BODYWORK & DASHBOARD

I changed the OE screws to SS ones, put neoprene rubbers in each screw to bodywork contact, and cleaned everything inside. And out. The speedometer has its needle broken and the unit, after disassembly, was completely shot, and on top of that,the speedo cable was too short, even disturbing the fork movement and the stability of the bike

I learned, painfully to my pocket, that the CBX 750 FE-FG speedo & cable don't fit on this model. Even although the speedo looks the same at the first view, when in hand it is absolutely different from mine, without a possibility to adapt it into the clock house. The frontal bodywork frame & the couple of beams are also different.

You must buy VF 1000 F2 Bol Dor spares. The problem with the 1000 speedo is that reads to 280km/h. Too much, looking at it, there is no movement at all until 140 km/h. When I do find a 2nd hand in eBay I will change it. I accept all sensible offers, thank you   ;-)

In November 2011 I bought a CBX 750 F2 dash, Japanese version. The problem now is the opposite, like my bike runs more than 180 km/h (in fact it is very easy to see 220 km/h) , it is so easy to get the needle passing the 180 km/h mark. You feel faster!. An English or German dashboard are expensive and difficult to find

I could fit a Brazil "Sete Galo" dashboard, as you see at the pic, but the numbers and pointers are white and there is no rear lamp indicator.

At the right, you can see the Brazilian FUSE cover with the Honda logo embodied, the inserted dashboard light switch (later explained) and the brake & clutch VFR 750 T 1994 master cylinders fitted. Its an eays mod. You only have to change the upper brake hose

BRAKES

Black metallic hoses installed not to break too much,   from the OE appearance. I cleaned the brake callipers expecting a lot of rust, but nope!, the callipers looked like news with a nice gold coloured  pistons. Anyway, I extended a little bit of Vaseline on them.

The front bike is excellent with a lot of feeling and force. The rear brake is better than my FJ with the GSXR rear one adapted.

GOLDFREN PADS

I bought these at eBay UK. Very cheap and I've read good reviews about them. Sintered HH pads, look like a good deal. The previous pads fitted in my Honda were Sintered HH Ferodo pads, but I didn't like them. A hard feeling from them, and not too much brakes, no way like the excellent brakes the Honda was acclaimed to have, when it first appeared to the press. In fact I was starting to think that my memories about the excellent brakes fitted to the CBR 600 87-90 (the same units) were only senile memories ,comparing brakes from 20 years ago.

But not, with the Goldfren pads, the brakes are fierce and aggressive, with a very good feeling, next to the level on my R1 fitted brakes for the FJ1200. Even touching them the Goldfren feel softer than the Ferodo, so, about the duration/wearing time, I think economy should not be the main issue when buying these pads. RECOMMENDED

ADJUSTABLE FRONT BRAKE LEVER ADAPTED

 As I wrote previously, brakes, although good, are more adequate than outstanding. The bike stops well, but the feeling is a bit spongy. I bought a master cylinder kit to improve the feel, but I have not got too much of a difference.

My FJ 1200 fits a Nissin master cylinder, as one as fitted by Fazer 600 1998-2002 / FZ 2001-2003/FJR 1300 1000 2003. Side to side with the Honda one, both are near identical. In fact, the Honda ones comes from Nissin too, so a simple attempt was worth it . The FJR lever fits perfectly!

But... (there is always a but) the FJR level shows a little step where it actuates with the switch brake light. The Honda level is flat, so when installing the FJR lever the brake light stays always on.

The left pic shows a simple way to fix: using a 2 component glue, NURAL 20 in my case, I stuffed the step, leaving the surface flat. Leaving the compound to solidify and sanding until leaving a soft and flat surface I've got a perfect fitting and working operation.

I don't like to change the Honda original aesthetic, but in this case it is compensated by more powerful brakes, and having more lever, more feel at the brakes and the possibility of adapting the lever to my hand size. RECOMMENDED

July 2013: Above, first pic in this page, you can see that I adapted the clutch & brake master cylinders from a VFR 750. Well, the look is improved but (and it is a BIG BUT) the brake master cylinder ratio is not correct for the calipers, so the feeling is that the brake system is not bleeded.

Then, I fit the VFR levers in the STD CBX brake & master cylinder. These fit straight on and you gain adjustable levers on both. RECOMMENDED

ENGINE

NGK DPR9 EA9 cold spark plugs, like the owners manual recommend for hot climates and hard riding. superb!. I've painted the engine with non-caloric paint and change a lot of screws for SS items. The engine looks gorgeous. It is a pity that it is covered for the fairing.

