020	XC155	2SW3, 2SW5, 2SW7, 2SW9, 2SWB	SG36Y	0001001	0003201

 

IMPORTANT: Affected Primary IDs may not be consecutive. Always check YDS Unit Status before starting any repair.

 

1. Refer to the XC155 Service Manual (P/N: LIT-11616-28-47) to remove the V-belt case cover and the primary sheave.

 

TIP: Moving the air cleaner case up out of the way makes removing the V-belt case cover easier. Remove the two bolts ① holding the air cleaner case (the forward one is under a plug ②). Disconnect the air hose at the back of the case, then push the air cleaner case up and secure it above the cover.

 

2. Tag the original sheave nut and washer with a Warranty Parts Tag and hold them for 90 days from the date you submit your recall claim.

 

3. Using Yamalube Brake & Contact Cleaner or similar product, thoroughly remove any grease, oil, or other contaminants from the primary sliding sheave surface ①, sheave threads ②, center of cam ③, primary fixed sheave surface ④, and the new washer from the kit ⑤.

 

4. Apply Ultramatic Grease (P/N: ACC-ULTRA-GS-16) or, if unavailable, Yamalube Polyurea Grease (P/N: ACC-POLYG-RS-05) to the threads and the contact surface of the flange end of the new nut (6) from the kit.

 

5. Reinstall the primary fixed sheave ④ and install the new washer ⑤ from the kit.

 

6. Install the new nut according to Service Manual instructions, and tighten to a NEW TORQUE SPECIFICATION:

53 Nm (5.3 m-kgf, 39 ft-lbf)

 

7. Make sure that the V-belt is tight within the primary and secondary sheaves. Reassemble the case cover and air cleaner case per the Service Manual. Be sure to apply grease to the secondary clutch spacer and O-ring.

 

IMPORTANT:

The Service Manual in the YDS Knowledge Center has been updated to include this new primary sheave tightening procedure. If you have any printed copies of the manual, be sure to note this new procedure and torque or print out page 2-14 and the “INSTALLING THE SECONDARY SHEAVE, V-BELT AND PRIMARY SHEAVE” procedure on pages 5-34~5-36 of the new manual to keep with your printed copy.

 

IDENTIFICATION PROCEDURE

After completing the procedure, make sure to properly record and submit the warranty claim for this campaign to ensure correct reimbursement and to update the unit’s repair history in Yamaha’s database.

New and old parts can be identified by their appearance:

NUT

Old Part	New Part
No flange	With flange
Black color	Silver color

 

WASHER

Old Part	New Part
Inner diameter: 12.5mm	Inner diameter: 12mm
Outer diameter: 28mm	Outer diameter: 27 mm
Thickness: 3 mm	Thickness: 2.3 mm
Black color	Silver color

 

PARTS INFORMATION

Order the XC155 Primary Sheave Nut kit.

PART NUMBER	DESCRIPTION	QTY	Application	DEALER COST
90891-10317-00	XC155 Primary Sheave Nut Kit Contains: Nut (90179-12019-00), Qty. 1 Washer (90201-12837-00), Qty. 1	1	XC155 (SMAX)	$0.44

 

WARRANTY INFORMATION

The owner of each registered scooter will receive a letter announcing this campaign. The customer’s letter includes the Vehicle Identification Number (VIN) and Recall Number.

The modification is authorized for all affected scooters, both sold and unsold, regardless of ownership or warranty status. You do not need the customer’s letter to perform the modification or to file for reimbursement.

Submit a Recall Claim as described below using Campaign Number 990145. The labor allowance is 0.7 hour.

To submit your Recall Claim on YDS, go to Service > Warranty Claims/Authorization > Claims/Authorization > New. Then, from the menu, select Recall / Service per Bulletin Claim.

If you have any questions about proper procedures for Factory Modification Campaigns, see Chapter 7 in your Warranty and Y.E.S. Handbook (LIT-11760-00-16).

