Topic: CB550 top end leak question

[Scott S]

 I have very low miles on my CB550 top end rebuild...about 700-750, if that. It started leaking after about 500 miles.

 I'm going to take a chance and pull the valve cover, retorque the head with a better TQ wrench, and use some sealant around the rubber pucks. If it works: BONUS! If not, I'll pull the head and do a proper re-seal with gaskets, etc.
 When doing some prep work today, I noticed oil around the end caps after I removed them. I used new o-rings, but didn't replace the washers. However, it doesn't appear that it's leaking around the washers but, possibly, the o-rings. (Ignore the oil in the end cap holes...that's supposed to be there).

 (This first pic is blurry, but it best illustrated the brown line of oil coming from the end cap holes down to the spark plug area)





 I have some non-hardening Blue Hylomar that's worked well on other engines. I plan on putting some around the rubber pucks and checking the TQ on the head. Would it hurt to use some around the end cap rubber o-ring if I use it sparingly and am very careful?

 And since I know someone is going to tell me to replace the cruch washer for the end cap (even though it's not leaking) can you tell me the proper size and where I can find one locally? Like, tomorrow....so I can get this thing back together and ride!

[LesterPiglet]

So what's leaking apart from the end caps? New o-rings each side and it's sorted. The end caps are sided, did you mix them up perchance?

[Scott S]

 I don't think I did, but.....how do I tell which one goes where? I know I have the angled "L" brackets for the end caps on the correct side. They're marked with an "L" and "R". I did install new end cap O-rings.

 It's possible that it's leaking from one of the rubber pucks or something around the head. Rubber pucks were new, too.

[LesterPiglet]

Hmm, maybe I'm mistaken about the end caps being sided and it's just the brackets. Dave500 is the man you need.

[Scott S]

 I'm looking as closely as I can with a flashlight and I don't see any evidence of lekas around any of the visible head bolts. I haven't removed the valve cover yet.
 I can peer into the head from the are where the end caps attach and don't see any signs of oil coming from the center of the head to the edges, such as it would if the pucks were bad, etc.

 This was a bad enough leak to make me address it....I've been doing the "tampon trick"; rolled up paper towels in the head fins. Can the end caps leak THAT much?

[LesterPiglet]

I don't know how much they can leak but I do know it is a very common problem. It's the only leak I had on my engine........until I rebuilt it. 
When they leak it looks very serious because of their location. The oil drips/blows over all the engine.

[dave500]

the caps can be either left or right it dosent matter,its the bracket which must be correct for its side,they are stamped with an L or R.

[Scott S]

 Those brackets are mounted correctly.

[Rgconner]

It is leaking from the valve rocker rod ends.

Replacing the o-rings should stop that, or you can do what I did and wrap the cap studs where the o-rings go in that yellow Teflon tape that is oil resistant.

Makes them hard to get back in, but makes a good seal!

I don't know if there is an o-ring or a seal for those rocker arm ends, you would have check the parts diagrams.

[Scott S]

 Well, it certainly appears that's the source of the leak. As mentioned before, I replaced those O-rings already. I'll look through my stash and see if I have some that fit tighter/better.

 What are your thoughts on using a thing smear of blue Hylomar (non hardening) on the O-rings when I reinstall them?

[Rgconner]

Tried, it blew out after a few runs. Back to oozing.

The Teflon is doing well after 1K miles, does ooze over 8K rpm for any length of time, like trying to run on the interstate with the big boys on Harleys and Gold Wings.

[chickenman_26]

Well, it certainly appears that's the source of the leak. As mentioned before, I replaced those O-rings already. I'll look through my stash and see if I have some that fit tighter/better.

 What are your thoughts on using a thing smear of blue Hylomar (non hardening) on the O-rings when I reinstall them?

Mine had the same leaks, and it drove me nuts till I got it stopped. I can tell you from experience, forget the Hylomar or any other sealer. The O rings are 6mm x 3mm. Go to a seal shop and buy 8 of them made of Viton. Replace the four on the shafts, and place one inside each hole. Replace the covers - you'll feel the O rings compress as you tighten the screw. That should stop up the leakage...from those particular places   

As a bonus, if your bike doesn't have the later pinned rocker shafts, the extra O rings will stop the shafts from rotating and getting noisy.

