Do both late model cams need replacing for 79 cam specs

Mike Barone #123 · Post by **Mike Barone #123** » Thu Jul 29, 2004 10:47 am

i just purchased a low mileage late model engine for installation in the dawgie redo

can someone tell us all ....maybe i am the only one that doesnt know....what late model cams if any are the same as the 79 cams

ie.... do i have to buy both 79 cams to bring the late model engine up to 79 specs

thx

mike

Passx · Post by **Passx** » Thu Jul 29, 2004 10:26 pm

Mike, without looking I believe that the exhausts are the same and only the intake is different, but personally I'd dial the late model cams in and leave it alone. I changed the cams on my 80 to the 79's and it was only worth 2hp on top and got softer in the bottom, I'd bet that if it were possible to drag race the 2 side by side the 80 cams would walk away from the 79's and then the 79's would have to run the 80's down.

My 81 has the best all around and with some careful tuning I'd bet would stomp the 80 (at the same weight) because it has great low to midrange for driving off the corners and just screams on the top, it just out weighs the 80 by a 100 or so lbs. Things to do to the late model is to set the carbs the same across the board, set the ignitors to 120degree spacing while you have the degree wheel hooked up to phase the cams. Setting the 79 intake cams to +5 degrees advance and the exhaust straight up. This gave the 80 2 more peak hp over the previous setup but gave it 8-10 hp and ft lbs through the midrange,,,big difference. Also careful tuning of the jetting has netted some of the biggest & best increases plus once it's right the mileage and power are very good but does make it cold blooded once it's right.

So I take that the Dawg gave it up after only 100k + miles,, must not have been put together right at the factory I'd say.

Hope this helps Steve P#5220

broook · Post by **broook** » Fri Jul 30, 2004 6:44 am

I would have to say he didn`t ride it hard enough so it just gave up.

Mike Barone #123 · Post by **Mike Barone #123** » Fri Jul 30, 2004 10:36 am

Passx wrote:

So I take that the Dawg gave it up after only 100k + miles,, must not have been put together right at the factory I'd say.

Hope this helps Steve P#5220

>>>>>>>>>>>>>>>>>>>>>

ha ha ha

actually the 100k 80 motor in the dawgie is fine. it did great last time i rode it at the beaver run track day....esp when i keep revs to redline vs way over

its a long, long story we will go over at a rally on why i am taking the motor out but none of it has to do with this being necessary. add it to the unexplainable things i do in my life all the time....which i am sure you have your own personal list by now now like eveyone else

right now the dawgie is in for final redo. jeff b is doing it for me and we have hopes of it being back on the road for the penna rally in sept.

sadly, it wont have alot of the patina/fit/finish the dawgie was known for after the redo and i guess as such.... it now will fit right in there with all the polished and pampered x's at rallies

give me a couple of months to take care of that......ie....no one has a photo of me washing/cleaning the dawgie and i just might not change that when the redo is complete and it is all proper and pretty once again.

later now and thx for reply. btw are you coming over to penna national in sept. call me sometime ...800-869-5763 then 1, then 4331 to go over a few q i have related to the cams. mid morn or late afternoon are best. i wont be in later today so next week is fine

mike

Mike Nixon · Post by **Mike Nixon** » Sun Aug 01, 2004 10:57 am

Post by **Ringnalda** » Tue Sep 04, 2007 3:50 pm

Only the intakes are different...

Jan

alimey4u2 · Post by **alimey4u2** » Tue Sep 04, 2007 3:55 pm

I switched my 80's inlet cams to 79's....I too am of the opinion that the exhaust cams are identical grinds....

EMS · Post by **EMS** » Tue Sep 04, 2007 8:56 pm

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.

alimey4u2 · Post by **alimey4u2** » Wed Sep 05, 2007 3:41 am

Well Poo, It looks like I was wrong again......

Interestingly, this setup of 80 exhaust & 79 inlet cured my severe off idle flatspot on my 29mm Smoothbore Mikunis, which I had been struggling with for decades... Not calculated but fell on by pure luck....

EMS · Post by **EMS** » Wed Sep 05, 2007 8:02 am

Larry, the 1980 exhaust cam was also advanced by 5Â° compared to the 1979 and had less overlap. The 469A advancer advanced the ignition faster and further than on the 1979. You putting a 1979 intake cam in your 1980 may have just done the right thing for your carbs and exhaust. Wow!

alimey4u2 · Post by **alimey4u2** » Wed Sep 05, 2007 5:09 pm

EMS wrote:Larry, the 1980 exhaust cam was also advanced by 5Â° compared to the 1979 and had less overlap. The 469A advancer advanced the ignition faster and further than on the 1979. You putting a 1979 intake cam in your 1980 may have just done the right thing for your carbs and exhaust. Wow!

Sometimes with all this tinkering someone gets lucky. The wonderful thing about this website is those lucky encounters may be shared for all.....

rbarber · Post by **rbarber** » Tue Oct 02, 2007 8:34 am

I know a place that makes new cams and modifies your old ones. If you know what you want, they can do anything. I know, they have done DOHC Honda cams for the CB750/900/1100Fs.