If you need to change the OE spark plug caps, you need 2 NGK SD05F for the inner cylinders and 2 NGK X05F caps for the outer ones.

I changed the distribution cam chain tensor with a lot of work and effort, only to check that the chain rumbling noise continues there. AAARGGGGGG! it is the primary chain, the one inside the crankcase that communicates the alternator with the crank. So the engine must be opened to change it, like I describe in the CBX engine section. With the rebuild the compression increased from the around 8 kgm2 to 12 kgm2, according standard values, with a notorious increase in power from around 7.500 rpm.

 FRONT RIM

The OE rim size is 2.25. To fit a 120/80/16 front tyre is necessary to get a 2.50 rim, with the objective, to get more front weight biased on the front wheel, due to lesser diameter of the 120 tyre. I bought a VF 750 F rim, to fit it straight on, with discs and all the hardware included. (both of bikes use the same front axle & speedo drive).

The problem is the colour: you can't paint it because the rim is anodised. And the you can't paint the CBX rear to match the VF front.

The VF front rim change a bit the OE shape, but carry a gold front and a black rear is a visual horror. Bad move.

LEDS REAR BULB

Don't try one of these because it doesn't work: if you fit it, the tell tail light is always red glowing because the leds bulb don't have the voltage consumption necessary, and the circuit thinks that the tail light is out of service.

15 th FRONT SPROCKET

I bought it in eBay in order to increase the acceleration, trading for max. speed (I don't need 230 km/h in Tenerife. I don't have open spaces to get there). It comes from the CBR 750 Japan only model, and the reference is 339.15. It was a clear buy being the OE reference 339.16. Well, NOT!. The chain doesn't fit. You have to mount the sprocket without the OE rubber damper, parts 19 and 20 at the photo. To download a useful gearing calculator to see the effects with different rear tyre size & front & rear sprockets combinations, click here to download

Update: We can choose even more different front sprocket sizes: the VFR 800 2002-2010 and the CBR 1000 F 87-96 front sprockets fit our CBX 750. The VFRs OE original equipment is the same 339.16. I've just fitted a Renthal front to my bike.

Magnetic oil pan screw

I bought it in eBay. The part number is exactly the same that fitted on the Honda VF 1000 F2 BolDor, so I ordered one for this. Recommended to visually inspect if anything wrong is occurring inside the engine on the next oil change, and to trap minor debris particles that could damage any part inside the engine

WINDSCREEN

It is near impossible to find it in Europe because no screen makers produce it. Our bike is a rare bird, no so in Brazil, where there are a lot of them. You could order from there knowing that the F2 is named "Sete Galo". The problem is that there is no eBay , so you must look for a seller in Brazil, and with an expensive delivery cost. Finally I found mine in New Zealand,  http://www.japmcdismantlers.co.nz, excellent service and without problems at all. There are screens clear, tinted and dark tinted. Mine is one of these. And they informed me that even although the VF1000F2 BoldDor looks identical, there are minor differences and it doesn't fit. RECOMMENDED

STEERING STEM BEARINGS

The Honda manual states the correct adjustment for the OE ball bearings. Around 2,5 kgm. Even then, the Honda produces a light head shake from 40 to 60 km/h. The solution is to fit  better quality roller bearings. The lower bearing is the same as per FJ 1100/1200 models. The upper one is a strange one, with the code printed at the race. To extract the lower race is a pain in the arse, exactly the same as with the FJ models. take a look to the FJ sections to learn a pair of tricks to extract the headraces.

When the new bearings mounted, to set them correctly, torque to 5,5 kgm the C nut when the bearings are installed to bed the bearings properly, then loose the C nut and re-torque it to 0,3 to 0,5 kgm. Yes, it is correct!. Very light torque, as in my FJ.

FRONT INDICATORS

For reasons of each country homologation laws, There are markets where the CBX comes with the ugly front indicators that you can see on photos of my bike, equal to the rear. In Japan and originally, the indicators are integrated into the fairing. Looking in my friend Mamel´s workshop I  found some white indicators. Thorough cleaning, a touch of TITAN paint for fridges (yes, the same white Honda colour) and they are perfect,fitted on my bike. Take a look at left upside photo

CARBURETION 

I don't know what are the specs for the F2 model, but the CBX 750 FE to FF run 115 main jets and the last FG model (1986) 112 ones, so like the F2 model comes from 1986 I deduct that 112 were the ones to find inside the carbs. On the other hand, the CB 750 92 on model run 112 main jets on 2 & 3 cylinder and 110 ones on 1& 4. When dismounting my bike, there were 112 on both inside carbs, 110 on the left carb and 115 on the right one. ??. And the Phillips screws were never touched, unmarked items. ??

