Topic: CB750 Cam tower oiling passage question

[edwardmorris]

The one circled in red, is it a return or a feed? I cleaned the set on my K2 and when I tested by dropping some acetone through the passages on the bottom of the tower, both these holes and the ones on the cam journals were dripping. The set I cleaned today, the circled ones aren't doing that. They don't seem blocked as I can push a machinist's wire through easily and blow compressed air as well. Could it be blocked deeper? I haven't cleaned the second set ultrasonically as my damned cleaner died today right as it fell outta warranty  If it is a return hole and not terribly important to have excessive flow through here, I'll keep the towers?

[flybox1]

That's a feed.
Blow air or carb cleaner up through hole in the bottom surface of the cam.tower.   
wear eye protection.

There are no return holes in cam.towers.  the oil drains to the valve spring areas and down the return passages into the sump.

[HondaMan]

I've usually been able to clear them with mechanics' wire and compressed air. There isn't much you can do to damage them, as their metering is done by the oil jets already. These particular holes are squirting some oil onto the cam lobe as it turns under the rocker foot, so the amount isn't terribly critical, so long as it squirts.

Worst case: there is a plug in the cross-drilled passage on the side of the Tower. This is the feed passage to these little holes. If you have to remove the plug, you can just tap the hole and install a screw or setscrew later to plug it back up: just peen over some small amount of the metal to prevent it unscrewing again later on. Racers do this sort of thing a lot.

[edwardmorris]

Thanks Fly and Mark! I tried some CRC and did see little bits of black come out, so I broke down and bought a new ultrasonic cleaner (ouch!). Few cycles and compressed air, little chunks blew out and they freed up. I held a hot water hose (small dia) with some pressure and water was coming out through all of them. With nothing covered, the cam journal and the non circled ones were squirting pretty high but the circled ones weren't exactly squiring although a ton of water was coming out. I wonder if its because of the way the recessed cuts are on these? When I close up some of the holes, these started squirting a bit. So I'm hoping that with the oil pump pressure and everything installed, these will work out. Again, thanks for the input!

[flybox1]

Going to do HondaMans cam oiling holes mod? 

[edwardmorris]

Going to do HondaMans cam oiling holes mod? 

Definitely on the K2 towers. These are for the K3 and the shafts don't turn, so not sure if that helps. I'll have to review his book 

[HondaMan]

Going to do HondaMans cam oiling holes mod? 

Definitely on the K2 towers. These are for the K3 and the shafts don't turn, so not sure if that helps. I'll have to review his book 

The mods only help if the little 5mm bolts are removed (which I do to most of these engines, unless requested not to). It raises the power on the hiway a little and makes the shaft wear nil over time.

[edwardmorris]

Going to do HondaMans cam oiling holes mod? 

Definitely on the K2 towers. These are for the K3 and the shafts don't turn, so not sure if that helps. I'll have to review his book 

The mods only help if the little 5mm bolts are removed (which I do to most of these engines, unless requested not to). It raises the power on the hiway a little and makes the shaft wear nil over time.

Off they'll go if I can figure it all out, will read through that section again and pm follow up qs

[evanphi]

Going to do HondaMans cam oiling holes mod? 

Definitely on the K2 towers. These are for the K3 and the shafts don't turn, so not sure if that helps. I'll have to review his book 

The mods only help if the little 5mm bolts are removed (which I do to most of these engines, unless requested not to). It raises the power on the hiway a little and makes the shaft wear nil over time.

Off they'll go if I can figure it all out, will read through that section again and pm follow up qs

Seems pretty simple. I'll be doing the same when I get my towers