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                                                                    EXHIBIT 4.10


                             SUPPLEMENTAL INDENTURE
                       DELIVERED BY SUBSEQUENT GUARANTORS

         SUPPLEMENTAL INDENTURE (this "Supplemental Indenture"), dated as of May
15, 2001, among Generac Portable Products, Inc.*, a Delaware corporation, (the
"Guaranteeing Subsidiary"), a subsidiary of Briggs & Stratton Corporation (or
its permitted successor), a Wisconsin corporation (the "Company"), the Company,
the other Guarantors (as defined in the Indenture referred to herein) and Bank
One, N.A., as Trustee under the indenture referred to below (the "Trustee").

                               W I T N E S S E T H

         WHEREAS, the Company has heretofore executed and delivered to the
Trustee an indenture (the "Indenture"), dated as of May 14, 2001, providing for
the issuance of an aggregate principal amount of up to $275,000,000 of 8.875%
Senior Notes due March 15, 2011 (the "Notes");

         WHEREAS, the Indenture provides that under certain circumstances the
Guaranteeing Subsidiary shall execute and deliver to the Trustee a supplemental
indenture pursuant to which the Guaranteeing Subsidiary shall unconditionally
guarantee all of the Company's Obligations under the Notes and the Indenture on
the terms and conditions set forth herein (the "Subsidiary Guarantee"); and

         WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee is
authorized to execute and deliver this Supplemental Indenture.

         NOW THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, the receipt of which is hereby acknowledged, the
Guaranteeing Subsidiary and the Trustee mutually covenant and agree for the
equal and ratable benefit of the Holders as follows:

         1.       CAPITALIZED TERMS. Capitalized terms used herein without
definition shall have the meanings assigned to them in the Indenture.

         2.       AGREEMENT TO GUARANTEE. The Guaranteeing Subsidiary hereby
agrees as follows:

                  (a)     Along with all Guarantors named in the Indenture, to
         jointly and severally Guarantee to each Holder of a Note authenticated
         and delivered by the Trustee and to the Trustee and its successors and
         assigns, irrespective of the validity and enforceability of the
         Indenture, the Notes or the obligations of the Company hereunder or
         thereunder, that:

                           (i)  the principal, premium, if any, of and interest
                  and Special Interest, if any, on the Notes will be promptly
                  paid in full when due, whether at maturity, by acceleration,
                  redemption, repurchase or otherwise, and interest on the
                  overdue principal of and interest and Special Interest on the
                  Notes, if any, if lawful, and all other Obligations of the
                  Company to the Holders or the Trustee hereunder or thereunder
                  will be promptly paid in full or performed, all in accordance
                  with the terms hereof and thereof; and

                           (ii) in case of any extension of time of payment or
                  renewal of any Notes or any of such other Obligations, that
                  the same will be promptly paid in full when due or performed
                  in accordance with the terms of the extension or renewal,
                  whether at stated maturity, by acceleration or otherwise,
                  subject to the limitations set forth in the Indenture. Failing
                  payment when due of any amount so guaranteed or any
                  performance so



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                  guaranteed for whatever reason, the Guarantors shall be
                  jointly and severally obligated to pay the same immediately.

                  (b)      The Obligations hereunder shall be unconditional,
         irrespective of the validity, regularity or enforceability of the Notes
         or the Indenture, the absence of any action to enforce the same, any
         waiver or consent by any Holder with respect to any provisions hereof
         or thereof, the recovery of any judgment against the Company, any
         action to enforce the same or any other circumstance which might
         otherwise constitute a legal or equitable discharge or defense of
         guarantor.

                  (c)      The following is hereby waived: diligence,
         presentment, demand of payment, filing of claims with a court in the
         event of insolvency or bankruptcy of the Company, any right to require
         a proceeding first against the Company, protest, notice and all demands
         whatsoever.

                  (d)      This Subsidiary Guarantee shall not be discharged
         except by complete performance of the obligations contained in the
         Notes and the Indenture, and the Guaranteeing Subsidiary accepts all
         Obligations of a Guarantor under the Indenture.

                  (e)      If any Holder or the Trustee is required by any court
         or otherwise to return to the Company, the Guarantors, or any Custodian
         acting in relation to either the Company or the Guarantors, any amount
         paid by either to the Trustee or such Holder, this Subsidiary
         Guarantee, to the extent theretofore discharged, shall be reinstated in
         full force and effect.

