Engine needs a refresh - make that a big bore!

[jnnngs]

Several old threads have been revisited. We may as well put down the numbers for later reference:

There were three different camshaft combinations used in the CBX:

1979 lift
in 8.3 mm
ex 7.5 mm

1980 lift
in 7.8 mm
ex 7.0 mm

1981/82 lift
in 8.0 mm
ex 7.5 mm

Ergo: Intake is different in all three combinations. Exhaust is the same in 1979, 1981 and 1982. 1980 is different.

Here you go.

Paul.

[Syscrush]

In the home stretch on the engine rebuild, Phil?
Cam specs. viewtopic.php?t=1218

No, I'm not in the home stretch. It may be starting sometime in the next few weeks and I want to be sure that everything is lined up as it should be. I was told that the new head assembly has '79 cams, but I'll feel a bit better if I see the numbers on a vernier caliper.

[Syscrush]

Here you go.

Paul.

This is a huge help, thanks.

My mechanic has measured the cams, and it looks like despite what I was told, I wasn't sent a '79 intake cam. The lift numbers as measured by him are ~7.7mm intake and ~7.4mm exhaust. It looks like it has Pro-link cams, which is consistent with the head having been black and needing silver paint to match my '79 engine. I know I asked specifically for '79 cams and was told that's what I'd get, but I can't find that in my emails. I'm gonna have to pull my old phone out of storage and go searching through my txt message history.

Am I pleased about this?

[Syscrush]

According to a local CBX used parts dealer, the "advancer" on the 1979 intake cams would be marked with number 422, and the 1980 would be 469 - he is away from his stash and doesn't remember the number for the 1981-82.

I'm assuming that by "advancer" he means either the sprocket, or the part of the cam where the sprocket mounts. Does this sound correct?

[FalldownPhil]

No, the advance unit is held in the clutch cover and is the mechanical advance for the timing of the spark.
Also, the 469 unit was recalled and replaced by the 469-A
Best,
Phil

[Syscrush]

No, the advance unit is held in the clutch cover and is the mechanical advance for the timing of the spark.
Also, the 469 unit was recalled and replaced by the 469-A

OK, that's very helpful, thanks. The spark timing was the only "advancer" I was aware of, I assumed that this guy was using that term for some cam timing adjustment since I asked him about cams.

In any case, that would not be helpful for figuring out the provenance of the cams in a head assembly. So there's no identifying mark on the cams themselves, and the only way to know is to measure lift, correct?

[daves79x]

All your guy has to do is physically measure the lobes on the cams. Exhaust cams on '79 and Pro-Link are identical, intake cams are different. If you need the specs, let me know. Cams nor sprockets are not marked for what year they are. You can use either the 422 or the 469A advancer, but has nothing to do with the cams as Phil said.

Dug out the specs - they are in the '79 shop manual - you DO have one? Intake lobes standard measurement 37.3-37.46mm service limit 37.2mm. Exhaust standard is 37.5-37.66mm service limit is 37.4mm.

Dave

[Syscrush]

All your guy has to do is physically measure the lobes on the cams. Exhaust cams on '79 and Pro-Link are identical, intake cams are different. If you need the specs, let me know. Cams nor sprockets are not marked for what year they are. You can use either the 422 or the 469A advancer, but has nothing to do with the cams as Phil said.

Dug out the specs - they are in the '79 shop manual - you DO have one? Intake lobes standard measurement 37.3-37.46mm service limit 37.2mm. Exhaust standard is 37.5-37.66mm service limit is 37.4mm.

Thanks very much, Dave.

[Syscrush]

Intake lobes standard measurement 37.3-37.46mm service limit 37.2mm. Exhaust standard is 37.5-37.66mm service limit is 37.4mm.

Are those backwards, or is the Exhaust lobe really taller than the Intake?

[daves79x]

Yep - they are correct.

Dave

[Syscrush]

Thanks all for the hard info and helpful advice. I picked up the cams from my mechanic and measured both dimensions of each of the 24 lobes, and came up with these values:



I measured using cheapie digital calipers, so I rounded measurements to the nearest 10th mm. The average (mean) values are formatted to 2 decimal places, as you can see.

From these previously-quoted lift and lobe specs:

1979 lift
in 8.3 mm
ex 7.5 mm

1980 lift
in 7.8 mm
ex 7.0 mm

1981/82 lift
in 8.0 mm
ex 7.5 mm

Intake lobes
standard measurement 37.3-37.46mm
service limit 37.2mm.

Exhaust
standard is 37.5-37.66mm
service limit 37.4mm.

It really looks like I ended up with a 1980 intake cam, and an exhaust from 1979, 81, or 82. So I am happy with the exhaust cam, but that intake has got to go.

The seller of these cams does not appear to be interested in working with me to correct this, and I am not interested in getting in a fight at this point as there's a relationship there that I want to maintain - so I've made arrangements with another seller closer to home who has the proper intake cams and is willing to swap. I'm gonna spend 5 hours on the road tomorrow night to get that deal done, and drop the final cams back at the shop on Sat. The engine is assembled other than cams, it should be running next week sometime - if nothing else goes wacky.

[Syscrush]

I should say that despite having to sort out this crap about being sent the wrong cam, there's some good news. Last night I saw the bike up on the stand with the cylinders and head assembled - which is the first time in over a year it's looked like a motorcycle. It was very good for my soul to see that.

Also, the coated pistons fit into the bores with no signs of interference, which suggests that the coater did his job correctly - this was a huge relief to me. Another relief is that with the pistons installed and the cylinders in place, the piston deck height for the pairs of pistons that move together measured to within ~50 microns of each other - so I feel good about the decision to leave the bottom end together.

[wyly]

"I am not interested in getting in a fight at this point as there's a relationship there that I want to maintain " yeah I've been there, professionals who won't take responsibility for their errors...is this a personal or business relationship you're trying to save...

[Syscrush]

is this a personal or business relationship you're trying to save...

Business. Once the bike is all together and working as it should be, I'm going to offer the vendor another chance to make things right by covering the cost I incurred replacing this part - but until then, I want to be able to keep everything friendly in case I need other support to complete the build.

[wyly]

oh how I can relate to that with the guy I entrusted to rebuild my engine ...I knew he was lying to me but I was in no position to do much about it, I wanted my engine back... I learned a very expensive lesson and now direct as many people as I can away from his shop...