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IMPORTANT SAFETY RECALL NOTICE

This notice applies to your vehicle, VIN xxxxxxxxxxxxxxxxx

_Model:

April 28, 2021
990145

 

Dear Yamaha Owner:

This notice is sent to you in accordance with the National Traffic and Motor Vehicle Safety Act. Yamaha Motor Corporation, U.S.A. has decided that a defect that relates to motor vehicle safety exists in 2015~2020 model XC155 (SMAX) scooters. Our records indicate you own the affected vehicle show above.

 

The reason for this recall:

In affected scooters, the primary sheave nut could loosen. If this happens, the loosened primary sheave can contact the case cover when the vehicle is in operation, most often causing an abnormal engine noise. If the vehicle continues to be ridden in this condition, the primary sheave nut may fall off. Then it is possible that the engine will stall and cannot be restarted, increasing the risk of loss of control and a crash with injury or death.

 

What Yamaha and your dealer will do:

Your authorized Yamaha dealer will replace the primary sheave nut with a new flanged nut and washer, tightened correctly to a new torque specification. The procedure takes around 45 minutes to perform, but your dealer may need to keep your scooter longer. There will be no charge to you for this procedure.

 

What you should do now:

Please call your Yamaha dealer to make a service appointment to have this procedure performed. At that same time, you can find out how long they expect to keep your SMAX scooter for this service. Remember to take this letter with you when you take in your scooter.

You should not operate your affected scooter shown above until modification is performed. 

If you are unable to return to the Yamaha dealer who sold you the scooter, this service will be performed by any authorized Yamaha Scooter dealer. For the name of a dealer near you, call 1-800-88-YAMAHA or visit the Yamaha web site at www.yamaha-motor.com.

If you have had this repair performed before you received this letter, you may be entitled to receive reimbursement for the cost of obtaining a pre-notification remedy of the problem associated with this repair. For more information, contact Yamaha Customer Relations at 1-800-962-7926.

Federal regulations require that any vehicle lessor receiving this recall notice must forward a copy of this notice to the lessee within 10 days.

 

If you need help:

If, after contacting your dealership, you have questions or concerns which the dealership is unable to answer, please write to:

Yamaha Motor Corporation, U.S.A.
Customer Relations Department
P.O. Box 6555
Cypress, CA 90630

Or call: 1-800-962-7926

If, after contacting Yamaha Customer Relations, you are still not satisfied that we have done our best to remedy the situation without charge and within a reasonable time, you may submit a written complaint to the Administrator, National Highway Traffic Safety Administration, 1200 New Jersey Avenue, SE., Washington, DC 20590; or call the Auto Safety Hotline at 1-888-327-4236 (TTY: 1-800- 424-9153); or go to https://www.safercar.gov. Refer to NHTSA recall number 21V251.

If you no longer own this Yamaha:

If you have sold your SMAX scooter to another party, please call us toll-free at 1-800-962-7926 with the name and address of the new owner, along with the Vehicle Identification Number shown above your name on this letter.

We’re sorry to cause you any inconvenience, but we are sincerely concerned about your safety and continued satisfaction with our products. Thank you for giving your attention to this important matter.

 

Sincerely,

Motorsports Service Support

Yamaha Motor Corporation, U.S.A.

 

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6 Affected Products

Vehicle

MAKE	MODEL	YEAR
YAMAHA	XC155	2015-2020

 

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7 Associated Documents

Recall Quarterly Report #1, 2021-2

RCLQRT-21V251-6337.PDF 211.152KB

 

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Owner Notification Letter(Part 577)

RCONL-21V251-1106.pdf 154.819KB

 

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Remedy Instructions and TSB

RCRIT-21V251-3584.pdf 1048.519KB

 

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Recall Acknowledgement

RCAK-21V251-6462.pdf 644.932KB

 

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Defect Notice 573 Report

RCLRPT-21V251-4532.PDF 216.228KB

 

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Recall Quarterly Report #3, 2021-4

RCLQRT-21V251-6247.PDF 211.336KB

 

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Recall Quarterly Report #2, 2021-3

RCLQRT-21V251-6079.PDF 211.249KB

 

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Latest Recalls Documents

https://www-odi.nhtsa.dot.gov/acms/cs/documentList.xhtml?docId=21V251&docType=RCL

 

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Last update on 2025-04-18 / Affiliate links / Images from Amazon Product Advertising API

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