CB1100 assymetrical cam timing, lift, and duration.

R

Roger the shrubber_imp

Running like a top
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I've been studying up a bit on our beloved CB, and one of the persistent oddities I discovered was the unusual decision by the engine design team to give the big CB some character by engineering in a little roughness. Apparently, the engine was deemed "too refined" so they retarded the intake cam timing on just two cylinders to give the bike some soul, I guess. Stranger still, they went through the trouble of utilizing a counterbalancer to make the engine smooth! Seems counterproductive.

Anyway, this assymetrical cam timing comes at a cost in achievable top end horsepower I believe, so I'm going to look into this by buying a set of stock cams and taking some measurements. My engine builder and machinist can re-profile the intake cam to a symmetrical timing configuration, perhaps even altering the duration to get more horsepower out of this powerplant. The cylinder head is also modestly configured with relatively small port area, so perhaps some improvements can be made there too.

115-125 hp seems achievable, as long as I can get the engine management system to play with these changes. Anyone else look into this or know about it?
 
Well the staggered cam timing was disussed on this forum ad nauseum when the bike came out in 2013, but not much been discussed lately.

Will be interesting to see what you come up with.
 
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From the early to late 1990s, I built a few engines with let's just say, "more than the designed safe horsepower" (within structural limits of course) Lol...

One of them was a project Kawasaki ZX11 D1 which dyno'd almost 175 normally aspirated rwhp. This came at a substantial cost, but it was tremendous fun to ride, if not a bit challenging. Luckily, the bike's large overall dimensions and generous wheelbase made it manageable to some degree.

Looking at the stock, off the showroom floor output of some of the newest supersport bikes, this doesn't seem like particularly earth shattering performance. I'm just left wondering what I can do about the calm demeanor of the aircoooled CB motor.:D
 
This could be cool. I'm betting that the cams in the are the major cork in our engines -- with the way this engine rides and it's powerband, they must be quite conservative. It'll be neat to see what your machinist comes up with.

I'm somewhat surprised that with how popular this bike has been, and how long it has been released overseas, that noone makes aftermarket cams.
 
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Me too. Absolutely no internal engine mods available from my observations. This may be the nefarious side effect of stringent emissions regulations in the countries the CB was introduced into first, and weak aftermarket support especially here in the US, where the bike thus far has only had a two year run. Consider however, that there are many other bikes in the same displacement category where high revs and max horsepower output happen at the 9,500-13,000 rpm range... those bikes are supersport models, a category that the CB has nothing in common with aside from the number of cylinders. It's not that kind of motorcycle.

Any extensive engine mods will likely require changes to the fuel injection and ignition mapping, perhaps a custom ECU and possibly larger injectors, among a few. Re-profile of the cams is easy enough and is something engine builders have done for decades. In the case of assymetrical cam timing, the cam can be cut in sections, lobe centers realigned, and then rewelded, ground, and hardened.

My 1982 CB900F had fully symmetrical cam timing and an engine counterbalancer, and it had a smooth, high revving air cooled engine producing 115 HP without the need to engineer in some "character" as the designers have done with the CB1100.
 
On Kawi's thread I commented that some basic mods should get you to the 100 - 120 neddies range. That's a lot of go for an eighties style UJM. Suspension mods etc would definitely need looking at, particularly for street use. I guess the drive train and frame would be up to it.

Keep us posted.

Cheers
 
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Well, the basic engine architecture is the same as it was 30 years ago, so I would expect that anything you do to an old CB750/900/1100F will work just as well now on the CB1100.

Porting the cylinder head, hotter cams, remapping the FI, exhaust..... it's all just footwork that someone needs to do, given enough interest and motivation.

Oh yeah, money too.
 
Roger the shrubber_imp said:
I've been studying up a bit on our beloved CB, and one of the persistent oddities I discovered was the unusual decision by the engine design team to give the big CB some character by engineering in a little roughness. Apparently, the engine was deemed "too refined" so they retarded the intake cam timing on just two cylinders to give the bike some soul, I guess. Stranger still, they went through the trouble of utilizing a counterbalancer to make the engine smooth! Seems counterproductive.

Anyway, this assymetrical cam timing comes at a cost in achievable top end horsepower I believe, so I'm going to look into this by buying a set of stock cams and taking some measurements. My engine builder and machinist can re-profile the intake cam to a symmetrical timing configuration, perhaps even altering the duration to get more horsepower out of this powerplant. The cylinder head is also modestly configured with relatively small port area, so perhaps some improvements can be made there too.

