Identify Briggs opposed twin pre 1980 with no stamping based on characteristics

@ Walt: thank you, Sir!
Interestingly I couldn't find out the stroke of the 40 and the 42 in the manual.
So I went out in the dark and measured a stroke of 55mm - together with the bore that gives abt. 658ccm - which makes it a 40, no doubt.

Cylinder reminded me very much of the 28 and it seems I wasn't wrong.
The head on the other hand reminds me from the inside of the 25.

@ Fish: so I'm going to go with 401707, thanks a lot!

Type should be below 0500 because of the lid for points and condensor - althought it's a magnetron on the engine.

Possible problems:

- the 393301 Carburetor Overhaul Kit (which sets the engine to pre 79031900, is that right?) is not available - can I use an aftermarket kit like this https://www.ebay.de/itm/Vergaser-Re...tor-B-S-16HP-18HP-393301-394034-/120995029011 hence it has gaskets for different versions in it?

- as one can see in the pics, one of the two hose couplings of the fuel-pump-body is broken. Someone in the past "fixed" it with a piece of brass-hose which looks quiet odd and presumably isn't airtight.
The old beige/white body 280197 isn't available anymore - will the successor in black be an 1-to-1 substitute?

- are there any other problems I will possibly run into with that old babe?

Thank you all,
have a good week,

Franz

Hi Fish!

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Fish said:

https://www.milfordpower.com/280197-Genuine-Briggs-Stratton-Fuel-Pump-Body-p/280197.htm

Click to expand...

found him already ... but: "This item must be picked up in our store."


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Fish said:

https://www.ebay.com/itm/Briggs-Stratton-691896-Fuel-Pump-Body-Replaces-280197-691896-/400477096584

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... but: "Does not ship to Germany"

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The question was NOT where I can buy it, the question was about 691896 "will the successor in black be an 1-to-1 substitute?"

Thank you,

Franz
.

Take a pic of both sides of it, and compare it to the ones on e-bay.
The one ad says that it replaces that part number.

The partstree site says that it replaces that part number...

"The old beige/white body 280197 isn't available anymore - will the successor in black be an 1-to-1 substitute?"

Yes, provided it has 3 screws in body rather than 4.

I thought the Service Manual had bore and stroke specs. IF it is a 40 series and that old it may be aluminum bore, hope not.

Walt Conner

)

@ Fish: You are right. I was mistaken there, before your link to partstree I looked up parts elsewhere and this wasn't quite clear as it seems to be now. Thank you.

Tinkerer200 said:

"The old beige/white body 280197 isn't available anymore - will the successor in black be an 1-to-1 substitute?"

Yes, provided it has 3 screws in body rather than 4.

Click to expand...

Good to know, thanks.
As I said, it's not the Nikki_6 and all the Walbros had three screws, right?
Pic Boxer_CarbPump_3Screw.jpg attached.

Tinkerer200 said:

I thought the Service Manual had bore and stroke specs. IF it is a 40 series and that old it may be aluminum bore, hope not.

Click to expand...

I thought so as well, but the manual just says "Bore (All) 3.4365” – 3.4375” (87.28 – 87.31 mm)". A number for stroke is nowhere given ...

As for the material of the bore: I fear for the the worst.

- Attached pic Boxer_CylBore_r.jpg shows the cylinder track, which has a gray color, looks like coated and seems in good condition.
- The sealing surface does not look like a cast iron sleeve in it ... what would you say, aluminum or iron?

That would be really bad, since the cylinders are not removable, so you can not just shrink a sleeve into it ...

In your country, the supply of replacement engines is good, you would just change the engine ... but what do I do if I want to keep this old engine running?

Many Thanks,
greeting
Franz

It is a side valve engine so you can get it sleeved without any problems as the head will hold a top hat sleeve in place.
Weather it is economically viable to do so is a different matter.
Lots of companies in the EU doing sleeves for motorcycle engines , usually about 100 Euro + fitting.

Hi Bert,

thanks for your reply and Goodday down there!

Lets put economical viability to one side for the moment, shall we? )

I've done it to Guzzi cylinders a few times to get a bigger bore e.g. 850-to-1000ccm, even to OHV engines with pushrods - no problem, you are right and the price is just a little bit too optimistic nowadays in this country.

Where I see the biggest problem is the sheer hugeness of of this motor-block: due to the fact that the cylinders are not detachable you have always this vast piece of metal cyl_1-block-cyl_2.
I can't measure right now but that must be as long as 80-90cm -> 800-900mm -> about 3' -> 35", almost as if you would try to do a BMW-Twin without detaching the cylinders first.

I don't know someone I can think of right now with a machine big enough to put an engine that size in it to do this job ... must be someone who rebuilds ship engines, but then this bore and the tolerances are perhabs a bit tight ... will research ... )

Thanks mate,
have a nice evening,
greets

Franz
.