cbr aero camshaft

[91cb-1]

I've decided after working the bike up to sell that i likes her too much and now she ooks perfect so i'm gonna hold on to her. however i would like to get a bit more power coming outda bends and corners i was wondering is there any difference in the cams off the cbr aero and our lovely -1. if anyone has done this mod please post up and let me know what else i need to do to make it work?!

[ptlcb1]

The article you should read, is "Cycle - The CB-1 from Heck", in the "Good, The Bad, and the Ugly" category on the forums page.  It gives a comparison of a stock CB-1, then with the 400RR cams in it.  The US CB-1s were de-tuned when they were sold here in the States.  The cams would give you more power.  A cheaper fix, maybe to go larger on the rear sprocket.  This will lower your top end speed, but will give you better acceleration... Just my 2 cents... 

[91cb-1]

I know about the US models having detuned cams in them all right. I'm in Ireland and have a Jap model, that,s why i'm wondering if the jap model has got the same cams as the aero or if installing the aero cams will improve my performance? I also have a spare head that i was thinking of getting a big bore kit for and seeing how that does but i need alot of time and money and concentration for that. i might wait til i'm finished college first!

[ptlcb1]

If my memory is working properly, I think the CB-1 was produced in Japan up to 1993.  What year is your CB-1?  Even stock, you have more power than the CB-1s they brought here to the States.  Whats the stock power of the Jap market CB-1s?  Here in the States, they were 45bhp.  I believe the Jap market CB400RR Aero engine was producing 55bhp.  How long was the Aero produced before Honda started producing the CBR400RR?  I think all the CBR400RRs were producing 59bhp.

Sure would be nice if we had a member on here from Japan...

[clarkdw]

I don't understand where the reference to different cams in the U.S. spec CB-1 comes from. There is only one part number for each cam no matter where the parts list is from. The performance on the dyno of the bike in the CB-1 from heck is about 10% underrated in the baseline and there are a number of discrepancies in the article which indicate that it is written for a deadline and contains quite a bit of guesswork. My totally stock bike has seen the dyno a number of times since I have had it and the power and tq match the articles Stage 1 power almost identically. Mine makes 49.8rwhp so approx 55flywheel. That is the same as any Japanese spec bike. Anyone have actual numbers for a Japan bike? Someone must have had their bike on a dyno? I think that the mythical Japanese cams are just that, a myth. I agree that there are cams that may fit and give more power from the CB400RR or the CBR400RR but I would suggest that this is definitely not a productive exercise with a street bike as it KILLS the bottom end on an already very low torque engine.

I would really like to see a chart of the different cams that can be used in the CB-1 but until I have seen a reliable source for that, I just don't believe that there is any differences in the engines worldwide.

I have been building race engines for many different forms of racing for more than thirty years and never have I seen an engine which has more "myths" attached to it than with the CB-1. It was never produced in high enough numbers to warrant any serious development for the track. An engine builder is not going to spend the incredible amount of time required to properly develop an engine which he will maybe see two of in his entire career. The cost for doing the work on a one-off would be way more than anyone would be willing to pay. To properly modify a head and get max power requires that you waste many head castings. If you are getting your head worked on then it is your engine builders best guess as to what will work. Some will gain you some power from years of experience on other engines but I can guarantee that it is a guess. Flow bench work developing heads is very time consuming and EXPENSIVE in terms of parts used.

End of rant.

[ptlcb1]

Its hard to agree with you regarding the Jap cams, because in the "CB-1 from Heck" article, Kaz does use another set of cams for the Stage 3 mods.  Kaz Yoshima is from Japan and I believe he worked for Honda for quite a while before he moved here to the States.  I think its safe to assume that he is still well connected over in Japan.  How, or where he acquired the CB400RR cams isnt stated in the article, but my guess is that those are the real deal. 

I agree that the changes would do nothing for the already weak bottom end of the CB-1, but the intent of the article was to see what kind of power they could get out of the CB-1 engine on a semi-budget.  All the testing was done at a race track and drag strip, according to the pictures that accompanied the original article.  There was no mention of any "around town" impressions.

It wasnt that the CB-1 wasnt produced enough to warrant performance companies to focus on building kits to up the power, the reason they didnt was because the bike didnt sell well here in the States.  If the bike was selling like hot cakes, Honda would have supplied enough to meet the demand, and performance companies would have built kits/part for them, but they just didnt sell here.  What hurt the CB-1 was there was no demand for it here, plus the high price.  It was only a few hundred bucks cheaper than the Hurricane 600!  So only the usually stuff was produced for it, (a few exhaust systems, jet kits, ignition advancers)

I do understand an engine builder not wanting to invest in building up one of these engines. I actually had a guy, in Canada, that wanted to "play" around with it, but I didnt have the money for it.    He saw it as a challenge and wanted to see what he could get out of it and still have it reliable.  He had many years experience wrenching in the GP's back in the 500cc 2-stroke days!  I told him I would like to have around 65-70 bhp and he said that could be done. 