So changing the OE screws, fitting SS Allen bolts and fitting a stage 1 Dynojet kit, with KN filter, has got a dramatic improvement in the throttle response (well, the screws are an  essential go-faster-look item ;-) ) With the medium main jet recommended, 102, now the bike pulls in 6th from 4-5.000 rpm without downshifting . STRONGLY RECOMMENDED.

MAC 4/1 EXHAUST SYSTEM

The OE collectors are double wall type, so if the bike is not frequently used they may crack by the inside due to the humidity, producing a disturbing CLACKCLACKCLACK, more if the engine is completely new, like in my bike.

Buying a new set or a 2nd hand ones soon or later the same problem is going to appear again, so I decided to change the complete system. When choosing for a system for the CBX 750 there are no too many alternatives: Motad (bad fitment, with blown holes impossible to sort out, read my FJ 1200 experience, exhausts from the main menu), SITO (as heavy as the OE system and very expensive) or a USA made MAC 4/1 complete system.

The problem with the MAC is that it is designed to fit the US Honda CB 700/750 Nighthawk 1983-1986 . Like both bikes (Nighthawk & CBX) fit the same engine & chassis layout I thought that I would have to make any mod in order to fit the exhaust, mainly to the rear hanger area.

Surprise! the exhaust fits straight on, sweet & perfectly, with no leakages. Even there is enough room to fit the front cowl. And it keeps clear access to the oil drain bolts (3) and the oil filter. And the complete system weights like only 1 OE muffler.

The only mod that I performed was to cut and to bend again the L shaped piece that goes attached to the canister and that works like a main stand stopper, like you see at the pic. It is made to gain ground clearance.

I reinstalled the 16 teeth front sprocket in order to not camouflage carburetion problems with a short gearing

I changed the main jet to the largest recommended by my Dynojet kit, 106, and performed my 2 carburetion tests, lightly different form that described by Dynojet (see Carburetion section at the main menu). The bike pulled strongly until 6.000 rpm., then refused to go above 7.000 rpm even in 4th gear.

So there were 2 ways: a lean or a rich mix.

The easiest following step before to dismantle the carbs again was testing the bike without the air filter and with the air box filter cover removed, in order to obtain a leaner fuel/air mix. If the problem was a lean mixture, it would be exacerbated, and if there was improvement the problem was a rich mixture.

The bike improved a lot, even the problems were manifested again from 5th gear. So I came back again to the main jet basic setting, 102.

How is it possible than when an open can is fitted, you keep the basic main jet? Looking for an explanation, I measured the 2 OE muffler exits, and these offer more exit area that the only Mac can, even if it is unrestricted. Considering that I've finished with the same base settings than with the OE cans, you could install the Mac exhaust with your OE carbs setting without any problem, gaining low down power in your standard CBX. Excellent!.

The sound is outrageous, savage & uncivilized... I love it ! and the bike has gained power through the complete power band. Now, it is not necessary to stay playing with the shift gear to keep the engine on the boil. It can be ridden FAST keeping the momentum in tight roads without needing to go above 7.000 rpm, and doing in one gear in places where it would be necessary 2 gears. You can feel it (and listen to it , wow!). STRONGLY RECOMMENDED

Fine-tuning carburetion

IN-LINE FUEL FILTER

August 2.011 carburetion settings update: after a carburetion problem that made me crazy for 3 weeks, the problem was due to debris in the fuel that went into the carbs until it clogged the float bowl valve steams, leaving those opened and causing flooding when the cubes were full of fuel, I've installed an in-line fuel filter, simply cutting a little piece of the fuel tube and inserting the filter there.

You can´t use paper filters, even hi-flow ones because the vacuum system is not strong enough and you will suffer fuel starvation. Use only metal or plastic ones (like at the pic).

 RECOMMENDED

FUEL TAP VACUUM BYPASS 

My bike was suffering from fuel starvation at 6.000 rpm and higher constant throttle, so I did this mod in order top detect if the vacuum tap was working correctly. In few words, the mod is to convert the vacuum tap into a gravity only tap. I discovered than the bike accelerates harder and fast. In fact, HRC recommended the supression of the vacuum system when a carburetted Honda was raced. You only have to be careful not to leave the fuel tap open when not riding the bike, but if your bike works correctly, there would not be any problem.

The basic procedure is to disassemble the fuel tap, disconnect the small rubber diaphragm (3) from the large rubber diaphragm and aluminum piece(4), disconnect the plastic retainer from the large diaphragm (4), connect the plastic retainer to the small diaphragm (3) and re-assemble it, discarding the spring and large rubber diaphragm (including the little aluminum piece).