115-125 hp seems achievable, as long as I can get the engine management system to play with these changes. Anyone else look into this or know about it?
Click to expand...
Without sleeve bore & stroke in addition of cams those ## are not obtainable. I've researched last year and no one has a kit available. Changing cam lobe may net you about 5 hp with a modified ECU and hours of dyno time. This would not be cost effective.

This is not a GS1100E motor that you can find a 1465 block. The CB putting out 125hp would require more modification than cams & bored, probably a new block which are not available.

Edit: Roger, Honda has the hardest ECU to crack without drilling it open, Don is the only guy I know and he's in PA. Any modification done to the cams would require the ECU to be re-mapped for timing and fuel. You would have to ship the bike to PA for dyno time.

Its not like the old days when a tuner can pull out his carb kit and change needle valves and main jets to tune.
 
One can use a Power Commander 5 to do all tuning and mapping without reflashing the ECU BUT you will still have the top speed limiter. It doesn't take hours of dyno time, more like an hour tops.
I did both, as I wanted the limiter gone!
 
I believe the ecu flash is required to adjust ignition timing as well, as PC5 only allows control over A/F ratios.


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Might be cheaper to buy a used 600cc sport bike if you want to go fast. To make significant horsepower will cost a bucket of money. A ZX-6R makes 112 hp out of the box which is about 40 percent more hp than the ol' CB and it handles better as well. Of course, you will have to invest in one of those leather crotch rocket riding suits and I personally wouldn't want the public to see in one of those outfits... scare the little kids and make the adjust ill I suspect.
 
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I'm definitely aware of the modifications I will have to make to get some additional HP out of my CBs, and that's primarily why I bought my third one, a 2014 standard as a test mule. I do have a number of motorcycles in my stable which would absolutely slaughter the CB in any speed contest, so I don't really care if I get 5 or 50 more HP out of it. I'm doing this for the fun of it and to see what works.
wiredgeorge_imp said:
Might be cheaper to buy a used 600cc sport bike if you want to go fast. To make significant horsepower will cost a bucket of money. A ZX-6R makes 112 hp out of the box which is about 40 percent more hp than the ol' CB and it handles better as well. Of course, you will have to invest in one of those leather crotch rocket riding suits and I personally wouldn't want the public to see in one of those outfits... scare the little kids and make the adjust ill I suspect.
Click to expand...
I prolly wouldn't dink around with a 600cc supersport bike. I have two CBR100ORRs, and a couple of R1s if I want to ride over my head. I built a Kawasaki ZX11D about 20 years ago which was pretty heavily modded, cams, cylinder head work, porting, five angle valve grind, big bore kit with special Arias pistons, Keihin FCR carbs and a special air box which retained the dual ram air intake. It took months to get it right, but it was and still is wickedly fast. Two dyno runs without ram air netted 175 rwhp.

I never cared much about dressing up like a Power Ranger to ride it for that matter, but it was a necessity on that bike. Lol...
1982 Honda CBX, 1986 Honda VF1000R, 1993 Kawasaki ZX11D1, 1994 Honda CB1000 Super Four, 1995 CB1000F, 1995 Yamaha FZR1000, 1996 Honda CR500, 1996 Suzuki RMX250, 2002 Kawasaki ZZR1200, 2003 Yamaha FZ1, 2004 Honda CBR1000RR, 2005 Honda CBR1000RR Repsol, 2006 Yamaha FJR1300AE, 2006 Yamaha R1 Raven, 2006 Yamaha R1 LE #318 of 500, 2007 Honda VFR800i ABS, 2013 Honda CB1100 ABS, 2014 Honda CB1100 Deluxe, 2014 Honda CB1100 Standard, 2015 Yamaha SR400...

Everyone lists their bikes in their posts. I thought about it, but.....
 
I think the service manual indicates the intake lobes on cylinders 1 and 2 open the valves 10 degrees after cylinders 3 and 4. I can verify this if you'd like. They also vary the fuel and ignition timing some as well. Let me know if you want the link to the Honda development story page. The idea was to give the engine "rumble" at 3,000rpm, which roughly translates to the national speed limit in Japan in top gear (100k/h). It's not meant to alter the balance of the piston/conn-rods/crankshaft, just to make it feel a little more like the unrefined air-cooled 70's in-lines... It bugs me a bit--wish they would have just left the timing the same on all cylinders. The rumble seems to go away when you really get cooking. Same thing for low speeds.

Shoot me an e-mail if you want the shop manual specs or the link to the CB1100 development page that talks about the design goals and details: josephnorris0106@yahoo.com
 
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