Honda CB750 CB900 CB1100 CBX DOHC Mystery Cylinder Head Plug
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- Опубліковано 6 жов 2024
- There is a somewhat mysterious plug on the cylinder head that begins to leak oil. I explain why I find it mysterious and demonstrate a quick repair.
Parts fiches at CMSNL:
www.cmsnl.com/...
The plug itself is Honda part no. 91208-422-003
Here's a tip when you're looking for an obscure part: try Googling with and without the dashes. In my experience, more/different links come up, especially as regards eBay listings.
CB750 DOHC Scheduled Maintenance:
• 1980 Honda CB750F DOHC...
Guma tee: guma.bandcamp.c...
gumaverse.com
Some oldhead mechanic who specialized in Hondas told me that hole is where we can put an oil pressure gauge, kind of like the early 750s that have them by our right foot. I don't know how true that is though, I will have to check the 750c's forums
Very helpful video.Thank you for posting very informative bike how to's.There was just some silicone sealer covering the hole on my 750 when i got it and it always had me thinking why it was there.
thank you so much Guma, I really needed this part. Very nice video. Cant wait to see your video about carbs. I have a 79 DOHC.
Exactly what I needed to watch, great job. Thank you 👍👍
Nicely done.
Anecdotally that plugg is meant to release overpressure in the crankcase before you blow a seal if the crankcase breather is blocked, if you use sealant on the plugg that function would be nulled. But that is only Anecdotal evidence but it seems plausible if somewhat redundant on a "air-cooled" motorcycle. Haven't disassembled a F engine so Haven't been able to check passages my self.
Plausible but redundant indeed! I can see how it would be the first thing to go if pressure was building in the top end
Wow who knew?! Thanks, super helpful!!
That looks like you could tap a thread and make up a metal grub screw.
Yeah, Ive seen that they sell these on a japanese website I came across one day. Has the thread you put in and the bolt to rotate in the thread slot. Im thinking we could just run up to an ACE hardware and just get that stuff ourselves though
Sehr schönes Motorrad..
Danke für den Bericht
Good info
I have a plastic plug/ nut on the chain cover side of a cb750f2n (1993 rc42), it has "do not remove" written into it.
Any idea what lives in there?
Probably blocking a hole that was created when the engine was cast out of aluminum.
Great!! Does the CBX use the same part? Also, can the 750F head be removed with the engine in the frame? I'm getting conflicting views...I remember the road test in CW magazine stating that the frame is arched to allow this, but my Climer manual for the 750 states that the engine must be removed from the frame to take the head off.
Richard, according to the parts fiche this part is on all three of these bikes. The 750 head cannot be removed in-frame. The valve cover yes, but there is not enough clearance for the head to come off.
👍🏻😀
Why not use PC7 to see to Plug hole -
I'd never use a paper towel inside a hole in any engine, your asking for a piece to catch and stay inside potentially clogging an oil passage.