You no longer need a vacuum line from the engine to the fuel tap. You will need to remove the vacuum hose and plug the hole on the intake port. Follow the hose to the intake. Remove the hose. Remove the metal part the hose attaches to and plug the hole with an appropriate screw and washer (look at the other intakes for an example of the screw/washer). The vacuum hose cannot be attached to the fuel tap anymore. 

After completing this procedure, the fuel tap should not leak, and if the carburettor floats and float needles are operating correctly, it should not overflow the carburettors if left sitting for a while. Also, initially, monitor the fuel tap to make sure it doesn't develop a leak soon after making this change. Leaks may not appear until after riding for a while. STRONGLY RECOMMENDED.

GIVI RACK 

eBay 2nd hand bought. It is ugly, but useful. It doesn't fit straight on. I've fitted the rack with a Kappa base. You must trim part of the front mounts to fit these to the OE Honda sub frame. There is not enough place in standard form. And don't tighten anything before to settle on the bike, because then it's impossible to fit it. Anyway it is an easy task simply with a hand hacksaw. When done, it is easy to fix, even time consuming. NOT RECOMMENDED

You can see at the pic the new seat upholstered, replicating a rear seat cowl was impossible to find, even if it exists!... or existed. With new foam replacing the shut OE one, you can feel the front end better, because you're sitting higher on the bike and push more weight over the front end. Excellent!.

 DEPOSIT CAP MOD

The theory is simple: allow more air into the vent tank circuit, so that the fuel flow faster to demands on throttle with less resistance from the vacuum created in the tank when lowering the fuel level. In my FJ the gains are notorious due to the electric fuel pump, it takes less effort to pump gasoline in the carburettors, thereby accelerating demands to the promptness of response of the gas obtained is spectacular. (See Carb tuning section at the main menu)
 

The Honda vacuum system makes the result not so incredible, but there is a clear improvement in driveability and gas response.
It is also very easy to do and completely reversible. As seen in the photograph, simply remove the rubber stopper on the inside of the key lock tank cup. Going to pressure, so use a little screwdriver and carefully remove it.

No need to remove the cap, but in my case as I did not know how to manipulate it, I disassembled. Only be careful not to drop the piece inside the deposit ESSENTIAL MOD

RELAY INSTALLATION TO AVOID OVERCHARGING THE BATTERY

When I bought the bike the battery was dry and shot, but with a new battery fitted I noticed that the water consumption was exorbitant, a clear symptom of an overcharging regulator. The previous owner must have thought the same thing as me, because among the various things that gave me the bike was another regulator. Once installed, the problem persisted and observed that both regulators charge readings were the same and correct. The voltmeter at the dash showed a 15 v. reading in all conditions, i.e., fully charged battery and overcharging system.

An easy solution in colder climates is to increase consumption by installing a 80/100 w bulb instead of 55/60 w that it takes, but eventually  in hot climates the higher bulb strength burns the optics inside.

Thanks to teamRC17 ,I learned that is a problem typical of this time with Honda models and later:

What happens is that the regulator feeds about 4 amps to the alternator field coil, depending on the rate at which it wants to charge the battery. The four amps comes from the battery through the ignition switch (if it came directly, the battery would discharge through the regulator when the bike was turned off).

There was a one volt drop through the switch, resulting in the regulator seeing the battery voltage minus one volt. So on a fully charged battery (13.8 volts) the regulator saw only 12.8, and kept charging. So due to this continue overcharging the battery dies prematurely.

A relay connecting the regulator output wire (which goes direct to the battery) to the regulator input, thus bypassing the ignition switch (but controlled by it) fix the problem 100%

Since the installation was done the voltmeter reads 12 to a little less than 14 v. Perfect! ESSENTIAL MOD

DOUBLE HEADLAMP FITMENT (credit to my friend Mingo for his excellent work)

My CBX 750 F2 fit a double or single headlamp due to the different country regulations: single for the Continental Europe versions (Italy, Germany, Swiss...) and double headlamp for UK, Pacific area (Australia, New Zealand...) and Brazil (Sete Galo model), countries where the way of traffic is by the left. The previous possible problem is this fact: like I live in Spain the headlamp could be designed to only this left way, so I would need to be dealing with duct tape or laborious adaptation, that it isn’t worth the effort.

Well, no. I bought a cheap second-hand headlamp in eBay and it doesn't have any determined optic design to direct the light beam. You can adapt the headlights to your country, by way of simply dealing with the adjustment screws, with easy access with a Phillips screwdriver ,only dismounting the windscreen grille. Incidentally  the CBX 750 FE-FG models don't fit. The one-piece double headlight is specific for this model.

