R&D platform


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bobcat
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Re: R&D platform

Post by bobcat »

EMS : a little history about jonesbear's 82 X.
Some years ago, in the course of a tune up, we decided to change the cam timing and slight jetting change to go with
the lean mixture of adding the K&N air filter. i set the cam timing at L.C.# 103 int. ,105 exh. . the jetting changes
included all described except the main jet, which i left stock (105) just richer low end-mid range. Recently ,jonesbear
found some 79 cams on e-bay and to verify that is what he received , very close measurement, using my 79 factory
shop manual and his 82 factory manual determined that they were indeed 79 cams. (specifications) once i had both
sets to compare and measure, i was able to verify that the 79 cams have : int. .5mm more lift , exh. .35mm more than
than the 82 cams. 80 thrugh 82 are the same , cam timing different, but only the 79 cams have more lift.(=torque).
I installed an degreed the 79 cams to the same L.C. #s and the only other change i made was to go from stock(105)
main jets to 108 to account for the increased lift. the first time i degreed the 82 cams and low- midrange jetting
changes, the X was (seat of the pants) significantly quicker throughout the RPM range. This time ,with 79 cams and
1/2 step up on the main jets, no other changes, jonesbear ...... well just read his entry !
Bob
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Re: R&D platform

Post by daves79x »

Bobcat:
Per the factory specs, EMS is correct. Only the intake cams differ between the '79 and the Pro-Link. Individual wear and even manufacturing variances may show slight differences in actual lift. As for the '80 cams - they are both unique to that year and share no common specs with any other. I contend much of the cam timing discrepancy is due to camchain stretch, but that is present to some degree in any engine. Degreeing them to a know spec will certainly fine-tune the entire feel of the engine and your point is well-made. I suppose the first camchain adjustment after putting on some miles will throw that off again?

Dave

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Re: R&D platform

Post by bobcat »

Dave , with all due respect, i disagree ! as soon as i can dig them out from where ever i put them, i have jonesbear's 82 cams
and 79 cams i bought on e-bay. once again i will measure them carefully and report back(along with other in depth research results).
i suspect that, based on research (based on p/n#s and manual specs.), that the p/n# for the 79 exh. cam is superceded to later models
(last 3 #s in the p/n : 010) , 79 discontinued ! will find the cams and measure and report my findings.

bobcat
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Re: R&D platform

Post by daves79x »

Bobcat:
I've measured lots of used cams over the years and generally used '79 cam lobes will measure right at the lower limit of Honda's spec. When you buy used ones, you don't know for sure until you measure them what year they are from. The seller can tell you anything. It is not arguable that the '79 and '81-'82 exhaust cams are the same spec - that's been common knowledge for years. If you are getting significant differences in exhaust lobe measurements of your supposed '79 and Pro-Link cams, then you don't have '79 and/or Pro-Link cams. The intakes ARE slightly different. And again, the '80 cams are both different specs from any other. This has been written about years ago in the Xpress and other places.

But your point about degreeing is quite valid - no matter which year of cams you are using. I'm sure there is a noticeable power band adjustment when you do what you did. I do believe the carb improvements are a lot of the reason as well. Any specs you can provide that disputes the above are welcome and I'll dig out what I have for specs here (somewhere!) and we'll see what we find. Thanks for the good discussion.

Dave

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Re: R&D platform

Post by EMS »

bobcat wrote: i suspect that, based on research (based on p/n#s and manual specs.), that the p/n# for the 79 exh. cam is superceded to later models
(last 3 #s in the p/n : 010) , 79 discontinued ! will find the cams and measure and report my findings.

bobcat

Can you explain that in simple words? Usually, the last 3 digits (classification code) in the part-number do not identify a different part. They identify a slight deviation, e.g.: a different manufacturer for an electric part. Following Honda's procedure, if the cams would have been different and exclusive for the 81/82, they would have a MA2 part-number. (Like the intake cams do)
In my parts lists, both the 79 and 81/82 ex cams have exactly the same p/n: 14131/14141-422-010.
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Re: R&D platform

Post by bobcat »

EMS wrote:
bobcat wrote: i suspect that, based on research (based on p/n#s and manual specs.), that the p/n# for the 79 exh. cam is superceded to later models
(last 3 #s in the p/n : 010) , 79 discontinued ! will find the cams and measure and report my findings.

bobcat

Can you explain that in simple words?

