Topic: CB750 F2 cam shaft in CB 750 K7: Has anyone done this?

[Wobbly]

Update:

One of the rubber pucks came off, causing the flood of oil. Reason: heat due to camshaft damage: cam, right cam holder and the four rocker arms are trash (all new parts). Reason: oil starvation. I have no clue why. I thought, perhaps there are two different towers, and I installed to left ones. But this isn't so. Looking closely at the set up though, I am not sure how oil pressure is supposed to build. But it worked the previous 37 years. I don't know where I went wrong.
Oh well. I ordered the parts already, F2 cam is on its way too (do I advance it by 5 degrees or not?).
I take off with the family to go to South Tyrol tomorrow for a week (spring break), taking the BMW RR while the wife enjoys the trip with two teenagers fighting each other in the car. I keep you updated on my progress after the trip. Perhaps, one fine day, I can actually tell you how the F2 cam runs in my K7. First, however, I have to figure out what has happened to end the life of this web cam so prematurely. As always, any input is appreciated.

[PeWe]

Did you have all 4 small o-rings under the cam towers?
2 around the oil holes enter the cam tower, 2:nd in the blind spot which will be the end of the cam tower oil lines. No o-ring here will cause less oil pressure. The cam towers have 2 holes to be able to sit 1-2 or 3-4.

Next if the small oil holes in head enter the cam towers do not have the alu inserts or if they are blocked with silicone or other gasket sealer.
One of the reasons I decided to open the engine was to check the o-rings. If I did OK (which I had).

I bought an extra set of cam towers complete with everything on except cam just for sure. Found a good set on eBay.de, shipped from Germany. This look much better than my old stuff with 97.000km's.

[MRieck]

Unfortunately one of the oil jets or upper case oil feeds became blocked. I Have seen the case feeds become blocked secondary to Loctite and installation of heavy duty studs. If you put the Loctite on the stud threads it will ride up the stud as it is crewed in. It will run off into the feed hole and block it. I know of 2 instances where this happened. You have to apply the Loctite to the case hole....not the stud thread. You also have to carefully check the feed holes.
 I have seen oil jets become blocked with slivers of metal, gasket sealer etc.
 The important thing to do after, bolting the head down, is to to blow compressed air through the oil jet hole. You should be able to hear and feel air moving through the main bearing saddles and oil filter feed.
 You have to check your oil pump and thoroughly clean out all the oil passages after smoking the cam and towers.

[Jerry Rxman Griffin aka MuthaF'er]

The F2/F3 cam (correct me if I'm wrong) is already advanced 5 degrees as it begins opening 5 degrees before the other cams and closes at the same position as the other cams thus providing more open duration.

Apply a SLIGHT amount of whatever case sealer you are using (Hondabond, Threebond etc) to the underside edges only on the pucks to hold them in place and seal them.

[PeWe]

.......
 The important thing to do is after, bolting the head down, is to to blow compressed air through the oil jet hole. You should be able to hear and feel air moving through the main bearing saddles and oil filter feed.
.........

Scheiße, I really need to buy the compressor I have found with less sound pressure level than 97dB as most of the others produce. Possible to be in the same room....  JWS30   blow job.... 

[Wobbly]

Thanks guys, for the replies. The O-rings were all replaced and are in place. Dowel and lock pins are in place. No sealant or Loctite was used, I don't see any blockage. I will use sealer for the pucks this time. But the reason the one leaked was because it was ruined by the heat from the failing cam and came off.
HondaMan had suggested in his thread to advance the F2 cam by 5 degrees in a K7/K8. That's why I asked.
I do not plan to take the head off. Will I be okay with the CycleX gasket although I have no HD studs and thus torque to Honda specifications? I am asking because of the comments made regarding this setup. I will retorque the head now, however. I only managed to drive about 200 miles before disaster struck, had planned to retorque after 600 miles anyway. I am so disappointed after all the work and money spent. This was the first time in 37 years that the Honda failed me. Well, I still made it home okay--oil dripping from my rear tire. The bike was supposed to be ready for my birthday. Instead, I spent yesterday to pull the engine and look at the disaster. Sometimes, life just sucks ass.
Thanks for all the input guys. I am very grateful.

[PeWe]

It must be a blocked oil line somewhere. Cam tower or before thru the head. The oil jet hole (small alu inserts) are possible to remove, just lift it up with a small grip tool.

It might be something in the oil that can block again..like the rubber wheels that the tensioners have. Primary and cam chain.  Open the oil pan and see how it look like. Oil pump mesh can have small particles blocking it.

Clutch OK? My clutch had one broken fiber plate due to wrong type inserted. The outer plate should have wider ears that mine did not have, too much play and off it went... probably when chain snapped before Kassel 1988...
I trusted the part companies too much 30 years ago.

[MRieck]

It must be a blocked oil line somewhere. Cam tower or before thru the head. The oil jet hole (small alu inserts) are possible to remove, just lift it up with a small grip tool.

It might be something in the oil that can block again..like the rubber wheels that the tensioners have. Primary and cam chain.  Open the oil pan and see how it look like. Oil pump mesh can have small particles blocking it.

Clutch OK? My clutch had one broken fiber plate due to wrong type inserted. The outer plate should have wider ears that mine did not have, too much play and off it went... probably when chain snapped before Kassel 1988...
I trusted the part companies too much 30 years ago.