[Rgconner]

The O rings are 6mm x 3mm. Go to a seal shop and buy 8 of them made of Viton. Replace the four on the shafts, and place one inside each hole. Replace the covers - you'll feel the O rings compress as you tighten the screw.

Bloody hell, that is to damn easy and obvious. Going to have to try this next time I have to pull the ends. Teflon tape only works one, then I have to re-wrap.

[Scott S]

 Replaced the NEW (~700 miles) o-rings today with NEW o-rings and a smear of sealant. Cured the leak, but also just confirmed that I have head gasket issues.
 I'll call the local Honda deasler on Tuesday and see if I can get a genuine head gasket. If not, I'll get the Cometic gasket from Dynoman. Looks like I'll be pulling the head in the near future. Bummer....it runs SO damn good.

[dave500]

kill as many birds as you can and turn it into an opportunity for improvement,,match the inlet manifolds to the head while its off,ive seen some bad mismatches,,and clean any casting dags from the ports,de carbon and lap the valves again,even new seals if they are old.

[Scott S]

 Dave, this bike already has a ported and polished head, match ported and smoothed manifolds, a 1.00mm overbore and a CB650 cam. That's why all the o-rings, etc., are new with only ~700 miles on them.

 I'm pretty sure the rubber pucks should be reusable with those low miles (they, too, were new with the top end rebuild). I plan on replacing the O-ring that go between the cylinders and head.....they're only a couple of bucks apiece from Honda.

 Honda also lists a head gasket for about $62. Or, I can get a Cometic gasket for about $52, shipped from Dynoman. Which would you use? Genuine Honda or Cometic?

[LesterPiglet]

For the sake of $10 I would go OEM.

[Duanob]

Scott use the OEM! Also spray some copper gasket sealant and replace the oil gallery O-rings with OEM as well. I had the same leak with an after market gasket that just didn't fit well around the oil passages and deformed the o-rings and after a few hours of running time on brand new Head Gasket, started leaking. Second time OEM gasket, OEM o-rings, copper gasket sealant: a couple thousand hours and no leaks.

[crazypj]

I would check the breather hose isn't kinked or trapped, even a slight increase in internal pressure can have a big effect on leaks (and yes, I know that's pressurised oil in there)
 Make sure the end brackets are 'square' to head, if they are slightly angled it can cause a leak when screw is tightened up

[Scott S]

For the sake of $10 I would go OEM.

 Yeah...it's not about the money. Just wanting to get the best gasket. I want this to be the LAST time I go in there!

 The head was checked and absolutely true, so I'm guessing it's an inferior gasket thing. The breather hose is not kinked and routed properly. I'll start rounding up OEM parts. Thanks, guys!

[Rgconner]

Ordered a pack of 25 from amazon.

http://www.amazon.com/gp/product/B005RUPA4Y/ref=ox_ya_os_product


Keeping some spares, 3 sets of 4 sent via US mail to SOHCers, free.

Scott has dibs 4th set if he wants em.

[Scott S]

 These are for the oil jets/galleys on the end of the head? How much for a pair?

[Rgconner]

No, these are for the stupid rocker shaft endcaps we were talking about. Tried locating them locally, but no soap.

Only place was a Aircraft supply house near here, they wanted $8 each.

Real Gulfstream replacement parts... $8 is probably dirt cheap.

[dave500]

diesel pump and injector repair shops have a miriad of o rings and copper washers.

[Duanob]

We have a place here called the "O-ring Store" but no dice on the 4.9mmx2.5mm. Honda part only (91301-426-010). Even ordering from a reputable Honda parts dealer online it still took 3 weeks on back order. I bought 3 pairs so I won't have to wait again. They are becoming unobtanium. And after my first experience I will only buy them from Honda from now on. It really sucks to have to pull the head for $4 worth of parts when they fail. Whatever Honda makes them from they seem to last longer than after market gasket kits.