TTS Performance over in England, does make a big bore kit for the CB-1  They use to have 2 kits listed, a 444cc kit and an 485cc kit.  They only list the 444cc kit now.  I know a guy here in the States, that has the 485 kit.  He raced and said that it was a missile!  He suggested that I get one. 

   

[91cb-1]

I'm glad i've generated such interest and possitive conflict here, this is great, what i've descovered from this however is that replacing even the jap spec with rr cams will improve my top end performance. now i need to figure out a way to improve everything else. 600 carbs? Fuel injection? it's all up in the air and like i said i'm going to wait and do a proper job of it! thanks everyone!

[oldsmoker]

Clarkdw,
 You need to check out megacyclecams.com under CB-1.
 This might help you dispell some of the myths.

[clarkdw]

I did not mean to imply in my post that there were no performance cams available for the cb-1. There obviously are. I said and still believe that the oem installed cams on CB-1's worldwide are the same. Nothing I have seen proves that there is a different cam in the Japanese bikes. The only suggestion or hint that there may be a different cam is from a vague cam timing chart I saw once that indicated that the exhaust cam listed was a California spec cam but even that reference did not list the specs for any other exhaust cam so even that would be suspect.  It would make sense with the stricter emissions laws there as it is cheaper and easier to clean up the emissions by reducing the overlap by closing the exhaust valves earlier than any other method.

I cannot find a part number for that "special" cam but possibly the idea that "American" CB-1's have different cams stems from that. So if you have a CB-1 with the rest of the CA emissions package, you MAY have a lower spec exhaust cam. I would love to see some actual numbers or dyno sheets.

Kaz's work on bike engines is legendary and I did not mean to suggest otherwise but even he was struggling in the short time allotted to get the performance that is available. I have no doubt that he had cams that raised the horsepower of the engine and they came from the CB400RR. The CBR400RR cams were even higher spec as indicated by the higher horsepower but just slapping a bunch of high spec parts together does not always result in a good combination that really works as they found out. A bunch more time and money spent on dyno development and aerodynamic work on the inlet would have netted them the kind of power that your friend saw as in there ptl.

The megacyclecams chart certainly lists different specs of cams but does not suggest that either of the "performance " options were from a stock bike. One is listed as a "Japanese performance profile" and that suggests to me that it is not oem but aftermarket designed for use with stock valvetrain. Maybe this winter if I get real ambitious when I check my valve clearances I will put my degree wheel and dial indicators on and get some specs from the stock cams as the website only lists lift and nothing else.

Unfortunately, oldsmoker, the myths still are thick around the "1" I still haven't seen anything that convinces me otherwise.

91cb-1 This certainly isn't meant to be creating a conflict. I am just very old and require very positive and convincing proof that things which I perceive to be "urban legends" are actually based on facts and not hearsay. Also not to try and deter you from anything you want to do to your bike but my suggestion if you want to be much faster out of the corners is to spend less than you would on the engine on a high performance riding school. No amount of money spent on the engine will ever make up the gains made learning how ride the bike at it's limit rather than your limit.

I have learned from many years of work that building a very high horsepower peaky engine even for the race track usually results in very fast qualifying times and a unhappy racer in the actual race. Very, very few racers, let alone street riders have the ability to utilize the engine to it's best when the power band is very narrow and high in the rev range.

Edit: I just had a flash. Maybe the reason that the baseline numbers on the CB-1 from Heck were so crappy is that it had the Cali spec exhaust cam??? Oh, if only there were more info available.

[91cb-1]

"91cb-1 This certainly isn't meant to be creating a conflict". Hell clark i said positive conflict, if this discussion had not taken place i would still be in the quandry i was in when i started this thread! i'm all for not hurting ppls feelings but fu*k man if you can't have a productive argument without offending everybody this world really is going head first down the bog!
Everything that has been said so far has been very informative and productive!

[ptlcb1]

Clarkdw,
    About 6 months ago, there was a Roadracing World issue that had Kaz in it.  It was under the section they do, which says something like, "20 yrs ago today".  Anyway, I was wondering if Kaz was still around.  I emailed the editor of RRW and asked.  He sent me a phone number for Kaz.  I have not called him...yet.  lol  Star struck I guess!  Anyway, I figure now is a good time to give "DA MAN" a ringy dingy!  If you could, PM me a list of questions regarding our much loved CB-1 engine and if/when I do get in contact with him, if he has the time, I will try and get answers for you.  I will also ask what his email is. 

[xstreamcanadian]

wow this is a GREAT thread, I agree, the arguing on here is 99% productive, opinions, facts etc all flying around, its great, and this topic is being discussed by our 'best minds'

keep it up guys