HONDA CB1100 ENGINE (interesting)

[RajunCajun_imp]

Engine "from HONDA"
Centrepiece of the CB1100 is its handsome DOHC engine. Air (via 2mm fins) and oil-cooled (via a 335mm 9-tier, front-mounted oil cooler), the finning is the finest found on any bike within the Honda range, and new production methods had to be found for its manufacture. It revs to 8,500rpm and features a compression ratio of 9.5:1. Maximum power output is 66Kw, with a peak torque figure of 93Nm @ 5,000rpm.

Importantly, however outright horsepower figures on Dynograph paper was not the goal – if the engine proved fun to use, then it would be deemed a success. Smooth, instantly accessible power and torque is what the CB1100's motor's all about, and plenty of it, anywhere in the rev range. No frantic thrashing to the redline; just dial in the throttle, and go. Four-stroke, four-cylinder motive thrust at its creamy, effortless best.

Extremely efficient PGM-FI fuel injection, utilising one 36mm throttle body, gives excellent fuel consumption of 25.1km/l (70.9mpg) @ WMTC.

Bore and stroke is set at 73.5mm x 67.2mm. Drive for the twin camshafts is via central chain, and the valve included angle is 26.5° inlet and exhaust. Inlet valve diameter is 27mm, with a 2.5mm stem; exhaust 24mm with 2.5mm stem. A single, secondary balancer shaft ensures smooth running and drive is transmitted via wet clutch and five-speed gearbox. Final drive is by 530 chain.

 

[the Ferret]

Im pretty good at squeezing mileage out of a bike but doubt i'll ever see 70 mpg unless coasting down Mt Washington in N.H.

Otherwise I 'm down with what it says.

I WISH it got 70 mpg :-/

 

[Scoobynut_imp]

Thanks for posting that Rajun. Until I saw your post, I never realized the bike had a balance shaft. If it makes it even smoother, I'm all for it.

 

[Lord Popgun]

The adjustment for it is on the right side of the engine at the bottom. Looks like a lever with a pinch bolt. Procedure is in the service manual.

 

[Inline4_imp]

I'm no engine guru, but doesn't this bike have 4 throttle bodies? I recall reading an early report stating that it incorporated only ONE throttle body but was later determined to have four.
I just got my FSM in the mail today....haven't even opened it yet so I'm not 100% certain either way.
I AM certain that someone a lot sharper than me will chime in and set the facts straight.
Jim

 

[Lord Popgun]

The manual says, on page 1-4, that throttle bore is 32mm

There is one throttle body Inline4. Look in section 5.

 

[vfrpaul98_imp]

correction, 1 throttle body assembly that contains 4 butterfly valve throttle bodies. see page 5-50 of the shop manual for illistration the butterfly valves are jointly connected by a common shaft so that all 4 throttle body butterfly valves open and close together and are factory synchronized. each throttle body has a 32 mm bore that feeds 1 cylinder head intake port.this engine has 1 throttle/butterfly valve feeding it's own port times 4 total.todays cars normally have 1 large throttle body/butterfly valve that feeds a intake plenum/ manifold that is split into the number of cylinders to be fed a fuel and air mixture. most common 1 large throttle body/butteryfly valve that feeds a 2 or 4 or 6 or 8 cylinder
engine on the auto side .
so instead of 4 carburators on this engine we have 4 throttle bodies and 4 fuel injectors.
Paul.

 

[Lord Popgun]

Thanks for clarifying that VFR. Now it makes a whole lot more sense.

 

[the Ferret]

correction, 1 throttle body assembly that contains 4 butterfly valve throttle bodies. see page 5-50 of the shop manual for illistration the butterfly valves are jointly connected by a common shaft so that all 4 throttle body butterfly valves open and close together and are factory synchronized. each throttle body has a 32 mm bore that feeds 1 cylinder head intake port.this engine has 1 throttle/butterfly valve feeding it's own port times 4 total.todays cars normally have 1 large throttle body/butterfly valve that feeds a intake plenum/ manifold that is split into the number of cylinders to be fed a fuel and air mixture. most common 1 large throttle body/butteryfly valve that feeds a 2 or 4 or 6 or 8 cylinder
engine on the auto side .
so instead of 4 carburators on this engine we have 4 throttle bodies and 4 fuel injectors.
Paul.

Im having a problem envisioning this, can you post up a pic?

 

[vfrpaul98_imp]

Scan0001.pdf (Size: 275.62 KB / Downloads: 207)
throttle body assembly that contains 4 individual 32 mm throttle valve venturi openings that mount to the intake ports on the cylinder head. each port is fed fuel by a single pressure fed electronicly triggered fuel injector.
Paul

 

[the Ferret]

Thanks. Kinda looks like 4 little carbs without float bowls doesn't it?

 

[_imp]

Thanks. Kinda looks like 4 little carbs without float bowls doesn't it?

LOL, I was about to post that riposte but you beat me to it.

 

[ChipBeck_imp]

Gentlemen,

That fuel injection is one of the main reasons I bought the CB. My bikes often sit for long periods and in AZ's heat the fuel dries out and carburetors then need rebuilding. My FI bikes can sit for a year and with a good battery they start right up. I've spent tons of $ rebuilding carbs over the years especially on our dirt bikes. FI is one of the best things to happen to motorcycles.

Chip

 

[The Spaceman_imp]

Motorcycle.com dynoed the engine. Both the torque and HP traces were literally straight lines. The author said he couldn't have made it straighter if he'd drawn it with a ruler.

Back in the days before TC, power "curves" like that were the Holy Grail for racing because it made the riders job so much easier. For us it means we get a super smooth ride with no drama. I love this engine!