Topic: 1978 CB750F - Piston Rings

[Wobbly]

392 is also what the K7 uses.

[cgarbe]

Hey guys, my mechanic told me about a place that makes custom piston rings for almost anything as long as you give them the bore size, groove size, etc. They are called Total Seal http://www.totalseal.com, I ust spoke with them and the cost for custom rings is $70-$80 for a pair of cylinders...so $140 to $160 for four cylinders. This is just an option I guess.

On a side note, I've been thinking about installing a big bore (836) however the kit is what $600 plus the price of re-boring the cylinders which costs about $70 per cylinder here in my area. This top-end engine rebuild for me has been quite the strain on my bank account.

New APE Brass Valve Guides: $80
Head Machining for New Valve Guides: $235
New Custom Piston Rings: $160
Labor for Top End Rebuild: $800

I've been trying to rebuild my 1975 CB400F while riding my 1978 CB750F...looks like the 400F project is on hold for a while.

[cgarbe]

KRONUS0100,

you said the 392 piston rings will work on a 1978 CB750F...correct? What is the part number for the rings you installed? I see a few on the cb750supply.com website:

Ring Set OEM Ref. #13011-392-004 (Std.)
Ring Set OEM Ref. #13021-392-004 (0.25mm.)
Ring Set OEM Ref. #13031-392-000 (0.50)

[flybox1]

KRONUS0100,

you said the 392 piston rings will work on a 1978 CB750F...correct? What is the part number for the rings you installed? I see a few on the cb750supply.com website:

Ring Set OEM Ref. #13011-392-004 (Std.)
Ring Set OEM Ref. #13021-392-004 (0.25mm.)
Ring Set OEM Ref. #13031-392-000 (0.50)

Standard Size Piston Ring Set

Ring Set OEM Ref. #13011-392-004 (Std.)
Japanese made Superior Quality

Fits: Honda CB750K (1977-78)
CB750F (1976) Use for engine serial numbers above #2551568
CB750F (1977)
CB750A (1976-78)

Note: This Set includes piston rings to rebuild four pistons.

Genuine Parts by OEM supplier
Part #: CB-71369

[cgarbe]

So I just spoke with my mechanic...the 392 piston rings do NOT fit...they are physically thicker than the ring grooves on the piston. I repeat... DO NOT FIT.

[flybox1]

So I just spoke with my mechanic...the 392 piston rings do NOT fit...they are physically thicker than the ring grooves on the piston. I repeat... DO NOT FIT.

IIWY, id get a second opinion from the F guys here, before i totally rule them out.

[Wobbly]

So I just spoke with my mechanic...the 392 piston rings do NOT fit...they are physically thicker than the ring grooves on the piston. I repeat... DO NOT FIT.

He's wrong.

http://www.cmsnl.com/honda-cb750f-750-super-sport-1977-usa_model491/ring-set-piston_13011392004/

[KRONUS0100]

Ring Set OEM Ref. #13011-392-004 (Std.)

[cgarbe]

UPDATE:

I'm sending my pistons to Total Seal to have them machine the piston grooves to fit Ring Set OEM Ref. #13011-300-024 (Std.) which fits the Honda CB750K-K6 (1969-76). Does anyone have any thoughts on this? I assume this set is going to be easy to find in the future.

[flybox1]

So I just spoke with my mechanic...the 392 piston rings do NOT fit...they are physically thicker than the ring grooves on the piston. I repeat... DO NOT FIT.

He's wrong.

http://www.cmsnl.com/honda-cb750f-750-super-sport-1977-usa_model491/ring-set-piston_13011392004/

why the time and expense when the above set will work?

[cgarbe]

I will order a set of 392 piston rings from cb750supply.com and see if they fit.

Update:
Actually cb750supply.com doesn't have any in stock...so i'm back to square one...do I wait for cb750supply.com to restock them or do I just sent them to Total Seal and have them machined to fit the #13011-300-024 (Std.) for $12.50 per ring?

Update:
I am mailing my pistons to Total Seal because I'm tired of not being able to find rings...so I'm having them fit to the OEM Ref. #13011-300-024 (Std.) Rings.

[Davidov]

KRONUS0100,

you said the 392 piston rings will work on a 1978 CB750F...correct? What is the part number for the rings you installed? I see a few on the cb750supply.com website:

Ring Set OEM Ref. #13011-392-004 (Std.)
Ring Set OEM Ref. #13021-392-004 (0.25mm.)
Ring Set OEM Ref. #13031-392-000 (0.50)

Standard Size Piston Ring Set

Ring Set OEM Ref. #13011-392-004 (Std.)
Japanese made Superior Quality

Fits: Honda CB750K (1977-78)
CB750F (1976) Use for engine serial numbers above #2551568
CB750F (1977)
CB750A (1976-78)

Note: This Set includes piston rings to rebuild four pistons.

Genuine Parts by OEM supplier
Part #: CB-71369

Ring Set OEM Ref. #13011-392-004 (Std.)

There's the answer.

[flybox1]

Sounds like he was bent on using old rings and milling his pistons to accept them.  That's fine.
I found the 13011-392-004 rings in stock at a few more places in case others are in need. . .

http://4into1.com/genuine-honda-piston-ring-set-standard-13011-392-004-cb750/

http://www.partzilla.com/parts/detail/honda/HP-13011-392-004.html?gclid=CjwKEAjwsZyqBRCT1aq6qcD53DQSJACcen4CTsNCdgRX0yNPwYslKB8yLtfsZxRu88oWbO4OE5LAihoC6-Hw_wcB

http://www.partsnmore.com/parts/honda/cb750k/?filters%5Bcategory%5D=controls&filters%5Bfitting%5D=custom

http://www.rockyswheelsanddeals.com/index.php?main_page=shopping_cart

http://www.gearhead.com/honda-13011-392-004.html#/s/HOM//13011-392-004/1