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  1. #1
    CB750 Member raene's Avatar
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    Rounded oil filter bolt

    So, I picked up my first bike - 1982 CB 750 Custom - and got it up, drained the oil, only to find that the oil filter assembly bolt is completely rounded off. It looks like the guy who owned it before me had the same problem, because I found an unused oil filter in the box of parts he gave me :P Sounds like someone gave up... obviously I don't want to do the same thing now, who knows how long that filter's been on there!

    Any tips or tricks to get that sucker off there? Also just looking at pictures of the assembly - it's not just a bolt, is it - I'm going to have to find another assembly or buy a spin-on conversion kit?

    Also, the dipstick is broken off - any lines on where to find a new one?

    Many thanks

  2. #2
    CB750 Addict dan1951's Avatar
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    Check ServiceHonda.com another Member on here mentioned them, They carry quite an array of parts unless there obsolete

  3. #3
    Moderator dirtdigger's Avatar
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    The oil filter bolt is the same as the one in the old 750 as well as many other model of Honda motorcycles it is a very common part and can be found anyway. Use a vise grip or you may have to have a nut welded to the end to have something to grab on to. I have welded nuts on many of the oil filter bolts as they tend to round off because most people tend to over tighten the bolt.

    You will have to find a used dipstick as I looked and they are discontinued. Start checking ebay, hate to say it but they have become the best source for obsolete parts.

  4. #4
    CB750 Member raene's Avatar
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    Thanks guys, I didn't even think of welding a nut on there as I've had such bad luck getting them to stick in the past, but it worked just fine now. Cover's off and filter is changed, much appreciated!

    Looks like Part # 15650-425-000 isn't available from servicehonda either, I did find this page: http://www.vintagecb750.com/products...gs-lubrication anybody have luck with ordering from this site?

    Also, anyone have experience converting to a spin-on filter kit? I'm concerned a) about leaks, b) knowing what filter to use, c) losing some cooling capacity since the OEM cover is finned.

    Thanks!

  5. #5
    Moderator dirtdigger's Avatar
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    Have order several times from them.

    No point in switching to spin on as you can just buy a new bolt, then you always will be able to get the oem honda filter if need be. In my opinion the oem honda filter setup is superior to the spin on filters, it has more filter area. I have never seen a reason to switch to spin on.

    The dipstick is discontinued from Honda you will need to look for a used one.

  6. #6
    CB750 Member raene's Avatar
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    Thanks again Do you figure the anti-drainback feature in modern filters could make a difference? It's somewhat disconcerting to see the oil light remain on for that second or two after starting.

  7. #7
    Moderator dirtdigger's Avatar
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    A second or two is perfectly normal.

  8. #8
    CB750 New Member gremmann's Avatar
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    I see this is an old question. I had the same problem. I bought a 81 CB750C and the bolt was rounded off on the oil filter.
    By now you've probably solved your issue, but for those who might have the same, I used a pipe wrench to get mine off.
    I'm going to try to salvage the bolt head by grinding a socket pattern.

  9. #9
    CB750 Guru amc49's Avatar
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    A tip that may help more than you think. Determine the new slightly smaller OD of the size you will grind to (use a common socket size) if the flats are gone. Then buy a cheap nut in the size that fits best, the outer tips of the flats must be even with the OD. Then glue the nut on to the filter bolt using say 3M weatherstrip or another glue that is stout but removeable by throwing the part into solvent when done. Then you have a flat sizing guide using the glued on nut. It makes it far easier to determine each flat width as well as the timing of them to be real even.

    I use that trick to remove say McGard wheel locks off wheels when the lock key has damaged to not find another and you are stuck with cannot remove wheels. Same nut trick on the McGards and say 10 minutes grinding with a rock in a dremel grinder and the lock comes off easily using a socket to match the newly created nut.

    Those filter bolts have a tendency to self tighten and almost always try to not come off, it's almost a law of physics there.

    BTW, that is not an anti-drainback feature in the bolt, rather, it is a blow off valve that opens up if the filter has not been changed or oil is cold. It allows unfiltered oil to bypass the filter to get to bearings easier.

    If a filter bolt rounds the corners off an 8" pipe wrench takes them right off.
    Last edited by amc49; 01-13-2020 at 11:30 PM.

  10. #10
    Moderator dirtdigger's Avatar
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    You can buy a new one from cb750supply for $14. They work fine. Or Oem honda they are available for about $40

  11. #11
    CB750 Guru amc49's Avatar
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    Emgo may make that cheaper one, they are cheap and they work. I'm not too big on their filters though, Honda are the best.

  12. #12
    CB750 New Member gremmann's Avatar
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    What a great idea! Thanks for the tip. I think I would have just winged it.
    BTW, your name, AMC49, are you and American Motors fan?

  13. #13
    CB750 Guru amc49's Avatar
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    Yes.

    The family used to drag race true AMX race cars.

  14. #14
    CB750 New Member gremmann's Avatar
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    By true AMX, I know you're referring to the 69-70 2 seaters.
    My 1st car was a 72 Gremlin X 304, then 74 Matador coupe, 80 Eagle wagon, 69 AMX, 73 Gremlin X 304.
    Guess we need to stop there, this is after all, a motorcycle forum.
    Again, thanks for the tip on the oil filter bolt, nice talking to you.

  15. #15
    CB750 Guru amc49's Avatar
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    Yes. Had a '70 Mark Donahue Special 390 Javelin too as well as a 360 Hornet. My best friend raced a 304 gremlin as well.

    The race AMX ran in the high nines in the mid '70s. One of the slightly later street AMX cars would do 10.70s at 130 through the mufflers and 3400 pound car-fully street legal, no gutting at all. We had a shop directly across the street from the local GM dealership and no 454 coming out of it would touch the AMX 401. So we began getting their workers' 454s to build and then that lead to pro stock fat blocks up to 700 inch and over 200 mph. We worked on one 358 inch Pro Hornet that ran in the eights at 150+somewhere in there.

    We also did a whopping amount of head porting and porting on other stuff too. I was used to it as I grew up with Japanese 2 strokes and I ported nearly every one I ever had. My favorite was Kaw 3 cylinders back then, man those things would run!

    I had the Dad everybody else wanted, we had like 15-20 bikes in the garage at one time and everybody showed up on weekends to go blasting. Then when we boys got older Dad went to AMC and bought the first AMX, before that his daily driver was a '64 Plymouth Fury with 426 wedge (just before the true hemi came out) 4 speed modded with big cam and 2X4 bbl. He loved wild mechanical stuff and where my gene came from, he flew as well, building Pipers from junked planes. Later he crew chiefed on A-7 Corsair II and sent to Pax River for the Navy testing trials.
    Last edited by amc49; 01-15-2020 at 03:44 PM.

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