                  (f)      The Guaranteeing Subsidiary shall not be entitled to
         any right of subrogation in relation to the Holders in respect of any
         Obligations guaranteed hereby until payment in full of all Obligations
         guaranteed hereby.

                  (g)      As between the Guarantors, on the one hand, and the
         Holders and the Trustee, on the other hand, (x) the maturity of the
         Obligations guaranteed hereby may be accelerated as provided in Article
         6 of the Indenture for the purposes of this Subsidiary Guarantee,
         notwithstanding any stay, injunction or other prohibition preventing
         such acceleration in respect of the Obligations guaranteed hereby, and
         (y) in the event of any declaration of acceleration of such
         Obligations as provided in Article 6 of the Indenture, such Obligations
         (whether or not due and payable) shall forthwith become due and payable
         by the Guarantors for the purpose of this Subsidiary Guarantee (subject
         to any subsequent rescission or cancellation of any acceleration in
         accordance with Section 6.02 of the Indenture).

                  (h)      The Guarantors shall have the right to seek
         contribution from any non-paying Guarantor so long as the exercise of
         such right does not impair the rights of the Holders under the
         Subsidiary Guarantee.

                  (i)      Pursuant to Section 10.02 of the Indenture, after
         giving effect to any maximum amount and any other contingent and fixed
         liabilities that are relevant under any applicable Bankruptcy Law or
         fraudulent conveyance laws, and after giving effect to any collections
         from, rights to receive contribution from or payments made by or on
         behalf of any other Guarantor in respect of the Obligations of such
         other Guarantor under Article 10 of the Indenture, this new Subsidiary
         Guarantee shall be limited to the maximum amount permissible such that
         the Obligations of such Guarantor under this Subsidiary Guarantee will
         not constitute a fraudulent transfer or conveyance.


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         3.       EXECUTION AND DELIVERY. Each Guaranteeing Subsidiary agrees
that the Subsidiary Guarantee shall remain in full force and effect
notwithstanding any failure to endorse on each Note a notation of such
Subsidiary Guarantee.

         4.       GUARANTEEING SUBSIDIARY MAY CONSOLIDATE, ETC. ON CERTAIN
TERMS.

                  (a)     Except as otherwise provided in Section 5 below, the
         Guaranteeing Subsidiary may not (i) consolidate with or merge with or
         into (whether or not such Guarantor is the surviving Person) another
         Person or (ii) sell, assign, transfer, lease, convey or otherwise
         dispose of all or substantially all of its assets in one or more
         related transactions to another Person unless:

                  (i)  subject to Section 5 below either: (x) the Person formed
                  by or surviving any such consolidation or merger (if other
                  than a Guarantor or the Company) or the Person acquiring the
                  assets in any such sale, assignment, transfer, lease,
                  conveyance or other disposition unconditionally assumes all
                  the Obligations of such Guarantor under the Notes, the
                  Indenture, the Subsidiary Guarantee and the Registration
                  Rights Agreement, pursuant to a supplemental indenture in form
                  and substance reasonably satisfactory to the Trustee, on the
                  terms set forth herein or therein; or (y) the Net Proceeds of
                  such sale, assignment, transfer, lease, conveyance or other
                  disposition are applied in accordance with the applicable
                  provisions of the Indenture; and

                           (ii) immediately after giving effect to such
                  transaction, no Default or Event of Default exists.

                  (b)      In case of any such consolidation, merger, sale,
         assignment, transfer, lease or conveyance and upon the assumption by
         the successor Person, by supplemental indenture, executed and delivered
         to the Trustee and satisfactory in form to the Trustee, of the
         Subsidiary Guarantee endorsed upon the Notes and the due and punctual
         performance of all of the covenants and conditions of the Indenture to
         be performed by the Guarantor, such successor Person shall succeed to
         and be substituted for the Guarantor with the same effect as if it had
         been named herein as a Guarantor. Such successor Person thereupon may
         cause to be signed any or all of the Subsidiary Guarantees to be
         endorsed upon all of the Notes issuable under the Indenture which
         theretofore shall not have been signed by the Company and delivered to
         the Trustee. All the Subsidiary Guarantees so issued shall in all
         respects have the same legal rank and benefit under the Indenture as
         the Subsidiary Guarantees theretofore and thereafter issued in
         accordance with the terms of the Indenture as though all of such
         Subsidiary Guarantees had been issued at the date of the execution
         hereof.