Exactly. And correct on all other points Per.

[PeWe]

I like to share my experiences on this site that has given me very much, experiences, facts and inspiration.
I've changed my mind about lifting the oil pan. It's a good idea to do that minimum once/year, maybe more. Problems will be visible here.

[Wobbly]

Every single components of the clutch, from the basket to the cover, including every bolt and washer, is new (all NOS).  It works flawlessly. All tensioners are new (cam and primary chain). The entire valve train and the cam towers are both new (NOS). Well, one is trashed now along with four rocker arms that I just ordered again. The oil pump mesh is new as well.  If I would consider it possible, I would blame the right cam holder. The oil surely is getting anywhere else. I look into it some more next week as I am in Italy right now with my other bike.
Thanks everyone for all your help.

[PeWe]

OK, that's really bad when everything is fresh and just put together. I suppose I have had luck in the past not getting oil lines to valve train blocked.
- I hope you can verify where the oil passage is blocked. Cam tower, head or under the the head.... Use compressed air like Mike suggested will show if blocked or not.

[Wobbly]

Everything checks out--no apparent reason for the cam failure. Here are some pics:

[Jerry Rxman Griffin aka MuthaF'er]

Just one side of the one cam tower? I'd check to see if it's related to the oil passages within that one cam tower on that end being blocked. That one cap wasn't too tight? Do the cap's lettering match the base's lettering? ie are the caps put in the right position?

[Wobbly]

Good thought: cap mismatch. But all work was done following the Honda shop manual which points out how they have to correspond.
But, yes, only the right side got it which is why I just ordered only one new holder (thanks God available new on German eBay for a fortune, however) and the four rockers from that side. I guess, no need to replace the new rocker shafts, right? New F2 cam is at hand--but I don't want to smoke new parts again.
I don't know what to think anymore.
Thanks for your input though. I much appreciate that you took the time to look at these pics.
Tom

[Jerry Rxman Griffin aka MuthaF'er]

Squirt some brake cleaning solution, WD40 etc through the entry point on the bad cam tower oiler hole on the bottom and see if all the oil passages are unblocked and flowing equally. I'd say compressed air but you can't see tha actual flow. I did mine in my parts washer and they all flowed good. I would have expected to see BOTH ends of the tower to be cooked.

[HondaMan]

Everything checks out--no apparent reason for the cam failure. Here are some pics:

A thought: have you removed the oil jets to check for possible blockage on them? The passage from the stud hole into the oil hole is small, and chunks of an old (fill in the blank, here) can block the passage from the stud hole to the oil jet. Occasionally, on engines where someone was there before me, I have found things like bits of the cylinder base gasket that must have fallen into the stud hole while someone scraped off the old gasket, or same from an old head gasket that remained in the head portion. Or, on more frequent occasions, someone's silicone seal (don't ever use that stuff in these engines...).

The oil jet itself is a 7-hole strainer on the bottom end, each hole is .002" smaller than the metering hole, so as to stop anything big enough to plug the metering hole (in theory, at least...). In essence, there are 7 "sacrifice" holes that could be plugged before the last one toasted the cam.

[Wobbly]

Thanks HondaMan. Yes, checking the oil jets was what others suggested too. I believe, however, that the oil is getting out. Before putting the engine back in, I will connect oil tank and starter and see what it is doing, cam and cover off, without and with holder.
Looking at the cam holder, I would think that this is the culprit. I don't see how oil pressure is built when you have a fat opening next to the jet so that the oil can go out that way. But since there is no left or right for them, and since they are both the same, it must work somehow--did so for 37 years. I just never gave it any thought before.

[Wobbly]

Looking at the cam holder, I would think that this is the culprit. I don't see how oil pressure is built when you have a fat opening next to the jet so that the oil can go out that way. But since there is no left or right for them, and since they are both the same, it must work somehow--did so for 37 years. I just never gave it any thought before.

Yes, the NOS cam towers are the culprit. I received the new 410 series holder today and can compare. Both NOS towers I put in are missing the pressed in plugs which seal the opening at the front, right underneath the rocker cam. Thus, no adequate oil pressure.  A bigger problem for the right side. How fuxxxx up is that and how is that possible? Live and learn and expect the unexpected. A very expensive lesson though.

[Wobbly]

[Wobbly]

UPDATE:
I finally got done redoing the cam and holders, put the engine back in, and and took her out for the first ride with the new F2 cam. Since the engine was just rebuilt, I did not go over 6,000 rpms and keep it that way for the first 600 miles. However, I can already tell that the engine didn't lose any power in the lower rpms--to say the least--while I wouldn't be surprised to see some small gains at higher rpms. Like others have predicted: I am very happy. The bike runs awesome, the engine sounds like a turbine. It starts up right away, runs great cold or warm. F2 cam in a K7? Absolutely--with no changes needed.

[70CB750]

Very good!

Congratulations!

[HondaMan]

WAY TO GO, WOBBLY!! 

[Jerry Rxman Griffin aka MuthaF'er]

Great news! and 5 degrees more duration on top of the increased lift. That F/F1 engine likes the F2/F3 cam. Never hurts to cam a stock engine a little more (most of the time).