Topic: CB750 sprocket oil seal

[mazingerzeca]

My bike (CB750 K8) is leaking oil through sprocket oil seal. It appears at David Silver and CMS as discontinued, so I tried to buy a non OEM oil seal, but I can not find the exact measures. As stated on the partslist, it should be 29,8x62x7, but I can only find 30x62x7. Wil it work or should I look for the exact measure?
Thank you.

[CB750F2]

The seal should work OK. It is almost 8 thou over size so it will be a tight fit. However, I would try to find the genuine part. Try your local Honda dealer. If the seals are still available they will be able to source one via their spare parts stocking system. Pat

[Raul CB750K1]

Ignacio, the original seal is a very tight fit. I bet that a bigger one, even if just slightly bigger, will be almost impossible to install. Specially when the sprocket shaft protrudes and therefore you will be unable to smack it flat -unless you use a piece of tubing or the like, but even then, chances are the engine case gets in the way as it happens with the K1 -don't ask me how I know...-

Get the part number and ask your local Honda dealer, chances are they will get it. They just have to insert the number in the computer. I have replaced all the seals in my CB350, and many in my CB750, and my Honda dealer has always been able to provide them.

[mazingerzeca]

The 29,8 number refers to the inner diameter of the seal. Number 62 is the outer diameter and 7 is the height of the seal, so a 30x62x7 is only 0.2 milimeter wider on the inner part of the seal, the part that adjusts with the seal. I tried to find the part through my Honda dealer, but they told me that it was unavailable.

[Raul CB750K1]

The 29,8 number refers to the inner diameter of the seal. Number 62 is the outer diameter and 7 is the height of the seal, so a 30x62x7 is only 0.2 milimeter wider on the inner part of the seal, the part that adjusts with the seal. I tried to find the part through my Honda dealer, but they told me that it was unavailable.

Ooops, you are right. In such a case, the inner lip is wider than it should. Worst thing that can happen is that it doesn't seal as it should, and you will have a leaking seal, therefore you will be exactly where you are now. And if it seals, you have fixed it.

I would say go for it.

[hijynx]

Hi, f.n.g. here, but maybe I can put in my .02 - a quick fix is to remove the spring from the inside of the seal & look at it very closely. you will be able to see where the spring is connected together to make a circle. untwist the ends like removing a nut from a bolt. the spring will straighten out. you will see one end of the spring has coils that decrease in radius forming a point & the other side is straight. cut a few coils - usually 3 or 4 coils from the straight side. twist the spring the same direction as when you disconnected the ends to preload a twist. put the ends together & let go & the pointed side will screw into the straight side as it was before making the spring slightly smaller loading the seal lip a little more. another solution would be a product called a speedi sleeve. it's a thin stainless steel ring that slides over the shaft giving the seal a new surface to ride on. if the shaft has a groove worn in it that may be your best option. hope this helps.

[Raul CB750K1]

Wecome to the forum hyjinx! Interesting info about the spring inside the seal -have seen many but never thought about adapting any. Glad that you decided to register and put your two cents.

[mazingerzeca]

Great idea hijynx. I will try that microsurgery on the seal. Maybe it will get tighter.