You need the specific grille that fit below the headlight too (the same as per VF 1000 R) and cut the two upper fibre OE headlight surround grille mounts to fit the new optics. You could cut the OE surround grille and adapt it to the new headlight.

Like it is a nonsense driving with the two headlights on by day, I've done the electric installation  this way:

- Riding on daylight only the left low beam and the right position light are on. The dashboard lights are off.

- With a switch we can on the right low beam and the dashboard.

- The high beam lights and flash lights are not affected in any case, working the 2 optics together, burning the hair off the driver in front.

To make the installation I recommend the following tips:

- The relays can be fitted below the headlight, by the right side, using a

convenient chassis flange OE fixed at this place. The earth wire can be fixed to a front fairing stay screw.

- The battery wire is positioned along the OE electric installation, and we can fit the fuse box with a 20A fuse directly below the seat, with easy and fast accessibility if requiered, like you see at the pic.

- The wire to the switch, fitted on the fuse cover, go through the dashboard by a little hole, situated just under the fuse cover, in a free space on the left under the cover. The hole needs to be enlarged only a bit, with a dremmel tool to give enough area to pass the wire. To install this wire, we look for the maroon/white wire on the OE connector (see the pic). We cut it and we take the wire to the switch.

I've installed to connectors to the cover mounted switch in order to simply disconnect the switch if I need dismount the fuse cover, and leave the wire long enough in order to only move it without disconnect the switch (to change a fuse, i.e.)

You can see the work done and the switch fitted just at the top of this page, at the speedo section pic.

130/80/18 vs 140/70/18

Since I bought the bike I've used the excellent Bridgestone BT45s. The only drawback is that with the abrasive Tenerife road tarmac, these tyres only last around 6.000 km... 6.000 km of fun, really!, because these tyres are fantastic, you don't miss any radial tyres. In fact, BT45s are much better than the Pilot roads fitted in my FJ 1200. When I changed from the Honda to the Yamaha the tyres don't give me any confidence compared with the Bridgestone and only encourages me to go slower.

There were no OE fitment available, so I've been using 140/70/18 rears... until now. What a difference!. The bike feels more stable , more planted, more aggressive and more flickable everything at the same time. Don't fit oversize rear!

COILS RELAY INSTALLATION TO IMPROVE THE IGNITION, GETTING A HOTTER SPARK AT THE PLUGS

If you ensure there is the proper voltage source at the stock coils, you cannot generate any more spark voltage, as long as the coils test within the specifications of the service manual. So fitting aftermarket coils is a nonsense as there no improvement at all, but anyway you CAN improve your ignition system: using a relay to feed system voltage to the coils directly (using a fatter wire), avoiding voltage drops elsewhere in the system.

The power to the coils runs thru the main (key) switch, and a bunch of connectors. Each connection/switch will have some resistance and an associated voltage drop across this resistance. These voltage drops add up and, in consequence, the device being fed this power gets less than battery voltage..... The relays eliminate the resistive connections and each device fed thusly will get nearly-full battery voltage. 

Using a tester I checked that the coils were feed by 11,92 v. (not too bad for a 26 years old wiring loom!) With a relay I've gained 1,45 v. More voltage in means more voltage out from the coils: better and hotter sparks.

I inserted the relay into the frame bridge where the CDI sits, and the fuse at the back of the relay to have good access. (Watch the pic)

The fatter wire from the battery goes to the front of the bike and under the fuel tank, where the coils live. I've done all connexions with travelling in mind: like every year I ride a lot of kilometres for Europe, in case of a relay breakdown I simply disconnect the relay wires on the OE connexions and re-connect the OE clamps.

The bike starts without choke and keeps the idle even cold, feels more sweet and more powerful, with a clear gain between 2-6.000 rpm., and vibrates less when trashed until to the redline.. even sounds better!. RECOMMENDED

The connexions are as follow

To battery:from relay nº 30 connection to the positive

To earth: from relay nº 85 connection to a chassis point

Red fatter wire from relay nº 87 connection to the coils

Coils connexions

Righ coil: - Upper connection: black & white wire connected to activate the relay, nº 86, as on the picture at the right.

                - Lower connection: to the relay connection nº 87, as on the picture at the right.

Left coil: - Upper connection: blanked. The black & white wire that was connected is insulated.

                - Lower connection: to the relay connection nº 87.

USEFUL CBX 750 DERESTRICTION INFO (Swiss and Pacific Area models)

CBR 600 F2 FRONT RIM INSTALLATION (credits to David von Olsen, proud and helpful teamRC17 member)