Greetings from Zimbabwe !!! Of all places...

[Mutton]

I'm helping a friend in re-assembling his '82 CBX that bent a couple of valves. He's now stripped the whole bike and is doing an engine rebuild and complete frame resto.
On removing the engine, he's removed the top end and barrels, and has further completely stripped the head. As he's a fitter and turner, one of the first things he did was to check specs of cam lobes and he then realised that on one of the cams, the lobes are different to all the other cams. He has a workshop manual which told him that there are 2 different sets of cams that are swappable, one set for the original and one set for the de-tuned motor.
Is this true? I've seen a few posts showing that the manual is incorrect. I'm just waiting for him to email me the spreadsheet with all the measurements so that members here can comment, but as he's not on the internet (!) and only occasionally collects email, I'll have to wait !
As we're new to this club, we will be posting some pictures, and then telling of adventures with trying to procure parts in the dark hole of Africa? I think that there are only about 4 CBX's in the whole country !
Any info about the cams would be well appreciated, thanks.

[EMS]

Complex issue. Several changes took place in the cams between 1979,1980 and 1981/82:

1979 had intake lift of 8.3mm. Exhaust lift of 7.5mm
1980 had intake lift of 7.8mm. Exhaust lift of 7.0mm. And the exhaust cam was advanced by 5°

1981/82( your friends) had intake lift of 8.0mm. Exhaust lift was back to 7.5mm like 1979
The intake closed now 5º earlier, both opening and closing of exhaust was retarded by 5º, making the exhaust cams the same as in the 1979 model.

There were no "detuned" motors within a certain year. The tuning was different between the different models years.

[Mouse]

To the group Mutton
From the Canadian Rockies.

[steve murdoch icoa #5322]

Hi ya, Mutton.
Good luck with the rebuild.
I think there has been 3 or 4 site members from South Africa join in the last year.

[Mello]

mutton.
Good luck with the rebuild. Ask questions - lots of very knowledgable folk here.
I recently had to get my '82 motor rebuilt after it dropped a valve. Luckily we managed to get some good used parts as the CBX was reasonably popular in SA.

[Mutton]

Hey guys, thanks for the welcomes and ,EMS, thanks for the info. I'm still waiting for the spreadsheet with all the specs so that we can decide on what we do actually have and the best route to follow from there.

[cross]

[Mutton]

FINALLY ! I've recieved the top end specs from Mike, but it was in a higgledy-piggledy format. I've now re-input all the data into a spreadsheet. If a .pdf would be better, please let me know. About the data that Mike is concerned about, they have all been surrounded by thick black boxes. Although the shims are necessary, the main issues are the 2 readings from the inlet 1 (36.31) and inlet 2 (36.33) cam lobe - what's the general consensus? Is it too worn? Why would there be, on the same cam, a 36.89 and a 36.31... that's more than half a mil difference? It does seem quite a bit. For a person who is quite pedantic about all specs being very close, Mike is quite concerned about these differences. Please excuse the few ares on the sheet that may be a bit hazy in explanation, this is the first translation of Mike's spreadsheet, I should be seeing him tomorrow and can tidy some of those up, but I just wanted to get this posted. Thanks in advance for your comments.

[Mutton]

Erm, how to attach my spreadsheet !?!? OK found it below....

[EMS]

E-mail me to mike.simon70@yahoo.com. Let's talk about this spreadsheet.

[EMS]

As I am looking at Martin's spreadsheet, I discover something weird:

My Honda service manuals do not give me a service limit for the 1980 cams. This is of particular interest as I am also working on my 1980 project to get the head overhauled.
My 1979-80 manual only gives the specs on pages 6-1 and 6-7 with a cam height tolerance and service limits, which are obviously for the 79 cams. there is nothing in the 1980 addendum.
The 1981/82 manual gives the same data for the Prolink motor. As the exhaust cams are the same as 79, it shows the same numbers for these, but the intake cams are again different.
Has anybody seen any cam height specs and service limits for the 1980 cams ( 7.8mm lift intake, 7.0mm lift exhaust)

[EMS]

Never mind! Found the info on page 22-19 of the 1980 addendum.
HOWEVER!!!!! The numbers are totally screwed up.
The exhaust cam lobe height is given with 37.800-37.160mm. Really strange, because the lower number should be listed first. Only when you convert the "inch" dimension to mm ( 1.4567 - 1.4630 ) you get 37.000 - 37.160. That is in line with the other years and with a cam base circle of 30mm, results in a lift of 7.000 mm. Sort of confirmed by the service limit of 36.9mm (6.9mm lift)
Same strange thing is going on with the intake numbers. The metric values for the cam lobe tolerances when new, have the higher number of 37.800 listed first and then 37.060. Converting the corresponding "inch" dimensions to mm, (1.4882 - 1.4945) they come out as 37.800 and 37.960. In the correct order: lower first, higher second. This does not match the other years for a base circle of 29mm. Only if the base circle would be 30mm, would the lift be 7.8mm - as specified for 1980.
Question now is: Do the 1980 cams indeed have a larger cam base circle than 1979 and 1981/82?

[Mutton]

Ok, since we're not going much further than these quite specific queries (thanks Mike), what is the general advice for this motor? As the exhaust cams all seem to be within spec and good, the only question is the 2 inlet cam lobes. As there is .3 to .4 of a mm difference between themm and the rest, should they be built up at a reputable machine shop, or should we just replace the inlet cams? As we are quite far away from anything here and there are a few reputable machine shops, our sentiment is to go with that. Obviously our brains, hearts and common sense says "replace", availability, price and reason says fix it... but PROPERLY. What's the boards' feelings?

[Mutton]

After discussions with Mike, the bike owner, he reckons we should just try and get a new set of inlet cams, as the inlets and exhausts are both about the same, at 7.5 mm lift. As the exhaust cams are all within the correct spec, and it's the inlets that are worn (and incorrect), we have agreed that this is the way to go. Anyone got a spare set of (mostly) good inlet cams that they would be willing to let go to a worthy cause?! If not, who could be the most reliable supplier? Mike S, as you have guided us and helped with info, your valued input would be ... most .......valued !!! Thanks to all for viewing and for the responses.

[cross]

You should be able to find some on eBay.
How many miles are on that engine?