Topic: Are replacement cam towers available?

[Jerry E.]

I plan on replacing my rockers/shafts/camshaft on my '75 cb750FO motor, and cannot find any info on cam tower replacement parts. Mine show definite wear marks from the old cam, altho I haven't plastigagaed them for clearance dimensions. Anyone know where I can find replacement towers? I haven't seen any reference in any build threads, where anyone has even mentioned checking these parts, let alone getting new ones. Are these still available from Honda? Have the part number, if so?

[brandEn]

Cam towers are available through ebay. I am pretty sure they are discontinued and nobody makes aftermarket jobs. Wear marks are ok, any gouges or scratches? They would have to be pretty bad to not be repairable or useable.

[Jerry E.]

no gouges or scratchs exactly, but a 1/4" wide or so noticable wear mark on the bottom center of the bearing radius. From the cam being pushed down by the rockers I suppose. Is this normal wear? I don't have the new cam yet to plastigauge the clearances. Will measuring the old cam to tower clearance tell me anything useful, since both are worn probably? Don't know the mileage of my motor, got it from a salvage yard. Thanks for the help, I've seen your build thread. Very nice bike.

[brandEn]

I suppose if you posted pics it would be better. Trying to help without seeing anything is near impossible.

[brandEn]

Oh and Thanks!

[MCRider]

Yeah, once you've seen a few you'll know most have wear marks or lets say an indication of wear, but very few are unusable. You'd know it if you saw a bad one.

The cam rides in pressurized journals and should never be in contact with the bearing material. What you are seeing is caused by polluted oil, (I think) but i repeat they are all that way. If the cam journal is OK, then the bearing should be OK. The cam is much harder than the bearing, and if it has a gauge in it, you've likely gota problem.

And the problem may be a blocked oil passage so clean and check them out.

I don't even know of engine builders who plastigauge them. They just look, say OK, and move on.

Pictures will help.

[cookindaddy]

I have one used cam tower in good condition with the cam retainer clamps for a 77/78 K if it helps you.

[MCRider]

I forgot to say they are NLA as far as I know. Maybe David Silvers Spares?

I have 3 pairs of good used Id sell, but unless yours are really wiped I doubt mine are any better.

[Jerry E.]

Thanks for the input. I don't have a camera that I can take downloadable photo's with. Though I am documenting my rebuild. I will check my cam tower, cam journal wear again when I get home(at work now). This is my first CB750, so I don't really know what "normal" wear looks like on these engines. I come from the car world, as far as working on engines. My Harley's rarely need work, only general maintenance. I bought this bike with the intention of doing a full rebuild, from the frame out. Cafe style. With a little extra power. This forum has been a tremendus help, from advice/knowledge, to parts sources. I'll try not to ask too many stupid questions, most of which have probably already been asked many times before.

[754]

 run your fingernail over it or a sztraightedge and hold it up to the light...lines are normal..

[Terry in Australia]

Yep, I've only ever bought a new set once, and that was after a total top end destruction, after a "mechanic" used silicon sealant on my old gaskets, rather than new gaskets, and the little blobs of silicon blocked off both oilways to the head, and I seized the engine's top end.

The towers were horrendously expensive back in 1982 (around 400 bucks for the pair, from memory) and I bought new rockers, shafts, and a new Andrews cam because the OEM Honda one was silly money too. It sounds like your towers are just a little "polished" and unless there are some deep scratches or gouging, you can still use them. Cheers, Terry.

[lucky]

Yep, I've only ever bought a new set once, and that was after a total top end destruction, after a "mechanic" used silicon sealant on my old gaskets, rather than new gaskets, and the little blobs of silicon blocked off both oilways to the head, and I sized the engine's top end.

The towers were horrendously expensive back in 1982 (around 400 bucks for the pair, from memory) and I bought new rockers, shafts, and a new Andrews cam because the OEM Honda one was silly money too. It sounds like your towers are just a little "polished" and unless there are some deep scratches or gouging, you can still use them. Cheers, Terry.

When i see silicone Orange,blue, whatever on a Japanese engine ,I know an amateur has worked on it, and you can expect damage.
Usually a car mechanic.

[Terry in Australia]

Yeah mate, in this case it was a Triumph mechanic, and I'm guessing that old Triumphs must have had much bigger oilways, because I've seen the stuff slathered on old Trumpy's with no apparent issues. It did teach me a lot about taking my bike to a "pro" though, I did the rebuild with a mate at home, and after I realised how simple CB750's are to work on, I never took one back to a shop again. Cheers, Terry.

[Jerry E.]

I rechecked my cam journals, and cam towers and did not see the scratching/gouges, just what sounds like normal wear from the previous posts. Thanks for the help. In the "car world" you never put a new cam in with used bearings, so I wasn't sure about my 750 motor, and what to do.

[Jerry E.]

I finally had the time to Plastigauge my cam bearings. The outside 2 journals are at .008, and the inside 2 are at .005 clearance. The manual says .008 is max, and Hondaman says they will run to .012( unless you are racing). So I guess I am within tolerances, and the bearing surface looks ok.