                  (c)      Except as set forth in Articles 4 and 5 of the
                  Indenture, and notwithstanding clauses (a) and (b) above,
                  nothing contained in the Indenture or in any of the Notes
                  shall prevent any consolidation or merger of a Guarantor with
                  or into the Company or another Guarantor, or shall prevent any
                  sale, assignment, transfer, lease or conveyance of all or
                  substantially all of the assets of a Guarantor to the Company
                  or another Guarantor.

         5.       RELEASES.

                  (a)      In the event of (i) a sale or other disposition of
         all or substantially all of the assets of any Guarantor, by way of
         merger, consolidation or otherwise, or (ii) a sale or other disposition
         of all the Capital Stock of any Guarantor, in each case to a Person
         that is not (either before or after giving effect to such transaction)
         a Significant Domestic Subsidiary of the Company, then such Guarantor
         (in the case of clause (ii)) or the



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         Person acquiring the assets (in the case of clause (i)) will be
         released and relieved of any Obligations under its Subsidiary Guarantee
         if the transaction described in clause (i) or (ii) complies with the
         applicable provisions of the Indenture, including without limitation
         Section 4.10 of the Indenture. Upon delivery by the Company to the
         Trustee of an Officer's Certificate and an Opinion of Counsel to the
         effect that such sale or other disposition was made in accordance with
         the provisions of the Indenture, the Trustee shall execute any
         documents reasonably required in order to evidence the release of any
         Guarantor from its Obligations under its Subsidiary Guarantee.

                  (b)      Any Guarantor not released from its obligations under
         its Subsidiary Guarantee shall remain liable for the full amount of
         principal of, premium and Liquidated Damages, if any, and interest on
         the Notes and for the other obligations of any Guarantor under the
         Indenture as provided in Article 10 of the Indenture.

         6.       NO RECOURSE AGAINST OTHERS. No past, present or future
director, officer, employee, incorporator, shareholder or other agent of the
Guaranteeing Subsidiary, as such, shall have any liability for any Obligations
of the Company or any Guarantor under the Notes, any Subsidiary Guarantees, the
Indenture or this Supplemental Indenture or for any claim based on, in respect
of, or by reason of, such Obligations or their creation. Each Holder of the
Notes by accepting a Note waives and releases all such liability. The waiver and
release are part of the consideration for issuance of the Notes.

         7.       NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW
YORK SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE BUT
WITHOUT GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT
THAT THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED
THEREBY.

         8.       COUNTERPARTS. The parties may sign any number of copies of
this Supplemental Indenture. Each signed copy shall be an original, but all of
them together represent the same agreement.

         9.       EFFECT OF HEADINGS. The Section headings herein are for
convenience only and shall not affect the construction hereof.

         10.      THE TRUSTEE. The Trustee shall not be responsible in any
manner whatsoever for or in respect of the validity or sufficiency of this
Supplemental Indenture or for or in respect of the recitals contained herein,
all of which recitals are made solely by the Guaranteeing Subsidiary and the
Company.


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         IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed and attested, all as of the date first above
written.



                                      GENERAC PORTABLE PRODUCTS, INC.

                                      By:    /s/ John S. Shiely
                                         ---------------------------------------
                                      Name:  John S. Shiely
                                      Title: President

                                      BRIGGS & STRATTON CORPORATION

                                      By:    /s/ John S. Shiely
                                         ---------------------------------------
                                      Name:  John S. Shiely
                                      Title: President

                                      GPPW, INC.

                                      By:    /s/ John S. Shiely
                                         ---------------------------------------
                                      Name:  John S. Shiely
                                      Title: President

                                      GPPD, INC.

                                      By:    /s/ John S. Shiely
                                         ---------------------------------------
                                      Name:  John S. Shiely
                                      Title: President

                                      GENERAC PORTABLE PRODUCTS, LLC

                                      By:    /s/ Carita Twinem
                                         ---------------------------------------
                                      Name:  Carita R. Twinem
                                      Title: Treasurer

                                      BANK ONE, N.A.,
                                        as Trustee

                                      By:    /s/ Marla S. Roth
                                         ---------------------------------------
                                             Authorized Signatory


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*  GPPD, Inc., GPPW, Inc. and Generac Portable Products, LLC each executed and
   delivered separate Supplemental Indentures in this form as the "Guaranteeing
   Subsidiary."



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