NO ! when i can find the 79 cams i bought on ebay (not jonesbear's cams) and jonesbear's 82 cams and re-measure , i will have something
uncomplicated to say. "the smaller your warehouse, the harder things are to find" !
Bob
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Re: R&D platform

Post by rpleines »

Jeff Bennetts wrote:Okay bob.
Quite awhile ago while visiting a long time ICOA member Rich Gerhold, he showed me a catalog that listed all the current Honda makes and models and their interchangeable parts by part number. I don't remember if it was a Honda publication or not but it would be a great guide to use now that parts are becoming scarcer. I know Jan has contact with Rich's son maybe he could ask if he came across it while going through Rich's stuff after he passed.
jb
Jeff I came across this site and was wondering if this is an example off the cross reference you were referring to? There is an International version available as well.

:text-link: http://www.zedder.com/itm00616.htm
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Re: R&D platform

Post by preston »

My main question would be " how much increase in horsepower and torque do you expect to gain by changing what Honda has designed"? I can understand you need that .01 horsepower increase if you are racing the motor and will be tearing it down after a few hours of running for inspection and retuning for the next race but most here wouldn't feel the difference if you added 5 hp to the engine.
Also, the mods you are making inside the engine, will they incerase or lessen the reliability of the engine. There are other areas inside the cases that can be modified to pick up the extra .01hp without compromising the reliability and auctually improve it.

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Re: R&D platform

Post by EMS »

preston wrote:My main question would be " how much increase in horsepower and torque do you expect to gain by changing what Honda has designed"? I can understand you need that .01 horsepower increase if you are racing the motor and will be tearing it down after a few hours of running for inspection and retuning for the next race but most here wouldn't feel the difference if you added 5 hp to the engine.
Also, the mods you are making inside the engine, will they incerase or lessen the reliability of the engine. There are other areas inside the cases that can be modified to pick up the extra .01hp without compromising the reliability and auctually improve it.

You hit it right there, Preston 8) :text-goodpost: If you consider that a 5% variation in actual power output is well withing the manufacturing specifications of any internal combustion engine, it is a waste of time to talk about hp increases of 5 or 10.
I am certainly amazed about the stories that you hear of putting 79 cams into an 80 and feeling a difference.......
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Re: R&D platform

Post by bobcat »

jonesbear wrote:
Sat Oct 08, 2011 5:24 pm
Just rejoined ICOA. I read this thread with great interest because my 82 CBX
has a set of 79 cams degreed and installed by Bobcat.

Bought the bike with 10k miles in 1998. Loved the handling, sound, smoothness…but never understood Honda’s decision to produce the bike in such a drastically mild state of tune. Always thought they left a lot of power on the table.

When I found a set of 79 cams on eBay this spring I called Bobcat (aka Rapid Robert) & asked if they’d make a worthwhile difference on my 82. He said what he always says: research we must.

When he found that the1979 cams factory settings opened both the intake and exhaust valves at about 107.5 degrees, he called me back. He suggested “right numbers” should be at 103 intake and 105.5 exhaust. He thought the extended overlap created along with the additional lift of the 1979 cams should make a tremendous difference in useful torque and horsepower.

Now came a tough decision. If we modified my X, would this really make it the bike I imagined?

I have always hated “molested” motorcycles. Bikes “modified” by idiots who drill out the exhaust pipes or punch holes in the intake manifold because they think they know better than 1500 Japanese engineers are a travesty. They sound like crap, backfire, die at the stop lights. Hideous.

ON the other hand, Bobcat has been the only tuner I have trusted my bikes to for almost 30 years.
When he puts a pipe on a bike, it runs like it came from the factory that way. Looks right, runs right, feels right.

I finally took a deep breath & decided I’d rather know for sure than wonder.

So my CBX went to Bob in May of this year The 79 cams were installed, degreed to his suggested settings. We used the 82 stock exhaust with the cross-over tube, slow jets upped to halfway between a 35 and 38, main jets upped from 105 to 108, K&N air filter, and the needles raised .020 with a shim washer. Mixture screws about 2 turns out

I got my CBX back just in time to ride it through the hottest Texas summer since we started keeping records. Kind of like an extreme test bed: nothing like riding in 108 degree air to test the system.

To put it bluntly: WOW. The difference in the bike’s power is astonishing. Useful torque from about 3k to “Holy Crap” from about 4800 to redline. Above 6k it is truly eye-opening. It’s like Bob removed the “Clark Kent’ parts and put on the “Superman” parts

The broader powerband was exactly what I was looking for. The bike is still as perfectly civilized and well-behaved to ride as it always was…except that now when I wick it on it has the same sort of “live wire” feeling that my GS 1100E does. Stuff happens really fast.

And the SOUND: the cams deeper breathing has awakened a growl—almost a roar- as it comes onto the power band. And that’s with stock pipes. Makes me wonder how a 6 into 1 would sound.

What we were shooting for was a combination of the best OEM parts for the mighty X (79 cams, Pro-Link suspension, 39mm forks and 82 pipes), put together and tuned the way it should have been sold in the 1st place.

I think we succeeded.The riding experience is completely natural. It feels like it always was this way and we just restored what was supposed to be in the first place.

One more thing: the more I ride it, the more convinced I am that somewhere, on some dusty shelf in a Honda factory shop,are a set of cams degreed just the way Bob did mine. I can't shake the feeling that "this is how it was supposed to be".
Wow ! I just found this. It's been a long time but I now own this bike. It needs the carbs cleaned and I think
I will go back to the 105 main jets but the rest stays as is. I've done a couple of other Pro Links the same
way except using the original cams with the same results. I believe the difference in performance comes
from the cam timing and jetting, not the 79 intake cam. I hope I can ride again soon before I get too old. :neutral:
Last edited by bobcat on Thu Oct 07, 2021 5:28 pm, edited 1 time in total.
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Re: R&D platform

Post by Larry Zimmer »

Never too old, Bob. It just changes the pace, not the grin. :D :D
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Re: R&D platform

Post by bobcat »

IMG_0200.JPG
I bought this since the work was done. Hopefully soon I can check where the cam timing is now after all these years.
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Re: R&D platform

Post by bobcat »

Larry Zimmer wrote:
Wed Oct 06, 2021 11:17 am
Never too old, Bob. It just changes the pace, not the grin. :D :D
Right now my only ride is a seat with wheels on either side. Meanwhile the ones
I want so badly to ride collect dust in my crowded little shop. Work is all but impossible
too which is why the R&D platform is shelved for now (hopefully) :handgestures-fingerscrossed:
At nearly 72 I feel a real sense of urgency. I have too much yet to do. I know :violin:
Bob
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Re: R&D platform

Post by bobcat »

Another reason to dig out the R&D platform is to finish development of my exhaust system
for my build project. I will need it to position this item under to configure the header tubes.
Being confined to this wheelchair has severely tested my sanity but given my mind
plenty of time to consider carefully the things I might otherwise have acted hastily upon.
As well it has kept me occupied doing a lot of real R&D reading and studying just about
everything motor and Honda racing history related I could find.
In short, I couldn't find an exhaust system I liked so I decided to just design and have built
one to fit my vision of what would go with my overall project/build.
More later if these hastily taken, somewhat out of proportion pics will post. The foundation of the
rest of the system :
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Bob
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Re: R&D platform

Post by Rick Pope »

I'm liking it so far......
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Either garage is too small or we have too many bikes. Or Momma's car needs to go outside.

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